1. RESULTS FROM PRIOR RESEARCH SUPPORTED BY PACS (2001-2004)
The objectives of our previous PACS project were to determine how continental monsoons
affect the mean climate and seasonal cycle of the eastern Pacific and physical processes that link
US warm season rainfall anomalies and the western Pacific anomalies. A number of published
papers summarized our results, which are listed below. For the reviewers’ convenience, we also
describe briefly those results which have not yet been published, but are most relevant to the
proposed study (See section 4. Appendix).
Published
Fu, X., and B. Wang, 2001: A Coupled Modeling Study of the Seasonal Cycle of the Pacific
Cold Tongue, Part I: Simulation and Sensitivity Experiments. J. Climate, 14, 756-779.
Wang, B. and X. Fu, 2001: Processes determining the rapid reestablishment of the equatorial
Pacific cold tongue/ITCZ complex. J. Climate, 14, 2250-2265.
Fu, X., B. Wang, and T. Li, 2002: Impacts of Air–Sea Coupling on the Simulation of Mean
Asian Summer Monsoon in the ECHAM4 Model. Mon. Wea. Rev., 130, 2889-2904.
Fu, X., and B. Wang, 2003: Influences of Continental Monsoons and Air–Sea Coupling on
the Climate of the Equatorial Pacific. J. of Climate, 16, 3132-3152.
Wang, Y., O. Sen, and B. Wang, 2003: A highly resolved regional climate model (IPRC
RegCM) and its simulation of the 1998 severe precipitation event over China: Part I: Model
description and verification of simulation. J. Climate, 16, 1721-1738.
Wang, B, 2003: Kelvin Waves, Encyclopedia of Meteorology. ED. J. Holton. Academic
Press. pp. 1062-1067.
Wang, Y., S. Xie, H. Xu, and B. Wang, 2003: Regional Model Simulation of Marine Boundary
Layer Clouds over the Southeast Pacific off South America. Part I: Control Experiment. Mon. Wea.
Rev., 132, 274-296.
Fu, X., and B. Wang, 2004: Differences of boreal summer intraseasonal oscillations simulated in
an atmosphere-ocean coupled model and an atmosphere-only model. J. Climate, 17, 1263-1271.
Fu, X., and B. Wang: The boreal summer intraseasonal oscillation simulated in a hybrid coupled
atmosphere-ocean model. Mon. Wea. Rev., In press. (Appendix)
Sen, O., Y. Wang, and B. Wang, 2003: Impacts of Indochina deforestation on the east-Asian
summer monsoon. J. Climate, In Press.
Submitted / to be submitted
Wang, B., X. Fu, Q. Ding, I.-S. Kang, K. Jin, J. Shukla, and F. Doblas-Reyes, 2004: A
fundamental challenge in climate prediction monsoon rainfall: Inadequecy of tier-2 strategy.
BAMS, Submitted. (Appendix)
Wang, Y., S. Xie, B. Wang, and H. Xu: Large-scale atmospheric forcing by southeast Pacific
boundary layer clouds: A regional model study. Submitted to J. Climate.
Sen, O., B. Wang, and Y. Wang: Impacts of re-greening the desertified lands in northwest
China: Implications from a regional climate model experiment. Accepted, J. Climate. (Appendix)
Wang, Z., and B. Wang: Rossby wave propagation through a southerly duct: A mechanism of
teleconnection between deep tropics and midlatitude. To be submitted. (Appendix)
Wang, Z., B. Wang, and C.-P. Chang: Great Plain summer rainfall variability:
teleconnection and its maintenance. To be submitted.
1
2. STATEMENT OF WORK
2.1 Introduction
The Climate in the Western Mountain Area The climate of the US Western Mountain
Area (WMA) (102oW-124oW) is considerably varied regionally due to large-scale land–ocean
configuration, tropical-extratropical interaction, and influences of complex terrain. As shown in
Fig. 1, the annual rainfall varies from less than 100 mm to above 2000 mm.
There are four types of precipitation regimes within the WMA. Much of the southeast WMA
is located within the domain of the Southwest monsoon where the rainy season peaks in July and
August. (Type I in Fig.1a). The northern tier of the WMA (north of 44oN) and the adjacent Great
Plains compose a moderate continental summer monsoon regime with a dry winter and peak
rainfall in May and June (Type II in Fig. 1a). The seasonal shift of upper- and low-level pressure
and wind patterns in early summer marks the end of a relatively wet regime there and heralds the
onset of the Southwest monsoon. However, the upper-level disturbances, meso-scale convective
systems, localized mountain valley circulations, and nocturnal low-level jet-related precipitation
ensures that these regions remain relatively wet compared with the drier winter months (Tang and
Reiter 1984).
In contrast to the Type I and II regimes, the regional climate west of 115oW is dominated by
the eastern Pacific subtropical high and exhibits a Mediterranean winter precipitation regime
(Type III in Fig. 1a). The summer rainfall in this region is less than 10% of the annual total (Fig. 6,
Higgins et al. 1997). The driest summer season in the US is located in western California and
Nevada (Type IV in Fig. 1a). The Type IV regime is an arid or semi-arid region where light rainfall
is more or less evenly distributed throughout the year due to synoptic influences from the west,
south and north.
II
III
IV
I
Figure 1. (a) Seasonal variation of precipitation (mm day-1) and (b) annual mean rainfall (contours, mm year-1)
overlapped with topography (shadings, meters).
The WMA climate has a prominent significance to the US climate variability. The Southwest
monsoon is the most pronounced summer monsoon in the US. Its rainfall is characterized by the
2
largest mean seasonal percent departure from normal within the North American Monsoon (NAM)
system (Higgins et al. 1999). A pronounced internal mode of variability of the US warm season
rainfall exhibits an out-of-phase relationship between the Arizona and New Mexico (AZNM) and
the northern tier-Great Plains and an in-phase relationship between the AZNM and the US east
coast. This mode occurs in the seasonal march from monsoon onset to decay phases (Higgins et al.
1997), and also in the interannual variations (Higgins et al. 1998) and intraseasonal variations (Mo
2000). The time-dependent anomalous westerly flow over the Rocky Mountains causes variability
in the strength of the southerly low-level jet (LLJ) and may cause flood and drought conditions in
the Midwest (Mo et al. 1995). In summary, the Southern WMA not only has the strongest monsoon
variability but also acts as an action center or indicator for the large-scale NAM system.
The climate variability over the WMA is controlled by changes in large-scale circulation
systems. Prediction of the climate variability and water cycle requires knowledge of the nature of
interactions among these circulation systems, the underlying ocean and land surface, and forcing
from remote regions (Fig.2).
During summer, the major circulation system that affects WMA in the mid- and upper
troposphere is the monsoon anticyclone over the western US/northwest Mexico, the westerlies to
its north, and the easterlies to its south (Fig.1 of Higgins et al. 1998). The region of upper level
divergence and mid-tropospheric ascent is located in the vicinity of and to the south of the
monsoon anticyclone while regions of upper-level convergence and surface subsidence are noted
to the east and north of the anticyclone. In the lower troposphere, the WMA is positioned between
the Bermuda High and the North Pacific Subtropical High. At low-levels the bulk of water vapor is
advected from the Gulf of California and the eastern tropical Pacific Ocean and from the Gulf of
Mexico, respectively, with the continental divide acting as a boundary between the two moisture
channels (Rasmusson 1967). The Great Plains LLJ is a component of the large-scale circulation
associated with the topographic effect of the WMA (Byerle and Paegle 2003). The WMA is also
affected by the variability in the Intertropical Convergence Zone (ITCZ) in the eastern North
Pacific. Strong surge events are characterized by persistent boundary layer southerly flow
extending along the entire Gulf of California and into Arizona, California, and as far north as
southern Nevada (Anderson et al. 2000a). Surge events are associated with the relative
configuration of the synoptic-scale upper-level midlatitude trough, tropical cyclones, and tropical
easterly waves, and are constrained by topographic effects.
