1. ECPC’s Forecast System

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. 2001a) to make routine experimental global forecasts. These global forecasts (daily out to 7days and weekly out to 16-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; Roads et al. 2002) in order to gain increased spatial resolution (50-25 km resolution) 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 discussed in Auad et al. (2002).

2. Forecast Skill Evaluations

Four years worth of forecasts (208 forecasts) have now 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. (2001a,b), Roads and Brenner (2002), 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, monthly and seasonal averages demonstrate significant skill (see Reichler and Roads 2002), which may be comparable to empirical long-range forecast methodologies. A recent evaluation of the corresponding RSM seasonal forecasts indicated similar skill (Roads et al. 2002d).

3. Global seasonal GSM forecasts and US monthly RSM forecasts

Fig.s 1,2,3,4 show the GSM and RSM seasonal forecast normalized anomalies normalized (by GSM or RSM standard deviations) of 2-m surface temperature, precipitation, soil moisture and the FWI for the Sept., Oct., Nov. 2002 time frame.

Above normal seasonal temperatures (Fig. 1) are now being forecast for equatorial Africa, eastern Australia, Europe, the central equatorial and subtropical Pacific Ocean as well as the subtropical south Atlantic. Below normal temperatures are being forecast for the western Pacific, equatorial Atlantic and the south Atlantic. The US temperatures are forecast to be normal, except for the slightly low temperatures in the Gulf of California.

Above normal seasonal precipitation forecasts (Fig. 2) include the northern Amazon, East Africa, Europe and western Russia, southern Argentina, equatorial and north Pacific ocean, and the ocean off the coast of China. A band of above normal precipitation over the southern hemisphere storm track is also forecast. Below normal precipitation is being forecast for Central America, West Africa, parts of China and the west Pacific, which may be related to a developing El Nino. Over the US, above normal precipitation is being forecast for the western US and eastern Mississippi River Basin, as well as the Gulf of Mexico. Below normal precipitation is still being forecast for the south Atlantic states.

Soil moisture (Fig. 3) forecasts are indicating that the north and equatorial Africa as well as parts of western Russia and Siberia and China will be dry, as will the northern Amazon and Australia. The US Mississippi River Basin is forecast to be relatively wet, while the Southwest and Mexico is forecast to again be relatively dry.

The seasonal FWI (Fig. 4is indicating potential fire danger in western Russia, Siberia and China, as well as southern Australia. Below normal fire danger is being forecast for the US and Canada, as well as Brazil and Argentina, North Africa and the Middle East.

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 2002: Ocean Forecasts. JGR (submitted)

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. and J. Roads, 2002: Role of initial and boundary conditions in seasonal predictability. Nonlinear Processes in Geophysics (in press)

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. 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.O., S-C. Chen and F. Fujioka, 2001a: ECPC’s Weekly to Seasonal Global Forecasts. Bull. Amer. Meteor. Soc., 82, 639-658.

Roads, J., B. Rockel, E. Raschke, 2001b: Evaluation of ECPC’s Seasonal Forecasts Over the BALTEX Region and Europe. Meteorologische Zeitschrift Vol. 10 (4) p. 283-294.

Roads, J. and S. Brenner, 2002: Global Model Seasonal Forecasts for the Mediterranean Region. Israel Journal of Earth Sciences. 51 (1), 1-16.

Roads, J., S. -C. Chen, J. Ritchie, 2002a: ECPC’s Weekly to Seasonal U.S. Forecasts of FWI, Soil Moisture, and Precipitation. ELLFB bulletin, June. 2002.

Roads, J., S.-C. Chen, M. Kanamitsu, 2002c: US Regional Climate Simulations and Seasonal Forecasts. Journal of Geophysical Research-Atmospheres (in press).

Roads, S. Chen, M. Kanamitsu, 2002d: Experimental US Seasonal Forecasts. (submitted)