Comparisons of Ice Water Path in Deep Convective Systems Among Ground‐Based, GOES, and CERES‐MODIS Retrievals

Abstract

Retrievals of convective cloud microphysical properties based on passive satellite imagery are difficult. To help quantify their uncertainties, ice water paths (IWPs) retrieved from the NASA Clouds and the Earth's Radiant Energy System project using Geostationary Operational Environmental Satellite (GOES) and Terra/Aqua MODerate‐resolution Imaging Spectroradiometer observations are compared with IWPs retrieved from Next‐Generation Radar (NEXRAD) observations over a large domain (32°N to 40°N and 105°W to 91°W) during the 2011 Midlatitude Continental Convective Clouds Experiment field campaign. Based on comparisons of pixel‐level (4 km × 4 km) daytime IWP retrievals from NEXRAD and GOES, it is found that NEXRAD‐ and GOES‐retrieved mean IWPs are 2.03 and 1.83 kg m−2, respectively, for ice‐phase cloud in thick anvil area. Their mean difference of 0.20 kg m−2 (with 95% confidence interval: 0.14–0.26 kg m−2) is within the uncertainty of NEXRAD retrievals. However, the low correlation between pixel‐to‐pixel comparisons indicates a large variation in GOES‐retrieved IWP. For mixed‐phase clouds in thick anvil areas, in addition to IWPs, total water paths (TWPs, sum of ice and liquid water path) are estimated with aid of aircraft measurements for NEXRAD retrievals and corrected using a TWP parameterization for GOES retrievals. The mean values of estimated TWPs from NEXRAD (corrected using aircraft in situ measurements) and GOES are similar. GOES and Clouds and the Earth's Radiant Energy System‐MODerate‐resolution Imaging Spectroradiometer‐retrieved IWPs/TWPs generally do not exceed 5 kg m−2. Large differences and low correlations exist between satellite and NEXRAD retrievals in stratiform rain areas. Possible reasons for the differences between retrievals are discussed.

Understanding Ice Cloud‐Precipitation Properties of Three Modes of Mesoscale Convective Systems During PECAN

“…The retrieval algorithms are capable of characterizing IWCs over the SR regions of midlatitude continental convective systems. The retrieved IWPs based on radar reflectivity are also used to compare with satellite‐retrieved IWPs to help quantify the uncertainties in the satellite retrievals (Tian et al, ).…”

“…In this study, most analyses are based on the radar-reflectivity-retrieved products; therefore, a significant amount of uncertainty could be realized during the generalization of the results. The retrieved IWCs for the SR region have been validated in Tian et al (2016Tian et al ( , 2018 and showed uncertainties around 20% to 40% against the in situ measurements. These uncertainties are consistent but smaller when compared to the K dp -retrieved IWCs and IWPs for the SR region.…”

CERES MODIS Cloud Product Retrievals for Edition 4—Part I: Algorithm Changes

“…Ice water paths for deep convective clouds determined from the Next-Generation Radar (NEXRAD) data over the south central United States were compared in [114] with Ed4 Terra and Aqua retrievals and with Ed4-like retrievals from GOES imager data. It was determined that the GOES and Ed4 retrievals underestimated the NEXRAD IWP by 4 ± 61% and 9 ± 59%, respectively, for the thick anvil portions of the convective systems, which had a mean IWP of 2.24 kg•m −2 .…”

Comparison of Cloud Microphysics Schemes in a Warn-on-Forecast System Using Synthetic Satellite Objects

“…For thick convective clouds, the determination of IWP and CWP from any type of sensor is less certain than for thin clouds. In comparisons with NEXRAD retrievals, Tian et al (2018) found that the SatCORPS IWP was, on average, 10% lower than the radar estimates for ice-only anvils. However, in stratiform rain portions of the convection, the IWP underestimate is 20% due to the prevalence of larger ice crystals lower in the cloud and to the SatCORPS optical depth retrieval limit of 150.…”