NERSC Initiative for Scientific Exploration (NISE) 2010 Awards

Surface Input Reanalysis for Climate Applications 1850 - 2011

Gil Compo, University of Colorado at Boulder

Associated NERSC Project: Surface Input Reanalysis for Climate Applications (SIRCA) 1850 - 2011 (m958), Principal Investigator: Gil Compo

High-quality six-hourly tropospheric circulation datasets for the period 1850 to present are urgently needed to validate the climate model simulations being generated to predict anthropogenic effects on climate. Prior to our work, there were no such circulation analyses available before 1948. We propose to use a newly developed Kalman filter-based technique to produce a global tropospheric circulation dataset at four-times daily resolution back to 1850, building on our successful production of a dataset back to 1891. The goal is to develop improvements to the Surface Input Reanalysis for Climate Applications (SIRCA) 1850-2011 system prior to production in 2011. The timely production of these data will provide an important check on the climate models that will be used to make 21st century climate projections in the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC).

We will improve the Ensemble Filter data assimilation by incorporating new observation types using a higher resolution system. In the current Ensemble Filter system of our previous INCITE allocation, the 20th Century Reanalysis Project, only surface and sea level pressure observations were assimilated at 2 degree latitude by longitude resolution and 28 vertical levels in the atmosphere. While extremely successful, several other surface data types are available in the historical observations. These data types include position of storms, near-surface temperature data, and near-surface wind data. All three of these candidates will be tested. Additionally, computing power has increased, making it feasible to test a doubling of the resolution to 1 degree latitude by longitude and an increase in the vertical resolution to 64 levels. This may help improve the representation of the near-surface atmospheric boundary layer and upper-tropospheric transition to the stratosphere, as many of the new levels are in these regions.