Advances in study of the climate variability of the North American Climate Recent
empirical and modeling studies have revealed a number of physical processes involved in the
interannual variations of the North American climate. These processes are summarized in the
schematic diagram shown in Fig. 2 and are discussed below.
The forcing from sea surface temperature (SST) anomalies, especially the El Nino/La Nina, is
one of the major sources of WMA climate variability. El Nino-Southern Oscillation (ENSO) exerts
its greatest impacts on the winter and spring precipitation over the WMA through Pacific-North
American teleconnection (Wallace and Gutzler 1980, Ropelewski and Halpern 1986). The leading
principal mode of the interannual variability of the summer NAM system is also associated with
ENSO (Yu and Wallace 2000, Higgins and Shi 2001). ENSO alters the strength and position of the
ITCZ and its associated tropical storm activity as well as the northward transport of moisture. La
Nina conditions favor the ITCZ shifting northward, resulting in a wet monsoon in south and
central Mexico (Higgins et al. 1999, Hu 2002). The opposite is true for an El Nino condition. The
SST anomalies over the North Pacific could be another source of variability in WMA and Great
Plains (Ting and Wang 1997, Gastro et al. 2001). Castro et al. (2001) noted the impacts of North
3
Pacific SSTs on the Southwest monsoon through the Pacific transition pattern or NP pattern.
However, such teleconnection patterns decay in the later part of the monsoon due to weakening of
the NP jet and strengthening of the monsoon ridge over North America. These NP SST signals can
be traced back to the preceding winter.
(Atmospheric Internal Dynamics)
MJO (ISO)
Atmos.
Tele.
Weather: TC, EW, BCW, surges…
Variability &
Predictability
of Climate &
Water Cycle
in WMA
N.A. Climate Circulation
System: MNS AC, WJ,
ITCZ, LLJ…
IDV
NP-NA
Snow, Veget., Topog.,
Soil moisture, Ts …
EEP, NP, GOC,…
SST
Land Surface
(Lower Boundary Conditions)
Figure 2. Physical processes controlling the variability and predictability of climate and water cycle in the US
Western Mountain Area.
Anomalous land surface conditions and atmosphere-land feedbacks also provide memory for
climate variation. Namias (1991) suggested that the initial conditions of the atmosphere and land
surface in early spring, as well as their positive feedbacks, are the prominent reasons for the
summer season rainfall variability in the US. Better forecast skill for monthly simulation was
found to reside in the initial moisture conditions and representation of soil moisture and strong
feedbacks between the land surface hydrology and precipitation (Mo et al. 1991, Beljaars et al.
1996, Fennessy and Shukla 1999, Viterbo and Betts 1999, Xue et al. 2001). Land surface
conditions influence not only the local radiation balance and total surface heat flux and thus the
local precipitation, but also influence downstream regions by changing large-scale circulation
(Gutzler and Preston 1997, Small 2001, Sen et al. 2004). Hu (2002) noticed that the correlation
between summer rainfall variation in the southwest US and the antecedent winter precipitation
anomalies in the western US varied considerably over the past 100 years. How the interdecadal
variations in the North Pacific-North American sector modulate the atmosphere-land interaction in
the WMA has not been understood.
The snow cover in the WMA has been recognized as a potential forcing to the Southwest
monsoon rainfall. An inverse snow-precipitation relationship was noted (e.g., Gutzler 2000). Ellis
and Hawkins (2001) identified an inverse relationship between July-August snow cover across
western North America and August precipitation across a portion of the southwestern US. During
4
a summer following low winter snow cover across western North America, the monsoon ridge
across the southern US was intensified, which is conducive to northward advection of low-level
moisture toward the southwest US. Matsui et al. (2003) found that, during the monsoon season,
there is a strong negative correlation between monsoon rainfall and the local surface temperature
(and the surface temperature in the southern Rocky Mountains). The substantial temperature
variability in the southern Rockys might modulate the land-ocean temperature gradient.
Intraseasonal oscillation (ISO) has a significant contribution to the variability of monthly
mean climate (Higgins and Shi 2001). Mo (2000) identified a 22-day mode that modulated wet and
dry periods of AZNM monsoon and the rainfall in the Great Plains. The rainfall anomalies
propagate eastward from the North Pacific through AZNM and the Great Plains to the eastern US.
During the wet phases of the AZNM monsoon, moisture transport intensifies from both the Gulf of
Mexico and the Gulf of California to the Southwest monsoon region. She also found a linkage
between western Pacific convection and AZNM monsoon. Higgins and Shi (2001) found that the
leading PC of the intraseasonal variation of NAM is strongly related to the eastward progression of
the Madden-Julian Oscillation (MJO) and the points of origin of tropical cyclones in the Pacific
and Atlantic basins. This MJO-related impact on NAM is linked to a regional meridional
adjustment in the eastern North Pacific. Of note is that surges of low-level moisture from the Gulf
of California are a significant part of the intraseasonal monsoon variability (Adams and Comrie
1997). Cavazos et al. (2002) also identified teleconnection patterns associated with the ISO. In
July-August a zonal three-cell anomalous mid-tropospheric height pattern over the North
Pacific-North American sector was recognized to be associated with the wettest AZ monsoon.
Another mode was found in August and September, which exhibited a meridional three-cell
pattern along the west cost of North America.
2.2 Major science issues
Roles of SST anomalies The impact of ENSO on subtropical and extratropical climate is
controversial. For instance, Namias (1991) found that the composite 700 hPa geopotential height
pattern during La Nina events showed little perturbation over North America. On the other hand,
Trenberth and his collaborators suggested that the severe 1988 North American drought was
largely caused by the SST anomalies in the tropical Pacific in association with the 1988 La Nina
(Trenberth et al. 1988, Trenberth and Branstator 1992, Trenberth and Guillemot 1996). Bell and
Janowiak (1995) found a strong relationship between the SST anomalies during 1992/93 El Nino
and the extratropical circulations that contributed to the 1993 floods in Midwest.
The role of local SST anomalies in the Gulf of California has been controversial. Mitchell et
al. (2002) found a close association between the Gulf SST variability and the onset and total
rainfall of the Southwest monsoon, especially over Arizona. On the other hand, observational
study indicates, and a regional model study confirms, that the impact of SST anomalies in the Gulf
of California are only significant locally over the Sierra Madre Occidental and are small relative to
the Southwest monsoon (Mo and Huang 2003). The large-scale flow has more influence than do
Gulf of California SSTs.
Roles and processes of atmosphere-land interaction Issues remain regarding whether
spring snow in the WMA has an impact on the Southwest summer monsoon. Lo and Clark (2002)
confirmed that spring snow water equivalent and July-August precipitation have an inverse
relationship for the period of 1948-97, although this relationship was unstable over time. On the
other hand, Matsui et al. (2003) found that the weak negative correlation between April snow
water equivalent and May-June surface temperature in the southern Rocky Mountains wanes after
5
the monsoon onset, thus spring snow does not have a direct influence on the July-August
Southwest monsoon rainfall.
Soil moisture-rainfall feedback is perhaps another issue of debate. Small (2001), using a
regional climate model, found that wet soil in the NAM region enhanced July precipitation within
that area, implying that a positive soil moisture-rainfall feedback exists. Findell and Eltarhir
(2003), using a one-dimensional boundary layer model, found that positive moisture-rainfall
feedback is likely in much of the eastern US; but over the western US the land surface conditions
are unlikely to impact the triggering of convection. The only area showing a negative feedback is
in the arid Southwest monsoon region.
Discrepancies exist regarding local water recycling rate. Berbery and Fox-Rabinovitz (2003)
concluded, by using a stretched-grid AGCM, that surges associated with strong Gulf of California
low-level jets account for 80-100% of simulated precipitation over AZ, western NM, and southern
Utah. The results of Bosilovich et al. (2003) suggest that within the core of the Mexican monsoon,
continental soil moisture provides much of the water vapor for precipitation whereas in regions
away from the Mexican monsoon (e.g., eastern Mexico and Texas), continental soil moisture
generally decreases after monsoon onset..
