| The newly available Advanced Very High Resolution Radiometer (AVHRR) Polar Pathfinder (APP) data set of 18 years over 1982 to 1999, subsampled to a 25 km resolution, was used to retrieve surface, cloud, and radiation properties for the Arctic. The extended products, called APP-x data set, were produced by CASPR (Cloud And Surface Parameter Retrieval system). Calibration analysis indicates that the probability of obtaining an unrealistic trend from a population with no trend is negligible. Validation study indicates that the APP-x data set is a reliable and accurate data set for the climate studies of the polar regions in terms of data quality in both spatial and temporal domains.; This study presents a successful attempt to take advantage of the long-term records of satellite data to study Arctic climate characteristics and recent trends spatially and temporally detailed. Arctic climate in surface, cloud, and radiation properties have been detailed, and its trends in those properties are also presented. It has been found that Arctic climate has been changing rapidly over the past two decades, but different seasons have different scenarios. An important feedback mechanism, called cloud forcing, was investigated and revealed at the first time that clouds have been responding to Arctic climate change by always exerting a damping effect on the rise in surface temperature. It indicates that cloud is a crucial factor affecting and regulating Arctic climate and its changes, and Arctic climate change must be strongly affected and related to the global climate change as evidenced in this study through the analysis of the relationship between Arctic climate change and global climate change. |
