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Bias Correction Methods for Aeolus Winds - Harmonic Bias Estimator and M1 Temperature Correlation

Marksteiner, Uwe and Weiler, Fabian and Reitebuch, Oliver and Nikolaus, Ines and Rennie, Michael and Kanitz, Thomas (2020) Bias Correction Methods for Aeolus Winds - Harmonic Bias Estimator and M1 Temperature Correlation. 2nd Aeolus Post Launch CalVal and Science Workshop, 02.-06. November 2020, Online (ursprünglich Darmstadt, Deutschland).

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The original justification of setting up a Harmonic Bias Estimator (HBE) was the need to correct Aeolus winds for potential harmonic contributors to the wind bias, which could be for example induced by pointing and thermal effects that depend on the latitudinal position of the satellite. Since Aeolus is an Earth Explorer mission and the first of its kind, i.e. due to lack of heritage, the construction of the HBE was based on theoretical assumptions about the harmonic errors, on best knowledge from models and on end-to-end simulations. However, reality proved to be more complicated. The current performance of the HBE is assessed and limitations of the purely latitude-based HBE are presented in order to explain why a correction via harmonic bias estimation is not the preferred option for the current systematic Rayleigh wind speed errors. On the basis of real Aeolus observations, it was found that the systematic Rayleigh wind speed error is strongly correlated with small variations in the temperature distribution across the primary mirror (M1) of Aeolus’ telescope. These temperature variations are a function of Earth’s outgoing short and longwave radiation at the top of the atmosphere and cause minimal distortions of the telescope structure. As a consequence, the wind bias shows complex patterns along the orbit that depend on latitude as well as on longitude. These patterns cannot be captured by the HBE approach. Methods are presented which correct for the distortion effect by applying a regression of the wind bias on the M1 temperature measurements contained in the housekeeping data. The improvement for the different approaches will be discussed, including the operational implementation. Thereby, an effective bias correction via the M1 temperature might pave the way for new findings on Aeolus’ wind bias dependencies and for a potential subsequent application of an HBE in the future aiming at any remaining biases.

Item URL in elib:https://elib.dlr.de/138931/
Document Type:Conference or Workshop Item (Poster, Other)
Title:Bias Correction Methods for Aeolus Winds - Harmonic Bias Estimator and M1 Temperature Correlation
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Marksteiner, UweDLR, IPAhttps://orcid.org/0000-0002-4335-922X
Reitebuch, OliverDLR, IPAhttps://orcid.org/0000-0002-8503-0094
Nikolaus, InesPhysics SolutionsUNSPECIFIED
Rennie, MichaelECMWF, Reading, UKUNSPECIFIED
Date:6 November 2020
Refereed publication:No
Open Access:Yes
Gold Open Access:No
In ISI Web of Science:No
Keywords:ADM, Aeolus, ALADIN, Bias, Harmonic Bias Estimator, HBE, Temperature, Lidar, Rayleigh, DLR, ESA, DISC, Satellite
Event Title:2nd Aeolus Post Launch CalVal and Science Workshop
Event Location:Online (ursprünglich Darmstadt, Deutschland)
Event Type:Workshop
Event Dates:02.-06. November 2020
Organizer:ESA (European Space Agency)
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: Marksteiner, Dr. Uwe
Deposited On:01 Dec 2020 12:50
Last Modified:01 Dec 2020 12:50

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