Predictability and modeling issues AGCM simulations of the Southwest monsoon show
that the spring and winter Pacific anomalies have a significant influence on precipitation,
especially in extreme years (Yang et al. 2003). However, recent predictability experiments using
the coupled UCLA GCM show that the atmospheric internal variability has the same magnitude as
the observed interannual variability in the Southwest monsoon region, implying that seasonal
forecasts are pessimistic (Farrara and Yu 2003). Using a set of coupled ocean-atmosphere models
and the superensemble method, Krishnamurti et al. (2002) have shown some useful skill of
seasonal forecasts of the Asian and North American monsoons over their respective climatologies.
The results are encouraging compared to the AMIP type of hindcasts.
Assessment of predictability skill in regional climate modes has been rare, however Kim and
Lee (2003) have recently made an effort to evaluate their model’s skill in hindcasting the water
cycle and climate variability in the NAM. On the regional modeling front, a number of studies
have shown that the climate simulation of the Southwest monsoon variability and water cycle can
differ substantially among runs with different cumulus parameterization schemes. However, no
consensus has yet been reached regarding which parameterization scheme is best (Gochis et al.
2002, 2003, Xu and Small 2002). Differences in simulated rainfall resulting from the use of
different combinations of schemes are much greater than the noise due to the atmospheric internal
dynamics (Xu and Small 2002), suggesting that the model’s uncertainties in physical
parameterization schemes may be a major roadblock for regional climate modeling.
2.3 Objectives and relevance to CPPA
The overall objective of this proposed project is to understand the origins of the intraseasonal
to interannual variability and predictability of the climate and atmospheric portion of the
hydrological cycle in the US WMA. Specifically, efforts will be made to determine major remote
and local processes causing principal interannual variability, to assess climate predictability in the
current NCEP model ensemble hindcast and to investigate methods for enhancing the climate
predictability using coupled atmosphere-ocean and regional climate models.
The three themes of the proposed study directly address one of the 2005 program priorities of
CPPA, i.e., the US western mountain climate. The proposed predictability and modeling studies
will use North American Monsoon Experiment (NAME) field observations, thus they will also
6
contribute to NAME objectives. This proposed work relies on numerical tools already established
as a part of our previous PACS project.
Regarding the origin of the climate variability/predictability in the US WMA, our general
hypothesis is that the climate variability and predictability in the US WMA are controlled both by
forcings from remote regions through atmospheric teleconnections and by local
atmosphere-ocean-land interactions. The relative importance of remote forcings and local
interactions depends on season and geographic location. It is our task to investigate the relative
contributions of the remote and local forcings in the different regional precipitation regimes of the
US WMA and during different phases of the seasonal cycle.
2.4 First thrust: Remote forcing and processes affecting principal modes of variability
As mentioned in 2.2, the impact of ENSO on extratropical summer climate remains an
un-resolved issue, albeit its impact on the tropical monsoon in the southwest Mexico is relatively
well understood. Controversies may arise from the nonlinear nature of the response of the
extratropical atmosphere to the anomalous tropical Pacific SST anomalies. This assertion is
motivated by the observations of Higgins et al. (1999). They found a weak association between La
Nina and a dry monsoon over AZNM; on the other hand, they also found a weak linkage between
El Nino and a dry monsoon over northwest Mexico. Their results suggest that dry Southwest
monsoons occurred in both El Nino and La Nina conditions, or that the Southwest monsoon
responds to opposite tropical forcing in a nonlinear fashion. This nonlinear response to ENSO
might explain why there exist controversial views regarding the impacts of ENSO on the
midlatitude WMA. Our diagnostic analysis and numerical experiments will focus on the roles of
the remote forcing from the tropical and extratropical Pacific SST anomalies as well as from the
inner seas of the Gulf of California and Gulf of Mexico.
Task Ia Diagnostic studies
To formulate a more concrete hypothesis, we begin with data analysis, which will consist of
two components as elaborated under the following two subtitles.
a. Dominant modes of intraseasonal and interannual variability in the WMA
A number of analyses of the major modes of variability in various domains of the North
American sector have provided very useful information on defining indices used for climate
variability (Higgins et al. 1997, 1999, Comrie and Glenn 1998, Gutzler 2000, Yu and Wallace
2000). Our analysis is geographically focused on the WMA defined as the region between 102oW
and 124oW of the US (Fig.1). In view of the complex precipitation regimes in the WMA (Fig. 1),
we anticipate that the interannual variability is strongly season-dependent. Previous studies have
focused on summer or winter separately; the linkage between different regimes of seasonal
anomalies has not been examined. However, the seasonal evolution of the interannual anomalies is
important for understanding the causes of the variability. Thus, our analysis will emphasize this
specific aspect. A new method called Season-Sequential EOF analysis will be employed for both
precipitation and circulation anomalies. In this approach, the evolving seasonal interannual
anomalies will be revealed. Emphasis is placed on the evolving patterns of the interannual
anomalies from one season to the next. We will attempt to divide the early (May 15-July 3) and
late (July 5 to September 30) seasons, following Gutzler (2004) who has shown fundamental
differences between these two sub-seasons, in particular in terms of the role of land surface
feedback.
7
Most previous principal mode analysis has been focused on the precipitation field. We will
pay specific attention to the mid-upper level monsoon anticyclone because it is a key element of
the WMA circulation system. There is evidence that the mid-upper level monsoon anticyclone
plays a central role in the climate variability in WMA as well as in NAM. The wet (dry) monsoons
are associated with a stronger (weaker) monsoon anticyclone. The variations of the out-of-phase
pattern between AZNM monsoon and rainfall over the Great Plains are related to the location and
strength of the monsoon anticyclonic ridge. The elevated sensible heating over the WMA
represents an important heat source for driving the subtropical monsoon anticyclone over the
western US. A detailed analysis of the intraseasonal and interannual behaviour of the monsoon
anticyclone will be conducted to test these ideas. Analysis of the thermal and dynamic structures of
the anomalous circulation system is our emphasis. This analysis will provide a basis for
understanding the origin of these circulation anomalies and their connections to the adjacent and
remote circulation anomalies.
For intraseasonal variability we will assess the significance, coherent dynamical structures,
and seasonal behaviours of the 20-25 day and 30-60 day modes. This information is important for
understanding the dynamics behind the intraseasonal variability. The analysis is aimed at forming
a new hypothesis concerning the mechanism of the 20-25 day midlatitude oscillation mode.
b. Sources of remote forcing and teleconnection
Upon deriving the principle modes of variability for the WMA, we will search for sources of
the remote forcing (especially SST anomalies) and the associated teleconnection patterns linking
the intraseasonal and interannual variations of the major modes. This search will be based on the
characteristic variables found in the analysis of the principal modes of WMA variability. The
so-called Green’s function approach will be employed to search for optimal forcing in the
framework of barotropic dynamics (Branstator 1985). Diagnostic study of the wave activity fluxes,
waveguide effects, barotropic instability, and ray tracing analysis will be performed to explain the
mechanisms responsible for the teleconnections.
In our recent study, we found a circumglobal summertime teleconnection pattern on the
interannual time scale. In association with this wavetrain, regions of significant rainfall anomalies
emerged in Europe, India, East Asia, and North America. The linkage between the WMA and this
circumglobal teleconnection will be a target for our analysis.
This analysis will be extended to the intraseasonal time scale as well. Particular attention will
be paid to searching for significant lead- or lag- correlation and predictors for the WMA rainfall.
We will compare the teleconnection dynamics on the intraseasonal and interannual time scales to
gain deeper understanding of the mechanisms. We will also investigate possible influences of the
interannual variability in the ISO on the seasonal mean climate variability. Identification of
precursors preceding an anomalous NAM would improve seasonal forecast skill.
