Changing Arctic Sea Ice, Its Trends and Climatic Impacts over 1982-2004

Changes in sea ice will significantly affect the complex exchanges of momentum, heat, and mass between sea and the atmosphere, along with profound socio-economic influences due to its role in transportation, fisheries, hunting, polar animal habitat and more. Over the last two decades of the 20th century, the Arctic underwent significant changes in sea ice as part of the accelerated global warming of that period. More accurate, consistent, and detailed ice extent, concentration, thickness, and volume data are critical for a wide range of applications. Satellite data provide an unprecedented opportunity to estimate and monitor the Arctic sea ice routinely with relatively high spatial and temporal resolutions. In this study, the algorithms for estimating ice concentration, extent, and thickness/age have been developed including a One-dimensional Thermodynamic Ice Model (OTIM) for sea and lake ice thickness estimation. The OTIM has been extensively validated against submarine and moored Upward-Looking Sonar measurements, meteorological station measurements, and comprehensive numerical model simulations.

The OTIM has been used with satellite data from the extended Advanced Very High Resolution Radiometer (AVHRR) Polar Pathfinder (APP-x) products for the Arctic sea ice thickness, and sequentially sea ice volume estimation, and following statistical analysis of spatial and temporal distribution 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. The preliminary results show clear evidence that the Arctic sea ice has been experiencing significant changes over the past two decades of the 20th century. The Arctic sea ice has been shrinking unexpected fast in the 20th century, the declines in sea ice extent, thickness, and volume are apparent in fall season. How does the changes in sea ice relate to Arctic climate change? What is the triggering mechanism of Arctic sea ice rapid decline in recent years? How does diminishing Arctic sea ice feed back on the Arctic and Global climate? Those important questions are confronting scientists. We try to unveil the mystery by looking into the relationships between sea ice change and large-scale circulation indices, such as Arctic Oscillation (AO), North Atlantic Oscillation (NAO), and Pacific Decadal Oscillation (PDO). The accelerated changes in the Arctic sea ice since the 20thcentury should be paid extensive attention for the global warming study.