This proposal requests support for a postdoctoral investigator to assist in implementing state-of-the-art models of Crater Lake which couple the observed atmospheric forcing with the heat budget, lake circulation, and the hydrologic budget. Crater Lake, the deepest lake in the United States, is a closed-basin caldera lake, located at an elevation of 1882 meters in the Cascade mountains of south- central Oregon. Ongoing Limnological studies funded by the National Park Service will be expanded by a new six-year study of climatic control on the hydrologic budget, the heat budget, and on the circulation of the lake. This program, will be funded by the Park Service as part of the new "Integrated Studies of National Park Ecosystems" and will be tied in with other elements of the Olympic Peninsula Biogeographic Area. As part of this project, we have deployed a permanent thermistor mooring covering the full water column. This continuous data set is also supported by CTD (conductivity, temperature, depth) data collected whenever the lake is accessible ( 3 months/year). Meteorological data is also being collected on the lake from a buoy and from instrumentation elsewhere within the Park. Precipitation data are collected from several locations and lake level is continuously monitored from a USGS gauging station. The primary effort will be the application of various one dimensional vertical models of mixing and heat fluxes in the system using the meteorological data sets to determine surficial fluxes and the thermistor data set for model parameterization and validation. Long-term goals for the modelling effort include the eventual development of a biological model of primary and secondary production for this ultra-oligotrophic system which must include a proper description of lake physics. The post-doctoral investigator will work closely with R. Collier (OSU Oceanography) and with G. Larson (NPS and OSU Forestry) to integrate the model(s) with on-going data collection and experimental design.