Summary of the High Ice Water Content (HIWC) RADAR Flight Campaigns

Abstract

NASA and the FAA conducted two flight campaigns to quantify onboard weather radar measurements with in-situ measurements of high concentrations of ice crystals found in deep convective storms. The ultimate goal of this research was to improve the understanding of high ice water content (HIWC) and develop onboard weather radar processing techniques to detect regions of HIWC ahead of an aircraft to enable tactical avoidance of the potentially hazardous conditions. Both HIWC RADAR campaigns utilized the NASA DC-8 Airborne Science Laboratory equipped with a Honeywell RDR-4000 weather radar and in-situ microphysical instruments to characterize the ice crystal clouds. The purpose of this paper is to summarize how these campaigns were conducted and highlight key results. The first campaign was conducted in August 2015 with a base of operations in Ft. Lauderdale, Florida. Ten research flights were made into deep convective systems that included Mesoscale Convective Systems (MCS) near the Gulf of Mexico and Atlantic Ocean, and Tropical Storms Danny and Erika near the Caribbean Sea. The radar and in-situ measurements from these ten flights were analyzed and correlations defined. Key results included 1) derived relationships between radar reflectivity factor (RRF), Ice Water Content (IWC), and ice particle size distributions, 2) characterization of HIWC conditions at the-50°C and other flight levels, and 3) verification of pilot observations, such as low radar reflectivity factor and pitot and total air temperature (TAT) anomalies. This data set also enabled new pilot radar HIWC detection algorithms to be developed and tested. A second campaign was conducted in August 2018 to test proposed HIWC radar detection algorithms within a new set of storm systems. Seven research flights were conducted from bases of operations in Ft. Lauderdale, Florida; Palmdale, California; and Kona, Hawaii. Flights were made into convective systems over the Gulf of Mexico and into an eastern-Pacific tropical system that developed into Hurricane Lane. Using a new, NASA-developed radar processing technique called "Swerling", regions of HIWC were identified, and estimates of IWC were produced, at distances up to 60 Nm ahead of the NASA DC-8. Subsequently, the DC-8 flew through these regions to acquire the insitu measurements to verify the radar-based IWC estimates.

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

“…where D eq is the equivalent volume diameter of an ice particle (Ryzhkov and Zrnić, 2019). The m s -D max relations are commonly used (e.g., Locatelli and Hobbs, 1974;Mitchell, 1996;Finlon et al, 2019;Ding et al, 2020), where D max is the maximal dimension 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

“…In order to explore the processes responsible for the occurrence of HIWC regions and the associated ice crystal properties within tropical convection, the High Altitude Ice Crystals -High Ice Water Content (HAIC-HIWC) international field campaigns (Dezitter et al, 2013;Strapp et al, 2016a) and the HIWC RADAR campaign (Ratvasky et al, 2019) were conducted. The first HAIC-HIWC field campaign took place near Darwin, Australia, during the monsoon season of 2014, with the second out of Cayenne, French Guiana, in May 2015.…”

Photoacoustic hygrometer for icing wind tunnel water content measurement: design, analysis, and intercomparison

“…Freezing precipitation containing supercooled large drops (SLDs) with drop diameters in excess of 50 µm and convective mixed-phase and glaciated clouds with high mass concentrations of ice crystals, i.e., ice water content (IWC) up to several grams per cubic meter, constitute two particular meteorological environments associated with severe icing events (Politovich, 1989;Bernstein et al, 2000;Cober et al, 2001b;Riley, 1998).…”