Task Ib Numerical studies
a. Remote forcing from tropical Pacific SST anomalies
The underlying hypothesis is that teleconnection and atmospheric intrinsic modes may play a
key role in the WMA response to tropical Pacific SST anomalies. Eastern equatorial Pacific SST
anomalies, for example, can displace the ITCZ meridionally and induce an anomalous Hadley
circulation (Higgins et al. 1998). The associated heating anomalies could excite a downstream
Rossby wave train, whose nature depends on the flow regime in the North American sector. The
8
wave train may induce anomalies in the monsoon anticyclone (Castro et al. 2001), thus shifting the
subtropical jet stream and affecting the Southwest monsoon and the cyclonic disturbances that
usually contribute to the major summer rainfall over northern tier and the midlatitude US.
The ECHAM and WRF models (a description of the models to be used is provided in section
2.7) will be used to examine the role of tropical and extratropical Pacific SST on interannual
variability and intraseasonal variability. Three suits of ensemble experiments are planned. The
“Climate run” will use climatological mean SST to drive ECHAM and generate boundary
conditions for the WRF model simulation of the WMA and NAM domain. WRF simulation will be
focused on the WMA. In the “El Nino runs” SSTA will be derived from composite El Nino events,
whereas in “La Nina runs” composite La Nina SSTA will be used. Ensemble means for each group
will be diagnosed to examine the impacts of ENSO on the interannual variability of the WMA
climate and the intensity, frequency, propagation and spatial structure of ISO. The model outputs
will also be used to study the predictability arising from the ENSO forcing in this set of models.
Similar experiments will be done for NP SST anomalies.
b. Effect of midlatitude stationary wave
In order to investigate the possible influences of midlatitude stationary waves, which are
independent of ENSO, on the intraseasonal and interannual variability of WMA, the key is to
remove the large-scale quasi-stationary wave anomalies in the lateral boundary conditions that
drive the regional model. This type of experiment was done previously by Pan et al. (1999) in
studying observed abnormalities of the North-Central US climate. With the use of an observed
large-scale driving field of an extreme WMA hydrological year as a representative event, a suite of
nested regional model experiments will be performed to identify the differences between the
control run and “filtered boundary” runs where the stationary wave component is removed in the
initial state and in the large-scale dynamic and thermodynamic boundary conditions. This method
will provide an effective tool to study the mechanism of midlatitude stationary waves on the
occurrence of climate anomalies over the WMA.
Thereafter, based on the Green function and preferred-mode detection analyses (Task Ia),
anomalous diabatic heating can be specified over sensitive regions in ECHAM to simulate a
realistic teleconnection pattern which will provide idealized lateral boundary conditions for WRF
with pure teleconnection information included. The first set of experiments forced by the observed
climatological SSTs aims to obtain the model’s mean state. The other set of ensemble experiments
is specified with the same climatological SSTs and an additional anomalous heat source. Output
from each group of GCM experiments will be used as inputs for the regional model, whose domain
will be centered on the WMA. The results of these two sets of simulations will be examined to
verify the possible teleconnection between WMA atmospheric variability and remote forcing.
2.5 Second thrust: Roles and processes of atmosphere-land interaction
The feedback associated with soil moisture and temperature directly affects the predictability
of precipitation regimes. Regional climate models have been widely used to study the hydrological
cycle in North America. These studies have investigated the water sources, moisture transport
pathways, water and energy balance, Gulf surge dynamics, atmosphere-land interaction, and
regional climate hindcast (Stensrud et al. 1995, 1997, Anderson et al. 2000a, b, Berbery 2001,
Fawcett et al. 2002, Bosilovich et al. 2003, Kim and Lee 2003). To assess the impacts of different
processes and to understand causal relationships among interacting variables, here we will rely on
numerical experiments using the WRF model.
9
Task IIa Roles of local forcing vs. transient disturbance through lateral boundaries
Summer continental air masses are typically conditionally unstable. It is conceivable that the
moist convection in the WMA is strongly modulated by atmospheric transient variability. These
transient disturbances may rely less on local instability but heavily on propagation of disturbances
into the domain from outside of the WMA. The local land surface–atmosphere interaction can
have a significant contribution, but the soil moisture-boundary layer interaction is also to a large
extent controlled by atmospheric disturbances. This hypothesis is in line with the finding of Findell
and Eltahir (2003) that over the western US, atmospheric conditions and the likelihood of moist
convection are largely determined by oceanic influences. This hypothesis may be more applicable
to the regions influenced by moisture transport and in the early seasons of the year when soil
moisture is low in the southwest US.
We will assess the relative importance of the local instability/land surface feedback and the
disturbances from outside of the WMA to the regional variability in precipitation, evaporation, and
moisture transport. This includes the onset and the intensity of the summer monsoon. Because the
transient activity may have large year-to-year variability, we will choose both extremely wet and
dry years in the WMA. Ensemble simulations with the WRF model will be used to perform control
and sensitivity experiments to address this issue. For instance, the use of “filtered” boundary
conditions versus real boundary conditions may help to determine the influence of the transient
eddies through lateral boundaries. In the first group of experiments, both seasonal variations (first
4 harmonics of the annual cycle or month-to-month variations) and transient eddies are included in
the lateral boundary conditions to simulate the monsoon onset. In another group pf simulations,
transient eddies will be excluded and only seasonal variations will be considered for the lateral
boundary conditions. Comparison of the two experiments will give us some ideas about the
relative roles of the transient (including ISO) and local instability/land feedback processes. It is
also planned to identify the impacts on precipitation of the ISO component passing through the
lateral boundaries.
Task IIb. Effects of snow pack and moisture on summer precipitation
The spring snow mass in the western US mountain area can affect the summer precipitation in
the WMA through changing the land surface energy balance and soil moisture content. However,
the relationship might be variable and there is a need to understand how other factors modulate
monsoon rainfall. A group of 5-10 member ensemble runs will be performed for the same given
boundary conditions (normal-year type) and different initial conditions. In the control run, the
initial snow mass will be specified as that is observed at the end of March or as the product of a
land surface model (which should be same as that used in the WRF) driven by the winter observed
snow field. The integrations will start from the beginning of April. In the sensitivity experiments
the initial amount of the specified snow mass will be reduced and enhanced. Results from the two
suites of experiments will be compared. A diagnosis of the evolution of the surface energy balance,
surface temperature, soil moisture, atmospheric convective instability, and surface fluxes between
the different simulations is expected to help pinpoint the causes of the differences.
The simultaneous relationship between snow depth over the western North America and the
summer monsoon over the WMA can also be tested using a WRF simulation embedded within
ECHAM. Two 122-day ECHAM-WRF experiments will be conducted for the boreal summer
(June to September) with climatological SST, using the same initial conditions except with 1x and
2x snow depth. Using the ECHAM output as a boundary condition for the WRF, the WRF model
will be run at two resolutions: a 4-deg resolution to compare with the ECHAM 4-deg resolution as
10
a baseline, and a higher resolution (30 km) to see the advantage of dynamic downscaling to higher
resolution. This experimental configuration makes it possible to examine the remote effect of
anomalous snow depth on the summertime WMA monsoon circulation, focusing specifically on
the strength and position of the mid-upper level monsoon anticyclone, the monsoon anticyclonic
ridge, and the associated low-level northward moisture transport.
Higgins et al. (1999) noticed that wet monsoons in AZNM tend to follow winters
characterized by dry conditions in the Southwest US and vice versa. This appears to suggest that
before the monsoon onset the land moisture feedback to rainfall is negative; large-scale forcing is
more important to force a wet monsoon. However, a positive feedback from moist land may occur
after the onset. We plan to specify land conditions in the model to examine the rainfall anomalies
over AZNM and other mountain areas. Specific interest centers on examining the spatial and
temporal dependence of the rainfall-soil moisture feedback processes and the changes in the
recycling rate during the course of the summer monsoon.
2.6 Third thrust: Assessment and enhancement of the climate predictability
The prospect of forecasting one season in advance remains extremely challenging and
demands urgent advancement in climate modeling studies. Present AGCMs have the capability to
simulate with certain degrees of accuracy the seasonal mean states of the atmosphere and the
anomalies associated with large-scale SST variations such as El Nino (Shukla et al. 2000). The
model’s predictability, however, is limited by the intrinsic climate noise arising from atmospheric
internal dynamics and the model’s uncertainties in physical parameterizations. The primary
purposes of the proposed study here are concerned with the following questions: What are the
predictable and unpredictable components of the climate variability in the WMA? What is the
potential predictability of the NCEP model? What are the spatial-temporal structures of the model
systematic errors? Is it possible to enhance the model’s predictability? These are critical issues for
producing skillful climate predictions.
