Author:
B. Sauvage ; R. V. Martin ; A. van Donkelaar ; X. Liu ; K. Chance ; L. Jaeglé ; P. I. Palmer ; S. Wu ; T.-M. Fu

Abstract:
We use a global chemical transport model (GEOS-Chem) to evaluate the consistency of satellite measurements of lightning flashes and ozone precursors with in situ measurements of tropical tropospheric ozone. The measurements are tropospheric O₃, NO₂, and HCHO columns from the GOME satellite instrument, lightning flashes from the OTD and LIS satellite instruments, profiles of O₃, CO, and relative humidity from the MOZAIC aircraft program, and profiles of O₃ from the SHADOZ ozonesonde network. We interpret these multiple data sources with our model to better understand what controls tropical tropospheric ozone. Tropical tropospheric ozone is mainly affected by lightning NO_x and convection in the upper troposphere and by surface emissions in the lower troposphere. Scaling the spatial distribution of lightning in the model to the observed flashes improves the simulation of O₃ in the upper troposphere by 5-20 ppbv versus in situ observations and by 1-4 Dobson Units versus GOME retrievals of tropospheric O₃ columns. A lightning source strength of 6±2 Tg N/yr best represents in situ observations from aircraft and ozonesonde. Tropospheric NO₂ and HCHO columns from GOME are applied to provide top-down constraints on emission inventories of NO_x (biomass burning and soils) and VOCs (biomass burning). The top-down biomass burning inventory is larger than the bottom-up inventory by a factor of 2 for HCHO and alkenes, and by a factor of 2.6 for NO_x over northern equatorial Africa. These emissions increase lower tropospheric O₃ by 5-20 ppbv, improving the simulation versus aircraft observations, and by 4 Dobson Units versus GOME observations of tropospheric O₃ columns. Emission factors in the a posteriori inventory are more consistent with a recent compilation from in situ measurements. The ozone simulation using two different dynamical schemes (GEOS-3 and GEOS-4) is evaluated versus observations; GEOS-4 better represents O₃ observations by 5-15 ppbv, reflecting enhanced convective detrainment in the upper troposphere. Heterogeneous uptake of HNO₃ on aerosols reduces simulated O₃ by 5-7 ppbv, reducing a model bias versus in situ observations over and downwind of deserts. Exclusion of HO₂ uptake on aerosols increases O₃ by 5 ppbv in biomass burning regions, reducing a model bias versus MOZAIC aircraft measurements.

Journal: Atmospheric Chemistry and Physics
Issn: 16807316
EIssn: 16807324
Year: 2007
Volume: 7
Issue: 3

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Technorati : GEOS-3, GEOS-4, GEOS-Chem, MOZAIC

Author:
Peter Janssen
Werner Alpers

Institution
ECMWF, Shinfield Park, Reading RG2 9AX, United Kingdom Institut für Meereskunde, Universität Hamburg, Bundesstrasse 53, D-20146 Hamburg, Germany

Summary
It would be desirable to have a tool for the global recognition for the phenomenon of rogue states or on the surface of the ocean Waves. Based on the theory of SAR imaging of the surface of the ocean waves developed in the 1980's, argues Despite the recent period, which claim the contrary, it is not possible for the data to SAR wave mode and the ERS The Envisat satellite.

The main reason is that due to the movement of the surface of the sea, the SAR imaging Mechanism is usually not very linear. The resolution SAR images of the ocean is a place very distorted wave Pictures of the ocean wave city, which is little resemblance to the reality of city water. The exceptions are Perhaps if narrow-band trains Swell on the rank in the direction of the wind, a lack of marine However, These cases are rare and can not be regarded as a representative cross-section of the global division of the sea, the United States.

The courts of the highest in the SAR image of the intensity or the "groupiness" picture distribution of intensity not Not as a rule are the locations for the maximum amplitude of the waves or in the "groupiness" in the water. So it is not possible to deal with this technology, reliable information on the probability of occurrence Extreme waves of the ocean in global

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Technorati : Extreme, Global, SAR, Wave