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October 1-3, 2007October 1-3, 2007 66thth Annual CMAS Meeting Annual CMAS Meeting 11

Effects of Liquid Water on Secondary Inorganic Aerosol in

Central California During a Winter Episode

1Planning and Technical Support DivisionAir Resources Board

California Environmental Protection Agency

2Department of Land, Air and Water ResourcesUniversity of California at Davis

Paul Livingstone1, Ajith Kaduwela1,2, Kemal Gurer1, Paul Allen1, and Bruce Jackson1


DISCLAIMERDISCLAIMER

The content of this presentation does not necessarily reflect the views and policies of the California Air Resources Board, nor does mention of trade names or commercial products constitute endorsement or recommendation for use.


Outline

• Introduction• Modeling Approach• Results and Discussions

– Liquid Water from MM5– Simulated SIA– Effects of Cloud and Rain

• Summary


Introduction

• Meteorological Parameters– Drive the distribution of tracers in the air– Used in key components of CMAQ

• Atmospheric Liquid Water – Medium for aqueous-phase reactions– Absorption, evaporation, deposition

• Effects of Liquid Water– Visible and invisible

– Small: insoluble gases, O3

– Large: soluble, H2O2, HCHO, SO2, Sulfate ion

– SIA (Ammonium ion, nitrate ion, sulfate ion)


The San Joaquin Valley

• One of the most productive agricultural regions in the world – Cadillac Dessert

• Major goods movement corridors

• Oil production in the southern Valley

• Air Quality: Second most polluted area in the US and second most studied area in the world

• Ozone pollution in the summer and PM pollution in the winter (but the annual PM standard is more restrictive)


Major field studies • 1970: Project Lo-Jet (identified summertime low-level jet and Fresno eddy)• 1972: Aerosol Characterization Experiment (ACHEX, first TSP chemical composition

and size distributions)• 1979-1980: Inhalable Particulate Network (first long-term PM2.5 and PM15 mass and

elemental measurements in Bay Area, Five Points)• 1978: Central California Aerosol and Meteorological Study (seasonal TSP elemental

composition, seasonal transport patterns)• 1979-1982: Westside Operators (first TSP sulfate and nitrate compositions in western

Kern County)• 1984: Southern SJV ozone study (first major characterization of O3 and meteorology in

Kern County)• 1986-1988: California Source Characterization Study (quantified chemical composition

of source emissions)• 1988-89: Valley Air Quality Study (first spatially diverse, chemical characterized, annual

and 24-hour PM2.5 and PM10 seasonal)• Summer 1990: San Joaquin Valley Air Quality Study/Atmospheric Utilities Signatures

Predictions and Experiments (SJVAQS/AUSPEX, first central California regional study of O3 and PM2.5) – Also known as SARMAP (SJVAQS/AUSPEX Regional Modeling Adaptation Project)

• Winter 1995: CRPAQS Pilot Study (IMS95, first sub-regional winter study)• December 1999 to February 2001: CRPAQS and CCOS (first year-long, regional-scale

effort)• December 1999 to present: Fresno Supersite (first multi-year experiment with advanced

monitoring technology)

Prof. John Watson, DRI


Seasonality of OSeasonality of O33 and PM and PM2.52.5

0

20

40

60

80

100

120

Dec-9

9

Jan-

00

Feb-0

0

Mar

-00

Apr-0

0

May

-00

Jun-

00

Jul-0

0

Aug-0

0

Sep-0

0

Oct-00

Nov-0

0

Dec-0

0

Mea

sure

d C

once

ntra

tion

8-Hour Ozone Max (ppb) Daily PM2.5 (ug/m3)

Fresno – 1st Street


Measurements

162 Air Quality Stations

365 Meteorology Stations


Modeling ApproachModeling Approach

• Episode: – December 25-30, 2000– Spin-up: December 22-24, 2000

• Meteorological inputs– MM5 with FDDA (NWS data)– MM5 with ‘observed’ liquid water

• radiation fog within PBL, MM5 cloud above • observed RH at stations and nearby grids• no rain

– MM5 with invisible liquid water only• CARB 2002 emissions inventory back-casted to 2000

(but not the inventory used in recent SIPs)• CMAQ with SAPRC-99 chemistry and ‘ae4’ aerosol

module


Observed RHObserved RHDay Night


Cloud Water from MM5Cloud Water from MM5Day Night

Col

umn

400

m A

GL


Rainwater from MM5Rainwater from MM5Day Night

Col

umn

400

m A

GL


Rain+Cloud Water from MM5Rain+Cloud Water from MM5

Day Night


Simulated SIASimulated SIADay Night


Simulated SOSimulated SO22Day Night


∆∆SOSO22 and and ∆∆SIA – Effect of LWSIA – Effect of LWD

ay

Nig

ht

SO2

SIA


∆∆SOSO22 and and ∆∆SIA – Constrained LWSIA – Constrained LWD

ay

Nig

ht

SO2

SIA


∆∆SOSO22 and and ∆∆SIA – Constrained LWSIA – Constrained LWD

ay

Nig

ht

SO2

SIA


Summary

• CMAQ was used to evaluate the effects of clouds and rain on SIA in San Joaquin Valley during December 25-30, 2000

• MM5 produced more liquid water than observed

• The impact of total water on SIA is significant, but that of rain+cloud is less significant. The importance decreased as the episode progressed


International Aerosol Modeling International Aerosol Modeling Algorithms (I AM A) ConferenceAlgorithms (I AM A) Conference

• Bi-annual in-depth look at the inner-workings of aerosol models (complements the annual CMAS Meeting)

• Wednesday, December 5th – Friday, December 7th, 2007 (just before the AGU meeting in San Francisco)

• University of California at Davis• Impressive list of U.S. and international invited

speakers• Information at http://airquality.ucdavis.edu/