THORPEX-Pacific Workshop Kauai, Hawaii Polar Meteorology Group, Byrd Polar Research Center, The Ohio State University, Columbus, Ohio David H. Bromwich 1,2 and Keith M. Hines 1 1 Polar Meteorology Group Byrd Polar Research Center The Ohio State University Columbus, Ohio, USA 2 Atmospheric Sciences Program Department of Geography The Ohio State University Columbus, Ohio, USA Arctic IPY ( ): Arctic System Reanalysis

THORPEX-Pacific Workshop Kauai, Hawaii Polar Meteorology Group, Byrd Polar Research Center, The Ohio State University, Columbus, Ohio Links Between the Pacific and Arctic n Aleutian Low – especially important for winter n PNA Pattern – ENSO/Wave propagation n Pacific Decadal Oscillation n September 2007 All-Time Minimum in Arctic Sea Ice Extent – concentrated in the Pacific Sector n IPY (2007/9) Overlaps with Wintertime THORPEX-Pacific (Jan.-Mar. 2009)

The storm of 19 October 2004 as depicted by the NCEP/NCAR global reanalysis. Contours represent isobars of sea level pressure at increments of 3 hPa. [from visualization package of NOAA Climate Diagnostics Center] The Figure shows an intense storm depicted in the NCEP/NCAR reanalysis for 19 October The storm led to flooding of Nome, Alaska, and has a central pressure of 949 hPa in the reanalysis. The actual central pressure deduced by the National Weather Service was as low as 941 hPa. The Need for Improved Atmospheric Reanalyses

Arctic System Reanalysis (ASR) an NSF-Funded IPY Project 1.Rapid climate change is occurring in the Arctic. An integrated picture of coupled atmosphere/land surface/ ocean interactions is needed on synoptic and climatic time scales. 2. Global reanalyses encounter many problems at high latitudes. The ASR would use the best available description for Arctic processes and would enhance the existing database of Arctic observations. The ASR will be produced at improved temporal resolution and much higher spatial resolution. 3. The ASR would provide fields for which direct observation are sparse or problematic (precipitation, radiation, cloud,...) at higher resolution than from existing reanalyses. 4. The system-oriented approach provides community focus including the atmosphere, land surface and sea ice communities. 5. The ASR will provide a convenient synthesis of Arctic field programs and integrate Pacific region observations.

ASR Outline A physically-consistent integration of Arctic and other Northern Hemisphere data Current Participants: Ohio State University - Byrd Polar Research Center (BPRC) - and Ohio Supercomputer Center (OSC) National Center Atmospheric Research (NCAR) Universities of Colorado, Illinois, and Alaska-Fairbanks High resolution in space (<20 km) and time (3 hours) - convenient for synoptic studies Begin with years (Earth Observing System) Also Interested: NOAA (Also provided start-up funds) NASA U.S. Department of Energy

ASR Numerical Model: Polar WRF Weather Research and Forecasting Model SHEBA 1997/8 Grid January 1998 Results Polar Optimization at the Byrd Polar Research Center: Fractional sea ice Sea ice albedo Morrison microphysics (2-moment) Noah LSM modifications Heat transfer through snow and ice

ASR High Resolution Domain Outer Grid: ~45 km resolution Inner Grid: ~15 km resolution Vertical Grid: ~70 levels ASR will detail the downstream impacts from the Pacific sector

Numerical Experiments within the ASR Framework The ASR will employ modern, efficient Data Assimilation techniques. Observing System Experiments (OSEs) are numerical model-based experiments to test the impact of new and existing observations. Sometimes called “data denial” experiments. Observing System Simulation Experiments (OSSEs) are numerical experiments that test impacts of future observing systems, e.g., new satellite sensors and Automatic Weather Stations Determine the observations needed to optimize the Arctic observing system.

Other Considerations for the ASR Impact of Pacific weather on Alaska and the Beaufort Sea, including extreme events Impact of Pacific weather on Alaska and the Beaufort Sea, including extreme events New and improved Data Assimilation in cloudy areas New and improved Data Assimilation in cloudy areas Optimized numerical modeling for the Arctic (e.g., mixed-phase clouds, variable sea ice characteristics, and realistic Arctic land representation – e.g., permafrost) Optimized numerical modeling for the Arctic (e.g., mixed-phase clouds, variable sea ice characteristics, and realistic Arctic land representation – e.g., permafrost) Interaction of Ocean and Sea Ice communities with the Atmospheric Reanalysis Interaction of Ocean and Sea Ice communities with the Atmospheric Reanalysis

THORPEX-Pacific Workshop Kauai, Hawaii Polar Meteorology Group, Byrd Polar Research Center, The Ohio State University, Columbus, Ohio Key Points for ASR and THORPEX-Pacific n Synoptic and Climate Applications n Detailing Arctic features downstream of the Pacific Sector n Combining remote sensing, modeling and in-situ observations n High resolution Polar WRF simulations n Advanced Data Assimilation n Expansion to the period? n ASR Planning Meeting late February at NCAR … consider THORPEX-Pacific contribution?