Evaluation of wet scavenging for the may 29 2012 dc3 severe storm case
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Evaluation of wet scavenging for the May 29, 2012 DC3 severe storm case. Megan Bela ( U. Colorado) , Mary Barth ( NCAR), John Wong, O. Brian Toon (U. Colorado), Hugh Morrison, Morris Weisman, Kevin Manning, Glen Romine, Wei Wang ( NCAR), Kristin Cummings ( U. Maryland),

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Evaluation of wet scavenging for the May 29, 2012 DC3 severe storm case

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Evaluation of wet scavenging for the may 29 2012 dc3 severe storm case

Evaluation of wet scavenging for the May 29, 2012 DC3 severe storm case

Megan Bela(U. Colorado),

Mary Barth(NCAR),

John Wong, O. Brian Toon(U. Colorado),

Hugh Morrison, Morris Weisman, Kevin Manning, Glen Romine, Wei Wang (NCAR),

Kristin Cummings (U. Maryland),

Kenneth Pickering (NASA/GSFC),

and the DC3 Science Team


Wet scavenging and lightning nox in wrf

Wet Scavenging and Lightning-NOx in WRF

  • WRF-Chem

    • Wet scavenging of trace gases based on Neu-Prather parameterization connected to Lin scheme cloud physics (Pfister et al., WRF workshop, 2011)

    • Now connected to Morrison cloud physics scheme

    • Lightning-NOx parameterization split into two parts

      • Lightning flashrate predicted in WRF/phys

      • Lightning-NOx production predicted in WRF/chem

  • DC3 Field Campaign

    • Offers chance to evaluate these parameterizations via case studies


Evaluation of wet scavenging for the may 29 2012 dc3 severe storm case

Deep Convective Clouds and Chemistry (DC3) Experiment

To characterize thunderstorms and how they process chemical compounds that are ingested into the storm (transport, scavenging, lightning and NOxproduction, chemistry)

To learn how the air that exits the storm in the upper troposphere (UT) changes chemically during the next day (chemical aging)

May-June 2012


Evaluation of wet scavenging for the may 29 2012 dc3 severe storm case

Strategy for Sampling Near Storms

RO2 or HOx

NOx

H2O2 CH3OOHCH3OH CH2O CH3COCH3

O3


29 may 2012 oklahoma severe storm

29 May 2012Oklahoma Severe Storm

photo from Don MacGorman


Evaluation of wet scavenging for the may 29 2012 dc3 severe storm case

WRF-Chem Setup

15 km CONUS: Grell 3D (G3) convective parameterization

3km: explicit convection

MOZART chemistry, GOCART aerosols with radiative feedback

∆x = 3 km

∆x = 15 km

WRF Max. 10 cm Radar Reflectivity (dBZ),

May 30, 2012 00Z


Evaluation of wet scavenging for the may 29 2012 dc3 severe storm case

Wet Scavenging Evaluation

3km: explicit convection

MOZART chemistry, GOCART aerosols with radiative feedback

∆x = 3 km

∆x = 15 km

WRF Max. 10 cm Radar Reflectivity (dBZ),

May 30, 2012 00Z


Evaluation of wet scavenging for the may 29 2012 dc3 severe storm case

WRF represents storm location but initiates early and has a larger area of high reflectivity

2012-05-29 21Z

  • WRF

  • Maximum 10cm reflectivity (dBZ)

NEXRAD

Composite Reflectivity


Evaluation of wet scavenging for the may 29 2012 dc3 severe storm case

WRF represents storm location but initiates early and has a larger area of high reflectivity

2012-05-29 22Z

  • WRF

  • Maximum 10cm reflectivity (dBZ)

NEXRAD

Composite Reflectivity


Evaluation of wet scavenging for the may 29 2012 dc3 severe storm case

WRF represents storm location but initiates early and has a larger area of high reflectivity

2012-05-29 23Z

  • WRF

  • Maximum 10cm reflectivity (dBZ)

NEXRAD

Composite Reflectivity


Evaluation of wet scavenging for the may 29 2012 dc3 severe storm case

WRF represents storm location but initiates early and has a larger area of high reflectivity

  • WRF

  • Maximum 10cm reflectivity (dBZ)

2012-05-30 00Z

NEXRAD

Composite Reflectivity


Evaluation of wet scavenging for the may 29 2012 dc3 severe storm case

WRF represents storm location but initiates early and has a larger area of high reflectivity

2012-05-30 01Z

  • WRF

  • Maximum 10cm reflectivity (dBZ)

NEXRAD

Composite Reflectivity


Evaluation of wet scavenging for the may 29 2012 dc3 severe storm case

Neu and Prather (2012) wet scavenging was coupled to MOZART chemistry and Morrison microphysics

gas

Henry’s Law

cloud water

retention

factor = 1

rain

hail

snow

evaporation

gas

Simulations:

  • With the wet scavenging

  • Without the wet scavenging

Scavenged: HNO3, H2O2, HCHO, CH3OOH

Transport only: CO, O3, NMHCs


Evaluation of wet scavenging for the may 29 2012 dc3 severe storm case

Compare vertical profiles from observations and model output

CO

O3

Observed

(Preliminary)

Inflow = DC8 and GV measurements restricted to just before/during storm

Outflow = DC8 and GV measurements when sampling anvil outflow, with stratospheric air (O3 > 100 ppb, CO < 100 ppb) removed

Inflow = Clear sky points just before storm where aircraft flew

Outflow = WRF anvil region where CO > 100 ppb at 11 km, and stratospheric air removed

WRF-Chem

Inflow

  • Ouflow - No Scav.

    Outflow - Scav.


Evaluation of wet scavenging for the may 29 2012 dc3 severe storm case

CO and O3 vertical structure is represented by model and affected little by wet scavenging

CO

O3

Observed

(Preliminary)

Inflow

Outflow

WRF-Chem

Inflow

  • Ouflow - No Scav.

