End to end simulator for the WIVERN W-band Doppler conically scanning spaceborne radar

Abstract

Abstract. The WIVERN (WInd VElocity Radar Nephoscope) mission, soon entering in Phase-0 of the ESA Earth Explorer program, promises to complement Doppler wind lidar by globally observing, for the first time, vertical profiles of winds in cloudy areas. This work describes an end to end simulator of the WIVERN conically scanning 94 GHz Doppler radar, the only payload of the mission. Specific features of the simulator are: the conically scanning geometry; the inclusion of cross-polarization effects and of the simulation of a radiometric mode; the applicability to global cloud model outputs via an orbital model; the incorporation of a mispointing model accounting for thermo-elastic distortions, microvibrations, star-trackers uncertainties, etc.; the inclusion of the surface clutter. Some of the simulator capabilities are showcased for a case study involving a full rotational scan of the instrument. The simulator represents a very useful tool for studying the performances of the WIVERN concept and possible trade-offs for the different configurations (e.g. different antenna sizes, pulse lengths, antenna patterns, .....). Thanks to its modular structure the simulator can be easily adapted to different orbits, different scanning geometries and different frequencies.

Filling the Gap of Wind Observations Inside Tropical Cyclones

“…• Instrument noise and stochastic noise are added to the reflectivities and to the Doppler velocities according to the procedure described in Battaglia et al (2022). In order to evaluate the effect of the sensitivity of the WIVERN radar, different reflectivity equivalent noise floors at 1 km are used: −20, −23, and −26 dBZ.…”

“…The precision of the Doppler measurements tends to improve with the correlation between the H and V pairs, the number of independent pulses that are averaged, higher levels of SNR (i.e., strong reflectivities), and signal-to-ghost ratio (SGR) (i.e., decreased contamination by ghosts). The standard deviation of the estimated Doppler velocity can be approximated as (Battaglia et al, 2022;Pazmany et al, 1999):…”

“…In this configuration, the computation of WIVERN Doppler velocities will be done via the polarization diversity pulse pair technique (Battaglia et al, 2022). Estimates of mean Doppler velocities from this technique are unbiased (apart when close to the Nyquist interval) and have an intrinsic noise associated with the phase and thermal noise (Pazmany et al, 1999).…”

“…The WIVERN (WInd VElocity Radar Nephoscope) mission (www.wivern.polito.it Illingworth et al, 2018;Battaglia et al, 2022), currently in Phase-0 within the ESA Earth Explorer program, promises to complement the Aeolus measurements, with a concept similar to the Radar Wind Sounder proposed by Moore et al (1996) or the DYCECT mission proposed by Lemaître and Viltard (2013). For the first time, it would provide global observations of vertical profiles of winds in cloudy and rainy areas thanks to a conically scanning W-band (94 GHz) radar with polarization diversity capability.…”

In orbit cross-calibration of millimeter conically scanning spaceborne radars

“…This novel observing system will enable more accurate forecasts of precipitation and extreme weather events to help people, countries and businesses mitigate the impact of severe weather events expected to exacerbate in a warming climate. A W-band conically scanning radar with polarization diversity Doppler capabilities aimed at providing in-cloud winds for improving numerical weather prediction is also undergoing ESA Earth Explorer 11 selection program Phase 0 studies as part of the Wivern mission (Illingworth et al (2018); Battaglia et al (2018Battaglia et al ( , 2022).…”