Arctic System Reanalysis: progress and plans

In the polar regions, its is difficult to place current weather and climate trends in a long-term climatological perspective, primarily because the meteorological records there are limited in time and space in comparison with other regions of the globe. The low spatial density of polar meteorological data makes it challenging to attribute changes to local effects or to hemispheric teleconnections. Reanalyses, which assimilate all available observations into physically-consistent, regularly-spaced and comprehensive datasets, can be especially helpful in these latitudes. The timeliness of such efforts is especially pronounced given the recently-observed dramatic changes in Arctic sea ice, land ice, and permafrost regions, whose causes are being debated. A new physically-consistent synthesis of Arctic observations will be achieved through the high-resolution reanalysis of the northern high latitude region, spanning poleward from the headwaters of the northward flowing rivers. The Arctic System Reanalysis (ASR) is a collaboration of the Ohio State University, the National Center Atmospheric Research, the University of Colorado, the University of Illinois, the University of Alaska-Fairbanks, and the Ohio Supercomputer Center. The production phase of the initial ASR has been funded by the National Science Foundation as an International Polar Year (IPY 2007-2009) project covering 2000-2010. The ASR will provide a high resolution description in space (15 km) and time (1-3 h) of the coupled atmosphere-sea ice-land surface system of the Arctic. Ingested historical data streams from the surface and space, along with measurements of the physical components of the Arctic Observing Network being developed as part of IPY will be assimilated by the ASR. Gridded output fields from the ASR will serve a variety of uses such drivers for coupled ice-ocean, land surface and other models, and will offer a focal point for coordinated model inter-comparison efforts. The ASR will permit detailed reconstructions of the Arctic system's variability and change, thereby complementing efforts of the global reanalyses in illuminating the causes of high northern latitude climate change. The project will also shape the legacy observing network of the IPY by providing a vehicle for observing system sensitivity studies of the Sustained Arctic Observing Network (SAON). ASR will result in improved Arctic atmospheric and land-surface modeling and advances in high latitude mesoscale data assimilation.