1. ECPC’s Forecast System
As previously discussed by Roads et al. (2001a),
the Scripps Experimental Climate Prediction Center (ECPC) currently uses the
reanalysis I version (Kalnay et al. 1996) of the National Centers for
Environmental Prediction’s (NCEP’s) medium range forecast (MRF) model or global
spectral model (GSM; Roads et al. 1999). These global forecasts (4xdaily-7 days
and weekly to 12-weeks) start from the NCEP operational 00UTC global analysis.
The GSM then forces a regional spectral model (RSM; Juang and Kanamitsu, 1994;
Juang et al. 1997; Chen et al. 1999, Anderson et al. 2000, Roads and Chen 2000)
in order to gain increased spatial resolution (50-25 km resolution) at shorter
time scales (4xdaily-7 days and weekly to 4 weeks) for several selected regions
(US, CA, SW, Brazil). At even smaller space (2-km resolution) and time scales
(8xdaily to 2 days) either the NCEP analysis or GSM forces a corresponding
nonhydrostatic mesoscale spectral model (MSM; Juang, 1997) for the Hawaiian
Islands. All atmospheric models are based upon the same physics used in the GSM
and can, in principle, be updated as the GSM is updated. Output products from
the atmospheric models include a fire weather index (FWI, see Roads et al.
1997) and associated variables such as 2m-temperature, relative humidity and
10m-windspeed as well as precipitation and soil moisture. The global atmospheric model is now forcing an ocean model
and corresponding ocean forecasts are shown in Auad et al. (2002).
2. Forecast Skill Evaluations
2 years worth of forecasts (104
forecasts) have been used to develop a GSM forecast climatology dependent upon
season as well as lag. Both means and standard deviations were derived in order
to provide normalized (by the standard deviation) anomalies. As discussed by
Roads et al. (2001b,c, d) and Chen et al. (2001), the GSM provides skillful
forecasts of temperature, precipitation, soil moisture and a fire weather index
at long forecast ranges. Although the greatest skill occurs initially and then
decays, daily, weekly or monthly forecast skill does not ever reach zero and forecasts
averaged into monthly and seasonal averages demonstrate significant skill (see
Reichler et al. 2001), which may be comparable to empirical long-range forecast
methodologies. Similar evaluation efforts are underway for the regional
forecasts, which currently use the GSM initial state and boundary conditions
3. Global seasonal GSM forecasts and US monthly RSM
forecasts
Figs 1,2,3,4 show the GSM seasonal
forecast normalized (by GSM standard deviation) anomaly forecasts of 2-m
surface temperature, precipitation, soil moisture and the FWI for Mar.-May
2002. We fully intend to show anomalous RSM forecasts in subsequent ELLFB
submissions since we are now actively developing an RSM climatology for the RSM
simulations.
Above normal seasonal temperatures (Fig.
1) are now being forecast for most southern US states, North Africa, Europe
Russia and Asia, the western tropical Pacific, and the midlatitude Southern
Hemisphere. Below normal temperatures are being forecast for the Eastern
Pacific, the Indian Ocean, and the Maritime continent as well as Australia and
South America.
Above normal seasonal precipitation
forecasts (Fig. 2) include the eastern US, Europe, eastern tropical Africa and
Asia. Below normal precipitation is being forecast for the western US, the
Great Lakes region, the eastern north and tropical Pacific, South Africa and
the eastern tropical Pacific.
Soil moisture (Fig. 3) forecasts are
indicating that most of the North American Continent will be dry, along with
eastern Brazil, West and South Africa, India, and eastern Australia. Wet
regions include Russia and East Africa.
The seasonal FWI (Fig. 4) is forecast to
be above normal in the US Northwest and Great Lakes region, Russia, India,
northern Australia and southern subtropical Africa. The FWI is forecast to be
below normal over the US Rocky Mountain Front Range, eastern equatorial Africa, and western Brazil. These
forecasts tend to follow the RH forecasts, which in turn tend to have and
inverse relationship with respect to temperature forecasts.
Other experimental GSM and RSM forecast
fields (wind speed, relative humidity) and additional forecast months) can be
found at http://ecpc.ucsd.edu/projects/ellfb/. Additional forecast ranges, variables, and
regions are displayed at http://ecpc.ucsd.edu/m2s/m2s_ECPC_forecasts.html/.
All forecasts and new experimental fire danger (USFS fire danger indices), land
surface, and ocean predictions (seasonal to decadal) can be linked from
http://ecpc.ucsd.edu/predictions/.
References:
Anderson, B.T., J. O. Roads,
S. -C. Chen, and H-M.H. Juang, 2000: Regional Simulation of the Low-level
Monsoon Winds Over the Gulf of California and Southwest United States. JGR-Atmospheres 105 (D14) 17,955-17969.
Auad, G., A.
Miller, J. Roads 2001: Ocean Forecasts. JGR (submitted)
Auad, G., J.O. Roads, A.
Miller, and D. Cayan, 2001: An ocean
model response to NCEP, COADS and FSU surface flux fields. Journal of Geophys. Res (in
press).
Chen, S. -C.,
J.O. Roads, H. -M. H. Juang, M. Kanamitsu, Global to regional simulation of
California's wintertime precipitation. J.
Geophys. Res., 104(24), 31517-31532, 1999.
Chen, S-C. J. O.
Roads, and M. Wu, 2001: ECPC’s Asia forecasts. Journal of
Terrestrial-Atmosphere-Oceanography, 12, 377-400.
Juang, H. -M. H., and M.
Kanamitsu, 1994: The NMC nested regional spectral model. Mon. Wea. Rev.,
122, 3-26.
Juang, H. -M. H., S. -Y.
Hong and M. Kanamitsu, 1997: The NCEP regional spectral model: an update. Bulletin
Amer. Meteor. Soc., 78, 2125-2143.
Kalnay, E. et al., 1996: The
NMC/NCAR reanalysis project, Bull. Am.
Meteor. Soc., 77, 437- 471.
Reichler, T., J. Roads, M. Kanamitsu,
2001: Role of initial and boundary conditions in seasonal predictability.
Nonlinear Processes in Geophysics (submitted)
Roads, J.O., S. -C. Chen, F.
M. Fujioka, H. Juang, and M. Kanamitsu. 1997. Global to Regional Fire Weather
Forecasts. Int. Forest Fire News, 33-37.
Roads, J.O., S. -C. Chen, M.
Kanamitsu, and H. Juang, 1999: Surface Water Characteristics in the NCEP Global
Spectral Model and Reanalysis, J.
Geophys. Res. 104, 19307-19327.
Roads, J.O. and S-C. Chen,
2000: Surface Water and Energy Budgets
in the NCEP Regional Spectral Model. JGR-Atmospheres.
105 (D24) p. 29, 539.
Roads, J., S. -C. Chen, J.
Ritchie, 2001a: ECPC’s Weekly to Seasonal U.S.
Forecasts of FWI, Soil Moisture, and Precipitation. ELLFB bulletin, Dec.
2001.
Roads, J.O., S-C. Chen and
F. Fujioka, 2001b: ECPC’s Weekly to
Seasonal Global Forecasts. Bull. Amer.
Meteor. Soc., 82, 639-658.
Roads, J., B. Rockel, E.
Raschke, 2001c: Evaluation of ECPC’s Seasonal Forecasts Over the BALTEX Region
and Europe. Meteorologische Zeitschrift. (in press).
Roads, J. and S. Brenner,
2001d: Global Model Seasonal Forecasts for the Mediterranean Region. Israel
Journal of Earth Sciences (in press)
