Polar Climate Introduction
In the changing climate, the poles are warming faster than the rest of the world. This heating has both regional and global effects, including loss of habitat, melting permafrost, and sea level rise. While some of these impacts have already been observed, many questions remain as to how the climate in the polar regions will evolve in the future. By studying satellite products, in-situ measurements, reanalyses, and climate model outputs, we work to better constrain the current state of the Arctic and Antarctic. In addition, we work towards understanding the atmospheric processes unique to these regions and how these processes may respond to the changing climate. Our work in this area is funded by NASA.
Quantifying Antarctic Surface Energy Balance
In order to establish benchmarks of today’s polar climates, we are comparing multiple observational platforms (NEWS), reanalyses (MERRA, MERRA-2, ERA-Interim, and JRA-55), and climate models (CMIP5 Ensemble) to estimate the annual mean energy imbalance in the Antarctic (as well as the Arctic). As the figure at the left shows, the spread amongst individual flux components is large, which affects the estimated imbalance. Our best estimate of the total imbalance of energy in the Antarctic is estimated to be 1.2 PW, implying this amount of energy is transported into the Antarctic from lower latitudes.
Quantifying Arctic Surface Energy Balance
To understand the drivers of these fluxes and explain observed changes, we have further calculate the radiative energy balance of the Arctic using satellite observations (CERES-EBAF) and partition it by surface type and cover, e.g. ice covered ocean or snow covered land. We investigate relationships between surface cover and surface albedo, planetary albedo, and surface and atmospheric contributions to planetary albedo with ocean sea ice trends. Additionally, we can compare observations and reanalyses (ERA-Interim, MERRA-2, ASR, NCEP) of albedos and radiative fluxes using the Arctic Observation and Reanalysis Integrated System (ArORIS) to assess reanalyses products.
Cloud Phase Considerations
Cloud phase (whether a cloud is composed of ice crystals, liquid droplets, or a mixture of both) is a determining factor in how a cloud influences both solar and terrestrial radiation. Our prior work has shown that persistent liquid containing clouds (LCCs) in the Arctic trap a significant amount of terrestrial radiation that would have otherwise escaped to space, leading to increased melt of the Greenland Ice Sheet (relative ice-only clouds). Global climate models have a difficult time reproducing the observed frequency of LCCs, having far too few and thus not trapping sufficient terrestrial radiation relative to the observed quantities. We continue to use NASA Satellite measurements to provide observational constraints and benchmarks for when and where LCCs occur in the polar regions that can be used to improve future climate models.