Task IIIa Assessment of the interannual predictability
In sharp contrast to the high predictive skills of the current AGCMs for the El Niño region
(10oS-5oN, 160oE-80oW), we have noted that in the Asian-Pacific summer monsoon region the
skills measured by the correlation coefficients between the observed and hindcast rainfall
anomalies were nearly zero (Wang et al. 2004). The performance of state-of-the-art GCMs, in
particular the NCEP climate prediction model, on the hindcast of extratropical WMA climate
anomalies needs to be carefully assessed.
We will assess the NCEP operational climate model’s potential predictability in precipitation,
surface temperature, 500hPa geopotential height, and 850hPa circulation by analyzing its hindcast
data. The details of the data can be found from http://www-pcmdi.llnl.gov/smip. This SMIP II web
page describes its underlying design for a two-season prediction for the 21-year period of 1979-99.
Five participating models (including NCEP model) carried out 10 ensemble integrations for a
duration of 7 months. The observed SSTs were prescribed for the integration. Therefore, the SMIP
II estimated the upper bound of seasonal predictability. We will determine predictability by
computing the signal-to-noise ratio of the seasonal prediction using variance analysis (Rowell
1998) and the anomaly corrections between the ensemble-mean predictions and the observations.
The model bias in representing the predictable component often appears in a systematic way
in both the climatological mean and the anomaly component. The mean bias of the NCEP model
can be corrected by subtracting the model prediction climatology. A major part of the anomaly
11
systematic error will be corrected by a statistical relationship between the prediction and observed
anomalies obtained by using the so-called coupled pattern technique (Graham et al 1994). Most
common methods developed so far are based on singular value decomposition (SVD) analysis and
canonical correlation analysis of the observation and model output (Barnstorn and Smith, 1996;
Ward and Navarra, 1997). We plan to use SVD-based coupled pattern projection method to correct
anomaly bias and re-inflate the variability afterwards (Feddersen et al. 1999). The spatial
distribution of the correlation coefficient between the corrected seasonal prediction and
corresponding observations will then be computed based on the double cross validation procedure
(Kaas et al., 1996). Similar assessment of multi-model ensemble prediction will also be carried out
to determine how much improvement can be made in reducing the uncertainties in individual
model parameterization schemes.
Task III b Enhancement of the climate predictability
The ISO is a dominant mode of tropical climate variability. The mechanism behind the
extratropical 22-day ISO mode in NAM is unexplained. The ISO is primarily determined by
atmospheric internal dynamics but may be regulated by atmosphere-ocean and atmosphere-land
interactions. It is not clear whether the ISO can be regarded as a climate noise like other synoptic
disturbances or as a contributor to predictability.
The numerical experiments of Ferranti et al. (1990) have demonstrated that the intraseasonal
oscillation of extratropical 500-hPa heights can be better simulated if the tropical atmosphere is
relaxed to the ECMWF analysis. If we can forecast correctly the tropical ISO and its extratropical
connections with a lead-time of one month, it would be possible to extend the current
medium-range forecast (Higgins and Shi 2001). However, this potential predictability is shortened
by the inability of current AGCMs to correctly represent the intensity and propagation of the ISO
(Chen and Alpert 1990, Lau and Chang 1992, Hendon et al. 2000). Waliser et al. (2003) found that
the predictability of the convective precipitation associated with ISO reaches a level of ~15 days.
The better the representation of ISO precipitation in a model, the longer the model can predict the
ISO.
Our recent studies showed that air-sea coupling significantly improved the simulation of the
ISO in both boreal winter and summer compared to a stand-alone atmospheric model (Fu et al.
2003, Fu and Wang 2004). Our hybrid coupled atmosphere-ocean model (a brief description of this
model is given in section 2.7) simulates eastward propagating MJO and local oscillations in the
eastern Pacific and WMA in a realistic manner (Fig. 3). The relatively realistic model ISO (Fu and
Wang 2004) enable us to further explore the possible modulation of the ISO on the WMA with this
model. Considering the complex terrain in the region, we propose to use the coupled GCM to
provide large-scale forecast fields as lateral boundary conditions for the WFR model, which is
used to do dynamical downscaling.
12
Figure 3. Left two panels: wavenumber-frequency spectral variance of precipitation associated with MJO from the
observations (OBS) and the hybrid coupled model. Right two panels: ISO rainfall in eastern North Pacific and US
Western Mountain Area.
a. Air-sea interaction
The possible impacts of tropical air-sea interaction on simulation of the ISO have been
investigated in a few numerical studies (Flatau et al. 1997, Waliser et al. 1999, Hendon 2000,
Kemball-Cook et al. 2002, Fu et al. 2002, 2003, and Inness and Slingo 2003). The consensus of
these studies is that active tropical air-sea interaction considerably improves simulated ISO. We
will assess how the air-sea interaction affects the model’s predictability.
We have performed two 50-year experiments with our hybrid coupled model and its
atmospheric component in which the simulations were forced by the same SST anomalies that
were generated by the coupled model (Fu and Wang 2004). We will make a parallel study of the
seasonal climate predictability for the WMA in both experiments. This allows us to examine how
the air-sea coupling changes the model’s practical predictability.
In order to address the role of air-sea interaction on the intraseasonal predictability, we plan to
examine the differences in the predictability between a coupled model run and a non-coupled (i.e.,
atmosphere-only) run. Including simulation results of many ISO events is expected to give more
robust conclusions. Therefore, we will use the procedure proposed by Waliser et al. (2003) and
conduct two-perturbation experiments for many ISO events so that the predictability in our
experiments can be quantified. Two suites of experiments will be conducted for these two models:
(1) a10-year control run, and (2) a group of two-perturbation runs.
b. Rainfall assimilation
In the tropics, the correct representation of moist convection and the associated atmospheric
circulations in a model is the key to success for the medium and extended-range weather forecast
(Kalnay 2003). The same principle could be applied to the prediction of the ISO (Hendon et al.
2000). Krishnamurti et al. (1991) developed a physical initialization to assimilate observed rainfall
into an atmospheric model. This procedure results in a high skill in the nowcasting of rainfall and
an improved medium-range weather forecast (Krishnamuri et al. 1994).
We hypothesize that in an atmosphere-ocean coupled model, this rainfall-assimilation
procedure would improve our model’s ability to predict tropical ISOs and their extratropical
teleconnections. The reason is that assimilating observed rainfall into the coupled model would not
only generate an atmospheric status consistent with observations, but also produce a coherent SST
variation in the ocean. This SST signal generated in the spin-up stage may aid the prediction of the
13
ISO and its extratropical teleconnections.
We plan to investigate the impact of rainfall assimilation in our coupled model on the
predictability of the ISO in the North American sector. The method used to assimilate observed
rainfall into the model should be simple yet effective. The reverse method developed by Treadon
(1996, 1997) will be used. The ISO events used in this investigation will be selected from NAME
observations (data available in summer of 2004). Because of the limited period of the NAME
experiment, we plan to pick up only a few events but will conduct a large ensemble of experiments,
following the procedure proposed by Tracton and Kalnay (1993) to fulfill our goal. Once an event
is selected, 10 ensemble forecasts with the hybrid-coupled model will be conducted with and
without rainfall assimilation, respectively. Their forecasts (after downscaling with the regional
climate model) will be compared to the NAME observations and the impact of rainfall assimilation
will be assessed.
