Estimating the Thermodynamic and Dynamic Contributions to Hydroclimatic Change over Peninsular Florida

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  • 1 Department of Earth, Ocean and Atmospheric Science, Florida State University, Tallahassee, Florida, U.SA.
  • 2 Center for Ocean-Atmospheric Prediction Studies, Florida State University, Tallahassee, Florida, U.SA.
  • 3 Florida Climate Institute, Florida State University, Tallahassee, Florida, U.SA.
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Abstract

In this study we examine the thermodynamically and dynamically forced hydroclimatic changes in the four representative seasons over Peninsular Florida (PF) from an unprecedented pair of high resolution regional coupled ocean-atmosphere model simulations conducted at 10km grid spacing for both the atmospheric and the oceanic components forced by one of the global climate models that participated in CMIP5. The model simulation verifies reasonably well with the observations and captures the distinct seasonal cycle of the region. The projected change in the freshwater flux in the mid-21st century (2041-2060) relative to the late 20th century (1986-2005) shows a precipitation deficit in the summer over PF, which is statistically significant. This projected change in freshwater flux over PF is enabled by the strengthening of the anticyclonic North Atlantic Subtropical High Circulation with corresponding changes in divergence of moisture, advection of moisture from changes in the winds and in the change in humidity gradient, and from the change in moisture flux convergence by the transient eddies. These changes suggest that a future warm climate could witness a drier summer over PF at the expense of a wetter West Florida Shelf. The analysis conducted in this study reveals that the changes in atmospheric circulation have a significant impact on the hydroclimate, far more than that implied by the Clausius Clapeyron Equation from changes in temperature.

Corresponding Author Email: vmisra@fsu.edu

Abstract

In this study we examine the thermodynamically and dynamically forced hydroclimatic changes in the four representative seasons over Peninsular Florida (PF) from an unprecedented pair of high resolution regional coupled ocean-atmosphere model simulations conducted at 10km grid spacing for both the atmospheric and the oceanic components forced by one of the global climate models that participated in CMIP5. The model simulation verifies reasonably well with the observations and captures the distinct seasonal cycle of the region. The projected change in the freshwater flux in the mid-21st century (2041-2060) relative to the late 20th century (1986-2005) shows a precipitation deficit in the summer over PF, which is statistically significant. This projected change in freshwater flux over PF is enabled by the strengthening of the anticyclonic North Atlantic Subtropical High Circulation with corresponding changes in divergence of moisture, advection of moisture from changes in the winds and in the change in humidity gradient, and from the change in moisture flux convergence by the transient eddies. These changes suggest that a future warm climate could witness a drier summer over PF at the expense of a wetter West Florida Shelf. The analysis conducted in this study reveals that the changes in atmospheric circulation have a significant impact on the hydroclimate, far more than that implied by the Clausius Clapeyron Equation from changes in temperature.

Corresponding Author Email: vmisra@fsu.edu
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