ARL Current & Forecast Meteorology

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gmcurcio
Posts: 5
Joined: May 16th, 2015, 12:08 pm
Registered HYSPLIT User: Yes

ARL Current & Forecast Meteorology

Post by gmcurcio »

Hello,

Does anyone know how the Pasquill Stability Product in the suite of ARL Current & Forecast Meteorology addresses the timing of 1 hour before and after sunset. Pasquill Stability is calculated differently for day and night times. I was wondering how the stability calculation specifically accomplishes this task in its code. Some meteorologists use the Solar Radiation Delta T method to address this. I would like to know how this ARL product accomplishes this need. Thanks.
Fantine
Posts: 108
Joined: November 8th, 2012, 3:41 pm

Re: ARL Current & Forecast Meteorology

Post by Fantine »

The utility program in HYSPLIT to compute the Pasquill-Gifford categories is "vmixing.f". It uses diffusivity (m2/s) to obtain the stability classes. The reference paper is Draxler (1979) Atmospheric Environ., Vol 13., pp.1559-1564.
Note that HYSPLIT has different options to estimate diffusivity. The default setting is to use the Kantha-Clayson method (KBLT=2 in SETUP.CFG). More detail about the diffusivity computation can be found here: https://www.ready.noaa.gov/hysplitusersguide/S625.htm
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