THE ENERGY BUDGETS UNDER DIFFERENT SYNOPTIC CONDITIONS OVER HUAIHE RIVER BASIN DURING HUBEX FIELD OBSERVATION PERIODS IN 1999

In different synoptic conditions and at different time scales,the analysis of the energy budgetsby Bowen Ratio Method and Bulk Schemes over Huaihe River Basin during the field observationperiods of HUBEX in 1999 shows that,(1)the averaged latent heat flux is an order of magnitudemore than the averaged sensible heat flux during the observation period:(2)the variation of totalcloud amount is out of phase with the terms of energy budgets except for the downward longwaveradiation which maybe is related to the cloud's height and class:(3)the values of sensible andlatent heat fluxes are small during rain episodes,but thereafter,the values become high and thenup to maximum.It is similar to the other terms of the energy budgets except for the downwardlongwave radiation.The diurnal variation of energy budgets indicates that the daytime precipitationexerts great influence to the energy budgets,but the nighttime precipitation makes little influence;(4)the variation of the latent heat flux is in phase with the evaporation,which indicates that thelatent heat flux calculated by bulk schemes is reliable:(5)the means of the sensible and latentheat flux and momentum flux by bulk schemes for the time period from May to August are,respectively,30.71W/m~2.116.81W/m~2.2.86×10~(-2)N/m~2 in 1998 and 30.28W/m~2,107.35W/m~2,2.74×10~(-2)N/m~2 in 1999.The values of these two years are similar.During summer in1999 the magnitude and activity of sensible heat flux are strongest in June and those of the latentheat flux are in August.     

NUMERICAL EXPERIMENTS OF THE EFFECTS OF SEA SURFACE TEMPERATURE ANOMALIES OVER THE PACIFIC ON PRECIPITATION IN 1991*

A zonal domain,primitive equation model is used in this paper to study the influences of the main sea surface temperature anomaly(SSTA) areas over the Pacific on precipitation in 1991.Some numerical experiments are made and the mechanisms of the influences are discussed.The results show that the influences of the SSTA are mainly confined within the tropical and the subtropical regions.The direct effect of the SSTA is to change the exchanges of the sensible heat and the water vapour between the air and the sea,through the consequent changes of temperature and the flow fields and the feedback process of condensation,the SSTA finally affects precipitation.