Airborne Radar Observations of Severe Hailstorms: Implications for Future Spaceborne Radar

Abstract

A new dual-frequency (Ku and Ka band) nadir-pointing Doppler radar on the high-altitude NASA ER-2 aircraft, called the High-Altitude Imaging Wind and Rain Airborne Profiler (HIWRAP), has collected data over severe thunderstorms in Oklahoma and Kansas during the Midlatitude Continental Convective Clouds Experiment (MC3E). The overarching motivation for this study is to understand the behavior of the dualwavelength airborne radar measurements in a global variety of thunderstorms and how these may relate to future spaceborne-radar measurements. HIWRAP is operated at frequencies that are similar to those of the precipitation radar on the Tropical Rainfall Measuring Mission (Ku band) and the upcoming Global Precipitation Measurement mission satellite's dual-frequency (Ku and Ka bands) precipitation radar. The aircraft measurements of strong hailstorms have been combined with ground-based polarimetric measurements to obtain a better understanding of the response of the Ku-and Ka-band radar to the vertical distribution of the hydrometeors, including hail. Data from two flight lines on 24 May 2011 are presented. Doppler velocities were ;39 m s 21 at 10.7-km altitude from the first flight line early on 24 May, and the lower value of ;25 m s 21 on a second flight line later in the day. Vertical motions estimated using a fall speed estimate for large graupel and hail suggested that the first storm had an updraft that possibly exceeded 60 m s 21 for the more intense part of the storm. This large updraft speed along with reports of 5-cm hail at the surface, reflectivities reaching 70 dBZ at S band in the storm cores, and hail signals from polarimetric data provide a highly challenging situation for spaceborne-radar measurements in intense convective systems. The Ku-and Ka-band reflectivities rarely exceed ;47 and ;37 dBZ, respectively, in these storms.

Signatures of Hydrometeor Species from Airborne Passive Microwave Data for Frequencies 10–183 GHz

“…1, the convection on this day was organized into a squall-line-like structure to the south oriented roughly north-south along 988W at this time with trailing discrete convective cells to the northwest. For information on the environmental conditions associated with this case, see Heymsfield et al (2013). As expected, hail and HG dominate in the convective cores while VI and aggregates dominate in the leading stratiform/anvil regions.…”

The Global Precipitation Measurement (GPM) mission's scientific achievements and societal contributions: reviewing four years of advanced rain and snow observations

“…These include the physics of, and methods to parametrize, the DSD (e.g. Liao et al, 2014;Williams et al, 2014;Raupach and Berne, 2017;Tokay et al, 2017), including new observations of small raindrops (<0.5 mm) and their impact on current approaches to representing the DSD in light rain (Thurai et al, 2017), radar multiple-scattering at DPR frequencies in strong convection (Heymsfield et al, 2013;Battaglia et al, 2016a,b), and hail signatures in radiometer data (Leppert and Cecil, 2015). Examples of multi-frequency ice and snow scattering studies include Molthan and Petersen (2011), Tyynelä and Chandrasekar (2014), Kneifel et al (2015) and Olson et al (2016), while measurements of snow water equivalent rate can be found in Moisseev et al (2017) and von Lerber et al (2018).…”

Similarities and Improvements of GPM Dual-Frequency Precipitation Radar (DPR) upon TRMM Precipitation Radar (PR) in Global Precipitation Rate Estimation, Type Classification and Vertical Profiling

“…However, because the structures of convection vary with different updraft characteristics, the microphysical composition and horizontal dimensions of the hydrometeors [74], convective precipitation is too complicated to make a direct comparison as we have done for stratiform precipitation. Greater efforts should be extended into the study of precipitation mechanisms and the exploration of the interactions between precipitation particles and radar's echo to obtain accurate Z-R relationships.…”