ABSTRACT Using data from 17 coupled models and nine sets of corresponding Atmospheric Model Intercomparison Project （AMIP） results, we investigated annual and seasonal variation biases in the upper 50 m of the sout...ABSTRACT Using data from 17 coupled models and nine sets of corresponding Atmospheric Model Intercomparison Project （AMIP） results, we investigated annual and seasonal variation biases in the upper 50 m of the south-central equatorial Pacific, with a focus on the double-ITCZ bias, and examined the causes for the amplitude biases by using heat budget analysis. The results showed that, in the research region, most of the models simulate SSTs that are higher than or similar to observed. The simulated seasonal phase is close to that observed, but the amplitudes of more than half of the model results are larger than or equal to observations. Heat budget analysis demonstrated that strong shortwave radiation in individual atmospheric models is the main factor that leads to high SST values and that weak southward cold advection is an important mechanism for maintaining a high SST. For seasonal circulation, large surface shortwave radiation amplitudes cause large SST amplitudes.展开更多
Water budgets terms, evapotranspiration (E), precipitation (P), runoff (N), moisture convergence (MC) and both surface as well as atmospheric residual terms have been computed with National Centers for Environmental P...Water budgets terms, evapotranspiration (E), precipitation (P), runoff (N), moisture convergence (MC) and both surface as well as atmospheric residual terms have been computed with National Centers for Environmental Prediction (NCEP) (1948-2007) and European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-40 (1958-2001) reanalysis data sets for Central Southwest Asia (CSWA).The domain of the study is 45° - 75°E & 25° - 40°N. Only the land area has been used in these calculations. It is noted in the comparison of both reanalysis data sets with Global Precipitation Climatology Centre (GPCC) that all three data sets record different precipitation before 1970. The maximum is from NCEP and the minimum with ERA-40. However, after 1970 all the data sets record almost the same precipitation. ERA-40 computes two phases of MC. Before 1975, the domain acts as a moisture source, whereas after 1975 it behaves as a moisture sink. The region CSWA is divided into six sub areas with rotational principle factor analysis and we distinguish them by different approached weather systems acting on each area. Finally, NCEP yearly precipitation is further divided into seasons;winter (November to April) and summer (May to October) and two phases have been noted. The variation in winter precipitation is more than summer during last 60-year analysis.展开更多
基金supported by the Global Change Research Great Scientific Research Plan Program: "Development and Evaluation of High Resolution Climate Models" (Grant No.2010CB951904)the National Natural Science Foundation of China (Grant Nos.41075059 and 41023002)
文摘ABSTRACT Using data from 17 coupled models and nine sets of corresponding Atmospheric Model Intercomparison Project （AMIP） results, we investigated annual and seasonal variation biases in the upper 50 m of the south-central equatorial Pacific, with a focus on the double-ITCZ bias, and examined the causes for the amplitude biases by using heat budget analysis. The results showed that, in the research region, most of the models simulate SSTs that are higher than or similar to observed. The simulated seasonal phase is close to that observed, but the amplitudes of more than half of the model results are larger than or equal to observations. Heat budget analysis demonstrated that strong shortwave radiation in individual atmospheric models is the main factor that leads to high SST values and that weak southward cold advection is an important mechanism for maintaining a high SST. For seasonal circulation, large surface shortwave radiation amplitudes cause large SST amplitudes.
文摘Water budgets terms, evapotranspiration (E), precipitation (P), runoff (N), moisture convergence (MC) and both surface as well as atmospheric residual terms have been computed with National Centers for Environmental Prediction (NCEP) (1948-2007) and European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-40 (1958-2001) reanalysis data sets for Central Southwest Asia (CSWA).The domain of the study is 45° - 75°E & 25° - 40°N. Only the land area has been used in these calculations. It is noted in the comparison of both reanalysis data sets with Global Precipitation Climatology Centre (GPCC) that all three data sets record different precipitation before 1970. The maximum is from NCEP and the minimum with ERA-40. However, after 1970 all the data sets record almost the same precipitation. ERA-40 computes two phases of MC. Before 1975, the domain acts as a moisture source, whereas after 1975 it behaves as a moisture sink. The region CSWA is divided into six sub areas with rotational principle factor analysis and we distinguish them by different approached weather systems acting on each area. Finally, NCEP yearly precipitation is further divided into seasons;winter (November to April) and summer (May to October) and two phases have been noted. The variation in winter precipitation is more than summer during last 60-year analysis.
