热带云团的修正对流组织势与水汽、云—辐射的关系OA

The convective self-aggregation observed in cloud resolving model simulations suggests that the tropical deep convection may self-organize have significant impacts on global climate.However,there is still a lack of understanding on convective aggregation in nature and how it is to associated with convective self-aggregation in idealized simulations.In order to improve the previous method of measuring the degree of convective organization(Convective Organization Potential,COP),a new index namely the Modified Convective Organization Potential(MCOP)was introduced,which considering the cloud cluster area weighting.Compared to COP,MCOP significantly reduces its dependence on non-physical factors such as arbitrarily defined thresholds of the cloud cluster size and spatial resolution of data when measuring the degree of cloud cluster aggregation.Using the infrared brightness temperature of the Himawari geostationary satellites and ERA5 reanalysis data,the relationships between MCOP and the water vapor,cloud and radiation effects are investigated over the 10°×10° domains in the Indo-Pacific warm poolregion.Results indicate that under the same domain-mean convective intensity,more aggregated convective states are associated with drier domain-mean atmosphere,mainly because of the drying of 500-850 hPa of environment atmosphere outside the convective area.More aggregated convection tends to have relatively colder deep cores,fewer anvil clouds and larger clear sky area,and thus results in higher domain-mean Outgoing Longwave Radiation(OLR).MCOP is better correlated(above 95%confidence level)with above moisture and OLR quantities as compared with COP.The composite results show that moisture/OLR are 23.0%/14.8%more sensitive to ranks of MCOP than that of COP.