Downloaded from SAE International by Kristopher Bedka, Monday, June 10, 2019 2019-01-1953 Published 10 Jun 2019 Analysis and Automated Detection of Ice Crystal Icing Conditions Using Geostationary Satellite Datasets and In Situ Ice Water Content Measurements Kristopher Bedka NASA Langley Research Center Christopher Yost Science Systems and Applications, Inc. Louis Nguyen NASA Langley Research Center J. Walter Strapp Met Analytics, Inc. Thomas Ratvasky NASA John Glenn Research Center Konstantin Khlopenkov, Benjamin Scarino, Rajendra Bhatt, Douglas Spangenberg, and Rabindra Palikonda Science Systems and Applications, Inc. Citation: Bedka, K., Yost, C., Nguyen, L., Strapp, J.W. et al., “Analysis and Automated Detection of Ice Crystal Icing Conditions Using Geostationary Satellite Datasets and In Situ Ice Water Content Measurements,” SAE Technical Paper 2019-01-1953, 2019, doi:10.4271/2019-01-1953. Abstract proximity (≤ 40 km) to convective updrafts were most likely ecent studies have found that high mass concentra- to contain high TWC (TWC ≥ 1 g m-3). These parameters are tions of ice particles in regions of deep convective detected using automated algorithms and combined to Rstorms can adversely impact aircraft engine and air generate a HIWC probability (PHIWC) product at the NASA probe (e.g. pitot tube and air temperature) performance. Radar Langley Research Center (LaRC). Seven NASA DC-8 aircraft reflectivity in these regions suggests that they are safe for flights were conducted in August 2018 over the Gulf of Mexico aircraft penetration, yet high ice water content (HIWC) is still and the tropical Pacific Ocean during the HIWC Radar II field encountered. The aviation weather community seeks addi- campaign. The convection sampled during four flights was tional remote sensing methods for delineating where ice observed by GOES-16 at 1- or 5-minute intervals, providing particle (or crystal) icing conditions are likely to occur, the first opportunity to analyze product performance from including products derived from geostationary (GEO) satellite this new satellite. This paper will (1) present initial compari- imagery that is now available in near-real time at increasingly sons between GOES-16 and IKP-2 datasets during HIWC high spatio-temporal detail from the global GEO satellite Radar II, (2) demonstrate GOES-16 products for select periods constellation. A recent study using a large sample of co-located when high TWC was encountered with an emphasis on three GEO satellite and in-situ isokinetic evaporator probe (IKP-2) flights with 1-minute imagery, (3) compare GOES observa- total water content (TWC) datasets found that optically thick tions and derived products from the HIWC Radar I and II clouds with tops near to or above the tropopause in close campaigns. Introduction opaque in visible wavelength imagery due to high concentra- eostationary (GEO) satellites routinely observe tions of ice particles in their tops and a deep layer of hydrome- hazardous deep convective storms across the world. teors below. Convective cloud tops are elevated to heights that GThe term hazardous here refers to weather conditions can exceed 20 km above ground in especially intense storms. such as lightning, flooding rainfall, damaging wind, hail, As the clouds rise, they become increasingly cold and the tornadoes, and aviation hazards such as turbulence and icing outflow from convective updrafts, commonly referred to as that are a threat to people, property, and/or transportation. “anvil cloud”, expands outward. Anvil temperatures typically Storms that produce these hazards exhibit a set of unique fall somewhere between the convective equilibrium level and spatial, temporal, and multi-spectral patterns in GEO imagery. the tropopause. Strong atmospheric instability near the updraft For example, convective clouds are extremely reflective and and other in-storm dynamical processes provide energy that © 2019 SAE International; NASA Glenn Research Center. Downloaded from SAE International by Kristopher Bedka, Monday, June 10, 2019 2 ANALYSIS AND AUTOMATED DETECTION OF ICE CRYSTAL ICING CONDITIONS enables cloud tops to penetrate through the anvil cloud. The A new set of NOAA Geostationary Operational height difference between the updraft cloud and anvil generates Environmental Satellites (GOES) have recently become opera- texture in satellite visible wavelength imagery and also a tional, providing observations over much of the Western temperature contrast in infrared (IR) imagery. These anvil- Hemisphere with four times better spatial detail than previous penetrating updraft regions, commonly referred to as “over- GOES satellites [22]. These GOES-16 and -17 satellites also shooting tops”, appear colder than the anvil usually by at least observe