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Rayleigh wind retrieval for the ALADIN airborne demonstrator of the Aeolus mission using simulated response calibration

Zhai, Xiaochun and Marksteiner, Uwe and Weiler, Fabian and Lemmerz, Christian and Lux, Oliver and Witschas, Benjamin and Reitebuch, Oliver (2020) Rayleigh wind retrieval for the ALADIN airborne demonstrator of the Aeolus mission using simulated response calibration. Atmospheric Measurement Techniques (AMT), 13 (2), pp. 445-465. Copernicus Publications. doi: 10.5194/amt-13-445-2020. ISSN 1867-1381.

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Official URL: https://amt.copernicus.org/articles/13/445/2020/amt-13-445-2020.html

Abstract

Aeolus, launched on 22 August in 2018, is the first ever satellite to directly observe wind information from the surface up to 30 km on a global scale. An airborne prototype instrument called ALADIN airborne demonstrator (A2D) was developed at the German Aerospace Center (DLR) for validating the Aeolus measurement principle based on realistic atmospheric signals. To obtain accurate wind retrievals, the A2D uses a measured Rayleigh response calibration (MRRC) to calibrate its Rayleigh channel signals. However, differences exist between the respective atmospheric temperature profiles that are present during the conduction of the MRRC and the actual wind measurements. These differences are an important source of wind bias since the atmospheric temperature has a direct effect on the instrument response calibration. Furthermore, some experimental limitations and requirements need to be considered carefully to achieve a reliable MRRC. The atmospheric and instrumental variability thus currently limit the reliability and repeatability of a MRRC. In this paper, a procedure for a simulated Rayleigh response calibration (SRRC) is developed and presented in order to resolve these limitations of the A2D MRRC. At first the transmission functions of the A2D Rayleigh channel double-edge Fabry-Pérot interferometers (FPIs) in the internal reference path and the atmospheric path are characterized and optimized based on measurements performed during different airborne and ground-based campaigns. The optimized FPI transmission functions are then combined with the laser reference spectrum and the temperature-dependent molecular Rayleigh backscatter spectrum to derive an accurate A2D SRRC which can finally be implemented into the wind retrieval. Using dropsonde data as a reference, a statistical analysis based on a dataset from a flight campaign in 2016 reveals a bias and a standard deviation of line-of-sight (LOS) wind speeds derived from a SRRC of only 0.05 and 2.52 m/s, respectively. Compared to the result derived from a MRRC with a bias of 0.23 m/s and a standard deviation of 2.20 m/s, the accuracy improved and the precision is considered to be at the same level. Furthermore, it is shown that the SRRC allows for the simulation of receiver responses over the whole altitude range from the aircraft down to sea level, thus overcoming limitations due to high ground elevation during the acquisition of an airborne instrument response calibration.

Item URL in elib:https://elib.dlr.de/138318/
Document Type:Article
Title:Rayleigh wind retrieval for the ALADIN airborne demonstrator of the Aeolus mission using simulated response calibration
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Zhai, XiaochunDLR, IPAUNSPECIFIED
Marksteiner, UweDLR, IPAhttps://orcid.org/0000-0002-4335-922X
Weiler, FabianDLR, IPAUNSPECIFIED
Lemmerz, ChristianDLR, IPAUNSPECIFIED
Lux, OliverDLR, IPAhttps://orcid.org/0000-0003-1491-0323
Witschas, BenjaminDLR, IPAhttps://orcid.org/0000-0001-7993-1470
Reitebuch, OliverDLR, IPAhttps://orcid.org/0000-0002-8503-0094
Date:5 February 2020
Journal or Publication Title:Atmospheric Measurement Techniques (AMT)
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:13
DOI :10.5194/amt-13-445-2020
Page Range:pp. 445-465
Publisher:Copernicus Publications
ISSN:1867-1381
Status:Published
Keywords:Aeolus, ALADIN Airborne Demonstrator, Rayleigh response calibration, Rayleigh-Brillouin spectrum
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Earth Observation
DLR - Research area:Raumfahrt
DLR - Program:R EO - Earth Observation
DLR - Research theme (Project):R - Projekt ADM (old)
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Atmospheric Physics > Lidar
Deposited By: Lux, Dr. Oliver
Deposited On:26 Nov 2020 10:34
Last Modified:26 Nov 2020 10:34

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