Impact of Microphysical Parameterizations on Satellite All-Sky Infrared Data Assimilation and Practical Predictability of Hurricane Harvey (2017)
Open Access
- Author:
- Rendon, Jordan
- Graduate Program:
- Meteorology and Atmospheric Science (MS)
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- November 14, 2023
- Committee Members:
- Yunji Zhang, Thesis Advisor/Co-Advisor
Eugene Edmund Clothiaux, Committee Member
Paul Markowski, Program Head/Chair
Xingchao Chen, Committee Member - Keywords:
- Data Assimilation
Tropical Cyclone
Cloud Microphysics
Remote Sensing
Numerical Weather Prediction
Predictability
Meteorology
Infrared - Abstract:
- Current geostationary satellites provide the majority of observations of Tropical Cyclones (TCs) when they are over the open ocean. These observations are under-utilized in operational global and regional forecasting models as most of the cloudy and precipitation-affected regions are discarded. Recent work performed using the PSU WRF-EnKF system has shown that assimilation of all-sky infrared (IR) radiances from these geostationary satellites improves track, intensity, and rainfall forecasts for Hurricane Harvey. However, we have learned that different choices for the microphysics scheme will lead to different forecasts when all-sky IR radiances are assimilated. This is because model hydrometeor fields that are used to simulate IR radiances are strongly constrained by the model microphysics scheme, and model-simulated IR radiances are an important aspect when assimilating observed all-sky IR radiances. This study examines how two different microphysical parametrization schemes impact all-sky IR radiance assimilation and subsequent forecasts. It also examines the sensitivities that exist between these schemes and Harvey’s practical predictability. Results show that the forecast errors are primarily controlled by different dynamical fields in the EnKF analyses and to a lesser extent, at certain stages of Harvey’s development, the hydrometeor and moisture fields. This was demonstrated by using these fields as initial conditions for multiple sensitivity forecasts. These initial fields produced by the EnKF analyses are influenced by the choice of the microphysics scheme during EnKF cycling. Since different schemes produce different cloud-top brightness temperatures (IR radiances), different schemes lead to different updates to these fields. The microphysics schemes used during the free forecasts generally have a very small impact on Harvey’s intensity forecasts.