Spatio-temporal variability of cloud top and tropopause heights over the Arctic from 10-year CALIPSO, GPSRO and MERRA-2 datasets

Abstract

The characteristics of cloud top heights (CTHs) and tropopause heights (TPHs) over the Arctic and their relationship were investigated using Cloud-Aerosol Lidar Infrared Pathfinder Satellite (CALIPSO) observations and Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2) data for approximately 10 years from June 2006 to March 2016. Global positioning system radio occultation (GPSRO) measurements were also used to validate the TPHs derived from the MERRA-2 reanalysis data. Results of the composite analysis indicate that CTHs over the Arctic generally constitute the low-top (lower than ~3 km) and high-top (higher than ~7 km) categories in all seasons. The high CTHs above approximately 8 km show a close relationship with TPHs in all seasons, with an especially strong positive correlation in winter. In general, both CTH and TPH for each season revealed by composite analysis exhibited a zonally symmetric pattern with greater heights at lower latitudes, except for the winter when significantly high CTHs and TPHs were observed in the Greenland Sea, Atlantic, and Scandinavian regions. The proportion of high CTHs in these regions was higher than that in other regions. Notably, CTH values in the range of approximately 9.7–10.5 km over these regions are slightly higher than the climatological TPHs in winter. From a detailed analysis of Atlantic storm tracks, we conclude that the Atlantic windstorms make a significant contribution to the higher CTHs and TPHs over the Norwegian, Greenland, Kara-Barents Seas, and Northwest Russian regions of the Arctic.