Airborne wind lidar observations over the North Atlantic in 2016 for the pre-launch validation of the satellite mission Aeolus

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

doi:10.5194/amt-2018-19

Cited by 10 publications

(20 citation statements)

References 27 publications

(30 reference statements)

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“…This result is consistent with previous verifications of the DWLmeasured wind speeds with dropsonde data [20,27]. Other studies [28][29][30][31] have shown comparisons of DWL data to dropsonde data that are in better agreement than with our study (i.e., smaller RMSE). This is most likely due to the fact that TCs have a highly variable wind field, and the different measurement volumes had different wind speeds in the comparison.…”

Section: Resultssupporting

confidence: 93%

Airborne Doppler Wind Lidar Observations of the Tropical Cyclone Boundary Layer

et al. 2018

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This study presents a verification and an analysis of wind profile data collected during Tropical Storm Erika (2015) by a Doppler Wind Lidar (DWL) instrument aboard a P3 Hurricane Hunter aircraft of the National Oceanic and Atmospheric Administration (NOAA). DWL-measured winds are compared to those from nearly collocated GPS dropsondes, and show good agreement in terms of both the wind magnitude and asymmetric distribution of the wind field. A comparison of the DWL-measured wind speeds versus dropsonde-measured wind speeds yields a reasonably good correlation (r 2 = 0.95), with a root mean square error (RMSE) of 1.58 m s −1 and a bias of −0.023 m s −1. Our analysis shows that the DWL complements the existing P3 Doppler radar, in that it collects wind data in rain-free and low-rain regions where Doppler radar is limited for wind observations. The DWL observations also complement dropsonde measurements by significantly enlarging the sampling size and spatial coverage of the boundary layer winds. An analysis of the DWL wind data shows that the boundary layer of Erika was much deeper than that of a typical hurricane-strength storm. Streamline and vorticity analyses based on DWL wind observations explain why Erika maintained intensity in a sheared environment. This study suggests that DWL wind data are valuable for real-time intensity forecasts, basic understanding of the boundary layer structure and dynamics, and offshore wind energy applications under tropical cyclone conditions.

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Section: Resultssupporting

confidence: 93%

Airborne Doppler Wind Lidar Observations of the Tropical Cyclone Boundary Layer

et al. 2018

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“…Already several years before the launch, an airborne prototype of the Aeolus payload, the ALADIN Airborne Demonstrator (A2D), was developed at DLR. Owing to its representative design and operating principle, the A2D provides valuable information on the wind measurement strategies of the satellite instrument as well as on the optimization of the wind retrieval and related quality-control algorithms [10,11]. In November 2018, the first airborne validation campaign after launch was carried out from the airbase in Oberpfaffenhofen, Germany.…”

Section: First Airborne Validation Resultsmentioning

confidence: 99%

Initial Assessment of the Performance of the First Wind Lidar in Space on Aeolus

Reitebuch¹,

Lemmerz²,

Lux³

et al. 2020

EPJ Web Conf.

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Soon after its successful launch in August 2018, the spaceborne wind lidar ALADIN (Atmospheric LAser Doppler INstrument) on-board ESA’s Earth Explorer satellite Aeolus has demonstrated to provide atmospheric wind profiles on a global scale. Being the first ever Doppler Wind Lidar (DWL) instrument in space, ALADIN contributes to the improvement in numerical weather prediction (NWP) by measuring one component of the horizontal wind vector. The performance of the ALADIN instrument was assessed by a team from ESA, DLR, industry, and NWP centers during the first months of operation. The current knowledge about the main contributors to the random and systematic errors from the instrument will be discussed. First validation results from an airborne campaign with two wind lidars on-board the DLR Falcon aircraft will be shown.

