Li, K., Slawski, B. L., Tian, B., Flemming, J., Bechtold, P., Wong, S., Worden, J.,
Waliser, D. E., Yung, Y. L., 2011, The Madden-Julian Oscillation of Tropospheric
Carbon Monoxide, AGU Abstract A11G-0177
ABSTRACT: Carbon monoxide (CO) is an important air pollutant that connects to
climate through its close relationship to greenhouse gases like methane, carbon dioxide
and tropospheric ozone [Shindell et al., 2006]. Precise knowledge on the spatial-temporal
variations of CO can provide critical constraints on carbon-cycle simulations. The
Madden-Julian Oscillation (MJO) modulation of CO near the tropical tropopause layer
has been reported [Wong & Dessler, 2007] but that in the tropical troposphere has not
been characterized. Here we report on the MJO modulation of CO observed from
multiple satellites, including the Measurements Of Pollution In The Troposphere
(MOPITT) for CO column, the Atmospheric Infrared Sounder (AIRS) and the
Tropospheric Emission Spectrometer (TES) for vertically resolved CO profiles. We also
found an MJO signal in CO assimilated in ECMWF Monitoring Atmospheric
Composition and Climate (MACC) products. These MJO-related variations in CO appear
to be strongly modulated by the CO sources over lands, such as biomass burning. The
findings will be discussed in light of the relationships found between the MJO and
tropospheric aerosols and carbon dioxide [Li et al., 2010; Tian et al., 2011].
Zhang, X., West, R. A., Shia, R., Yelle, R. V., Yung, Y. L., 2011, Non-LTE Modeling of
the Stratosphere of Jupiter, AGU Abstract P12A-03
Abstract: Thermal infrared emission from Jovian atmosphere itself is absorbed and reemitted and causes the atmospheric cooling to space. Above about 1 mbar, Non-Local
Thermodynamic Equilibrium (Non-LTE) effect may be important for the IR cooling rate
and therefore the atmospheric heat balance. In this study, a Non-LTE radiative transfer
model is introduced to calculate the cooling rate via the IR bands of the hydrocarbon
species including CH4 at 7.7 μm, C2H6 at 12.2 μm, and C2H2 at 14 μm. Collisional deactivation (quenching) rates of the excited states of these hydrocarbon species in a
hydrogen-rich atmosphere are the major unknown parameters in the current literature.
However, our results show that, the radiative budget of the upper stratosphere of Jupiter
depends crucially on the quenching rates. The effect on the stratospheric circulation and
hydrocarbon distribution is discussed.
Wang, S., Sander, S. P., Li, K., Yung, Y. L., Minschwaner, K. R., 2011, Intra-annual
variations and trends of HOx and the ratio of HO2/OH, AGU Abstract GC23A-0921
ABSTRACT: The middle atmospheric OH and HO2 are known for their important roles
in catalytic HOx reaction cycles (involving OH, HO2, and H) that destroy ozone. Since
OH and HO2 are mainly produced through photolysis, their variations and trends are
strongly affected by solar forcing. These variations and trends have to be understood for a
better understanding of the related variability in middle atmospheric O3. The Microwave
Limb Sounder (MLS) on board the Aura satellite, launched in July 2004, provides the
first simultaneous global measurements for OH and HO2 on a daily basis, making it
possible to investigate the variability in these species and the partitioning between them.
This study focuses on the intra-annual variability of daytime HOx, which is a combined
result of the solar forcing (solar zenith angle change during the course of year) and the
seasonal variation of the source species of HOx (such as O3 and H2O). In addition, the
longer-term ( 5 - 6 years) trends will also be showed, in which the solar 11-year cycle
plays a role. MLS measurements at various latitudes between the altitudes of about 45 65 km, where the partitioning between OH and HO2 is believed to be fairly constant with
respect to altitude, were investigated. OH clearly shows an intra-annual variation with an
annual maximum in late June, which is mostly due to the smallest solar zenith angle at
that time of year and the short lifetime of OH. However, the HO2 data suggest an annual
maximum that is 2 - 3 weeks later than that of OH. The ratio of HO2/OH thus shows a
similar seasonal cycle and a peak that occurs at an even later time of the year. In terms of
longer-term trend, while OH clearly shows a decreasing trend from 2004 to 2009, which
is associated with the solar 11-year cycle, HO2 trend is not as clear. A 1-D model is used
to further investigate these variations. Possible causes of this apparent lag in
HO2 variation will be discussed in detail based on the middle atmospheric chemistry and
the variation of other related parameters, e.g. O3 and temperature.
