Re: lightning

[Mary Barth]

Hello Manish,

The lightning parameterization determines the x,y location of the lightning flash. For parameterized convection, it is the grid point where the convective parameterization is predicting convective rain (based on level of neutral buoyancy). For resolved convection, it finds x,y locations based on 20 dBZ radar reflectivity.

The lightning-NOx parameterization distributes the NO emissions at those x,y points using a prescribed vertical profile. For parameterized convection, the vertical distribution is based on Ott et al. (2010). For resolved convection, the vertical distribution is based on DeCaria et al. (2000) which does different distributions depending if it is an IC or CG flash. The IC and CG flashes are determined based on prescribed values (or a rough variation with location for the US), or potentially predicted based on Price and Rind (1993).

Please take a look at these papers to see how those vertical distributions are determined.

Cheers,
Mary

On 8/5/20 9:33 AM, Shrivastava, Manishkumar B wrote:

Hi Mary

 

The  lightning  parameterization in WRF does not predict any cases where lightning is seen all the way from top to bottom of deep convective systems i.e. lightning extending from boundary layer to free troposphere.

I have run it with 10 km. I am hoping 2 km grid spacing may be better. But please let me know if you have any thoughts of which option/settings may help to simulate the vertical profile of lightning and lightning NOx better.

 

Manish

[Mary Barth]

Manish,

It is quite possible that the vertical wind is moving lightning-NOx to the main outflow level of the storm.

Also, I believe most of the observational evidence of lightning-NOx is in the upper troposphere. However, there are not a lot of measurements at mid and low altitudes due to safety of the aircraft.

-- Mary

On 8/5/20 1:30 PM, Shrivastava, Manishkumar B wrote:

Thanks Mary. From my new WRF-Chem simulations for the Amazon, I find lightning NOx is very important for ozone chemistry and particle number, but most of its effects are seen at 12 km altitude.

That’s why I was wondering if this has to do with prescription of vertical profiles of lightning NO.

 

Manish

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Mary Barth                                Phone:  303-497-8186
Senior Scientist                          email: bar...@ucar.edu

National Center for Atmospheric Research                        
P.O. Box 3000                  
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https://staff.ucar.edu/users/barthm  
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