A modified vertical eddy diffusivity parameterization in the HWRF model based on large eddy simulations and its impact on the prediction of two landfalling hurricanes

Li, Xin; Pu, Zhaoxia; Zhang, Jun A.; Zhang, Zhan

doi:10.3389/feart.2023.1320192

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A modified vertical eddy diffusivity parameterization in the HWRF model based on large eddy simulations and its impact on the prediction of two landfalling hurricanes

2023
By Li, Xin ; Pu, Zhaoxia ; Zhang, Jun A. ; ...

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Journal Title:

Frontiers in Earth Science
Personal Author:

Li, Xin ; Pu, Zhaoxia ; Zhang, Jun A. ; Zhang, Zhan
NOAA Program & Office:

OAR (Oceanic and Atmospheric Research) ; AOML (Atlantic Oceanographic and Meteorological Laboratory) ; CIMAS (Cooperative Institute for Marine and Atmospheric Studies) ; NWS (National Weather Service) ; NCEP (National Centers for Environmental Prediction) ; EMC (Environmental Modelling Center)
Description:

Vertical eddy diffusivity (VED) in the planetary boundary layer (PBL) has a significant impact on forecasts of tropical cyclone (TC) structure and intensity. VED uncertainties in PBL parameterizations can be partly attributed to the model’s inability to represent roll vortices (RV). In this study, RV effects on turbulent fluxes derived from a large eddy simulation (LES) by Li et al. (Geophys. Res. Lett., 2021, 48, e2020GL090703) are added to the VED parameterization of the PBL scheme within the operational Hurricane Weather Research and Forecasting (HWRF) model. RV contribution to VED is parameterized through a coefficient and varies with the RV intensity and velocity scale. A modification over land has also been implemented. This modified VED parameterization is compared with the original wind-speed-dependent VED scheme in HWRF. Retrospective HWRF forecasts of Hurricanes Florence (2018) and Laura (2020) are analyzed to evaluate the impacts of the modified VED scheme on landfalling hurricane forecasts. Results show that the modified PBL scheme with the RV effect leads to an improvement in 10-m maximum wind speed forecasts of 14%–31%, with a neutral to positive improvement for track forecasts. Improved wind structure and precipitation forecasts against observations are also noted with the modified PBL scheme. Further diagnoses indicate that the revised PBL scheme enhances moist entropy in the boundary layer over land, leading to improved TC intensity prediction compared to the original scheme.
Keywords:

General Earth and Planetary Sciences
Source:

Frontiers in Earth Science, 11
DOI:

https://doi.org/10.3389/feart.2023.1320192
ISSN:

2296-6463
Format:

PDF
Publisher:

Frontiers Media SA
Document Type:

Journal Article
License:

https://creativecommons.org/licenses/by/4.0/
Rights Information:

CC BY
Compliance:

Submitted
Main Document Checksum:

urn:sha256:d2bc3edc3b9f23eb794c291ec438583c89cede4504bffe26a48d1055f910381b
Download URL:

https://repository.library.noaa.gov/view/noaa/56430/noaa_56430_DS1.pdf
File Type:

[PDF - 6.15 MB ]

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