WORLD METEOROLOGICAL ORGANIZATION
____________________
COMMISSION FOR BASIC SYSTEMS
Distr.: RESTRICTED
GPC-SIF/Doc. 5.8
(16.I.2003)
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WORKSHOP OF GLOBAL PRODUCERS OF
SEASONAL TO INTERANNUAL FORECASTS
Geneva, 10-13 February 2003
ITEM: 5.8
Original: ENGLISH
PRODUCTS ON SEASONAL TO INTERANNUAL FORECASTS GENERATED BY THE
CENTER FOR WEATHER
PREDICTION AND CLIMATE STUDIES
(Submitted by Dr José A. Marengo)
GPC-SIF/Doc. 5.8, p. 1
PRODUCTS ON SEASONAL TO INTERANNUAL FORECASTS
GENERATED BY THE CENTER FOR WEATHER
PREDICTION AND CLIMATE STUDIES
Contribution from
Centro de Previsão de Tempo e Estudos Climáticos (CPTEC)
Instituto Nacional de Pesquisas Espaciais (INPE)
Rod. Pres. Dutra km 40, Cachoeira Paulista, 12630-000, São Paulo, Brazil.
http://www.cptec.inpe.br/
I- Introduction
The Center for Weather Prediction and Climate Studies (CPTEC) of the National Institute for
Space Research (INPE), located in Cachoeira Paulista, São Paulo, Brazil, develops,
produces and disseminates real time weather forecasts, as well as seasonal climate
forecasts since early 1995. This Center is part of the research network of the Ministry of
Science and Technology (MCT) of Brazil. CPTEC is a leader in operational meteorology and
climate research and forecasts in South America. Its focus is numerical seasonal climate
forecasts for Brazil and the rest of the South American continent. Currently, the main users of
CPTEC weather and climate products are research groups, universities, federal and state
government agencies, civil defense, meteorological and hydrological services, the media
(TV, radio, newspaper), hydropower, agricultural, industry and tourism sectors, as well as the
private sector not only from Brazil but also from the rest of the South American countries.
II- Infrastructure requirements for the operational generation of the products
1.
Computational infrastructure
CPTEC has two NEC supercomputers: the SX4 (peak performance of 16 GFlops) and the
recently purchased SX-6 (peak performance of 256 GFlops). From 2003, all meteorological
operations will migrate to SX6, and SX4 will be dedicated to research. Currently, the SX-6
operates with 32 processors, 128 Gbytes of memory and disk capacity of 4 Tbytes). The SX6
cluster will grow to 96 processors and 768 Glops towards end of 2003. This improvement in
the computer capability makes possible the application of a larger number of integrations for
weather and climate prediction experiments, using the ensemble technique for weather and
climate forecasts.
2
Global and regional models
Numerical Weather Prediction is carried out using the CPTEC Atmospheric General
Circulation Model (AGCM), which was originally derived from the NCEP model by COLA.
Global analyses from NCEP are used as initial conditions. The current resolutions are
T62L28 and T126L28, with the SX6 we expect to run the model with a T170L42 (~70 km) by
2002 and later with T254L42 (~50 km).
Seasonal climate predictions are made using the same CPTEC AGCM. The seasonal
forecasting system comprises a 30-member ensemble run for 6 months, in which 15
members use persisted sea surface temperature (SST) anomaly and 15 members use
predicted SST anomaly.
A coupled ocean-atmosphere global model from COLA was implemented at CPTEC and is
being tested. Assimilation of oceanic surface and subsurface data from PIRATA array is
GPC-SIF/Doc. 5.8, p. 2
being planned as well as numerical experiments in seasonal climate forecasts using the
coupled model.
Since 2002, the Eta regional model, with 40 km horizontal resolution, is run on a monthly
basis to produce seasonal forecasts for the whole South American. The Eta/CPTEC model
runs with the boundary conditions provided by the CPTEC AGCM.
CPTEC has developed also a statistical model, the SIMOC (”Sistema de Modelagem
Estatística dos Oceanos”). It is based on canonical correlations using Pacific and Atlantic
SST’s as predictors of seasonal rainfall anomalies for many areas of South America
(Northeast Brazil, Southeastern South America, etc). Another module of the SIMOC model
also produces forecasts of SST anomalies over the tropical Atlantic. These predicted
anomalies are input to the CPTEC AGCM as lower boundary conditions. The SIMOC model
outputs can be made available to any center in the world.
