Validation of Satellite Snowfall Measurements in CONUS

The Global Precipitation Measurement (GPM) Core Observation satellite, launched in February 2014, was developed in partnership with the National Aeronautics and Space Administration (NASA) and the Japan Aerospace Exploration Agency (JAXA). The satellite anchors a global network of satellites from other countries that also collect precipitation measurements. Since GPM is new, one requirement of the satellite is to detect falling snow. The goal of this study was to use data from GPM’s Dual-Frequency Precipitation Radar (DPR) to validate falling snow events as observed on the surface. If GPM can detect falling snow and classify it as such, then it could lead to increased knowledge of fresh water resources. Many areas of the world rely on snowfall for yearly fresh water supplies. GPM can lead to a better understanding of the full picture of the water cycle and the effects precipitation has on the availability of fresh water. This can result in identifying patterns of precipitation systems over land.

Snow events that occurred in CONUS, east of the Rocky Mountains, between March 2014 and February 2016 were collected. Only a number of these collected events were studied due to GPM’s lack of coverage of an event or a lack of observations available for an event. Ground observations were used for validation. Observations that reported snow were compared with GPM’s precipRateNearSurface and phaseNearSurface variables. The observed snowfall intensity (light, moderate, or heavy) and precipitation rate were compared to determine common precipitation rates for snowfall intensities. The observed visibility was also compared with the precipitation rate to determine if there was any correlation. The phase of precipitation, measured by GPM, was compared with the observations to determine if GPM detected snow when the observation reported snow.

This study found that GPM can detect snow when it is snowing which confirms the main objective of this study. It was also found that precipitation rates correlate with snowfall intensity. For example, precipitation rates were higher for moderate snow than for light snow. Visibilities do not necessarily correlate with precipitation rates. It was expected that visibility would decrease with an increase in precipitation rate, but this was not the case for light snow observations.