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Introduction
Brochure
Science:
Envisat
Data assimilation
Objectives
Links:
ASSET database
Current data
Ozone intercomparison
Partners
Publications
Calendar
Document archive 
Contacts
= ASSET members and
PAG only
 = ASSET members and
PAG; others may request access from the coordinators
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The specific objectives of ASSET are:
1. To assess the strategies for exploiting research satellite data
by the NWP community
| The combination of research satellite data (e.g.
from Envisat) and operational data in NWP systems is desirable for
weather, seasonal, chemical and UV forecasting, the derivation of
wind information in the lower stratosphere, and the production of
value-added ancillary atmospheric fields for climate change and attribution
studies. Using three leading European NWP systems (those of the Met
Office (UK), Meteo-France
and ECMWF) based on
global circulation models (GCMs), ASSET will investigate the impact
of Envisat assimilation of temperature, ozone, water vapour and other
chemical species with different measurement geometries (limb/nadir),
different data types (retrieved geophysical data/radiance data) and
different approaches to modelling photochemistry (parametrizations
and coupled NWP/chemistry systems). To reflect the various approaches
to assimilating Envisat data, each NWP system will be set up differently.
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2. To investigate the distribution and variability of atmospheric
chemical species by exploiting research satellite data
| The relatively simpler configuration of, e.g.,
a chemistry-transport model (CTM) compared to an NWP system allows
one to include a large number of chemical species measured by, e.g.,
Envisat, and provides a tool for investigating the distribution and
variability of these species. The CTMs allow the testing of photochemical
theories, and the production of climatologies of observed and unobserved
species (using the model photochemical relations). Using four leading
European photochemical models (those of KNMI,
UPMC, BIRA-IASB
and FRIUUK), ASSET
will assimilate Envisat data to investigate the distribution and variability
(in time and space) of the key species ozone, NOy (NO+NO2+HNO3 plus
other related species) and stratospheric aerosol, plus a number of
key species in the troposphere (e.g. boundary layer aerosol, O3, NO2,
CH2O, CH4, and CO). ASSET will investigate the spatial distribution
and variability of these key species in terms of pressure, latitude
and longitude, and their temporal distribution on time-scales from
days to a season. To reflect and cover the various key species and
areas investigated by ASSET, each modelling team will focus on one
of ozone, NOy, stratospheric aerosol, and the troposphere. |
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