Quality control and error assessment of the Aeolus L2B wind results from the Joint Aeolus Tropical Atlantic Campaign

Lux, Oliver; Witschas, Benjamin; Geiß, Alexander; Lemmerz, Christian; Weiler, Fabian; Marksteiner, Uwe; Rahm, Stephan; Schäfler, Andreas; Reitebuch, Oliver

doi:10.5194/amt-2022-223

Cited by 3 publications

(5 citation statements)

References 31 publications

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“…It can be seen that Mie-cloudy winds in general contain more outliers. This also confirms that the QC by means of the validity flag and the EE threshold is not sufficient and that an additional QC by means of the modified Z score is needed, especially for the Mie-cloudy winds (Lux et al, 2022b). Following the same logic as for the Rayleigh-clear winds, an optimal EE threshold of 5.5 m s −1 is determined for the Mie-cloudy winds of the AVATAR-I data set and 5.0 m s −1 for the Mie-cloudy winds of the AVATAR-T data set.…”

Section: Quality Control Of Aeolus Datasupporting

confidence: 60%

“…A discussion about the selection of EE thresholds is given in Sect. 4.3 as well as in a dedicated publication by Lux et al (2022b). The Falcon wind measurements are treated in a similar way.…”

Section: Adaption Of the Measurement Gridmentioning

confidence: 99%

“…Ideally, the EE thresholds are chosen such that the Aeolus wind errors with respect to the validation instrument (i.e., the 2 µm DWL or the Falcon in situ winds) are normally distributed, since the random error is defined as the standard deviation of a Gaussian distribution in the Aeolus mission requirements (ESA, 2016). While the comprehensive approach to determining the EE threshold is described separately by Lux et al (2022b), only a rough outline of the procedure is presented here.…”

Section: Quality Control Of Aeolus Datamentioning

confidence: 99%

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Validation of the Aeolus L2B wind product with airborne wind lidar measurements in the polar North Atlantic region and in the tropics

et al. 2022

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Abstract. During the first 3 years of the European Space Agency's Aeolus mission, the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt, DLR) performed four airborne campaigns deploying two different Doppler wind lidars (DWL) on board the DLR Falcon aircraft, aiming to validate the quality of the recent Aeolus Level 2B (L2B) wind data product (processor baseline 11 and 12). The first two campaigns, WindVal III (November–December 2018) and AVATAR-E (Aeolus Validation Through Airborne Lidars in Europe, May and June 2019), were conducted in Europe and provided first insights into the data quality at the beginning of the mission phase. The two later campaigns, AVATAR-I (Aeolus Validation Through Airborne Lidars in Iceland) and AVATAR-T (Aeolus Validation Through Airborne Lidars in the Tropics), were performed in regions of particular interest for the Aeolus validation: AVATAR-I was conducted from Keflavik, Iceland, between 9 September and 1 October 2019 to sample the high wind speeds in the vicinity of the polar jet stream; AVATAR-T was carried out from Sal, Cape Verde, between 6 and 28 September 2021 to measure winds in the Saharan dust-laden African easterly jet. Altogether, 10 Aeolus underflights were performed during AVATAR-I and 11 underflights during AVATAR-T, covering about 8000 and 11 000 km along the Aeolus measurement track, respectively. Based on these collocated measurements, statistical comparisons of Aeolus data with the reference lidar (2 µm DWL) as well as with in situ measurements by the Falcon were performed to determine the systematic and random errors of Rayleigh-clear and Mie-cloudy winds that are contained in the Aeolus L2B product. It is demonstrated that the systematic error almost fulfills the mission requirement of being below 0.7 m s−1 for both Rayleigh-clear and Mie-cloudy winds. The random error is shown to vary between 5.5 and 7.1 m s−1 for Rayleigh-clear winds and is thus larger than specified (2.5 m s−1), whereas it is close to the specifications for Mie-cloudy winds (2.7 to 2.9 m s−1). In addition, the dependency of the systematic and random errors on the actual wind speed, the geolocation, the scattering ratio, and the time difference between 2 µm DWL observation and satellite overflight is investigated and discussed. Thus, this work contributes to the characterization of the Aeolus data quality in different meteorological situations and allows one to investigate wind retrieval algorithm improvements for reprocessed Aeolus data sets.

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Section: Quality Control Of Aeolus Datasupporting

confidence: 60%

Section: Adaption Of the Measurement Gridmentioning

confidence: 99%

Section: Quality Control Of Aeolus Datamentioning

confidence: 99%

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Validation of the Aeolus L2B wind product with airborne wind lidar measurements in the polar North Atlantic region and in the tropics

et al. 2022

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“…And as the EE is varying over time and geographical location due to the different solar , 2016). While the comprhensive approach to detemine the the EE threshold is described separately by Lux et al (2022b), only a rough outline of the procedure is presented here.…”

Section: Quality Control Of Aeolus Datamentioning

confidence: 99%

Validation of the Aeolus L2B wind product with airborne wind lidar measurements in the polar North Atlantic region and in the tropics

