A Demonstration of Modern Geostationary and Polar-Orbiting Satellite Products for the Identification and Tracking of Elevated Mixed Layers

Abstract

The elevated mixed layer (EML) can be an important aspect for severe thunderstorm forecasting. Because its thermodynamic characteristics vary as it moves eastward, tracking the EML is a crucial part of the forecasting process, something that previously has been quite challenging owing to the limited spatial and temporal resolution of observed soundings and numerical weather prediction (NWP) output. New satellite capabilities allow for improved monitoring/tracking of the EML. These include the 7.34-µm band on the Geostationary Operational Environmental Satellite-R series, as well as microwave instruments on polar-orbiting satellites used in the advected layer precipitable water product. Herein it is demonstrated—using several case studies—how using a combination of these products, in tandem with sounding data and NWP output, allows the forecaster to efficiently monitor the EML at greater spatial and temporal resolutions.

Extrapolating shortwave geostationary satellite imagery of clouds into nighttime using longwave observations

“…The central wavelengths for all 16 ABI channels are listed in Table 1 along with common nicknames and brief descriptions of each channel's application(s). 7,[19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] Since this work is primarily motivated by inferring and visualizing cloud properties in SW data, we do not attempt to extrapolate SW reflectance in clear sky conditions. The extrapolation method presented could be applied to clear sky conditions but would likely have different optimal parameters and error characteristics than those presented herein.…”

“…Table 1 List of ABI channels, their central wavelengths, common nicknames, applications, and use in the final extrapolation algorithm. 7,[19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] Channel (band) number 7 Central wavelength (μm) 7 Common nickname 19 Common application(s) 19,[32][33][34][35] The precise times of observations are all within 10 min of the top of the hour. The subsolar points at 1500, 1700, 1800, and 2100 UTC on the 2018 autumnal equinox are shown in Fig.…”

“…These channels primarily contain information about the moisture content of the atmosphere above cloud top and are thus used for tracking water vapor and the jet stream. 19,[24][25][26][27][28][29][30] The only SW channel with similar properties is channel 4 and water vapor channels do lower RMSE slightly for this channel in particular (not shown). Also omitted from the algorithm, channel 12 is sensitive to ozone absorption and used to discern upper troposphere dynamics as well as total column ozone.…”

“…In addition, ABI channels 8 to 10 (i.e., the water vapor channels), which are important for deriving winds and monitoring moisture in the atmosphere, are proving to be more difficult to accurately extrapolate given their unique characteristics and low correlation to LW window radiances under some conditions. 19,[24][25][26][27][28][29][30] Although it is unlikely the extrapolation approach can completely mitigate the GOES-17 LHP problem, the work conducted to date demonstrates valuable recovery and mitigation can be achieved. Additional research underway will provide better statistics on the quality and limitations of this application.…”