two ~1000x1000 km “Mesoscale Domain Sectors” at 5 degrees Kelvin (K). When these strong convective updrafts 1-minute intervals and can observe a region up to every penetrate through the anvil level, where the atmosphere is 30 seconds when these Sectors are aligned. Automated NASA stable and resistant to vertical motions, gravity waves are gener- LaRC HIWC detections applied to GOES-14 1-minute “super ated that provide a visual indication of where strong ice mass rapid scan” imagery collected during the 2015 NASA HIWC flux away from the updraft is occurring. The waves also Radar I field campaign 8[ ] showed the best correlation with generate texture in visible imagery and occasionally tempera- in-situ TWC observations to date from any satellite-derived ture oscillations that are less prominent compared to texture product [9,11]. Previous satellite-based HIWC studies were and cold anomalies from overshooting top (OT) updrafts. based on imagery collected at 10- to 30-minute intervals by Convective updrafts rapidly transport high concentrations GOES-13, Meteosat Second Generation, or the Multifunction of ice particles into the anvil cloud layer. Recent studies have Transport Satellite-1R (MTSAT-1R), a sampling frequency documented many events since the early 1990s where aircraft that is often inadequate for resolving rapidly evolving storm flight through deep convective storms and anvil cloud has processes responsible for generating HIWC. resulted in jet engine power loss, loss of engine control, and/or NASA conducted the HIWC Radar II field campaign in engine damage [1, 2, 3]. [2] reported that engine events occurred August 2018 to collect in-situ measurements within deep in seemingly innocuous cloud regions with only light to convection to compare to data collected in previous HIWC moderate turbulence, infrequent lightning, and where the pilot’s flight campaigns and to test new algorithms that can be applied radar indicated green or weaker echoes (< approximately to onboard aircraft weather radar observations to detect 30 dBZ), leading to their hypothesis that the aircraft were HIWC regions [8,13]. These measurements can also be used encountering high mass concentrations of small ice particles to further develop and test GEO satellite-based HIWC detec- associated with convective updrafts, and ice accretion in the tion methods. Seven NASA DC-8 aircraft flights were engine by ingested ice particles was likely the cause of the events. conducted from 2-20 August 2018. The first two flights were These encounters of high mass concentrations in low radar based in Fort Lauderdale, Florida and sampled scattered reflectivity have been termed high ice water content (HIWC) convection and MCSs in the Gulf of Mexico. As the campaign events. Icing of aircraft air data probes (e.g. air temperature progressed, the environment over the western Atlantic and sensors and pitot airspeed indicators) has also been recognized Gulf of Mexico regions became extremely unfavorable for to occur in the same type of cloud conditions [1,2,4,5]. At the significant deep convection, so campaign operations were present time, there is no formal definition of HIWC based on moved to the NASA Armstrong Flight Research Center in in-situ ice water content. Many in the community choose > 1.0 Palmdale, CA where the DC-8 aircraft is based. The five g m-3 as the HIWC threshold, but [5] found that air data probe remaining flights were devoted to sampling tropical cyclone anomalies can occur with ice water content > 0.5 g m-3 averaged Lane, from the time of first classification as Tropical over a 10-minute period, and [43] found that 0.5 g m-3 could Depression 14-E on 15 August through Category 3 and 4 impact engine performance. Therefore, in this paper we refer hurricane status on 20 August. Detailed descriptions of the to TWC measurements that exceed 0.5 g m-3 as “high TWC”. campaign and corresponding aircraft radar-based HIWC Automated algorithms have recently been developed at research are provided by [8,13] NASA Langley Research Center (LaRC) to identify patterns Storms sampled by three HIWC Radar II flights were in cloud tops associated with hazardous convection and ice observed via GOES-16 at 1-minute intervals through a particle icing conditions. A large and diverse database of request to NOAA from the campaign Forecast Team. in-situ total water content (TWC) observations has recently Another flight was observed at 5-minute intervals. These been collected by NASA and other international research data provide an excellent opportunity to analyze the perfor- aircraft during the European High Altitude Ice Crystal mance of the LaRC PHIWC product as well as to continue (HAIC) [6] and North American High Ice Water Content to study cloud evolution coincident