Arctic Sea Ice Changes, Interactions, and Feedbacks on the Arctic Climate during the Satellite Era

Of all the components of the Earth climate system, the cryosphere is arguably the least understood even though it is a very important indicator and an effective modulator of regional and global climate change. Changes in sea ice will significantly affect exchanges of momentum, heat, and mass between the ocean and the atmosphere, and have profound socio-economic impacts on transportation, fisheries, hunting, polar animal habitat and more. In the last three decades, the Arctic underwent significant changes in sea ice as part of the accelerated global climate change. With the recently developed One-dimensional Thermodynamic Ice Model (OTIM), sea and lake ice thickness and trends can be reasonably estimated. The OTIM has been extensively validated against submarine and moored upward-looking sonar measurements, meteorological station measurements, and comprehensive numerical model simulations. The Extended AVHRR Polar Pathfinder (APP-x) dataset has 25 climate parameters covering surface, cloud, and sea ice properties as well as surface and top-of-atmosphere radiative fluxes for the period 1982 - 2004 over the Arctic and Antarctic at 25 km resolution. The OTIM has been used with APP-x dataset for Arctic sea ice thickness and volume estimation. Statistical analysis of spatial and temporal distributions and trends in sea ice extent, thickness, and volume over the satellite period has been performed, along with the temporal analysis of first year and multiple year sea ice extent changes. Preliminary results show clear evidence that Arctic sea ice has been experiencing significant changes over the last two decades of the 20th century. The Arctic sea ice has been shrinking unexpectedly fast with the declines in sea ice extent, thickness, and volume, most apparent in the fall season. Moreover, satellites provide an unprecedented opportunity to observe Arctic sea ice and its changes with high spatial and temporal coverage that is making it an ideal data source for mitigating the shortcomings of current climate models in the projections of future climate change and feedback mechanisms at high latitudes. Interactions and feedbacks between clouds, sea ice, and various atmospheric circulation patterns in the Arctic are also investigated based on multi-decadal satellite products, including cloud characteristics and radiation fluxes from the MODerate resolution Imaging Spectroradiometer (MODIS) data and the APP-x dataset, sea ice products from Special Sensor Microwave/Imager (SSM/I), and various atmospheric parameters from reanalysis data sets. Results demonstrate that changes in sea ice concentration and cloud cover played major roles in the magnitude of recent Arctic surface temperature trends. Interactions between sea ice and clouds are strong, such that recent shrinking of sea ice extent might influence future cloud cover changes. Not surprisingly, cloud cover is also affected by changes in large-scale atmospheric circulation patterns. Quantitative analyses of the relationships between trends in these parameters provide new insight into polar climates.