Deep Convecton and Lightning

Ken Pickering – NASA/GSFC

Chris Cantrell – NCAR

Tropospheric Chemistry Future Activities Meeting

March 8, 2007

Deep Convection and Lightning

Ken Pickering – NASA GSFC Chris Cantrell – NCAR

Tropospheric Chemistry Future Activities Meeting March 8, 2007

July 12, 1996 STERAO-A storm – NE Colorado

Topics

• Effects of deep convection on atmospheric chemistry - examples

• Science questions• What is needed for a successful mission?• Discussion

Effects of Deep Convection

“Polluted Regions”

- Venting of boundary layer pollution

- Transport of NOx, NMHCs, CO, and HOx precursors to the UT (and sometimes to the LS), where chemical lifetimes are longer and wind speeds greater

- Downward transport of cleaner air to PBL

- Transported pollutants allow efficient ozone production in UT, resulting in enhanced UT ozone over broad regions

- Increased potential for intercontinental transport

- Enhanced radiative forcing by ozone

Effects of Deep Convection

“Clean” Regions- In remote regions low values of O3 and NOx are

transported to UT- Potential for decreased ozone production in UT- Larger values of these species transported to

PBL where they can more readily be destroyedAll Regions- Lightning production of NO- Perturbation of photolysis rates- Effective wet scavenging of soluble species- Nucleation of particles in convective outflow

Aircraft Measurements of Trace Gas Redistribution in Oklahoma PRESTORM June 15, 1985 MCC

CO

O3

Dickerson et al., 1987, Science

Pickering et al., 1990

Pickering et al., 1996

NASA GTE/TRACE-A

Cloud-resolved Storm Simulations with Lightning

Storm Location ReferencesSTERAO - 7/12/96 NE Colorado DeCaria et al.(2000, JGR;

2005, JGR)STERAO – 7/10/96 NE Colorado Ott et al. (2006, Ph.D; 2007,

JGR, in prep.)

EULINOX – 7/21/98 Bavaria Ott et al. (2007, JGR, in press)

Fehr et al. (2004, JGR)CRYSTAL-FACE

7/29/02* S. Florida Ott et al. (2006, Ph.D; 2007, JGR, in prep.)

7/16/02** S. Florida ditto

* Run using MM5** Run using ARPS

EULINOX July 21, 1998

PCG = 360 moles/flashPIC = 414 moles/flash

Output from UMD CSCTMdriven by cloud-resolved MM5simulation

Latitude (deg)

CRYSTAL-FACE

CRYSTAL-FACE

Model

Ridley NO obs. + PSS NO2

Ridley NO obs. + PSS NO2

& j(NO2) x 2

IC/CG = 5PCG = 590 moles/flPIC = 354 moles/fl

Lightning NO Production Scenarios

Summary of Five Storms

Means: 500 moles/flash 0.94 ratio

Orville et al., 2002

Flashes km-2 min-1

10-year Mean Flash Rate from the OTD & LIS Satellite Instruments10-year Mean Flash Rate from the OTD & LIS Satellite Instruments

Need Measurements in Tropical Africa

Should span entire troposphere (will require multiple aircraft)

What is the NOx yield for tropical IC and CG flashes?

Annual Mean SCIAMACHY NOAnnual Mean SCIAMACHY NO22 Sampled During Months With Enhanced Lightning Sampled During Months With Enhanced Lightning

Martin et al., in press

Cooper et al., 2006

Impact of Lightning in INTEX-NA

FLEXPART model

Barth et al., in prep.

Cloud-resolving Chemical Model Intercomparison

Bertram et al., 2007

Chemical Clock for Convective Influence – INTEX-NA

54% of air sampled between7.5 and 11.5 km influencedby convection in the pasttwo days

Fu et al., 2006

MLS Shows Impact of Convective Transport of Pollution

Science Questions (1)

• What are the relative characteristics of convective transport for various types of convection (squall lines, single cell, multicell, supercell)? What are the inflow regions (lower BL, upper BL, above BL)? What are primary entrainment/detrainment layers? How much stratospheric air is entrained into the anvil? How much transport is there into the lowermost stratosphere?

• What is the transport efficiency of BL air in various types of convection and in different environmens? What percentage of BL air reaches the UT/LS?

Science Questions (2)• What is the average amount (and range) of NO produced

per cloud-to-ground and per intracloud lightning flash?

• Does the NO produced from lightning correlate with length of flash or with flash intensity (e.g., peak current)?

• Does the mean production per flash vary from one region of the world to another?

• What shape does the vertical profile of lightning NOx take upon dissipation of a thunderstorm?

• How should lightning NOx be best represented in regional and global chemical models?

Science Questions (3)

• What is the fate of soluble species in deep convection?

• How is the convective transport of soluble species affected by phase changes of hydrometeors? What fractions of these species are retained in the ice phase after freezing?

• What is the effect of convection on downwind photochemistry? By how much are NOx and HOx levels perturbed? How much ozone is produced in the convective outflow over the 12 – 48 hours following a storm? How does the downwind UT chemistry vary with different surface emissions and lightning flash rates?

Science Questions (4)

• How well do parameterizations represent convective transport of chemical tracers in regional and global models?

• How important are regions of monsoon convection in the vertical transport of pollution?

• How effectively (and on what time scale) do thunderstorms replace UT air with lower tropospheric air (convective recycling) over particular regions of the globe?

• What is the net global effect of deep convection on tropospheric ozone?

Mission Requirements

• Multiple aircraft for:

Characterizing boundary layer

Performing anvil transects

Obtaining full undisturbed tropospheric profiles

Tracking downwind chemical evolution of convective outflow

Storm penetration

• Thunderstorm forecasting capability

• Dual-Doppler Radar

• VHF 3-D total lightning mapping systems

• Enhanced rawinsonde network

Mission Requirements

• Satellite Observations

Trop. NO2 column – OMI, SCIAMACHY,

MetOp/GOME-2

Profiles of CO, O3 – TES, MLS

UT HNO3 – TES, MLS, ACE

Trop. O3 column – OMI-MLS, MetOp/IASI

Clouds – GOES, CloudSat, CALIPSO

• Cloud-resolved modeling with chemistry – testing transport, representation of soluble species and lightning

• Regional and global modeling – testing convective parameterizations, testing UT photochemistry in outflow