Updates in the NCEP GFS PBL and Convection Models with Environmental Wind Shear Effect and Modified Entrainment and Detrainment Rates and their Impacts on the GFS Hurricane and CAPE Forecasts

Han, Jongil; Peng, Jiayi; Li, Wei; Wang, Weiguo; Zhang, Zhan; Yang, Fanglin; Zheng, Weizhong

doi:10.1175/waf-d-23-0134.1

i

Updates in the NCEP GFS PBL and Convection Models with Environmental Wind Shear Effect and Modified Entrainment and Detrainment Rates and their Impacts on the GFS Hurricane and CAPE Forecasts

2024
By Han, Jongil ; Peng, Jiayi ; Li, Wei ; ...

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Journal Title:

Weather and Forecasting
Personal Author:

Han, Jongil ; Peng, Jiayi ; Li, Wei ; Wang, Weiguo ; Zhang, Zhan ; Yang, Fanglin ; Zheng, Weizhong
NOAA Program & Office:

EMC (Environmental Modelling Center) ; NCEP (National Centers for Environmental Prediction) ; NWS (National Weather Service)
Description:

To reduce hurricane intensity bias, the NCEP Global Forecast System (GFS) planetary boundary layer (PBL) and convection schemes have been updated with a new parameterization for environmental wind shear and enhanced entrainment and detrainment rates with increasing PBL or sub-cloud mean turbulent kinetic energy (TKE) in their updraft and downdraft mass-flux schemes. Tests with the GFS show that the updated schemes significantly reduce the hurricane intensity bias by reducing the momentum transport in the mass-flux schemes. Along with the reduced intensity bias, the hurricane intensity and track errors have also been reduced. On the other hand, to reduce the PBL overgrowth over areas with a higher vegetation fraction or larger surface roughness, the entrainment rate in the PBL mass-flux scheme has also been increased with increasing vegetation fraction or increasing surface roughness. This entrainment rate increase has increased near surface moisture, and as a result, helped to increase the underestimated convective available potential energy (CAPE) forecasts over the continental United States.
Keywords:

Atmospheric Science
Source:

Weather and Forecasting (2024)
DOI:

https://doi.org/10.1175/waf-d-23-0134.1
ISSN:

0882-8156 ; 1520-0434
Format:

PDF
Publisher:

American Meteorological Society
Document Type:

Journal Article
Rights Information:

Other
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Library
Main Document Checksum:

urn:sha-512:3a1fdcca97fea25ac595771f12148f3c5883fea451d6e10e84103ab0dd04b5738fe9439968670960d728b62f3c03245969c7be4f465d36ccd10510a0ba3fa363
Download URL:

https://repository.library.noaa.gov/view/noaa/63668/noaa_63668_DS1.pdf
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[PDF - 17.29 MB ]

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