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“…Following WindVal III in late 2018, two additional airborne validation campaigns were conducted within the first year of the operational phase of Aeolus. Whereas the AVATARE campaign (Airborne VAlidation Through Airborne lidaRs in Europe) was again carried out from Oberpfaffenhofen, Germany, in May/June 2019, AVATARI (Airborne VAlidation Through Airborne lidaRs in Iceland), performed in September 2019, had its air base in Keflavík, Iceland, which was also the location of the WindVal II cam-paign in 2016 prior to the launch (Lux et al, 2018;Schäfler et al, 2018). The two campaigns not only considerably extended the available dataset to validate Aeolus wind observations in different geographical regions and under different atmospheric conditions in terms of cloud types and dynamics but also served to assess the accuracy and precision of the Aeolus wind product in different phases of the mission.…”

Section: Overview Of Validation Campaigns and Datasetsmentioning

confidence: 99%

“…The A2D was developed by the European Aeronautic Defence and Space (EADS) Astrium (now Airbus Defence and Space) in cooperation with the DLR in the early 2000s. Its design and operating principle were extensively described in several previous publications (Paffrath et al, 2009;Reitebuch et al, 2009;Lux et al, 2018Lux et al, , 2020a. Therefore, only a brief description is provided here.…”

Section: Avatarimentioning

confidence: 99%

“…After the masking procedure, the ground detection is performed for both channels. The applied scheme is very similar to that of Aeolus and was developed in the frame of the WindVal II data analysis (Weiler, 2017;Lux et al, 2018). The identification of ground bins leads to additional masks for the two channels that further restrict the number of bins in the final wind curtain.…”

Section: The A2d Wind Retrievalmentioning

confidence: 99%

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Retrieval improvements for the ALADIN Airborne Demonstrator in support of the Aeolus wind product validation

et al. 2022

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Abstract. The realization of the European Space Agency's Aeolus mission was supported by the long-standing development and field deployment of the Atmospheric LAser Doppler INstrument (ALADIN) Airborne Demonstrator (A2D) which, since the launch of the Aeolus satellite in 2018, has been serving as a key instrument for the validation of ALADIN, the first-ever Doppler wind lidar (DWL) in space. However, the validation capabilities of the A2D are compromised by deficiencies of the dual-channel receiver which, like its spaceborne counterpart, consists of a Rayleigh and a complementary Mie spectrometer for sensing the wind speed from both molecular and particulate backscatter signals, respectively. Whereas the accuracy and precision of the Rayleigh channel is limited by the spectrometer's high alignment sensitivity, especially in the near field of the instrument, large systematic Mie wind errors are caused by aberrations of the interferometer in combination with the temporal overlap of adjacent range gates during signal readout. The two error sources are mitigated by modifications of the A2D wind retrieval algorithm. A novel quality control scheme was implemented, which ensures that only backscatter return signals within a small angular range are further processed. Moreover, Mie wind results with large bias of opposing sign in adjacent range bins are vertically averaged. The resulting improvement of the A2D performance was evaluated in the context of two Aeolus airborne validation campaigns that were conducted between May and September 2019. Comparison of the A2D wind data against a high-accuracy, coherent DWL that was deployed in parallel on board the same aircraft shows that the retrieval refinements considerably decrease the random errors of the A2D line-of-sight (LOS) Rayleigh and Mie winds from about 2.0 to about 1.5 m s−1, demonstrating the capability of such a direct detection DWL. Furthermore, the measurement range of the Rayleigh channel could be largely extended by up to 2 km in the instrument's near field close to the aircraft. The Rayleigh and Mie systematic errors are below 0.5 m s−1 (LOS), hence allowing for an accurate assessment of the Aeolus wind errors during the September campaign. The latter revealed different biases of the Level 2B (L2B) Rayleigh-clear and Mie-cloudy horizontal LOS (HLOS) winds for ascending and descending orbits, as well as random errors of about 3 m s−1 (HLOS) for the Mie and close to 6 m s−1 (HLOS) for the Rayleigh winds, respectively. In addition to the Aeolus error evaluation, the present study discusses the applicability of the developed A2D algorithm modifications to the Aeolus processor, thereby offering prospects for improving the Aeolus wind data quality.

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Airborne wind lidar observations over the North Atlantic in 2016 for the pre-launch validation of the satellite mission Aeolus

Cited by 10 publications

References 27 publications

Airborne Doppler Wind Lidar Observations of the Tropical Cyclone Boundary Layer

Airborne Doppler Wind Lidar Observations of the Tropical Cyclone Boundary Layer

Initial Assessment of the Performance of the First Wind Lidar in Space on Aeolus

Retrieval improvements for the ALADIN Airborne Demonstrator in support of the Aeolus wind product validation

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