Arctic cloud radiative forcing in contemporary atmospheric reanalyses
Abstract
The Arctic region is characterized by a top-of-atmosphere (TOA) annual net radiative flux that is strongly directed upward for most of the year. Arctic clouds play an important role in modifying TOA solar and longwave fluxes, but over snow and ice-covered surfaces these effects are complex. Clouds are also thought to affect the underlying cryospheric surface properties by altering surface radiative fluxes. Atmospheric reanalyses are generally thought to have a poor representation of cloud processes at high latitudes, although the depiction of trends over the Arctic sea ice pack is less well known. Here, atmospheric TOA energy fluxes from contemporary reanalyses are examined in comparison to satellite measurements from the CERES-EBAF version 4.1 product. The reanalyses examined are the NASA MERRA-2, the ECMWF ERA5 and ERA-Interim, the JRA-55, and the regional Arctic System Reanalysis version 2. We briefly examine several methods for computing clear-sky radiative fluxes in reanalyses and the effects of uncertainty on comparisons with satellite data. In agreement with previous observation-based studies, changes with time in the shortwave cloud radiative forcing in reanalyses are found to be negligible despite strong trends in the absorbed shortwave. Over the full satellite period, there is large disagreement in the seasonality of longwave cloud forcing trends. These differences are reduced during the CERES-EBAF observing period (2003-present). An examination of the trends with respect to sea ice cover changes in each of the reanalyses is conducted.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMGC13H1241C
- Keywords:
-
- 3305 Climate change and variability;
- ATMOSPHERIC PROCESSES;
- 3307 Boundary layer processes;
- ATMOSPHERIC PROCESSES;
- 3339 Ocean/atmosphere interactions;
- ATMOSPHERIC PROCESSES;
- 4207 Arctic and Antarctic oceanography;
- OCEANOGRAPHY: GENERAL