III Products, confidence levels and dissemination
1.
Products (climatic, hydrological and environmental)
CPTEC’s seasonal climate and “environmental” products at global and regional scale
include:
1.1
Seasonal (up to 6 months) global and regional climate forecasts, based on the
CPTEC AGCM-T62L28, for rainfall and 2 meter air temperature anomalies.
1.2
Seasonal (up to 3 months) regional climate forecasts, based on the 40-km
Eta/CPTEC regional model, forecasts of rainfall and 2 meter air temperature.
1.3
Seasonal statistical rainfall anomalies in Northeast Brazil and Southern Brazil
using the SIMOC statistical model.
1.4
Seasonal statistical SST anomalies over Tropical Atlantic Ocean
1.5
Seasonal forecasts of risks of fire in South America (derived from the global and
regional seasonal climate forecasts.
1.6
Seasonal soil moisture content and soil moisture storage (experimental for the
Northeast Brazil, soon to be extended to South America using the CPTEC AGCM
T62L28 and the 40-km Eta/CPTEC models.
1.7
Seasonal river streamflow forecasts (experimental for the La Plata River Basin in
southern Brazil-Argentina-Uruguay) for generation of hydroelectricity activities
(based on CPTEC AGCM T62L28 and the 40-km Eta/CPTEC models.
2.
Skill and confidence levels, assessments of climate predictability
Measurements of model skill used at CPTEC include the (a) Anomaly correlation, (b)
Relative Operating Characteristics ROC, (c) Brier skill score, (d) Bias score, and (e) the Root
Mean Square Error (RMSE). These diagnostics permit direct intercomparison of results
across different geographical regions, forecast ranges, etc. For these verifications, we have
used the CMAP-Xie/Arkin rainfall data sets as “rainfall observations”’, and we are about to
include the CRU-Hulme/New data sets for rainfall and air temperature data sets for future
studies.
1.1.1 products are presented as seasonal (3-month) anomaly maps based from a 10-year 9member ensemble climatology from the CPTEC AGCM forced with observed SST anomalies
during the 1982-91 period. Indices of skill and confidence levels were assessed based on
this 10-year climatology. Together with the rainfall anomaly maps from the ensemble mean,
maps of masked rainfall anomalies, with correlations larger than 0.3, are also presented. In
addition, seasonal maps of probabilities of rainfall categories above normal, near normal and
below normal, as well as a “rebuilt ” forecast are presented for South America, based on the
1982-91 climatology of the CPTEC AGCM.
GPC-SIF/Doc. 5.8, p. 3
Given the limitations of this short model climatology, a 50-year climatology for the period
1949-2000 is being run jointly at IRI and at CPTEC (using the new SX-6 supercomputer).
These products are presented for South America only because of our regional interests, but
can be issued at global scale.
Regional Eta/CPTEC seasonal forecasts are presented as total rainfall and temperature
maps, since the regional model climatology is not yet known. for South America.
For research purposes, stratification according to the state of ENSO is made based on the
10-year model climatology. When the 50-year model climatology is ready, the analyses will
be re-done since the 1949-200 period allows more ENSO events in this hindcast period.
Scores are to be provided for each of three categories:
All hindcast seasons
Seasons with El Niño active
Seasons with La Niña active
3.
Product dissemination
The dissemination of products is made via internet mainly, and CPTEC’s web site
(www.cptec.inpe.br) is accessible in Portuguese, English and Spanish. In this web site
products available at CPTEC include monthly, seasonal forecasts of global and regional
precipitation, air temperature and other atmospheric fields, and figures of precipitation
anomalies and probabilities are presented for South America. Additional information includes
maps of 1consensus seasonal forecasts of rainfall for Brazil and South America. This
information is freely available from the CPTEC web site, whereas model outputs from the
CPTEC AGCM are of restricted access for registered users. Additionally, bulletins and are
also available., Climate Diagnostic Forum meetings in Brazil and in South America occurs
regularly and takes major contribution from CPTEC.