2.7 Data and numerical models
a. Data
The NCEP-NCAR reanalysis daily and monthly mean data (Kalnay et al. 1996) and ECMWF
reanalysis data are the primary upper air data and useful for estimating moisture transport. The
monthly global SST for the period 1948-2001 is taken from Reynolds reconstruction of the
comprehensive Ocean-Atmosphere Data Set (COADS) SST (Smith et al. 1996). Three datasets are
used for precipitation analyses: (1) the CPC .25x.25 US UNIFIED Precipitation and CPC Hourly
US Precipitation (Higgins et al. 1996), (2) the precipitation data set with land-only coverage from
1950 to 1996 assembled by the University of Delaware (http://climate.geog.udel.edu/
~climate/html_pages/README.ghcn_clim.html), and (3) CMAP pentad and monthly mean
rainfall data (Xie and Arkin 1996). The snow datasets include snow water equivalent (SWE) data
(Matsui et al. 2003), snow depth derived from the Nimbus-7 Scanning Multichannel Microwave
Radiometer (SMMR), and NOAA Daily Global Summary of Day (GOBALSOD) Station Data,
which is a collection of daily data from over 10000 weather stations located around the world,
including precipitation amount and snow depth. The CPC US soil moisture data will be used which
are estimated by using a one-layer hydrological model (Huang et al., 1996, van den Dool et al.,
2003). The model takes observed precipitation and temperature and calculates soil moisture,
evaporation and runoff. The potential evaporation is estimated from observed temperature
(http://www.cpc.ncep.noaa.gov/soilmst/). The first space-borne precipitation radar launched on
the Tropical Rainfall Measuring Mission (TRMM) satellite, TRMM PR 2a25, has enabled us to
obtain vertical profiles of the precipitation rate over any places of the tropics. The classification
between convective and stratiform rain (Awaka et al., 1998) is crucial in evaluating the impact of
precipitating systems on the dynamical fields. Statistical features of vertical heating profiles and
the horizontal distribution of precipitation will be examined to elucidate the precipitation
characteristics and to gain insights into the precipitation processes over the WMA.
b. Numerical models
The coupled ECHAM-UH upper layer ocean model
The hybrid-coupled model used in this study is the ECHAM/UH (Fu et al. 2002). The
ECHAM AGCM was documented in detail by Roeckner et al. (1996). The mass-flux cumulus
parameterization of Tiedtke (1989) for deep, shallow, and midlevel convection has been used with
modified closure schemes for penetrative convection and the formation of organized entrainment
14
and detrainment (Nordeng 1995). The model’s land-surface scheme is a modified bucket model
with improved parameterization of rainfall-runoff (Dumenil and Todini 1992). The radiation
scheme is a modified version of the ECMWF scheme. Two- and six-band intervals are used in the
solar and terrestrial part of the spectrum, respectively.
The UH ocean model is a tropical upper ocean model with intermediate complexity, which was
originally developed by Wang et al. (1995) and improved by Fu and Wang (2001). It is a 2½-layer
system, consisting of a surface mixed layer and a thermocline layer, overlying a deep motionless
ocean. The ocean model is able to realistically reproduce the annual cycles of SST, upper-ocean
currents, and mixed-layer thickness in the tropical Pacific (Fu and Wang 2001, Wang and Fu 2001).
In this study, the ocean model domain covers both the Indian and Pacific Oceans (from 30oS to
30oN) with realistic coastal geometry. The spatial resolution of the model was 0.5o longitude by
0.5o latitude. This hybrid-coupled model has been tested in its simulations of the Asia-Pacific
mean climate, seasonal cycle, ENSO, and ISO. The encouraging results are reported in Fu et al.
(2003) and Fu and Wang (2004).
The regional climate model
The Weather Research and Forecasting (WRF) model is a community mesoscale forecast
model and assimilation system suitable for both research and prediction. Based on the dynamics of
NCAR/PSU MM5 and physics of NCEP ETA, the WRF model incorporates advanced numerics
and data assimilation techniques, multiple relocatable nesting capability, and numerous improved
physics options, particularly for the treatment of convection and mesoscale precipitation. This
model is well suited for idealized types of simulations to study baroclinic waves, idealized storm
dynamics, or topographically induced flows, as well as for detailed numerical weather prediction
cases with real-data initial states and boundary conditions at a variety of grid sizes. Version 2.0 of
WRF released in May, 2004, will be used in this study and is available to the general community
for download at http://www.wrf-model.org.
Use of theWRF for dynamic downscaling is a challenging, yet worthwhile effort. Drawing on
our previous successful developmental work on the land surface component of our IPRC regional
climate model (e.g., Wang et al. 2003), we will extend this capability to the WRF. In fact, we have
made initial preparations to modify the current land surface component of the WRF.
2.8 Timelines
The proposed works will take three years. Concrete progress plan is shown below.
Tasks
Year 1
Year 2
Year 3
Ia
__________
Ib
___________
IIa
________________
IIb
________________
IIIa
__________
IIIb
____________________
15
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19
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and its simulation of the 1998 severe precipitation event over China: Part I: Model description
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20
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21
4. APPENDIX
Abstracts of unpublished papers that are most relevant to this proposal
1. Wang, B., X. Fu, Q. Ding, I.-S. Kang, K. Jin, J. Shukla, and S. Doblas-Reyes: A fundamental
challenge in climate prediction of Monsoon rainfall: inadequacy of Tirer-2 strategy.
Submitted to BAMS.
The scientific basis for climate prediction lies in the climate systems’ predictability
determined by variations of the ocean and land surface conditions. Here we show that the
state-of-the-art atmospheric general circulation models (AGCMs), when forced by observed sea
surface temperature (SST), are unable to simulate with any accuracy Asian-Pacific summer
monsoon rainfall. The models tend to yield positive SST-rainfall correlations in the summer
monsoon that are at odds with observations. The observed lead-lag correlations between SST and
rainfall suggest that treating monsoon as a slave to prescribed SST results in the models’ failure.
We demonstrate that an AGCM, coupled with an ocean model, simulated realistic SST-rainfall
relationships; however, the same AGCM fails when forced by the same SSTs that are generated in
its coupled run. Neglect of atmospheric feedback makes the forced solution depart from the
coupled solution in the presence of initial noises or tiny errors in the lower boundary. This suggests
that the coupled ocean-atmosphere processes are extremely important in the Asian-Pacific region
during summer. The present finding calls for reshaping of current strategies for predicting
monsoon climate and validating AGCMs. The traditional notion that climate can be predicted by
prescribing the lower boundary (Tier 2 approach) where AGCM is forced by pre-forecasted SST is
inadequate for predicting summer monsoon rainfall, especially in the Asian-Pacific region.
2. Fu, X. and Bin Wang: The boreal summer intraseasonal oscillation simulated in a hybrid
coupled atmosphere-ocean model. (Mon. Wea. Rev., In press)
The boreal-summer tropical intraseasonal oscillation (BSISO) simulated by an
atmosphere-ocean coupled model is validated with the long-term observations. This validation
focuses on the three-dimensional water vapor cycle associated with the BSISO and its interaction
with underlying sea surface. The advantages of a coupled approach over stand-alone atmospheric
approaches on the simulation of the BSISO are revealed through an inter-comparison between a
coupled run and two atmosphere-only runs. This coupled model produces a BSISO that mimics the
one presented in the observations over the Asia-western Pacific region. The similarities with the
observations include 1) the coherent spatio-temporal evolutions of rainfall, surface winds and SST
associated with the BSISO; 2) the intensity and period (or speed) of the northward-propagating
BSISO; and 3) the tropospheric moistening (or drying) and overturning circulations of the BSISO.
The inter-comparison between a coupled run and two atmospheric runs suggests that the
air-sea coupled system is the ultimate tool needed to realistically simulate the BSISO. Though the
major characteristics of the BSISO are very likely determined by the internal atmospheric
dynamics, the correct interaction between the internal dynamics and underlying sea surface can
only be sustained by a coupled system. The atmosphere-only approach, when forced with
high-frequency (e.g. daily) SST, introduces erroneous boundary interference on the internal
dynamics associated with the BSISO. The implications for the predictability of the BSISO are
discussed.
