star pdf file

Under a joint agreement between the National Aeronautics and Space Agency (NASA) and the Russian Aviation and
Space Agency (RASA), the Stratospheric Aerosol Gas Experiment III (SAGE III) instrument was launched in low earth orbit
on December 10,2001 aboard the Russian Meteor-3M satellite from the Baikonur Cosmodrome. SAGE III is a spectrometer
that measures attenuated radiation in the 282 nm to 1550 nm wavelength range to obtain the vertical profiles of ozone,
aerosols, and other chemical species that are critical in studying the trends for the global climate change phenomena. This
instrument version is more advanced than any of the previous versions and has more spectral bands, elaborate data gathering
and storage, and intelligent terrestrial software. There are a number of Russian scientific instruments aboard the Meteor
satellite in addition to the SAGE III instrument. These instruments deal with land imaging and biomass changes,
hydro-meteorological monitoring, and helio-geophysical research. This mission was under development for over a period of
six years and offered a number of unique technical and program management challenges for both Agencies. SAGE III has a
long space heritage, and four earlier versions of this instrument have flown in space for nearly two decades now. In fact, SAGE
II, the fourth instrument, is still flying in space on NASA s Earth Radiation Budget Satellite (ERBS), and has been providing
important atmospheric data over the last 18 years. It has provided vital ozone and aerosol data in the mid latitudes and has
contributed vastly in ozone depletion research. Ball Aerospace built the instrument under Langley Research Center s (LaRC)
management. This paper presents innovative approaches deployed by the SAGE III and the Meteor teams in performing the
initial on-orbit checkout. It further documents a number of early science results obtained by deploying low risk, carefully
coordinated procedures in resolving the serious operational issues of this satellite.
Author
Climate Change; Imaging Techniques; Aerosols; Climatology; Stratosphere
20030025350 NASA Goddard Space Flight Center, Greenbelt, MD, USA
A New Look into the Effect of Large Drops on Radiative Transfer Process
Marshak, Alexander; [2003]; 1 pp.; In English; No Copyright; Avail: Other Sources; Abstract Only
Recent studies indicate that a cloudy atmosphere absorbs more solar radiation than any current 1D or 3D radiation model
can predict. The excess absorption is not large, perhaps 10-15 W/sq m or less, but any such systematic bias is of concern since
radiative transfer models are assumed to be sufficiently accurate for remote sensing applications and climate modeling. The
most natural explanation would be that models do not capture real 3D cloud structure and, as a consequence, their photon path
lengths are too short. However, extensive calculations, using increasingly realistic 3D cloud structures, failed to produce
photon paths long enough to explain the excess absorption. Other possible explanations have also been unsuccessful so, at this
point, conventional models seem to offer no solution to this puzzle. The weakest link in conventional models is the way a size
distribution of cloud particles is mathematically handled. Basically, real particles are replaced with a single average particle.
This ’ensemble assumption‘ assumes that all particle sizes are well represented in any given elementary volume. But the
concentration of larger particles can be so low that this assumption is significantly violated. We show how a different
mathematical route, using the concept of a cumulative distribution, avoids the ensemble assumption. The cumulative
distribution has jumps, or steps, corresponding to the rarer sizes. These jumps result in an additional term, a kind of Green’s
function, in the solution of the radiative transfer equation. Solving the cloud radiative transfer equation with the measured
particle distributions, described in a cumulative rather than an ensemble fashion, may lead to increased cloud absorption of
the magnitude observed.
Author
Radiative Transfer; Climate Models; Cloud Physics; Solar Radiation
20030025354 NASA Goddard Space Flight Center, Greenbelt, MD, USA
MODIS Satellite Data and GOCART Model Characterization of the Global Aerosol
Kaufman, Yoram; Chin, Mian; Remer, Lorraine; Tanre, Didier; Lau, William K.-M., Technical Monitor; [2003]; 1 pp.; In
English; Harvard University Conference, 31 Jan. - 1 Feb. 2003, Cambridge, MA, USA; No Copyright; Avail: Other Sources;
Abstract Only
Recently produced daily MODIS aerosol data for the whole year of 2001 are used to show the concentration and dynamics
of aerosol over ocean and large parts of the continents. The data were validated against the Aerosol Robotic Network
(AERONET) measurements over land and ocean. Monthly averages and a movie based on the daily data are produced and
used to demonstrate the spatial and temporal evolution of aerosol. The MODIS wide spectral range is used to distinguish fine
smoke and pollution aerosol from coarse dust and salt. The aerosol is observed above ocean and land. The movie produced
from the MODIS data provides a new dimension to aerosol observations by showing the dynamics of the system. For example
in February smoke and dust emitted from the Sahel and West Africa is shown to travel to the North-East Atlantic. In April
heavy dust and pollution from East Asia is shown to travel to North America. In May-June pollution and dust play a dynamical
80