Abstract
AbstractEarth‐orbiting satellites have long been used to examine meteorological processes. In the context of severe weather, brightness temperatures (BTs) at infrared wavelengths allow the determination of convective cloud properties. The anvils of cumulonimbus clouds, for example, typically produce BTs close to the tropopause temperature. Particularly severe storms generate overshoots that penetrate the stratosphere and are cooler than the anvil. In this study, we describe clustered storm overshoots in the tropical West Pacific on December 29, 2018 that resulted in the Visible Infrared Imaging Radiometer Suite (VIIRS) aboard NOAA‐20 measuring a temperature of 161.96K (−111.2°C), which is, to our knowledge, the coldest on record. We describe the local meteorological conditions, examine the VIIRS overpass that produced the cold temperature, compare VIIRS with other sensors that observed the region and, finally, analyze the historical context provided by two other satellite instruments to show that such cold temperatures may be becoming more common.
Highlights
Convection, the lifting of warm air from low altitude to higher altitudes, is a key meteorological process and is responsible for much of our hazardous weather, such as lightning, hail, and extreme rainfall (Doswell, 2001)
We describe clustered storm overshoots in the tropical West Pacific on December 29, 2018 that resulted in the Visible Infrared Imaging Radiometer Suite (VIIRS) aboard NOAA-20 measuring a temperature of 161.96K (−111.2°C), which is, to our knowledge, the coldest on record
This study discusses a cold set of cloud top temperatures associated with deep convective overshoots in the South West Pacific on December 29, 2018 that culminated in a cloud top temperature of 161.9K being measured by the VIIRS sensor
Summary
Convection, the lifting of warm air from low altitude to higher altitudes, is a key meteorological process and is responsible for much of our hazardous weather, such as lightning, hail, and extreme rainfall (Doswell, 2001). Complementary to the geostationary sensors that provide high temporal resolution at relatively low spatial resolution, Low Earth Orbit (LEO) satellites typically have a much higher spatial resolution (better than 1 km in both visible and infrared wavelengths) but with a lower temporal resolution, typically providing only one or two views of a location per day (Schueler et al, 2002). These LEO data allow better examination of small-scale features within a storm, such as OTs and is often better calibrated than GEO data, allowing more accurate cloud temperatures to be retrieved.
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