22
3. Sen, O., B. Wang, and Y. Wang: Impacts of re-greening the desertified lands in northwest
China: Implications from a regional climate model experiment, J. Climate, Accepted.
Replacing desert and semi-desert areas with grass in the test area increases net surface
radiation and hence total heat flux from the surface to atmosphere, resulting in enhanced ascending
motions and moisture supply locally, which increases rainfall in the whole test area. However, the
increase in rainfall largely occurs due to an increase in intensity rather than an increase in
frequency. The increase in rainfall in the highlands and far eastern parts of the test area, which
already receive more frequent rainfall, may help support a restored vegetation cover in these
regions. The enhanced ascending motions over the test area are compensated by increased
subsidence to the east, centered over Yellow River Delta, resulting in a higher-pressure and
anticyclonic circulation anomaly there. Consequently, rainfall decreases in these areas. This
anticyclonic anomaly provides significant northeasterly low-level anomalous winds that enhance
cyclonic shear vorticity in the Yangtze River Basin and South China when they meet
southwesterly monsoonal flow. This causes strong ascending anomalies over southern China and
the Sichuan Basin, and increases rainfall in these regions.
4. Zhuo Wang and Bin Wang: Rossby wave propagation through a southerly duct: A
mechanism of teleconnection between deep tropics and midlatitude, to be submitted.
Rossby wave propagation theory predicts that tropical mean easterlies do not allow Rossby
waves escaping from tropics to extratropics. Here we show that a southerly flow in the basic state
may transfer Rossby wave source downstream; thus, a forcing embedded in deep tropical
easterlies may excite a Rossby wave response in the extratropical westerlies. It is shown that a
southerly duct determines the location of the effective Rossby wave source and the extratropical
response is relatively insensitive to the location of the tropical forcing as long as the tropical
response can reach the southerly duct area. A stronger southerly flow favors stronger extratropical
response, but the spatial scale of the extratropical response is determined by the extratropical
westerly basic flows.
23
5. CURRICULUM VITAE
PI: BIN WANG
EDUCATION
Ph. D. (1984), Geophysical Fluid Dynamics, Geophysical Fluid Dynamics Program, Florida
State University.
M. S. (1981), Meteorology, Graduate School, University of Science and Technology of China.
PROFESSIONAL EMPLOYMENT AND EXPERIENCES
Jan. 1987 - Jun. 1989-July 1992: Assistant, Associate, and Full Professor, Dept. of Meteorology,
University of Hawaii.
Jan. 1988 - present: Senior fellow, JIMAR.
Nov. 1984 - Dec. 1986: Visiting Scientist, GFD Program, Princeton University.
Aug. 1984 - Nov. 1984: Research Associate, GFDI, FSU.
May 1981 - Jul. 1984: Research Assistant, Dept. of Meteorology and GFDI, FSU.
Oct. 1978 - Apr. 1981: Assistant Researcher, IAP, Chinese Academy of Sciences.
RECENT REFEREED PUBLICATIONS (2002-present)
1. Wang, B.: Fundamental Dynamics, Chapter 3 in Tropical Intraseasonal Oscillation in
the Atmosphere and Ocean. Ed. K.-M. Lau and D. E. Waliser.
2. Fu, X. and B. Wang: Different solutions of intraseasonal oscillation exist in
atmosphere-ocean coupled model and atmosphere-only model. J. Climate, In press.
3. Drbohlav, H-K Lee, and B. Wang: Mechanism of the northward propagating intraseasonal
oscillation in the south Asian monsoon region: results from a zonally averaged model. J.
Climate, Accepted.
4. Wu, L. and B. Wang: Assessment of global warming impacts on tropical cyclone track. J.
Climate, In press.
5. Wang, B. and T. Li: East Asian monsoon and ENSO interaction, East Asian Monsoon. World
Scientific Publishing Company Book Series, 2, In press.
6. Yu, R., B. Wang, and T. Zhou: Climate effects of the deep continental stratus clouds generated
by Tibetan Plateau. J. Climate, Revised.
7. Fu, X. and B. Wang, 2004: Differences of Boreal Summer Intraseasonal Oscillations Simulated
in an Atmosphere–Ocean Coupled Model and an Atmosphere-Only Model. J. of Climate, 17,
1263-1271.
8. Wang, B., In-Sik Kang, and June-Yi Lee, 2004: Ensemble Simulations of Asian–Australian
Monsoon Variability by 11 AGCMs. J. Climate, 17, 803–818.
9. Wang, B., LinHo, Y. Zhang, and M.-M. Lu, 2004: Definition of South China Sea Monsoon
Onset and Commencement of the East Asia Summer Monsoon. J. Climate, 17, 699–710.
10. Jiang, J., B. Wang, K. Goya, K. Hocke, S. D. Eckermann, J. Ma, D. L. Wu and W. G. Read,
2004: Geographical Distribution and Inter-Seasonal Variability of Tropical
Deep-Convection: UARS MLS Observations and Analyses. J. G. R., 109, D03111.
11. Teng, H. and B. Wang, 2003: Interannual Variations of the Boreal Summer Intraseasonal
24
Oscillation in the Asian–Pacific Region. J. Climate, 16, 3572-3584.
12. Fu, X and B. Wang, 2003: Influences of Continental Monsoons and Air–Sea Coupling on the
Climate of the Equatorial Pacific. J. Climate 2003, 16, 3132-3152.
13. Wang, B., S. C. Clemons, and P. Liu, 2003: Contrasting the Indian and East Asian monsoons:
implications on geologic timescales. Marine Geology, 201, 5-21.
14. Li, T., B. Wang, C.-P. Chang, and Y. Zhang, 2003: A theory for the Indian Ocean dipole-zonal
mode. J. Atmos. Sci., 60, 2119-2135.
15. Fu, X., B. Wang, T. Li, and J. McCreary, 2003: Coupling between Northward-Propagating,
Intraseasonal Oscillations and Sea Surface Temperature in the Indian Ocean. J. Atmos. Sci.,
60, 15, 1733-1753.
16. Wang, B., R. Wu, T. Li, 2003: Atmosphere-Warm Ocean interaction and its impact on
Asian-Australian Monsoon variation. J. Climate, 16, 1195-1211.
17. Wang, B, 2003: Kelvin Waves, Encyclopedia of Meteorology. ED. J. Holton. Academic Press.
pp. 1062-1067.
18. Fu, X., B. Wang, and T. Li, 2002: Impacts of Air–Sea Coupling on the Simulation of Mean
Asian Summer Monsoon in the ECHAM4 Model. Mon. Wea. Rev., 130, 2889-2904.
19. Wu, R., and B. Wang, 2002: A Contrast of the East Asian Summer Monsoon and ENSO
Relationship between 1962-1977 and 1978-1993. J. Climate, 15, 3266-3279.
20. Wang, B., and Q. Zhang, 2002: Pacific-East Asian teleconnection, part II: How the Philippine
Sea anticyclone established during development of El Nino. J. Climate, 15, 3252-3265.
21. LinHo and B. Wang, 2002: The time-space structure of the Asian-Pacific summer monsoon:
A fast annual cycle view. J. Climate, 15, 2001-2019.
22. Wang, B., and J. C. L. Chan, 2002: How strong ENSO events affect tropical storm activity
over the Western North Pacific. J. Climate, 15,1643-1658.
23. Kemball-Cook, S., B. Wang, X. Fu, 2002: Simulation of the ISO in the ECHAM4 model: The
impact of coupling with an ocean model. J. Atmos. Sci., 59, 1433-1453.
24. Wang, B., and S.-I. An, 2002: A mechanism for decadal changes of ENSO behavior: Roles of
background wind changes. Climate Dynamics, 18, 475-486.
25. Wang, B. and LinHo, 2002: Rainy seasons of the Asian-Pacific monsoon. J. Climate, 15,
386-398.
