Publication Date:
2017-04-04
Description:
The Ground-Based Millimeter-wave Spectrometer
(GBMS) was designed and built at the State University
of New York at Stony Brook in the early 1990s and since
then has carried out many measurement campaigns of stratospheric
O3, HNO3, CO and N2O at polar and mid-latitudes.
Its HNO3 data set shed light on HNO3 annual cycles over
the Antarctic continent and contributed to the validation of
both generations of the satellite-based JPL Microwave Limb
Sounder (MLS). Following the increasing need for long-term
data sets of stratospheric constituents, we resolved to establish
a long-term GMBS observation site at the Arctic station
of Thule (76.5 N, 68.8 W), Greenland, beginning in January
2009, in order to track the long- and short-term interactions
between the changing climate and the seasonal processes
tied to the ozone depletion phenomenon. Furthermore,
we updated the retrieval algorithm adapting the Optimal
Estimation (OE) method to GBMS spectral data in order
to conform to the standard of the Network for the Detection
of Atmospheric Composition Change (NDACC) microwave
group, and to provide our retrievals with a set of averaging
kernels that allow more straightforward comparisons with
other data sets. The new OE algorithm was applied to GBMS
HNO3 data sets from 1993 South Pole observations to date,
in order to produce HNO3 version 2 (v2) profiles. A sample
of results obtained at Antarctic latitudes in fall and winter
and at mid-latitudes is shown here. In most conditions, v2
inversions show a sensitivity (i.e., sum of column elements
of the averaging kernel matrix) of 100±20% from 20 to
45 km altitude, with somewhat worse (better) sensitivity in
the Antarctic winter lower (upper) stratosphere. The 1 uncertainty
on HNO3 v2 mixing ratio vertical profiles depends on altitude and is estimated at 15% or 0.3 ppbv, whichever
is larger. Comparisons of v2 with former (v1) GBMS HNO3
vertical profiles, obtained employing the constrained matrix
inversion method, show that v1 and v2 profiles are overall
consistent. The main difference is at the HNO3 mixing ratio
maximum in the 20–25 km altitude range, which is smaller
in v2 than v1 profiles by up to 2 ppbv at mid-latitudes and
during the Antarctic fall. This difference suggests a better
agreement of GBMS HNO3 v2 profiles with both UARS/ and
EOS Aura/MLS HNO3 data than previous v1 profiles.
Description:
Published
Description:
1317-1330
Description:
1.7. Osservazioni di alta e media atmosfera
Description:
JCR Journal
Description:
open
Keywords:
Atmospheric composition and structure
;
Instruments and techniques
;
01. Atmosphere::01.01. Atmosphere::01.01.01. Composition and Structure
;
01. Atmosphere::01.01. Atmosphere::01.01.04. Processes and Dynamics
;
01. Atmosphere::01.01. Atmosphere::01.01.08. Instruments and techniques
;
05. General::05.05. Mathematical geophysics::05.05.99. General or miscellaneous
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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