The Arctic Climate and Its Change Revealed by Surface and Cloud Properties and Radiation Fluxes Based on the AVHRR Polar Pathfinder Data Set

摘要

The newly available Advanced Very High Resolution (AVHRR) Polar Pathfinder (APP) data set of 18 years from 1982 to 1999, subsampled to a 25 km scale, was used to retrieve cloud amount, cloud optical depth, cloud particle size, cloud temperature, cloud particle phase, surface temperature, surface broadband albedo, radiation fluxes and shortwave and longwave cloud forcing over the Arctic ocean and surrounding land areas. The spatial and temporay distributions of those retrieved Arctic climate parameters together with an analysis of the seasonal and interannual variability in those parameters, especially surface temperature, surface broadband albedo, cloud amount and precipitable water, are presented. Results show that the Arctic climate has indeed warmed up as indicated by surface temperature, cloud amount, cloud particle size and phase at confidence level of higher than 95% for Spring and Summer times, but cooled down in winter. The surface broadband albedo has decreased significantly in Autumn indicating the late onset of sea ice and snow, especially for the Arctic ocean area. The Arctic ocean surface temperature has decreased during the wintertime at confidence level of 97%, especially for the central and eastern Arctic oceans. The Arctic Oscillation(AO) has strong correlation relationship with the surface temperature and cloud amount for some Arctic areas at the confidence level of almost 100%. For different areas in the entire Arctic region, the correlation relationship is different. The surface temperature and cloud amount in Greenland have negative correlation with the AO simultaneously, while that correlation turns to be positive in the north Europe area, indicating the different Arctic areas have different effects and feedback on the global climate system or vice versa.