Limb and Bias Correction Applied to MODIS Air Mass RGB Imagery

MODIS Air Mass RGB Imagery with limb correction applied to the water vapor and ozone channels.  1859 UTC, 13 May 2014

MODIS Air Mass RGB Imagery with limb correction applied to the water vapor and ozone channels. 1859 UTC, 13 May 2014

The Air Mass RGB imagery product via MODIS has often appeared to lack “green” coloring near the edge of the swath and there have been noticeable differences between the channels from Aqua and Terra used within the RGB.  Forecasters from the Great Falls, MT and Albuquerque, NM WFOs applying this experimental data noted these issues.  The above image is a limb and bias corrected version of the Air Mass RGB.  The water vapor and ozone channels tend to “cool” near the swath edge as they pass through more atmosphere and the differences in satellite instrument quality result in physical characteristics between the images having different coloring.  SPoRT has worked to develop a non-linear function to correct much of the limb cooling as well as a bias correction, both through comparison of the MODIS instruments to the EUMETSAT SEVIRI instrument.  Annotations to the image attempt to classify the various features indicated by the resulting composite color during a MODIS pass from 1859 UTC on 13 May 2014 when a cold air mass was moving into the upper Midwest.  Simple interpretation guides can be found via SPoRT’s Training page or EUMETSAT. For comparison, additional plots of GOES Water Vapor,  and NAM 500mb Temperature, Humidity, and Height 0-hour analysis and 6-hour forecasts are provided below for reference. There is also a single image of the Hybrid GEO/LEO Water Vapor / Air Mass RGB product that loops GOES Water Vapor imagery and inserts the MODIS Air Mass RGB swath as it is available because the RGB is largely made up of water vapor channels.  Both the Hybrid and single-swath MODIS files are available in netCDF format for use in AWIPS I or II as well as KML format.

This new limb/bias corrected Air Mass RGB product is credited in large part to graduate student work being done at the University of Alabama Huntsville in conjunction with NASA/SPoRT. Primary contributors are:
Nicolas Elmer (UAH graduate student)
Dr. Emily Berndt (NASA/SPoRT Post-Doctoral Scientist)
Dr. Gary Jedlovec (NASA/SPoRT PI)

Additional contributors include:
Frank LaFontaine (Raytheon, Data processing and analysis)
Kevin McGrath (Jacobs, Product code development and real-time processing)
Matthew Smith (UAH, Data processing and product code development)
Dr. Andrew Molthan (NASA/SPoRT, RGB code development and research science)

g13.2014133.1845_US_wv

GOES Water Vapor Imagery at 1845 UTC, for 13 May 2014

 

 

 

 

NAM 500mb, 0-hour forecast valid 1200 UTC, 12 May 2014 of Temperature, Humidity, and Height via

NAM 500mb, 0-hour forecast valid 1200 UTC, 13 May 2014 of Temperature, Humidity, and Height via NCAR RAL website

NAM 500mb, 0-hour forecast valid 1200 UTC, 13 May 2014 of Temperature, Humidity, and Height via NCAR RAL website

N

NAM 500mb, 6-hour forecast valid 1800 UTC, 13 May 2014 of Temperature, Humidity, and Height via NCAR RAL website

NAM 500mb, 6-hour forecast valid 1800 UTC, 13 May 2014 of Temperature, Humidity, and Height via NCAR RAL website

CAR RAL website

Example: SPoRT Hybrid GEO/LEO Water Vapor and Air Mass RGBimagery

Example: SPoRT Hybrid GEO/LEO Water Vapor and Air Mass RGBimagery

Leave a Reply

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s