POLES is a broad investigation into the role of polar regions in the global energy and water cycles, and the atmospheric, oceanic and sea ice processes that determine that role. The primary importance of our investigation is to show how these polar processes relate to global climate.
The objectives of our current research are:
The Atmosphere and Surface Fluxes-The atmospheric advection of energy into the Arctic from lower latitudes, and the deposition of that energy within the Arctic provides a primary link between the Arctic and the global climate system. We are analyzing an 18-year record of TOVS Polar Pathfinder temperature and moisture profiles, adding NCEP winds, and producing a climatology of heat and moisture advection into the Arctic. We are exploring the variability of these transports and their connection with hemispheric atmospheric oscillations.
Radiative fluxes dominate the surface energy budget over snow and ice throughout much of the year and in most high-latitude regions. We are producing critical data sets on cloud properties and their effect on radiative forcing of the sea ice cover and are intercomparing these radiative flux data sets with those commonly used in ice models and those computed in the NCEP and ECMWF reanalyses. We have created and analyzed a 2-m air temperature data set from buoy and station data and have reported a warming trend for May and June: an earlier onset of the summer season.
The Ocean and Sea Ice-Significant changes in Arctic climate have been observed in the late 1980s and 1990s. Our models show that Atlantic Water inflow to the Arctic Ocean has increased during the high NAO phase in the early 1990s, and that this increase is mainly via the Barents Sea. We have discovered a remarkable and related reduction in the extent of the Cold Halocline Layer of the Arctic Ocean, as observed by both icebreaker and submarine cruise data.
Ice-Ocean Model Development and Testing-Ice-ocean models are an important component of global climate models. We are improving ice-ocean models, testing them, and making them more computationally efficient. We have undertaken a comparison of thickness as modeled and as observed by submarines. Such tests provide a new and crucial measure of performance for sea ice models. We have constructed a global ice-ocean model that couples the latest GFDL Modular Ocean Model (MOM2) with our sea ice model and our latest numerical scheme for ice dynamics which is an order of magnitude faster than previous schemes. Together with our existing regional ice-ocean model for the north polar ocean, the global ice-ocean model allows us to examine the effects of global-scale ocean circulation and poleward oceanic heat transport on the behavior of the ice-ocean systems in both polar regions.
Algorithm Development, Data Set Production, and Validation-We have put considerable energy into improving algorithms for polar cloud and surface variables, and producing data sets based on these algorithms in collaboration with the AVHRR and TOVS Polar Pathfinders. Our strategy is to intercompare cloud and radiation products from AVHRR, and from TOVS with each other and with available in situ and buoy data sets. By the end of this year we will have a full 18 years of TOVS Polar Pathfinder data and 14 years of AVHRR Polar Pathfinder data. As early products have been produced, we have worked to improve the performance of these algorithms and the efficiency of radiation codes by replacing the radiative transfer code Streamer with a neural network FluxNet..