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Chemistry-climate interactions: a new direction for GEOS-CHEM

1993

2003

2050

GEOS-CHEM research to date

GCAP project

Current project: drive GEOS-CHEM into the future with GISS GCM III.

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CACTUS (Chemistry, aerosol, climate: Tropospheric unified simulation)�Collaborators: Caltech, GISS, Irvine, Carnegie Mellon, Georgia Tech

GISS GCM II’

GHGs, solar flux, land surface, etc.

CalTech aerosol module

Harvard chemistry module

meteorology

emissions

oxidants, nitric acid

aerosol

ozone

emissions

Previous chemistry-climate work at Harvard used the CACTUS model.

aerosol

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GEOS-CHEM studies of natural emissions are consistent with studies of preindustrial ozone in CACTUS model.

Standard model

Observations

Adjusted model

Best match with observed surface ozone:

  • Increased isoprene emissions by 50%
  • Lightning NOx scaled to 1.0 Tg/y

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Mickley et al., 2001

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In 2003, we started GCAP (Global Climate and Air Pollution).� collaborators: David Streets, John Seinfeld, David Rind, Joshua Fu

Number of summer days with 8-hour ozone > 84 ppbv, average for northeast U.S. sites

1988, hottest on record

days

Many meteorological factors control air quality, e.g.:

  • Temperature
  • Ventilation
  • Circulation patterns
  • Rainfall
  • Cloudiness

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Basic question: how will surface air quality respond as climate changes?

Lin et al., 2001

Work so far: CACTUS model with tracers of anthropogenic pollution.

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GCAP approach: archive met fields from GISS GCM and apply to GEOS-CHEM

1950 2000 2025 2050 2075 2100

23L GISS GCM (Model 3), with changing GHGs

Spin-up of ocean

GEOS-CHEM

Calculates chemistry, aerosol

precursor emissions

archived temperatures, humidity, winds, etc

CMAQ regional model

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GCAP Progress

1950 2000 2025 2050 2075 2100

23L GISS GCM (Model 3), with changing GHGs

Spin-up of ocean

GEOS-CHEM

precursor emissions

archived temperatures, humidity, winds, etc

CMAQ regional model

New version frozen

Future emissions prepared

Interface completed

Interface completed

Validation ongoing

Interface ~done

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New EPA-STAR project, 2005: “GCAP + Fire”� collaborators: Jennifer Logan, David Diner, Daewon Byun

How will changing fire frequency in the future affect surface air quality?

1950 2000 2025 2050 2075 2100

23L GISS GCM with fire prediction scheme

Spin-up of ocean

GEOS-CHEM

Calculate chemistry, aerosol

precursor emissions

archived met fields and areas burned

CMAQ regional model

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To be continued with Shiliang’s talk at 5:15

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Progress so far

  • New version of GISS GCM 23-layer received (Model III), includes new boundary layer scheme. (David Rind).

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  • Tracers tested in Model III (David Rind).

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  • GISS meteorological fields implemented into GEOS-CHEM. (Loretta Mickley, Shiliang Wu)

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  • GEOS-CHEM results for present-day validated. (Shiliang Wu).

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  • Interface between GEOS-CHEM and CMAQ tested. (Joshua Fu).

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  • Future emission inventories completed. (David Streets).

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GCAP continued. . .

23L GISS GCM, with changing GHGs

GEOS-CHEM

archived met fields

1950 2000 2025 2050 2075 2100

Spin-up of ocean

2000 2025 2050 2075 2100

1. Develop future climatology for ozone and aerosols

2. Recalculate meteorology with ozone, aerosol trends