In orbit cross-calibration of millimeter conically scanning spaceborne radars

Battaglia, Alessandro; Scarsi, Filippo Emilio; Mróz, Kamil; Illingworth, Anthony J.

doi:10.5194/amt-2022-213

Cited by 2 publications

(3 citation statements)

References 22 publications

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“…Realistic Doppler velocities that would be observed by WIVERN have been simulated for various reflectivity equivalent noise floors (20, −23, and −26 dBZ) and various integration lengths (1, 2, and 10 km). From the reflectivity and Doppler velocity gradients averaged over 1 × 5 km boxes, NUBF and WS errors corrections (Battaglia et al., 2023) provide unbiased velocity estimates which are compared to the LoS wind velocity, finally yielding the wind residual statistics. Results are similar for forward and side pointing (only the results for forward pointing are shown in Figures 8b and 9 for simplicity).…”

Section: Discussionmentioning

confidence: 99%

Filling the Gap of Wind Observations Inside Tropical Cyclones

Tridon,

Battaglia,

Rizik

et al. 2023

Earth and Space Science

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The WIVERN (WInd VElocity Radar Nephoscope) mission, currently under the Phase‐0 of the ESA Earth Explorer program, promises to provide new insight in the coupling between winds and microphysics by globally observing, for the first time, vertical profiles of horizontal winds in cloudy areas. The objective of this work is to explore the potential of the WIVERN conically scanning Doppler 94 GHz radar for filling the wind observation gap inside tropical cyclones (TCs). To this aim, realistic WIVERN notional observations of TCs are produced by combining the CloudSat 94 GHz radar reflectivity observations from 2007 to 2009 with ECMWF co‐located winds. Despite the short wavelength of the radar (3 mm), which causes strong attenuation in presence of large amount of liquid hydrometeors, the system can profile most of the TCs, particularly the cloudy areas above the freezing level and the precipitating stratiform regions. The statistical analysis of the results shows that, (a) because of its lower sensitivity, a nadir pointing WIVERN would detect 75% of the clouds observed by CloudSat (45% of winds with 3 m s−1 accuracy, in comparison to CloudSat sampling of clouds), (b) but thanks to its scanning capability, WIVERN would actually provide 53 times more observations of clouds than CloudSat in TCs (30 times more observations of horizontal winds), (c) this corresponds to about 350 (200) million observations of clouds (accurate winds) every year. Such observations could be used to shed light on the physical processes underpinning the evolution of TCs and in data assimilation in order to improve numerical weather prediction.

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Section: Discussionmentioning

confidence: 99%

Filling the Gap of Wind Observations Inside Tropical Cyclones

Tridon,

Battaglia,

Rizik

et al. 2023

Earth and Space Science

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“…4. Jensen-Shannon distances (like in Battaglia et al, 2023) between ascending and descending pdfs computed in step 3 and for A/D pdfs shifted by different wind biases (e.g. ±2 m s −1 corresponding to azimuth biases of 400 µrad).…”

Section: Cloudsat-based Analysismentioning

confidence: 99%

“…5. Threshold values expressed in terms of integration time or number of measured winds where different bias levels become detectable according to the Jensen-Shannon distances computed in step number 4 (like in Battaglia et al, 2023).…”

Section: Cloudsat-based Analysismentioning

confidence: 99%

Mispointing characterization and Doppler velocity correction for the conically scanning WIVERN Doppler radar

Scarsi,

Battaglia,

Tridon

et al. 2024

Atmos. Meas. Tech.

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Abstract. Global measurements of horizontal winds in cloud and precipitation systems represent a gap in the global observation system. The Wind Velocity Radar Nephoscope (WIVERN) mission, one of the two candidates to be the ESA's Earth Explorer 11 mission, aims at filling this gap based on a conically scanning W-band Doppler radar instrument. The determination of the antenna boresight mispointing angles and the impact of their uncertainty on the line of sight Doppler velocities is critical to achieve the mission requirements. While substantial industrial efforts are on their way to achieving accurate determination of the pointing, alternative (external) calibration approaches are currently under scrutiny. The correction of the line of sight Doppler velocity error introduced by the mispointing only needs knowledge of such mispointing angles and does not need the correction of the mispointing itself. Thus, this work discusses four methods applicable to the WIVERN radar that can be used at different timescales to characterize the antenna mispointing both in the azimuthal and in the elevation directions and to correct the error in the Doppler velocity induced by such mispointing. Results show that elevation mispointing is well corrected at very short timescales by monitoring the range at which the surface peak occurs. Azimuthal mispointing is harder but can be tackled by using the expected profiles of the non-moving surface Doppler velocity. Biases in pointing at longer timescales can be monitored by using a well-established reference database (e.g. ECMWF reanalysis) or ad-hoc ground-based calibrators. Although tailored to the WIVERN mission, the proposed methodologies can be extended to other Doppler concepts featuring conically scanning or slant viewing Doppler systems.

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In orbit cross-calibration of millimeter conically scanning spaceborne radars

Cited by 2 publications

References 22 publications

Filling the Gap of Wind Observations Inside Tropical Cyclones

Filling the Gap of Wind Observations Inside Tropical Cyclones

Mispointing characterization and Doppler velocity correction for the conically scanning WIVERN Doppler radar

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