25
Co-PI: Xiouhua Fu, Assistant Researcher
IPRC, University of Hawaii
1680 East West Road, POST Bldg., 4th Floor
Honolulu, Hawaii96822
Tel: 808-956-2629; Fax: 808-956-9425
E-mail: xfu@hawaii.edu
Education:
Ph.D., Meteorology, Department of Meteorology, University of Hawaii, 1998
M.S., Atmospheric Physics, Chinese Academy Sciences, 1988
B. S., Meteorology, Chengdu Meteorological College, 1985
Employment (1999-present):
Assistant Researcher, IPRC, University of Hawaii, Jul. 2002-present
Coupled atmosphere-ocean modeler, IPRC, University of Hawaii, Oct.1999-Jun. 2002
Postdoctoral fellow, Wyrtki Center, University of Hawaii, Jan.1999-Oct.1999
Research Interests:
 Climate modeling
 Ocean-atmosphere-land interactions
 Asian-Pacific-American climate variability and predictability
Relevant Publications:
Fu, X. and B. Wang, 2004: The boreal-summer intraseasonal oscillations simulated in a hybrid
coupled atmosphere-ocean model. Mon. Wea. Rev., In press.
Fu, X. and B. Wang, 2004: Differences of boreal-summer intraseasonal oscillations simulated in
an atmosphere-ocean coupled model and an atmosphere-only model. J. Climate, 17,
1263-1271.
Fu, X., B. Wang, T. Li, and J. McCreary, 2003: Coupling between northward-propagating
intraseasonal oscillations and sea surface temperature in the Indian Ocean. J. Atmos. Sci.,
60, 1733-1753.
Fu, X., and B. Wang, 2003: Influences of continental monsoons and air-sea coupling on the
climate of equatorial Pacific. J. Climate, 16, 3132-3152.
Fu, X., B. Wang and T. Li, 2002: Impacts of air-sea coupling on the simulation of mean Asian
summer monsoon in ECHAM4 model. Mon. Wea. Rev., 130, 2889-2904.
Kemball-Cook, S., B. Wang and X. Fu, 2001: Simulation of the intraseasonal oscillation in the
ECHAM4 model: The impact of coupling with an ocean model. J. Atmos. Sci., 59,
1433-1453.
Wang, B., and X. Fu, 2001: Physical processes determining the rapid reestablishment of the
equatorial Cold Tongue/ITCZ complex from March to May. J. Climate, 14, 2250-2265.
Fu, X. and B. Wang, 2001: A coupled modeling study of the annual cycle of Pacific cold tongue.
Part I: Simulation and sensitivity experiments. J. Climate, 14, 765-779.
Wang, B., R. Wu, and X. Fu, 2000: Mechanism of ENSO monsoon interaction during
26
mature-decaying phases of ENSO cycle. In: East Asian and Western Pacific Meteorology
and climatology, Ed. C.-P. Chang.
Fu, X., and B. Wang, 2000: Understanding the annual cycle of equatorial Pacific as a
result of ocean-atmosphere-land interactions. In: “Dynamics of Atmosphere-Ocean
Circulation and Climate”, IAP, Chinese Academy of Sciences, Beijing, China.
Wang, B., R. Wu and X. Fu, 1999: Pacific-East Asian teleconnection: How does ENSO affect
East Asian Climate? J. Climate, 13, 1517-1536.
Fu, X. and B. Wang, 1999: On the roles of cloud-longwave radiation forcing and boundary
layer thermodynamics in forcing tropical surface winds. J. Climate, 12, 1049-1069.
27
6. CURRENT AND PENDING SUPPORTS
6.1 Current support
Dr. Bin Wang:
P.I., Bin Wang, NSF: Dynamics of the boreal summer intraseasonal oscillation, Co-PI: T. Li
Oct. 2003-Sep. 2006, $452,166.
P.I., Bin Wang, ONR: Dynamical control of rapid tropical cyclone intensification by
environmental shears, Co-PI: T. Li, Y. Wang, Apr. 2002-Mar. 2005, $795,000.
P.I., B. Wang, NOAA/PACS: Remote Forcing on the US warm Season Rainfall and the Eastern
Pacific Climate, Co-PI: T. Li, X. Fu. Jul. 2001-Jun. 2004. $365,981.
P.I., B. Wang, NOAA/PACIFIC: Impacts of warm pool and Extratropical Processes on ENSO,
Co-PI: S.-I. An, Mar. 2003-Feb. 2006. $363,290.
Dr. Xiouhua Fu:
P. I., X. Fu, NASA: Application of satellite data to improve the simulation and prediction of
tropical intraseasonal oscillation (TISO), Co-PI: B. Wang, X. Xie, Jul 2004-Jun 2007,
$272,333.
6.2 Pending proposals
This proposal.
28
7. REQUESTED FUNDS
1 Oct 2004 – 30 Sept 2005
Year 1
A. Salaries and Wages
Man-Month
Total
Bin Wang
0.5
6420
Xiouhua Fu
1.0
5400
12.0
50000
1. Senior Personnel
2. Post-doc Researcher
B. Fringe Benefits
7753
C. Travel
4500
D. Publication
5000
E. Materials and Supply
3800
F. Computer Service
3200
G. Others
500
Total Direct Costs (A through G)
86573
Indirect Costs (36.3 %) – excluding computer services
30264
Total Costs
$116,837
29
1 Oct 2005 – 30 Sept 2006
Year 2
A. Salaries and Wages
Man-Month
Total
Bin Wang
0.5
6741
Xiouhua Fu
1.0
5670
12.0
51750
3. Senior Personnel
4. Post-doc Researcher
B. Fringe Benefits
8028
C. Travel
4500
D. Publication
5000
E. Materials and Supply
3800
F. Computer Service
3200
G. Others
500
Total Direct Costs (A through G)
89189
Indirect Costs (36.3 %) – excluding computer service
31214
Total Costs
$120403
30
1 Oct 2006 – 30 Sept 2007
Year 3
A. Salaries and Wages
Man-Month
Total
Bin Wang
0.5
7078
Xiouhua Fu
1.0
5954
12.0
53562
5. Senior Personnel
6. Post-doc Researcher
B. Fringe Benefits
8313
C. Travel
4500
D. Publication
5000
E. Materials and Supply
3800
F. Computer Service
3200
G. Others
500
Total Direct Costs (A through G)
91907
Indirect Costs (36.3 %) – excluding computer service
32201
Total Costs
$124108
31
Cumulative
1 Oct 2004 – 30 Sept 2007
A. Salaries and Wages
Man-Month
Total
7. Senior Personnel
Bin Wang
1.5
20239
Xiouhua Fu
3.0
17024
36.0
155312
8. Post-doc Researcher
B. Fringe Benefits
24094
C. Travel
13500
D. Publication
15000
E. Materials and Supply
11400
F. Computer Service
9600
G. Others
1500
Total Direct Costs (A through G)
267669
Indirect Costs (36.3 %) – excluding computer services
Total Costs
93679
$361348
32
Budget Explanation
Personnel
The PIs will devote 1 summer month and 1 academic month in each year of the project, while only
0.5-month summer salary for BW and 1-month salary for XF are requested. A post-doc researcher
will work on this project. Computation of fringe benefit is based on 15% for the post-doc and
2.14% for the PIs.
Travel
The travel is based on an estimate of three domestic trips per year (5 days per trip) for the PIs and
co-workers to present scientific results at national and international conferences. $1500 per trip (1
RT airfare - $750, 5 days per diem @ $130/day, ground transportation - $100).
Other direct costs
The materials and supplies represent the costs of office supplies, copy charge, transparency etc..
The publication cost is based on estimation of about 40 pages published in refereed journals at a
page charge of $110, plus printing/copying charges of $600 per year.
Computer services include network charge for 4 workstations @ $800/ea for system software
support and maintenance. In addition, the proposed work requires substantial disk space to
facilitate numerical computations of coupled ocean-atmospheric models and output data analysis.
The budget here includes the upgrade of workstations and the increase of hard disk and memory.
The other costs reflect postage, telecommunications, and miscellaneous items.
Indirect costs:
The University of Hawaii charges indirect costs at a rate of 36.3 % of the total modified direct
costs1.
1
The modified direct costs do not include equipment and computer service charges.
33