Khara Lombardi December 1, 2004 EAS 6792 A Sensitivity Analysis of Fluxes Between the Atmosphere-Ocean Interface Using the Kantha – Clayson Ocean Model Khara Lombardi December 1, 2004 EAS 6792

Outline Introduction Model Used Data Methodology Results Summary and Conclusions Questions

Model Used in this Analysis Ocean model developed by Kantha and Clayson (1994). The model uses wind stress, solar radiation flux, other fluxes combined (longwave and turbulent), evaporation, and precipitation data. Within the model, there are four parameters that can be varied, and thus, this is how the model can be used to do a sensitivity analysis study. The four parameters that can be varied are: solar radiation flux, heat flux loss, surface stress, and precipitation. The model runs with the user defined parameter amounts and then outputs the future profiles of TKE, temperature, winds, shear and buoyancy production, and precipitation amounts.

Data All data were obtained from the SeaFlux website: http://curry.eas.gatech.edu/SEAFLUX/valdata-cg.html Data selection was based on location and necessary variables. To perform a proper sensitivity analysis based on latitudinal location, three data sets, each from a different region, were obtained. SHEBA (Surface HEat Budget of the Arctic Ocean): Oct. 1997 – Sept. 1998, ship that drifted with an ice pack from 75N, 144W, to 80N, 165W. ASTEX (Atlantic Stratocumulus Transition EXperiment): June 1992, 30N, 36W. PACS (PanAmerican Climate Studies): Apr. 1997 – Sept. 1998, 9.96N, 125.39W, and 2.778S, 124.66W.

Data (continued) Temperature and salinity profiles were also necessary for the model to run properly. Levitus94 Ocean Climate data was used to obtain these values: http://iridl.ldeo.columbia.edu/SOURCES/.LEVITUS94/.dataset_documentation.html

Methodology Levitus94 data was interpolated so that changes within 150 meters from the surface could be evaluated. SHEBA, ASTEX, and PACS data were interpolated such that there were 15 minute time steps in the data. Three analyses were done on each data set varying the heat flux loss and surface stress parameters: Normal case: the heat flux loss and surface stress parameter in the code is not changed Doubled case: the two parameters are doubled Low case: heat flux loss and surface stress is set to zero

Results - PACS High Regular Low

Results - ASTEX High Regular Low

Results - SHEBA High Regular Low

Summary of Results During the regular phase for all three programs, the temperature cooled down over the process of ten days. For all three low cases, TKE dropped to zero over all depths and temperature showed a more typical profile. For all three high cases, TKE increased greatly. TKE profiles were the highest in the regular and high cases for the SHEBA program.

Conclusions TKE was highest in the polar region, as the the surface of the ocean was cooler than the water at depth, thus mixing is strong at all times. Thus, changes in TKE were not as high. TKE also did not change much in the tropics as mixing is not strong in this region regardless of the variations in the parameters. The mid-latitudes had the greatest changes in TKE and temperature when the heat flux loss and surface stress terms were varied as mixing is variable in this region. This region was the most sensitive to the changes in the model. All TKE values went to zero during the low case as mixing was totally shut down without any heat flux loss and surface stress effects acting upon the ocean surface.

References “ASTEX Overview and Objectives.” NASA. Online. Microsoft Internet Explorer. 17 March. http://asd-www.larc.nasa.gov/fire/FIRE_II/3.5.2.html   Kantha, L. H., C. A. Clayson, 1994: An Improved Mixed Layer Model for Geophysical Applications. J. Geo. Res., 99, 25235-25266. “Levistus94 Ocean Climatology.” IRI. Online. Microsoft Internet Explorer. 17 March. http://www.ldeo.columbia.edu/edu/dees/ees/data/monthly/levi_temp.htm “PanAmerican Climate Studies (PACS).” JISAO. Online. Microsoft Internet Explorer. 15 March. http://www.jisao.washington.edu/pacs/ “SHEBA.” APL. Online. Microsoft Internet Explorer. 18 March. http://sheba.apl.washington.edu/