Validation of Automated Cloud Height Algorithm (ACHA) Cloud Top Heights in Tropical Cyclones using Observations from the NASA Global Hawk

Infrared (IR) imagery from geostationary satellites is a common way to view tropical cyclones (TCs). The IR brightness temperature is often used as a proxy for the vigor of the convective eyewall region, but it is also informative to know the heights the clouds are achieving for practical purposes like aviation hazard avoidance, and for assigning altitudes to cloud-tracked wind vectors. Other applications include model validation, satellite intercalibration studies, and TC research that depends on knowing the height of features such as the outflow.

An advanced geostationary satellite-derived cloud analysis algorithm is under development at NOAA/NESDIS/STAR. In this study, we apply the Automated Cloud Height Algorithm (ACHA) to estimate cloud-top heights (CTH) in TCs, and validate these estimates by comparing to other airborne and satellite cloud height identifiers. These include CTH estimates from the Cloud‐Aerosol Lidar with Orthogonal Polarization (CALIOP) and the W-band radar aboard CloudSat over western Pacific typhoons, as well as measurements from the Scanning High-resolution Interferometer Sounder and Cloud Physics Lidar flown aboard the Global Hawk (GH) during the 2012 and 2013 NASA Hurricane and Severe Storm Sentinel (HS3) field campaigns. The ACHA CTH product was used extensively in real time during the HS3 campaign in 2013 to assist with safe maneuvering of the GH flying over and around Atlantic TCs.