Yung, Y. L., Liang, M., Li, K., Jiang, X., Camp, C. D., 2011, Solar Cycle Variability in
Tropical Column Ozone, AGU Abstract GC23A-0924
ABSTRACT: Using an empirical orthogonal function (EOF) method [Camp et al., 2003],
we analyzed the Merged Ozone Data (MOD) set from late 1978 to the present. The
decadal variability of column ozone in the tropics follows that of the sun over three solar
cycles. The peak-to-peak amplitude is about 10 DU (Dobson Units), consistent with the
conclusion of Camp et al. [2003], who analyzed the MOD data up to and including 2000.
Previous attempts to model the amplitude of the observed solar cycle in ozone were
unsuccessful, as models tended to underestimate the solar cycle effect. Using the Whole
Atmosphere Community Climate Model (WACCM) in combination with the latest
satellite measurements of solar variability in the UV [McClintock et al., 2005; Harder et
al., 2009], we correctly simulate the solar cycle signal in the total column ozone for the
first time. The implications for solar forcing on middle atmosphere chemistry are
discussed.
Jiang, Y., Aumann, H. H., Yung, Y. L., Analyzing of Tropical Expansion from
Atmospheric Infrared Sounder (AIRS) Measurements, AGU Abstract A31D-0127
ABSTRACT: Of all the various phenomena that characterize the tropical region is the
intertropical convergence zone (ITCZ). The ITCZ lies in the equatorial trough and
constitutes the ascending branch of the Hadley circulation. This permanent low pressure
feature marks the meteorological equator where the trade winds, laden with heat and
moisture from surface evaporation and sensible heating, converge to form a zone of
increased mean convection, cloudiness, and precipitation. The expansion of the tropical
belt will definitely result in the variation or the migration of the ITCZ. Deep convective
cloud offers a clear location of tropical jet streams. Its formation and its feedback to the
climate dynamics is influenced by many factors both dynamically and chemically, and
still under active investigations. We have analyzed the high cloud from AIRS
(Atmospheric Infrared Sounder) measurements in the tropics and it shows the trend +1.04
degree ±1.94 degree(2σ)/decade.
Kuai, L., Worden, J., Kulawik, S., Olsen, E. T., Wunch, D., Shia, R., Connor, B. J.,
Miller C. E., Yung, Y. L., 2011, Comparison of free tropospheric CO2 from TCCON
profile retrievals to those from TES and AIRS, AGU Abstract A33C-0216
ABSTRACT: The Total Carbon Column Observing Network (TCCON) provides
measurements of column abundances of CO2, CO, CH4 and other molecules that absorb
in the near infrared with high accuracy and high precision (e.g.< 0.25% for CO2).
Therefore, this dataset serves as a link between satellite measurements and ground-based
in situ network. In this study, a retrieval algorithm is developed to provide the CO2
profile information in addition to the estimation of column-averaged dry-air mole
fractions. The retrieved CO2 profiles have ~ 3 pieces of information, and can distinguish
the lower troposphere from the upper troposphere and consequently can be compared to
satellite observations from the Aura TES and Aqua AIRS instruments, which measure the
thermal infrared emissions from space to estimate the atmospheric CO2 in the middle and
upper troposphere. In this presentation we show preliminary results from CO2 profile
retrievals and their comparisons with TES, AIRS and aircraft CO2 measurements.
Jiang, X., Olsen, E. T., Kulawik, S., Miller, C. E., Yung, Y. L., 2011, Comparison
Between Satellite CO2 Retrievals With In-situ Measurements, AGU Abstract A33C-0217
ABSTRACT: We have compared AIRS, TES, and GOSAT CO2 data sets with in-situ
measurements (NOAA ESRL Surface CO2, Aircraft CO2, and TCCON CO2) and
utilized zonal means over land to characterize variability and distribution of CO2. In
general, zonal averaged CO2 over land for the three satellite data sets are consistent with
the surface and TCCON column CO2 data. Retrievals of CO2 from all three satellites
show more CO2 in the northern hemisphere than that in the southern hemisphere. The
standard deviation of GOSAT column CO2 at each latitude band is larger than those from
AIRS and TES mid-tropospheric CO2. GOSAT column CO2 is lower than the AIRS and
surface site CO2 in the northern hemisphere high latitudes. The difference between three
satellite CO2 retrievals might be related to the different weighting functions in the three
satellites CO2 retrievals. Latitudinal distribution of CO2 seasonal cycle amplitudes will
be compared between satellite CO2 and in-situ measurements.
Olsen, E. T., Jiang, X., Chen, L., Licata, S., Pagano, T. S., Yung, Y. L., 2011,
Application of AIRS Stratospheric CO2 to investigate Stratospheric Transport and
Troposphere-Stratosphere Exchange, AGU Abstract A33C-0219
ABSTRACT: We are developing an AIRS stratospheric CO2 product, with a sensitivity
peak at 15-30 hPa. Initial AIRS stratospheric CO2 global maps show more stratospheric
CO2 in the tropical region and less stratospheric CO2 in the high latitudes, which is
consistent with the Brewer-Dobson circulation in the stratosphere. The latitudinal
variations of AIRS stratospheric CO2 agree well with the sparse in-situ measurements of
CO2 but not with model results. The latitudinal gradient of stratospheric CO2 is smaller
in the models than that in the AIRS stratospheric CO2. There is also significant
troposphere-stratosphere CO2 exchange in the mid-latitudes beyond the tropical pipe.
