Multispectral imagery for detecting stratospheric air intrusions associated with mid-latitude cyclones

Abstract

Introduction of upper-level potential vorticity (PV) to developing surface low pressure systems is a key component to cyclogenesis. These anomalous PV features generally occur in regions where stratospheric air has penetrated into the troposphere. Operational forecasters need tools to quickly identify PV anomalies via both cloud patterns and atmospheric characteristics because time is limited to make decisions and issue forecasts. A multispectral red, green, and blue (RGB) imagery product from the Moderate Resolution Imaging Spectroradiometer (MODIS) is presented that combines the utility of single-channel cloud information from infrared and water vapor imagery with information about ozone content into a single satellite image that assigns specific colors to specific atmospheric characteristics. Referred to as the Air Mass product, it provides detection of cloud and PV features associated with cyclogenesis as demonstrated for a Nor'easter in October 2011 by comparing the imagery to PV in Global Forecast System model analyses and total ozone from the Atmospheric Infrared Sounder. Development of the Air Mass RGB product from MODIS serves as a precursor and training tool for capabilities from the forthcoming operational Geostationary Operational Environmental Satellite R series Advanced Baseline Imager.

Next generation satellite RGB dust imagery leads to op-erational changes at NWS Alburquerque

“…Referred to as "RGB Imagery" or "RGB Products," brightness temperatures or paired band differences are used to set the red, green, and blue intensities of each pixel in the final image, resulting in a false-color composite specifically designed to highlight features of interest by distinct colors. The European Organization for the Exploitation of Meteorological Satellites (EUMETSAT) has established a "best practices" set of guidelines for various RGB products (EUMETSAT 2009), such as the RGB Air Mass product evaluated by Zavodsky et al (2013), and other multi-spectral imagery products used to highlight various atmospheric features (e.g., low clouds and fog, intense convection, etc. ), or to create a natural or true color view of the earth's surface.…”

Limb Correction of MODIS and VIIRS Infrared Channels for the Improved Interpretation of RGB Composites

“…where (TB, DTB, R, DR) is the brightness temperature (BT), brightness temperature difference (BTD), reflectance, or reflectance difference, respectively; MAX is the upper threshold value; MIN is the lower threshold value; and g is the gamma enhancement value (EUMETSAT 2009;Zavodsky et al 2013;Fuell et al 2016). The color components are then combined together into a false color RGB composite, enhancing the features pertaining to the forecast challenge.…”

“…However, the limited number of spectral channels on most operational weather satellites precludes their use for more comprehensive applications conducted with multispectral imagery from research satellites such as the Moderate Resolution Imaging Spectroradiometer (MODIS), including mapping areas of reduced visibility due to dust and smoke and identifying airmass characteristics, storm dynamics, and fog and low clouds at night (Zavodsky et al 2013;Fuell et al 2016). New multispectral sensors on the operational Suomi-National Polar-Orbiting Partnership (SNPP; Cao et al 2014), the follow-on Joint Polar Satellite System (JPSS), and the Geostationary Operational Environmental Satellite-R Series (GOES-R) satellites include many visible, near-infrared, and thermal infrared (IR) channels, and will provide operational forecasters with new diagnostic capabilities.…”

Satellite tools to monitor and predict Hurricane Sandy (2012): Current and emerging products

“…Multispectral imagery products are available from the GOES-Sounder, the MODIS instrument on NASA's Aqua and Terra satellites, and the combined Visible Infrared Imaging Radiometer Suite (VIIRS) and Cross-track Infrared Sounder (CrIS) on the new Suomi-National Polar-orbiting Partnership (S-NPP) satellite. Details regarding the RGB Air Mass recipe, interpretation table defining the color associated with each air mass, and an additional example application for extratropical cyclogenesis are available in Zavodsky et al (2013). Forecasters had been introduced to this product in 2011 and found it useful in identifying potential vorticity (PV) anomalies and possible stratospheric intrusions.…”

“…15 shows an example of the product with PV values from the GFS reanalysis at approximately the time that Sandy was undergoing ET showing the collocation between elevated total ozone values and regions of PV associated with stratospheric air intrusions. Additional details of the product along with another example of its use are highlighted in Zavodsky et al (2013).…”