Arctic sea ice and its change over the last two decades of the 20th century

Ice and snow, commonly called the cryosphere, exist at all latitudes and in about one hundred countries. Not only do the cryosphere and its characterization and distribution play a significant role in weather forecasting and climate analysis, it also has profound socio-economic value due to its role in water resources and its impact on transportation, hazards, recreation, fisheries, hunting, herding, and agriculture. The Arctic is a key component of the global cryosphere. Over the last two decades of the 20th century, the Arctic underwent significant changes in sea ice extent and thickness as part of the accelerated global warming of that period. In this study, a One-dimensional Thermodynamic Ice Model (OTIM) has been developed to estimate sea ice thickness and its “age” based on the surface energy balance at a thermo-equilibrium state, containing all components of the surface energy balance. The OTIM has been extensively validated against submarine upward-looking sonar measurements, meteorological station measurements, and comprehensive numerical model simulations. Overall, OTIM-estimated sea ice thickness is accurate to within about 20% error when compared to Canadian meteorological station measurements for ice less than 3 m. From the estimated ice thickness, sea ice can be classified into seven ice “age” categories.

The OTIM has been applied to the Arctic to estimate sea ice thickness and age distributions and trends over the last two decades of the 20th century, using the extended Advanced Very High Resolution Radiometer (AVHRR) Polar Pathfinder (APP-x) products. APP-x products currently include surface, cloud, and radiation properties covering the period of 1982-2004, with ice properties being added in the near future. Monthly mean sea ice extent, concentration, thickness, and age will be done for individual year and multiple year averages as well. The changes of the Arctic sea ice extent, concentration, thickness, and age will be studied for the period of 1982-2004 and statistical results will be presented.