NASA Scientific and Technical Aerospace Reports

for an artificial offset likely induced by spectral structure on the diffuser plate of the GOME instrument. The stratospheric
column is determined from NO2 columns over the remote Pacific Ocean to minimize contamination from tropospheric NO2.
The air mass factor (AMF) used to convert slant columns to vertical columns is calculated from the integral of the relative
vertical NO2 distribution from a global 3-D model of tropospheric chemistry driven by assimilated meteorological data
(Global Earth Observing System (GEOS)-CHEM), weighted by altitude dependent scattering weights computed with a
radiative transfer model (Linearized Discrete Ordinate Radiative Transfer), using local surface albedos determined from
GOME observations at NO2 wavelengths. The AMF calculation accounts for cloud scattering using cloud fraction, cloud top
pressure, and cloud optical thickness from a cloud retrieval algorithm (GOME Cloud Retrieval Algorithm). Over continental
regions with high surface emissions, clouds decrease the AMT by 20- 30% relative to clear sky. GOME is almost twice as
sensitive to tropospheric NO2 columns over ocean than over land. Comparison of the retrieved tropospheric NO2 columns for
July 1996 with GEOS-CHEM values tests both the retrieval and the nitrogen oxide radical (NOx) emissions inventories used
in GEOS-CHEM. Retrieved tropospheric NO2 columns over the USA, where NOx emissions are particularly well known, are
within 18% of GEOS-CHEM columns and are strongly spatially correlated (r = 0.78, n = 288, p less than 0.005). Retrieved
columns show more NO2 than GEOS-CHEM columns over the Transvaal region of South Africa and industrial regions of the
northeast USA and Europe. They are lower over Houston, India, eastern Asia, and the biomass burning region of central Africa,
possibly because of biases from absorbing aerosols.
Author
Retrieval; Stratosphere; Nitrogen Dioxide; Atmospheric Chemistry; Meteorological Parameters
20040111406 Harvard Univ., Cambridge, MA, USA
Interannual and Seasonal Variability of Biomass Burning Emissions Constrained by Satellite Observations
Duncan, Bryan N.; Martin, Randall V.; Staudt, Amanda C.; Yevich, Rosemarie; Logan, Jennifer A.; Journal of Geophysical
Research; 2003; ISSN 0148-0227; Volume 109, No. D2, pp. 1-1 - 1-22; In English
Contract(s)/Grant(s): NAG1-2307; NSF ATM-99-03529; Copyright; Avail: Other Sources
We present a methodology for estimating the seasonal and interannual variation of biomass burning designed for use in
global chemical transport models. The average seasonal variation is estimated from 4 years of fire-count data from the Along
Track Scanning Radiometer (ATSR) and 1-2 years of similar data from the Advanced Very High Resolution Radiometer
(AVHRR) World Fire Atlases. We use the Total Ozone Mapping Spectrometer (TOMS) Aerosol Index (AI) data product as
a surrogate to estimate interannual variability in biomass burning for six regions: Southeast Asia, Indonesia and Malaysia,
Brazil, Central America and Mexico, Canada and Alaska, and Asiatic Russia. The AI data set is available from 1979 to the
present with an interruption in satellite observations from mid-1993 to mid-1996; this data gap is filled where possible with
estimates of area burned from the literature for different regions. Between August 1996 and July 2000, the ATSR fire-counts
are used to provide specific locations of emissions and a record of interannual variability throughout the world. We use our
methodology to estimate mean seasonal and interannual variations for emissions of carbon monoxide from biomass burning,
and we find that no trend is apparent in these emissions over the last two decades, but that there is significant interannual
variability.
Author
Biomass Burning; Emission; Aerosols; Atmospheric Composition; Carbon Monoxide
20040111407 Harvard Univ., Cambridge, MA, USA
Sources of Tropospheric Ozone along the Asian Pacific Rim: An Analysis of Ozonesonde Observations
Liu, Hong-Yu; Jacob, Daniel J.; Chan, Lo Yin; Oltmans, Samuel J.; Bey, Isabelle; Yantosca, Robert M.; Harris, Joyce M.;
Duncan, Bryan N.; Martin, Randall V.; Journal of Geophysical Research; 2002; ISSN 0148-0227; Volume 107, No. D21,
pp. 3-1 - 3-16; In English; Original contains color and black and white illustrations
Contract(s)/Grant(s): NAG1-2307; Copyright; Avail: Other Sources
The sources contributing to tropospheric ozone over the Asian Pacific Rim in different seasons are quantified by analysis
of Hong Kong and Japanese ozonesonde observations with a global three-dimensional (3-D) chemical transport model
(GEOS-CHEM) driven by assimilated meteorological observations. Particular focus is placed on the extensive observations
available from Hong Kong in 1996. In the middle-upper troposphere (MT- UT), maximum Asian pollution influence along the
Pacific Rim occurs in summer, reflecting rapid convective transport of surface pollution. In the lower troposphere (LT) the
season of maximum Asian pollution influence shifts to summer at midlatitudes from fall at low latitudes due to monsoonal
influence. The UT ozone minimum and high variability observed over Hong Kong in winter reflects frequent tropical
intrusions alternating with stratospheric intrusions. Asian biomass burning makes a major contribution to ozone at less than
32 deg.N in spring. Maximum European pollution influence (less than 5 ppbv) occurs in spring in the LT. North American
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