 |
| Titel |
First Results of Inversion for Far Infrared Limb Sounding |
| VerfasserIn |
Jian Xu, Franz Schreier, Adrian Doicu, Peter Vogt, Thomas Trautmann |
| Konferenz |
EGU General Assembly 2011
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250051159
|
|
|
|
|
|
| Zusammenfassung |
| A number of new generation instruments for remote sensing of the stratosphere have recently
been launched in order to measure emission from space in the infrared (IR) and microwave
spectral range to map atmospheric species. IR/microwave limb sounding is a well
established technique for the observation of stratospheric trace gas species and has
several advantages of meeting the research requirements that make the observations
preferable.
With support from SRON in the Netherlands and RAL in UK, the Remote Sensing
Technology Institute (IMF) at the German Aerospace Center (DLR) has developed a new
stratospheric balloon-borne submillimeter limb sounder, so-called TELIS (Terahertz
and submillimeter LImb Sounder), which can be regarded as the successor of the
THOMAS heterodyne instrument that has successfully been operated on DLR’s
FALCON research aircraft. Together with MIPAS-B instrument TELIS is acting as a
precursor of further space-borne instruments for IR/microwave limb sounding.
SMILES (Superconducting subMIllimeter-wave Limb-Emission Sounder), a joint
space-borne mission between JAXA and NICT in Japan, aims to demonstrate highly
sensitive submillimeter-wave soundings and to monitor global distributions of the
stratospheric trace gases. Future missions will obviously utilize the millimeter and
submillimeter waves that enable simultaneous observations of many trace species. High
sensitivity is particularly essential for these missions to clarify trends of trace gases in
mid-latitudes and to detect dynamical features of the atmosphere. Therefore, the
development of instruments contributes to an increased interest and demand in high
resolution radiative transfer modeling and advanced inversion strategy for better
understanding of atmospheric environment by analyzing the recent limb sounding
measurements.
The goal of our data analysis is to determine the atmospheric profile -ăx with the data
vector -ăy comprising the signal measured by the instrument. Thus, we have to solve a
minimization problem
min = -¥-ăF(-ăx)- -ăy-¥2 ,
-ăx
(1)
which leads to an iterative solution by applying the Gauss–Newton method
[ ]-1
δ-ăx = A (-ăx0)TA (-ăx0) A(-ăx0)T δ-ăy .
(2)
Here, -ă
F and A denote the analytical measurements (model spectra) generated by the
forward model, and the Jacobian matrix (first-order partial derivatives of function),
respectively.
A new code PILS (Profile Inversion for Limb Sounding), whose forward model is built
on the Line-by-Line code GARLIC/MIRART, has been developed by DLR-IMF for solving
the nonlinear inverse problems arising in the analysis of atmospheric measurements by recent
limb sounders. This program emphasizes efficient and reliable algorithms and techniques for
the computation of radiance and transmission, the Jacobian matrix evaluation, and
constrained nonlinear least squares optimization.
In this work we present first results of retrieval of the gas concentration profiles as well as
sensitivity studies from the far infrared limb sounding observations. In particular,
automatic differentiation techniques and numerical regularization schemes shall be
studied. |
|
|
|
|
|
|