WORLD METEOROLOGICAL ORGANIZATION
____________________
COMMISSION FOR BASIC SYSTEMS
WORKSHOP OF GLOBAL PRODUCERS OF
SEASONAL TO INTERANNUAL FORECASTS
GPC-SIF/Doc. 8(3)
(7.II.2003)
_________
ITEM: 8(3)
Original: ENGLISH
Geneva, 10-13 February 2003
Contribution and proposals of JMA as a global producing center
(Submitted by Mr Nobutaka MANNOJI)
GPC-SIF/Doc. 8(3)
Contribution and proposals of JMA as a global producing center
Abstract
JMA is to make Seasonal to Interannual (SI) forecast products available on its web page
so as to serve as a global producing center.
JMA also presents climate system
monitoring on the web page so as to help to issue the SI forecast. Moreover, JMA is
conducting reanalysis project in cooperation with Central Research Institute of Electric
Power Industry (CRIEPI). The product can be effective both in climate system monitoring
and in verification of hindcast. JMA proposes intercomparisons of hindcasts in order to
promote the improvement of seasonal forecast model.
1.
Forecast Data
JMA is to provide grid point values (GPV) of operational four-month forecast on the
web page of Tokyo Climate Center (TCC) ("http://cpd2.kishou.go.jp/tcc/") in September 2003.
GPVs of the one-month forecast have been already available there since October 2002. The
verification of hindcast following SVS and necessary documentation are to be presented.
JMA will gradually increase the variation of products provided as a Global Producing
Center (GPC) according to the list proposed at CBS Ext.2002 in Cairns, Australia. In addition,
JMA will develop forecast maps over the tropics and the Asian monsoon area, since particular
climate characters in Region II and Region V should be considered. In the workshop of
capacity building for forecasters of NMHSs of south-eastern Asia in December 2002, Tokyo
held by JMA, many of them stated demands for forecast maps such as precipitation in the
tropical area. JMA will respond to these requests in 2003. JMA suggests that RCCs develop
proper products for each Region considering the different characteristics of climate and
demands of NMHSs in its Region, and that GPCs provide appropriate products to assist
RCCs' work. NMHSs would benefit if this kind of regional products are provided by several
centers.
2.
Climate System Monitoring
Climate system monitoring, that is important to issue SI forecast, is also available at
the TCC web page. Monthly features of extratropical circulation, tropical circulation and
convection, oceanic conditions are described and updated on a monthly basis.
This
monitoring is based on objective analysis data produced with the four dimensional data
assimilation (4DDA) system of JMA's NWP system.
Since a climate system monitoring
provides a different point of view for operational 4DDA system designed for short range
forecast, requirements from climate system monitoring contribute to improvement of overall
performance of 4DDA system in any NWP center or GPC.
The contents will be upgraded, and updating frequency is to be increased from
monthly to weekly in 2004. Reliable climate data as well as reliable real-time objective
GPC-SIF/Doc. 8(3), p. 2
analysis are necessary to operate the climate system monitoring system, since departure from
climate values and comparison with historical data have important meanings. In this regard,
JMA and Central Research Institute of Electric Power Industry (CRIEPI) of Japan are jointly
conducting re-analysis project "JRA-25" described below to produce climate data.
3.
Reanalysis project "JRA-25"
JMA has been conducting reanalysis project called "JRA-25" in cooperation with
CRIEPI ("http://www.jreap.org/indexe.html") since 2001. JRA-25 was started to meet urgent
needs for homogeneous analysis data. Operational analysis at many centers differs each
other due to different assimilation systems. Moreover, as a result of continuous improvement
of the assimilation system, the older the analysis is, the poorer its quality becomes. Especially
in the tropics, where observational data is relatively few and cumulus convection as a heat
source driving global circulation is active, differences among assimilation systems are
substantial.
The products are expected to be valuable for SI forecasts. First, the dataset is to be
used as an initial condition and verification data for hindcast. Secondly, the dataset can be
used for operational climate system monitoring. After the JRA-25 data are accomplished, the
same system for JRA-25 is to be extended as a Climate Data Assimilation System. Then,
climate system monitoring of JMA becomes consistent using the homogeneous dataset for
climate data as well as real-time objective analysis.
We pay special attention to tropical cyclones and the circulation over the Western
Pacific, both of which would have very important role to ensure high quality reanalysis data
over Region II and Region V. For this end, retrieved wind data surrounding historical tropical
cyclones (TCs) provided by Dr. M.Fiorino (LLNL/PCMDI) is to be assimilated.
In addition,
cloud motion winds by GMS recalculated by the Meteorological Satellite Center (MSC)/JMA
for the period from April 1987 onward is to be assimilated. The latter is expected to contribute
to the precise wind and height field over the Western Pacific.
In this way, JMA, as well as other organizations that conduct reanalysis projects, tries
to incorporate observational data that were not available in the previous operational analyses
as much as possible. Therefore, rescuing historical data, which is one of RCC's major
functions, would be very useful for reanalysis projects.
A high quality, homogeneous, long time climate dataset from 1979-2005 will be
accomplished by March 2006, and JMA will provide the dataset for the meteorological
communities including researchers and NMHSs. JMA would release parts of the dataset while
the assimilation is going on.
4.
Hindcast
Hindcast is to be conducted prior to the operational SI forecast. JMA proposes
intercomparisons of hindcasts, that would promote to improve NWP models of each GPC.
GPC-SIF/Doc. 8(3), p. 3
Although SVS is proposed to verify forecast of each GPC's products, it seems to be designed
for users, not for modelers. The first step would be comparisons of bias of each model. Then,
it might be beneficial to compare how some characteristic phenomena are predicted among
the models, such as major teleconnection patterns, durations of the Arctic Oscillation and
frequency of blocking highs.
5.
Summary and proposals
Products of SI forecasts and global climate system monitoring are important to
develop operational SI forecast of each NMHS over the world.
GPCs should be located in several Regions since the characteristics of climate as
well as demands for SI forecast would differ from Region to Region. Since each GPC would
pay special attention to the forecast skill of its region as well as global skill, a GPC would
improve its model in different ways from GPCs in other Regions. In addition, if many GPCs
operate a variety of models, the performance of multi-model ensemble with these models
could be bettered.
JMA proposes intercomparisons of hindcasts in order to identify outstanding issues to
improve each model. It is also desirable that many GPCs conduct reanalysis and real-time
analysis with the same system for consistent climate system monitoring.
RCCs should encourage NMHSs to report CLIMAT in operation, and should try to
rescue historical data that are not utilized so far. Those activities will improve the quality of
climate system monitoring and reanalysis, and would promote to improve products of GPCs
eventually.
JMA has just started to provide data related to SI forecast, and it will provide a variety
of SI forecasts and climate system monitoring products at the TCC web page. JMA is willing to
serve a role of GPC.