Effects of Liquid Water on Secondary Inorganic Aerosol in Central California During a Winter Episode

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Effects of Liquid Water on Secondary Inorganic
Aerosol in Central California During a Winter
Episode
Paul Livingstone1, Ajith Kaduwela1,2, Kemal
Gurer1, Paul Allen1, and Bruce Jackson1

• 1Planning and Technical Support Division
• Air Resources Board
• California Environmental Protection Agency
• 2Department of Land, Air and Water Resources
• University of California at Davis

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DISCLAIMER

• 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.

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Outline

• Introduction
• Modeling Approach
• Results and Discussions
• Liquid Water from MM5
• Simulated SIA
• Effects of Cloud and Rain
• Summary

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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)

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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)

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Major field studies
Prof. John Watson, DRI

• 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)

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Seasonality of O3 and PM2.5
Fresno 1st Street
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Measurements
162 Air Quality Stations 365 Meteorology Stations
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Modeling 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

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Observed RH
Day
Night
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Cloud Water from MM5
Day
Night
Column
400 m AGL
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Rainwater from MM5
Day
Night
Column
400 m AGL
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RainCloud Water from MM5
Day
Night
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Simulated SIA
Day
Night
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Simulated SO2
Day
Night
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?SO2 and ?SIA Effect of LW
Day
Night
SO2
SIA
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?SO2 and ?SIA Constrained LW
Day
Night
SO2
SIA
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?SO2 and ?SIA Constrained LW
Day
Night
SO2
SIA
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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 raincloud is less significant. The
  importance decreased as the episode progressed

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International Aerosol Modeling Algorithms (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/