Implementation of the AIRS stratospheric CO2 product spanning the operational lifetime
of AIRS offers a new opportunity to constrain the stratospheric transport and
troposphere-stratosphere exchange in the chemistry-transport models.
Su, Z., Li, K., Natraj, V., Shia, R., Miller, C. E., Yung, Y. L., 2011, Space-borne
measurements of atmospheric CH4 by high-resolution near infrared spectrometry of
reflected sunlight, AGU Abstract A33C-0220
ABSTRACT: Methane (CH4) is the second most important anthropogenic greenhouse
gas in the terrestrial atmosphere. It constitutes about 20% of the anthropogenic climate
forcing by greenhouse gases on Earth [IPCC, 2007]. The seasonal cycle of surface
methane varies with latitude, going from ~0.6% at the equator to ~2.6% in the midlatitudes [Butler et al., 2004]. Thus, to understand and quantify climate change due to
CH4, we have to know its sources, sinks and spatiotemporal distribution with high
precision. We introduce a strategy for measuring the CH4 mixing ratio profile from a
space-borne platform. It employs high-resolution spectra of reflected sunlight taken
simultaneously in the near-infrared (NIR) CH4 (1.6-μm and 2.3-μm) and O2 (0.76-μm)
bands. The CH4 profile retrieval algorithm involves three major components. The first
component is the forward model, which produces radiances and weighting functions in a
scattering, absorbing, emitting atmosphere. As a starting point, the same model is used to
generate the synthetic spectrum. The second component simulates the instrument’s
spectral resolution, spectral range as well as several instrument noise sources. The third
component is an inverse method based on optimal estimation theory [Rodgers, 2000] for
retrieving the CH4 profile from the synthetic spectra. We use the VLIDORT code [Spurr,
2006] to model the radiative transfer. We explore methods to characterize scattering by
clouds and aerosols and evaluate the random and systematic errors in the retrievals.
Wang, J., Jiang, X., Olsen, E. T., Pagano, T. S., Chen, L., Licata, S., Yung, Y. L., 2011,
Variation of Polar CO2 and O3 During Sudden Stratospheric Warming, AGU Abstract
A33C-0235
ABSTRACT: The global distributions of chemical species retrieved from the
Atmospheric Infrared Sounder (AIRS) offer a unique opportunity to study the large-scale
dynamics in the polar region. In this study, we investigate the influence of sudden
stratospheric warming (SSW) on AIRS CO2 and O3 in the polar region in March 2005.
Results from observation demonstrate that the polar mid-tropospheric CO2 (O3) will
increase (decrease) during the stratospheric major warming. To better investigate the
influence of SSW on tracers, we also calculate the Eliassen-Palm (EP) flux and
divergence. The EP-flux divergence is negative before the SSW, as a result the westerly
wind in the stratosphere decreases. During the SSW, polar zonal mean wind switches to
easterly and the temperature increases by about 4 K. The polar vortex is much weaker
during the SSW. Mid-latitude CO2 (O3) is transported to the high latitudes and lead to
the increase (decrease) of mid-tropospheric CO2 (O3) concentrations in the polar region,
which is seen in the AIRS CO2 and O3 retrievals.
Newman, S., Jeong, S., Fischer, M. L., Xu, X., Gurney, K. R., Alvarez, S. L.,
Rappenglueck, B., Haman, C. L., Lefer, B. L., Miller, C. E., Yung, Y. L., 2011, CO2
Emissions from the Los Angeles Basin During Spring of 2010 – Measurements vs.
Model, AGU Abstract GC33A-1049
ABSTRACT: More than half of the world’s population now lives in urban areas,
contributing large fluxes of greenhouse gas to the atmosphere. Quantifying the
spatiotemporal distribution of these emissions is critical for providing independent
verification of future mitigation activities. We have used high precision measurements of
CO2 and CO to determine the contribution of fossil fuel combustion (ffCO2 mixing ratio)
to the total CO2 emissions in the Los Angeles basin during the CalNex-LA ground
campaign of May-June 2010 in Pasadena. The ratio of COxs/CO2xs (the excess of each
species above free tropospheric levels) varies significantly by time of day, giving a proxy
for the fraction of ffCO2/CO2xs. Using an emission ratio for CO/CO2 for fossil fuel
combustion of 0.011±0.002 (Wunch et al., 2009, Geophys Res Lett 36, L15810), we
determined that burning of fossil fuels contributed ~50% overnight - 100% during
midday of the total local contribution, resulting in ffCO2 of 13 - 23 ppm, respectively.
