In:
Atmospheric Measurement Techniques, Copernicus GmbH, Vol. 14, No. 2 ( 2021-02-24), p. 1425-1438
Abstract:
Abstract. In order to validate satellite measurements of
atmospheric composition, it is necessary to understand the range of random
and systematic uncertainties inherent in the measurements. On occasions
where measurements from two different satellite instruments do not agree
within those estimated uncertainties, a common explanation is that the
difference can be assigned to geophysical variability, i.e., differences due
to sampling the atmosphere at different times and locations. However, the
expected geophysical variability is often left ambiguous and rarely
quantified. This paper describes a case study where the geophysical
variability of O3 between two satellite instruments – ACE-FTS
(Atmospheric Chemistry Experiment – Fourier Transform Spectrometer) and
OSIRIS (Optical Spectrograph and InfraRed Imaging System) – is estimated
using simulations from climate models. This is done by sampling the models
CMAM (Canadian Middle Atmosphere Model), EMAC (ECHAM/MESSy Atmospheric
Chemistry), and WACCM (Whole Atmosphere Community Climate Model) throughout
the upper troposphere and stratosphere at times and geolocations of
coincident ACE-FTS and OSIRIS measurements. Ensemble mean values show that
in the lower stratosphere, O3 geophysical variability tends to be
independent of the chosen time coincidence criterion, up to within 12 h; and
conversely, in the upper stratosphere geophysical variation tends to be
independent of the chosen distance criterion, up to within 2000 km. It was
also found that in the lower stratosphere, at altitudes where there is the
greatest difference between air composition inside and outside the polar
vortex, the geophysical variability in the southern polar region can be
double of that in the northern polar region. This study shows that the
ensemble mean estimates of geophysical variation can be used when comparing
data from two satellite instruments to optimize the coincidence criteria,
allowing for the use of more coincident profiles while providing an estimate
of the geophysical variation within the comparison results.
Type of Medium:
Online Resource
ISSN:
1867-8548
DOI:
10.5194/amt-14-1425-2021
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2021
detail.hit.zdb_id:
2505596-3