Witschas

Lemmerz

Geiß³

et al. 2022

Preprint

Self Cite

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Abstract. During the first three years of European Space Agency’s Aeolus mission, the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt, DLR) performed four airborne campaigns deploying two different Doppler wind lidars (DWL) on-board the DLR Falcon aircraft, aiming to validate the quality of the recent Aeolus Level 2B (L2B) wind data product (processor baseline 11 and 12). The first two campaigns, WindVal III (Nov/Dec 2018) and AVATAR-E (Aeolus Validation Through Airborne Lidars in Europe, May/Jun 2019) were conducted in Europe and provided first insights in the data quality at the beginning of the mission phase. The two later campaigns, AVATAR-I (Aeolus Validation Through Airborne Lidars in Iceland) and AVATAR-T (Aeolus Validation Through Airborne Lidars in the Tropics), were performed in regions of particular interest for the Aeolus validation: AVATAR-I was conducted from Keflavik, Iceland between 9 September and 1 October 2019 to sample the high wind speeds in the vicinity of the polar jet stream. AVATAR-T was carried out from Sal, Cape Verde between 6 September and 28 September 2021 to measure winds in the Saharan dust-laden African easterly jet. Altogether, 10 Aeolus underflights were performed during AVATAR-I and 11 underflights during AVATAR-T, covering about 8000 km and 11000 km along the Aeolus measurement track, respectively. Based on these collocated measurements, statistical comparisons of Aeolus data with the reference lidar (2-µm DWL) as well as with in-situ measurements by the Falcon were performed to determine the systematic and random error of Rayleigh-clear and Mie-cloudy winds that are contained in the Aeolus L2B product. It is demonstrated that the systematic error almost fulfills the mission requirement of being below 0.7 m s-1 for both Rayleigh-clear and Mie-cloudy winds. The random error is shown to vary between 5.5 m s-1 and 7.1 m s-1 for Rayleigh-clear winds and is thus larger than specified (2.5 m s-1), whereas it is close to the specifications for Mie-cloudy winds (2.7 to 2.9 m s-1). In addition, the dependency of the systematic and random errors on the actual wind speed, the geolocation, the scattering ratio and the time difference between 2-µm DWL observation and satellite overflight is investigated and discussed. Thus, this work contributes to the characterization of the Aeolus data quality in different meteorological situations and allows to investigate wind retrieval algorithm improvements for reprocessed Aeolus data sets.

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“…Additionally, Aeolus regular operation has undergone other major changes. During the second half of June 2021 Aeolus orbit setting changed from ANX4.5 to ANX2.0 in the framework of upcoming tropical campaigns activities in Cape Verde (Fehr et al, 2021(Fehr et al, , 2022Lux et al, 2022b): Joint Aeolus Tropical Atlantic Campaign (JATAC), causing the orbit characteristics (e.g., ground track) to significantly shift.…”

mentioning

confidence: 99%

Validation Activities of Aeolus Wind Products in the Southeastern Iberian Peninsula

Abril-Gago

Ortiz-Amezcua²,

Bermejo-Pantaleón³

et al. 2022

Preprint

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Abstract. A statistical validation campaign of Aeolus L2B wind products has been performed with a ground-based Doppler lidar system and radiosondes at the ACTRIS/AGORA facility in Granada (Spain). The validation activities with the automatic ground-based lidar system lasted from the release of the reprocessed Aeolus data to the orbit shift of June 2021. This validation was performed using 109 B10 and B11 Aeolus products (within 100 km around the station) and 30-min averages of coincident ground-based lidar measurements (mean bin distance of ~50 km). The comparison yielded an approximately equal overestimation and underestimation of Aeolus HLOS wind speed during that period for the Rayleigh clear and Mie cloudy configurations. However, the reliability of the results was constrained to Aeolus’ lowermost bins (roughly up to 3.5 km asl), due to the limited vertical coverage of the ground-based lidar measurements. Several spin-off analyses were performed varying the maximum distance to consider an Aeolus bin into the comparison and the average of the ground-based lidar measurements, in order to confirm the reliability of the criteria considered. An additional study was performed with Aeolus products after the orbit shift (B12 with a mean bin distance of ~75 km). A set of 7 radiosondes were launched between June 2021 and July 2022 (B12, mean bin distance of ~75 km) aiming to increase their coincidence in space and time with the satellite overpass (~30 minutes before). The radiosondes could provide full vertical coverage of Aeolus profiles (from surface up to ~20 km asl) and the comparison yielded that the Rayleigh clear HLOS wind speed presented an approximately equal overestimation and underestimation, while the Mie cloudy HLOS wind speed was significantly overestimated. Spin-off analyses were performed in order to test how the spatiotemporal colocation of the radiosonde affected the results.

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Quality control and error assessment of the Aeolus L2B wind results from the Joint Aeolus Tropical Atlantic Campaign

Cited by 3 publications

References 31 publications

Validation of the Aeolus L2B wind product with airborne wind lidar measurements in the polar North Atlantic region and in the tropics

Validation of the Aeolus L2B wind product with airborne wind lidar measurements in the polar North Atlantic region and in the tropics

Validation of the Aeolus L2B wind product with airborne wind lidar measurements in the polar North Atlantic region and in the tropics

Validation Activities of Aeolus Wind Products in the Southeastern Iberian Peninsula

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