# Presentation: 802787

## Lightning NO Productionin the GMI Model

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- Lightning NO Productionin the GMI Model

- Kenneth E. Pickering
- Dale J. Allen
- Department of Meteorology
- University of Maryland
- College Park, MD

## Outline

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- Current procedure in GMI model
- Necessity of co-locating lightning NO with convective transport
- Available parameterizations
-  What can be done in the GMI model?

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## Current Procedure

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- Current Procedure

- Climatological monthly spatial distributions of total (CG+IC) lightning flashes (Price et al., 1997) based on ISCCP deep convective cloud top heights (Price and Rind, 1992).
- CG fraction based on cold cloud depth (Price and Rind, 1993)
- PCG = 10 PIC ;   PCG= 6.7 x 1026 molec/flash    (Price et al., 1997)
- Grid cell NO production values scaled such that global production equals a specified value (e.g., 5 TgN/yr)
- Vertically distributed according to C-shape profiles  derived from cloud-resolving model simulations of Pickering et al. (1998)

## Lightning NO and Convective Transport

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- Use of climatological lightning NO production results in lightning NO not being injected into the model at same times and locations as at which the model convective transport occurs
- Therefore, lightning NO and convectively-transported species (HOx precursors, NO, CO, NMHC) are introduced to the upper troposphere in different locations
- Results in “fuzzy” middle and upper tropospheric chemistry
- Lightning and convection need to be co-located!

## Lightning and Convection

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- Therefore, it is not advisable to use climatological lightning based on ISCCP or 	based on OTD/LIS observations
- Also, should not try to use OTD/LIS daily data (in addition to same location problem, daily data is a tiny, very unrepresentative sample of actual lightning
- LIGHTNING FLASH RATES MUST BE PARAMETERIZED IN TERMS OF VARIABLES FROM THE MODEL CONVECTIVE SCHEME

## Available Parameterizations

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- Cloud-height-based approach
- 	Price and Rind (1992)
- Cloud-mass flux based approach
- 	Allen and Pickering (2002)
- Convective precipitation based approach
- 	Allen and Pickering (2002)
- All using fields from driving GCM/DAS
- IC/CG ratios calculated using cold cloud depths as before

## Available Parameterizations

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- IC/CG ratio from cold-cloud depth method vs. from OTD/NLDN measurements
- NO production per flash:   PCG = 10 PIC   ???
- 		- NO spikes observed from aircraft (mostly 	associated with IC flashes) show 2 orders of 	magnitude variability in terms of molecules 	NO per meter of flash length
- 		- STERAO-A results (DeCaria et al, 2000) 	show average NO production per IC flash 	nearly equal to that per CG flash

## Slide 9

| Author | Production (molecules NO per m flash length) | Field Project |
| --- | --- | --- |
| Stith et al. [1999] | 2 x 1020 – 1.0 x 1022 | STERAO |
| Skamarock et al. [2002] | 1.0 x 1021 | STERAO |
| Höller et al. [1999] | 1 – 4 x 1022 | LINOX |
| Huntrieser et al. [2002] | 2.7 x 1021 | EULINOX |

- Analyses of Observed NO Spikes

- For the midpoint of this range (3 x 1021) and a 30-km flash length
-  ~1 x 1026 molecules NO/flash

## Model-simulated vs. Measured NOx Profiles

- CG: 460

- IC:46

- CG: 460

- IC: 460

- CG: 460

- IC: 345

- CG: 460

- IC: 690

- Moles NO

- Per Flash

- For Four Lightning NO Production Scenarios

- DeCaria et al. (2000)

**460 moles NO/flash ******** ~3 x 10 ****26**** molecules NO/flash**

**STERAO-A   July 12, 1996   NE Colorado**

## What can be done in the GMI model?

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- Run a flash rate parameterization for the year of interest, producing IC and CG flash rates for every meteorological data interval (e.g., 6 hours)
- Calculate NO production for each grid cell for each meteorological data interval
- Compute total global annual production
- Scale time series of gridded production values to some reasonable desired global annual production
- Input the scaled time series to the CTM

## Which flash rate parameterizationshould be used?

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- Which flash rate parameterizationshould be used?

- Cloud-top height method does not yield realistic variability in flash rates when implemented with GEOS-DAS data
- Cloud mass flux method underpredicts flash rates in Africa and overpredicts flash rates in Western Pacific when used with GEOS/STRAT data
- 		- GEOS-3 cloud mass fluxes smaller than in 	GEOS-STRAT
- 		- GEOS-3 TRMM assimilation of 		precipitation over oceans (1998 – present)
- 		- Rondonia Brazil lightning network (’99-’01)

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## GEOS-3 Control and GEOS-3 TRMM vs. OTD

**GEOS-3 Control and GEOS-3 TRMM vs. OTD**

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## Apply cloud-top height and cloud mass flux parameterizations with:

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- GEOS-3/TRMM -DAS
- GEOS-4 DAS
- GISS
- CCM3
- Others?
- Perform sensitivity runs in the GMI model and make a decision on the formulation to be used

## Time Line

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- 1) Nov. 03 – Jan. 04:  Work with GEOS-3
- 	TRMM DAS and Brazil observed lightning at U. of MD to improve parameterizations in tropics
- 2) Feb 04 – Mar. 04:  Compute lightning NO source using CLDHT and MFLUX parameterizations for each set of met. fields and perform sensitivity testing (collaboration of U. of MD and GMI Core Team)
- 3) Apr. 04 – June 04:  Work on paper(s) concerning changes in model chemistry resulting from change to co-located lightning and convection (Chatfield, Pickering, Allen, others)

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