Investigation of the Contemporary and Paleo Climates of the McMurdo Dry Valleys, Antarctica

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The Office of Polar Program, Antarctic Science Divison, Ocean & Climate Systems Program has made this award to suppport a series of atmospheric modeling exercises for examining climate variability in the McMurdo Dry Valleys region. Various implementations of the Polar MM5 atmospheric model that has been adapted for polar conditions will be used to characterize spatial and temporal variability of the contemporary climate and its controlling mechanisms. Boundary conditions for the model will be adjusted to address the question of how lakes much larger than the current ones persisted in the Dry Valleys during the last Glacial Maximum and into the Holocene despite nearby ice core evidence suggesting an annual mean temperature 4-8 degree C cooler than present. A nested modeling approach will be undertaken with larger scale conditions provided by archived model runs from the Antarctic Mesoscale Prediction System that is a collaborative experimental numerical weather forecasting project focused on Antarctica and having resolution that varies regionally from 60-km to 2.2-km. To study contemporary spatial and temporal variability, the PI will nest a 1-km horizontal resolution version of Polar MM5 that extends in 32 levels from the surface to the stratosphere with output at hourly intervals for a full year interval. Interannual variability and larger-scale (El Nino-Southern Oscillation and the Southern Annular Mode) climate interactions will be assessed over the melt season with lesser horizontal resolution (2-km) simulations from 1985 to the present. To address the paleo question, the LGM topography will be employed and ice and humidity adjusted to simulate paleo conditions. The PI demonstrated in the proposal that an existing 2.2-km implementation of Polar MM5 could be adjusted in logical ways to obtain closer agreement with Automatic Weather Station observations in the Dry Valleys. This lends confidence that proposed additional improvements including proper land type depiction, reduced model reinitializations and parameterizing the effects of shading and slope aspect on the amount of solar radiation will result significant progress in modeling capabilities and understanding of Dry Valley climate variability. Broader impacts: The outcome of this project could have important implications for ongoing Long-Term Ecological Research projects in the Dry Valleys. Results from the proposed project are to be posted on a local web site and given to the National Snow & Ice Data Center for broader dissemination. This proposal constitutes the first NSF support obtained by the PI who currently has postdoctoral status at Ohio State University hence it provides early career support. The material generated by this project will be used in university lectures by the co-PI and it is intended to be used in outreach efforts in the form of visits with lectures to Columbus Public Schools whose student bodies are made of a dominant fraction of underrepresented groups. Collaboration with the Byrd Polar Research Center outreach coordinator is intended to yield data and visualization materials for middle and high school student visitors to the Center and eventually an LTER DVD intended for teachers.