Determination of ice water content (IWC) in tropical convective clouds from X-band dual-polarization airborne radar

Abstract

This paper presents a methodology for ice water content (IWC) retrieval from a dual-polarization sidelooking X-band airborne radar. Measured IWC from aircraft in situ probes is weighted by a function of the radar differential reflectivity (Z dr ) to reduce the effects of ice crystal shape and orientation on the variation in IWC -specific differential phase (K dp ) joint distribution. A theoretical study indicates that the proposed method, which does not require a knowledge of the particle size distribution (PSD) and number density of ice crystals, is suitable for high-ice-water-content (HIWC) regions in tropical convective clouds. Using datasets collected during the High Altitude Ice Crystals -High Ice Water Content (HAIC-HIWC) international field campaign in Cayenne, French Guiana (2015), it is shown that the proposed method improves the estimation bias by 35 % and increases the correlation by 4 % on average, compared to the method using specific differential phase (K dp ) alone. Wolde and Vali, 2001). It has been shown that the radar-Published by Copernicus Publications on behalf of the European Geosciences Union.

Microphysical processes producing high ice water contents (HIWCs) in tropical convective clouds during the HAIC-HIWC field campaign: evaluation of simulations using bulk microphysical schemes

“…However, they found the pilot X-band weather radar on the Canadian National Research Council (NRC) Convair-580 aircraft did not have adequate sensitivity to detect HIWC regions when calibrated using the NRC X-band research radar. Nguyen et al (2019) proposed a retrieval method for IWC using the specific differential phase (K dp ) and differential reflectivity ratio (Z dr ) data from X-band dual-polarization airborne radar. This method was demonstrated to be superior to the power-law fits between IWC and reflectivity as accounting for Z dr reduced the dependency of IWC on the variation in the shapes and orientation of ice particles.…”

Microphysical Processes Producing High Ice Water Contents (HIWCs) in Tropical Convective Clouds during the HAIC-HIWC Field Campaign: Evaluation of Simulations Using Bulk Microphysical Schemes

“…Regions with high ice water content (HIWC), mainly composed of small ice crystals with median mass diameters (MMDs) as low as 300 µm, frequently occur over oceanic convective systems (Mason and Grzych, 2011;Ackerman et al, 2015;Leroy et al, 2016b). Such HIWC regions, with relatively low equivalent radar reflectivities (Z e ) (often less than 20 dBZ; Mason et al, 2006;Fridlind et al, 2015;Protat et al, 2016;Wolde et al, 2016;Leroy et al, 2017), are hard to detect with pilot radars onboard commercial aircraft and are thus potentially hazardous.…”

“…The HIWC RADAR campaign was conducted out of Florida in August 2015. Data collected during these campaigns have been being analyzed to understand HIWC conditions (Leroy et al, 2015(Leroy et al, , 2016a(Leroy et al, , 2017Protat et al, 2016;Wolde et al, 2016;Korolev et al, 2020), to develop warning products that can identify HIWC regions (Yost et al, 2018;Bedka et al, 2019;Harrah et al, 2019;Haggerty et al, 2020), and to characterize the high-altitude HIWC environment to assess a new ice crystal aircraft certification envelope.…”

Climatology of the Vertical Profiles of Polarimetric Radar Variables and Retrieved Microphysical Parameters in Continental/Tropical MCSs and Landfalling Hurricanes

“…Notable is a prominent increase of K DP and Z DR in the dendritic growth layer (DGL) centered at the −15°C altitude (8 km). High K DP associated with low Z in the ice part of the storm is a classical feature of the tropical cyclones indicating relatively high concentration of small-size ice particles with quite substantial IWC (Nguyen et al, 2019;Ryzhkov & Zrnic, 2019).…”