    Outflow - Scav.


Evaluation of wet scavenging for the may 29 2012 dc3 severe storm case

CH2O enhanced in outflow, H2O2 scavenged

CH2O

H2O2

Observed

(Preliminary)

Inflow

Outflow

WRF-Chem

Inflow

  • Ouflow - No Scav.

    Outflow - Scav.


Neu prather wet scavenging scheme in the 3 km wrf chem simulation

Neu-PratherWetScavengingSchemein the 3 km WRF-Chemsimulation

Summary

Convective transport of non-soluble species is reasonably well represented by the 3 km WRF-Chem simulation

Observed mean vertical profiles of some soluble species in outflow are better represented in the model with scavenging, while others are overly scavenged

Currently implementing a more detailed scavenging scheme (Barth et al., 2001, 2007)  role of ice (retention during freezing and adsorption of gases)

Evaluation of lightning-NOx scheme being done by U. Maryland (Pickering, Allen, Cummings, Li)


Lightning flash rate parameterization

Lightning Flash Rate Parameterization

  • Lightning-generated NO (LNOx) is an important emission in the upper troposphere where background NO is low

  • The production of LNOx depends on lightning flash rate, type of lightning, and NO produced

  • WRFV3.5

  • flash rate parameterization is now in physics directory

  • NO production and emission is in chem directory

  • Able to evaluate lightning flash rate without overhead of running chemistry

  • Parameterizations available for both parameterized convection (Wong et al., 2013, GMD) and resolved convection (Barth et al., 2012, ACP)


Lightning flash rate parameterization in the 15 km wrf chem simulation

Lightning Flash Rate Parameterizationin the 15 km WRF-Chem simulation

15 km CONUS: Grell 3D (G3) convective parameterization

MOZARTchemistry, GOCART aerosols with radiative feedback


Evaluation of wet scavenging for the may 29 2012 dc3 severe storm case

Lightning Prediction for Parameterized Convection

FR = 3.44x10-5 ztop4.9

ztop = radar cloud top (20 dBZ height; agl) (Williams, 1985)

ztop = level neutral buoyancy – 2 km

(Wong et al., 2013)

500 moles NO/flash placed vertically following Ott et al. (2010) curves

From Takahashi and Luo (2012) GRL

CloudSat radar reflectivity profile of a tropical deep convective cloud observed on February 24 2007 over Amazon (unit: dBZ). The size of the system is about 140 km and the highest point is about 17 km.


Evaluation of wet scavenging for the may 29 2012 dc3 severe storm case

May 29, 2012 DC3 Case Study

Evaluation of Lightning Flash Rate

Flash count for 2100-2200 UTC

35-40N, 95-100W, 2200-0100 UTC

NLDN (obs of CG flashes)

WRF

NLDN

WRF (mdl of IC+CG flashes)

Limit flash rate to regions where

1. qtotmax> 0.5 g/kg

2. ppt > 5 mm/hr


Evaluation of wet scavenging for the may 29 2012 dc3 severe storm case

Evaluation of Lightning Flash Rate

2200 UTC 29 May

NLDN observations

LNB only

Qtot > 0.5 g/kg

ppt > 5 mm/hr

Spatial location and magnitude of flash rate better predicted when flash rate is restricted to regions of resolved cloud or high precipitation rates


Evaluation of wet scavenging for the may 29 2012 dc3 severe storm case

Evaluation of Lightning Flash Rate

0000 UTC 30 May

NLDN observations

LNB only

Qtot > 0.5 g/kg

ppt > 5 mm/hr

Spatial location and magnitude of flash rate better predicted when flash rate is restricted to regions of resolved cloud or high precipitation rates


Evaluation of wet scavenging for the may 29 2012 dc3 severe storm case

Evaluation of Lightning Flash Rate

0200 UTC 30 May

NLDN observations

LNB only

Qtot > 0.5 g/kg

ppt > 5 mm/hr

Spatial location and magnitude of flash rate better predicted when flash rate is restricted to regions of resolved cloud or high precipitation rates


Evaluation of wet scavenging for the may 29 2012 dc3 severe storm case

May 29 Case Study

Evaluation of NOx in Upper Troposphere

ppt > 5 mm/hr

Qtot > 0.5 g/kg

Bkgd: WRF-Chem model results for NOx at z = 11 km and 00 UTC 30 May.

Circles: GV and DC-8 observations of NOx at 10 < z < 12 km and 23-01 UTC

 Location is off somewhat (because of storm location), and magnitude is underpredicted


Evaluation of wet scavenging for the may 29 2012 dc3 severe storm case

  • Summary

  • Restricting flash rate to regions of high precipitation or resolved cloud improves location and magnitude of flash rate

  • Next Steps

  • Finish tweaking flash rate parameterization

    • Evaluate with lightning mapping array data which gives total flash rate (= IC + CG)

    • Adjust NO production per flash

  • Use set up for simulating other DC3 cases at Δx = 15 km

  • Recommend refinement to the lightning flash rate parameterization for parameterized convection

Thank you!

DC3 is sponsored by the National Science Foundation (NSF), NASA, NOAA, and DLR

DC3 Preliminary Data Provided by the following Instrument Teams:

DC-8 CO: DACOM - G. Diskin, G. Sachse, J. Podolske (NASA/LaRC)

DC-8 O3: CSD CL –T. Ryerson, I. Pollack, J. Peischl (NOAA/ESRL/CSD)

GV CO, O3: CARI–A. Weinheimer, F. Flocke, T. Campos, D. Knapp, D. Montzka (NCAR)

May 29, 2012 severe storm in northern Oklahoma (photo from Don MacGorman)


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