These values compare very well with those calculated from Δ14C for measurements of
two samples aggregated from 7-8 flask samples collected at 14:00 PST on alternate days
during the first and second half of the CalNex-LA campaign: 17 and 24 ppm ffCO2,
respectively. We then compared the measured values of ffCO2 with predictions
combining a diurnally averaged version of the Vulcan 2.0 ffCO2 emission inventory
(http://www.purdue.edu/eas/carbon/vulcan/index.php) and mesoscale transport computed
with the Weather Research and Forecast (WRF) and Stochastic Time-Inverted
Lagrangian Transport (STILT) models. To evaluate transport model uncertainty, we
compared predicted and measured planetary boundary layer height (PBLH) and found
WRF predictions compared favorably with ceilometer measurements made during the
day at the Pasadena site. Initial comparison of the diurnal cycle of ffCO2 determined by
the CO/CO2 ratios to that predicted with a temporally constant map of diurnal mean
emissions shows the prediction to have a larger diurnal amplitude than the measurements,
suggesting that the diurnal cycle of emitted ffCO2 compensates for daytime dilution in
the PBL.
Hearty, T. J., Fetzer, E., Tian, B., Yung, Y. L., Vollmer, B., Savtchenko, A. K., Smith, P.
M., Theobald, M., Ostrenga, D., 2011, Observational Sensitivity to Climate Variability
using AIRS/Aqua and MERRA, AGU Abstract U41B-0017
ABSTRACT: The El Nino Southern Oscillation (ENSO) and North Atlantic Oscillation
(NAO) are two of the largest climate variabilities seen in AIRS observations of
temperature, water vapor, and clouds. Numerous climate feedbacks are involved in these
oscillations. We examine these oscillations using observations from the Atmospheric
Infrared Sounder (AIRS) and the Modern Era Retrospective-Analysis for Research and
Applications (MERRA). Since sampling can be an issue for infrared satellites in low
earth orbit, we examine the MERRA data sampled at the AIRS space-time locations both
with and without the AIRS quality control. We estimate the sampling bias of an AIRS
climatology and the atmospheric conditions where AIRS has a lower sampling rate and
examine the apparent differences in the ENSO and NAO based on the different sampling.
While the AIRS temperature and water vapor sampling biases are small at low latitudes,
they can be more than a few degrees in temperature and 10 percent in water vapor at
higher latitudes. While these numbers are small they can be important for understanding
climate variability.
Liang, M., Lin, L., Tung, K. K., Yung, Y. L., 2011, Climate Sensitivity and Solar Cycle
Response in Climate Models, AGU Abstract GC43B-0932
ABSTRACT: Climate sensitivity, broadly defined, is a measure of the response of the
climate system to the changes of external forcings such as anthropogenic greenhouse
emissions and solar radiation, including climate feedback processes. General circulation
models provide a means to quantitatively incorporate various feedback processes, such as
water-vapor, cloud and albedo feedbacks. Less attention is devoted so far to the role of
the oceans in significantly affecting these processes and hence the modelled transient
climate sensitivity. Here we show that the oceanic mixing plays an important role in
modifying the multi-decadal to centennial oscillations of the sea surface temperature,
which in turn affect the derived climate sensitivity at various phases of the oscillations.
The eleven-year solar cycle forcing is used to calibrate the response of the climate
system. The GISS-EH coupled atmosphere-ocean model was run twice in coupled mode
for more than 2000 model years, each with a different value for the ocean eddy mixing
parameter. In both runs, there is a prominent low-frequency oscillation with a period of
300-500 years, and depending on the phase of such an oscillation, the derived climate
gain factor varies by a factor of 2. The run with the value of the eddy ocean mixing
parameter that is half that used in IPCC AR4 study has the more realistic low-frequency
variability in SST and in the derived response to the known solar-cycle forcing.
Lee, H., Huh, C., Yung, Y. L., Liang, M., 2011, A fourteen-year time series of rainwater
7Ve and 210Pb fluxes in northern Taiwan, AGU Abstract A51A-0258
ABSTRACT: Rainwater samples were collected in northern Taiwan at weekly intervals
continuously for 14 years (1996-2010). The samples were analyzed for 7Be and 210Pb by
gamma spectrometry to obtain fluxes of these two nuclides. Spectral analysis of the time
series reveals oscillations at annual, interannual and decadal periodicities. The annual and
interannual oscillations are closely related to precipitation through East Asian monsoon
and ENSO, respectively. The decadal variability may be a consequence of low-frequency
ENSO oscillations and eleven-year solar cycle forcing. Such a long record is instrumental
to study factors controlling the changes of regional meteorology and climate on monthly
to decadal time scales.