GACP Meetings
First Science Team Meeting
Notes from Discussion Group B: Use of Transport Modeling in Integrated Climatologies
Moderator: Joyce Penner; Rapporteur: Cathy Chuang
Discussion outline:
- In what specific areas will transport models contribute the most for the development of aerosol climatology?
- What types of aerosol source data are available and what else do modelers need in simulation of global aerosol cycle?
- How to use current satellite and in situ data for validation of model simulations?
- What kinds of new data will be available from the Science Team?
To examine the climate impacts by aerosols first requires a quantitative understanding, on a global basis, of the sources, transformation and removal processes for aerosols and aerosol precursors, as well as the cycles and budgets for the trace species which comprise the aerosols. Although field studies and satellite measurements provide useful data of aerosol distribution, a global model might be the best approach able to identify and analyze the responsible processes as well as to address the relative importance of anthropogenic and natural emissions in the global aerosol distribution. The model studies performed within the Science Team domain are listed in Table 1.
| Investigator | Aerosol types | Meteorology |
|---|---|---|
| M. Chin | sulfate, dust, sea salt, carbonaceous | Geos DAS |
| C. Chuang | sulfate, dust, sea salt, carbonaceous | NCAR CCM |
| A. Del Genio | sulfate, dust, sea salt, carbonaceous | GISS CCM |
| U. Lohmann | sulfate, dust, sea salt, carbonaceous | ECHAM |
| J. Penner | dust, biomass aerosols | Nudged ECHAM |
| G. Pitari | sulfate, aircraft aerosols | low resolution climate model |
| P. Rasch | sulfate, dust, carbonaceous | CCM3 |
| O.B. Toon | dust | NCEP |
| D. Westphal | sulfate, dust, sea salt, carbonaceous | NOGAPS |
Atmospheric aerosols are derived from a variety of sources. Complete aerosol emission inventory is a crucial element in the future advancement of climate/aerosol models. The available emission data for aerosols and aerosol precursors at this moment include:
- for a particular single year
- SO2,, DMS, H2S and COS
- dust
- biomass burning and fossil fuel carbonaceous aerosols
- sea salt
- natural organic aerosols
- 1996 burned area in Africa (Barbosa et al., 1998)
- 1993 world fire atlas (burned spots)
- 1950 - 1994 fossil fuel SO2
However, the modelers also need both source inventories and meteorological fields for 1980 - present in order to quantitatively define the global distributions of aerosol (direct and indirect) radiative forcings for the period of satellite data (1979-near future).
One of the most important tasks for modelers is to compare the simulated total aerosol concentrations and optical properties not only with the in-situ data from field campaigns or from surface networks designed for long-term observations but also with data retrieved from remote sensing instruments. These comparisons can validate whether the aerosol emission fields are correct and whether the treatments of transport and transformation are reasonable. The data sets available for validation at this moment include:
- TOMS absorbing index (1978 - present)
- AVHRR aerosol optical depth (1979 - present)
- SAM II, SAGE I, SAGE II (1978 - present)
- GLOBE Lidar (1989, 1990)
- LITE (1994)
- Raman Lidar aerosol height profiles
- Data compilation - optical depth (Dave Covert)
- Surfaced-based AERONET data
- SO2 surface concentration data and sulfate wet deposition data:
- EMEFS, July 1988 to May 1990
- EMEP, 1983 - 1992
- Organic and black carbon data (various data)
- AEROCE, NOAA, and IMPROVE surface data sets
- WMO observing stations with free troposphere data sets (e.g., Mauna Loa; Izaña; Summit, Greenland; Jungfraujoch)
- U. Wyoming Balloon Sondes
The new data sets which will be available from the Science Team members are listed in Table 2.
| Investigators | Data types |
|---|---|
| A. Clarke | spatial, temporal, regional and meteorological characterization of aerosol size distribution, optical properties and chemistry for the North and South Pacific |
| T. Bates | shipboard aerosol properties |
| G. Kukla | hourly surface solar radiation for clear, partly cloudy and overcast sky at selected stations |
| Z. Li | climatology of clear sky difference between observed and pollution-free radiative energy using satellite and surface measurements over boreal forest and oceans |
| T. Novakov | TC, OC, and BC data evaluation plus changes over last 20 years |
| L. Poole | aerosol extinction profiles at 1 ?m (1978-1993; 1979-1981) and profiles at 4 wavelengths (1984-present); aerosol backscatter profiles at Langley since 1974 |
| C. Randall | El Chichon aerosols |
| L. Remer/Y. Kaufman | smoke effects on clouds |
| P. Russell | airborne sunphotometer (events campaigns) |
| L. Stowe | AVHRR Pathfinder |
| P. Stackhouse | site specific, monthly average clear sky broadband difference between observed and pollution-free solar insolation (1983-1992) |
| R. Stuhlmann | arctic haze and clouds - March/April 1998 and Meteosat ERB aerosol and cloud properties > 2000 |
| O. Torres | clear sky optical depth of non-absorbing aerosols and clear sky optical depth of absorbing aerosols when vertical distribution is available (1979-1985; 1996-1997; 1997-present) |
| E. Uthe | aerosol/cloud optical characteristic from campaigns , DC-8 LIDAR - vertical distribution |
| D. Winker | aerosol extinction and backscatter cross section, optical depth, boundary layer height - September 1994 |
Recommendation 1: Dust particles play an important role in the assessment of aerosol climate forcing but the estimates of global dust source strength vary in a large range (500 - 5000 Tg/year), a workshop should be held for comparison of dust source algorithm and the model simulated dust distribution.
Recommendation 2: To further validate the chemistry and transport processes in global models, a thorough comparison to detailed mesoscale models which have higher resolution in apace and time might be helpful to reduce the uncertainty resulted from the computational limitation in global models.
