Sensitivity of An Idealized Tropical Cyclone to the Configuration of the Global Forecast System–Eddy Diffusivity Mass Flux Planetary Boundary Layer Scheme
| Autor: | Jun A. Zhang, Mrinal K. Biswas, Kathryn M. Newman, Evan A. Kalina |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Mass flux
Atmospheric Science 010504 meteorology & atmospheric sciences Planetary boundary layer tropical cyclone 0208 environmental biotechnology Prandtl number 02 engineering and technology Environmental Science (miscellaneous) lcsh:QC851-999 Atmospheric sciences 01 natural sciences planetary boundary layer Eddy diffusion symbols.namesake model physics idealized model 0105 earth and related environmental sciences Momentum (technical analysis) 020801 environmental engineering Hurricane Weather Research and Forecasting model symbols Environmental science HWRF lcsh:Meteorology. Climatology Tropical cyclone Radius of maximum wind |
| Zdroj: | Atmosphere, Vol 12, Iss 284, p 284 (2021) Atmosphere Volume 12 Issue 2 |
| ISSN: | 2073-4433 |
| Popis: | The intensity and structure of simulated tropical cyclones (TCs) are known to be sensitive to the planetary boundary layer (PBL) parameterization in numerical weather prediction models. In this paper, we use an idealized version of the Hurricane Weather Research and Forecast system (HWRF) with constant sea-surface temperature (SST) to examine how the configuration of the PBL scheme used in the operational HWRF affects TC intensity change (including rapid intensification) and structure. The configuration changes explored in this study include disabling non-local vertical mixing, changing the coefficients in the stability functions for momentum and heat, and directly modifying the Prandtl number (Pr), which controls the ratio of momentum to heat and moisture exchange in the PBL. Relative to the control simulation, disabling non-local mixing produced a ~15% larger storm that intensified more gradually, while changing the coefficient values used in the stability functions had little effect. Varying Pr within the PBL had the greatest impact, with the largest Pr (~1.6 versus ~0.8) associated with more rapid intensification (~38 versus 29 m s−1 per day) but a 5–10 m s−1 weaker intensity after the initial period of strengthening. This seemingly paradoxical result is likely due to a decrease in the radius of maximum wind (~15 versus 20 km), but smaller enthalpy fluxes, in simulated storms with larger Pr. These results underscore the importance of measuring the vertical eddy diffusivities of momentum, heat, and moisture under high-wind, open-ocean conditions to reduce uncertainty in Pr in the TC PBL. |
| Databáze: | OpenAIRE |
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