Aerosol Workshop
PANEL A:
DIRECT AEROSOL FORCING
J. Penner (Facilitator), Y. Kaufman
(Recorder), T. Nakajima, L. Stowe, I Sokolik
Panel A Summary by Recorder
(Yoram Kaufman)
The satellite record can be used to document the
spatial distribution of optical thickness and derived
fluxes (which may be more accurate). Comparison with
models at specific locations can reveal problems in
the satellite record and models.
Field data can be used to improve the satellite
inversion, even to some degree for past times.
Past data can be improved by use of several
channels of TOMS and AVHRR. Note that the AVHRR and
TOMS instruments need to characterized regarding their
spectral response and other characteristics for the
sake of long records.
There are a number of issues about the direct
radiative forcing that need to be investigated, for
example, the refractive index of dust aerosols.
The data record will be continued and improved with
the new satellites, which can also be used for
comparisons with the AVHRR and TOMS retrievals.
Yoram Kaufman suggestions are specified in the
following box:
Form Forcing and Satellite
Teams
- Form teams of 10-15 scientists to deal with
aerosol forcing for specific types/regions; do not
separate direct and indirect effects. Use data
from past concentrated field experiments (SCAR,
TARFOX, ACE) for detailed information on aerosol
and cloud properties. NASA can select the team
leaders directly or via the NRA.
- Form a team for analysis of satellite data,
applying algorithms globally (AVHRR, TOMS,
GOES/Meteosat, POLDER, OCTS, MODIS, MISR ...).
There should be joint membership between this and
other teams.
- Include foreign participants, providing only
travel funds.
Tasks for the Forcing
Teams
- Derive changes in aerosol forcing for the past two
decades from models, with validation using
satellite data and ground/air measurements. It is
not clear that this is possible; let's see if good
proposals are generated.
- Derive changes in aerosol forcing for the past two
decades using satellite data. Models and in situ
measurements will supply coefficients in the
analysis of satellite data. Derive separately the
direct forcing, indirect forcing and the combined
forcing, and see if they add up. Each method could
be applied by different investigators. Examples of
applications could include:
- Total forcing computed from the spectral
angular radiance using models that convert radiance to
fluxes, based on cloud coverage and surface
conditions.
- Indirect forcing obtained from correlation
between aerosol loading and cloud properties for
several cloud temperatures. It can be derived from
satellite data or from aircraft data (e.g., SCAR).
Examine whether the effect on clouds has changed with
time, and whether it depends on cloud type and
meteorological conditions. Compute the integrated
effect for each region and month.
- Analyze new satellite data (MODIS, MISR, POLDER
... including CERES for fluxes) to derive the
present forcing and its dependence on the aerosol
concentration. Compare this future aerosol
concentration with the results for earlier times.
Check whether the processes change with time (e.g.,
aerosol spectral properties, cloud dependence on
aerosols).
- Analyze changes in sources with time (e.g.,
population, urbanization/industrialization, fire
count) and the corresponding aerosol optical
thickness and cloud properties.
Tasks for Satellite Teams
- Characterize the properties of the satellite data
as a function of time.
- Develop algorithms to derive aerosol properties
and cloud properties simultaneously, making use of
pathfinder projects and Nakajima's effort. Apply
more than one algorithm for the sake of comparison.
Workshop Homepage *
Agenda *
Summary
Sessions:
1,
2,
3,
4,
5,
6
Panels:
A,
B,
C,
D *
Participants
