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Announcement: Please visit out new web application, SLIDER, for every pixel of real-time GOES-16 and Himawari-8 imagery.

NHC Red-Blue-Green (RGB) Air Mass Product

Figure 1: Air mass product example. Tropical air is displayed in green and red where the green regions have higher moisture content than the red regions. Mid-latitude air has a bluish color and areas or dark red show areas of subsidence and high ozone and PV.

1) Product Information:

- Who is developing and distributing this product?

This product is being developed by The Cooperative Institute for Research in the Atmosphere (CIRA) in Fort Collins, Colorado, together with the NOAA/NESDIS/STAR RAMM Branch.

- Who is receiving this product, and how?

The Red-Blue-Green (RGB) Air Mass Product is being disseminated to the NOAA’s National Hurricane Center (NHC) via secure web pages using Keyhole Markup Language (KML) files, which can be displayed at NHC using Google Earth. This dissemination method was coordinated with NHC and fits within NOAA’s overarching network security. Furthermore, imagery and RGB products are being archived for the duration of the Proving Ground Demonstration period and can be supplied to NHC for post-season applications.

- What is the product size?

Original hi-res (3 km) images of 4096 x 4096 pixels are created every 15 minutes along with a text file with image coordinates for geolocation.

2) Product Description:

- Purpose of this product:

The purpose of the product is to provide the NHC forecasters with an additional decision aid for their tropical cyclone forecasting task. The product strongly highlights differences between dry, tropical and cold air masses.

- Why is this a GOES-R Proving Ground Product?

The RGB air mass product demonstrates the kind of imagery that will be possible in the GOES-R era. The product is currently based on Meteosat Second Generation (MSG) data, simulating the future features the GOES-R Advanced Baseline Imager (ABI) sensor. ABI will be able to produce both a higher spatial resolution (2 km), higher temporal resolution (5 min), and higher spectral resolution than the current GOES satellites do.

- How is this product created now?

The RGB air mass product is generated from MSG channels 5 (WV6.2), 6 (WV7.3), 8 (IR9.7), and 9 (IR10.8). The raw imagery is ingested from NESDIS operational servers and generated using Man computer Interactive Data Access System (MCIDAS) and the following recipe developed by European Organization for the Exploitation of Meteorological Satellites (EUMETSAT).

Beam Channel Range Gamma
Red WV6.2 - WV7.3 -25 ... 0 K 1
Green IR9.7 - IR10.8 -40 ... +5K 1
Blue WV6.2 +243 ... +208 K 1

The channel differences are scaled over the ranges provided above and the individual color composites are created in satellite projection. These components are then remapped into a 3 km rectilinear grid. These remapped components are then combined to create a composite RGB.

3) Product Examples and Interpretation

The air mass product is an RGB composite based upon data from infrared and water vapor channels from Meteosat Second Generation (MSG). Originally designed and tuned to monitor the evolution of extra-tropical cyclones, in particular rapid cyclogenesis, jet streaks and PV (potential vorticity) anomalies by scientists at (EUMETSAT), it is also useful for tropical/subtropical applications. The product highlights differences between dry, tropical and cold air masses, as can be seen in the example below. This is accomplished by differencing the two water vapor channels (i.e., ch. 5 at 6.2 µmicro;m and ch. 6 at 7.3 µmicro;m) as depicted in the red colors, where red is associated with dryer air mass conditions locally, by Ozone differences by differencing ch. 8 at 9.7 µmicro;m and ch. 9 at 10.8 µmicro;m, where green indicates low Ozone & typically thus tropical air masses, and by using ch. 5 at 6.2 µmicro;m to indicate gross air mass temperature differences.

Figure 2: Air mass product example. Tropical air is displayed in green and red where the green regions have higher moisture content than the red regions. Mid-latitude air has a bluish color and areas or dark red show areas of subsidence and high ozone and PV.

The air mass product helps discriminate tropical air masses (i.e., moist and lower ozone) that are predominantly green, from subtropical air masses (i.e., dryer) that are depicted greenish red, and mid-latitude air masses, typically having more blue colors. For tropical applications it should be helpful in determining and tracking the origin of air parcels as they interact with tropical systems, and improved identification of shallow upper level features (cold lows and jets streaks). For more information on the interpretation of this product see (Kirkman, cited 2010). An annotated example is provided below.

Kirkman, J., cited 2010: Applications of Meteosat Second Generation (Meteosat-8), AIRMASS. [available on-line at http://oiswww.eumetsat.org/IPPS/html/bin/guides/msg_rgb_airmass.ppt]

Google Earth loops of GOES-E imagery over the CONUS are available at http://rammb.cira.colostate.edu/products/google_earth/

4) Advantages and Limitations

The RGB air mass product provides a simple decision aid tool to NHC forecasters by visually discriminating tropical air masses from subtropical air masses. For tropical applications it should be helpful in determining and tracking the origin of air parcels as they interact with tropical systems, and improved identification of shallow upper level features (cold lows and jets streaks). The current product is limited to the MSG sector.