Green-1 9/17/2015 Green Band Discussion Satellite Instrument Synergy Working Group September 2003

Green-2 9/17/2015 ‘Green’ on Satellite Systems Research Instruments w/ Green Band –MODIS* –MISR –SeaWiFS –POLDER Operational Environmental Satellites –Current Meteosat MSG does not Other GEO’s do not –Future NPOESS VIIRS will have Green Meteosat MTG calls for Green Operational Land Resources Satellite –LANDSAT has Green Note: One of the most requested products from the 36-band MODIS is the RGB images

Green-3 9/17/2015 ‘Green’ – Phenomenology Maximum in human eye’s spectral response Peak in solar spectral irradiance arriving at Earth’s surface A primary color in (R-G-B) ‘true-color’ composite imagery

Green-4 9/17/2015 The Human Vision (peaks at green)

Green-5 9/17/2015 Solar Irradiance from and through the Top of the Atmosphere

Green-6 9/17/2015 Solar Irradiance from and through the Top of the Atmosphere

Green-7 9/17/2015 ABI ‘Green’ Band Arguments ‘True-Color’ Imagery –(For) Readily incorporated into R-G-B imagery –(Against) Can approximate G from R, B, and NIR Ocean ‘Color’ –(For) Cannot use other-color surrogate –(Against) HES and VIIRS will provide quantitative product Aerosol Properties –(For) Standard reference wavelength is green (0.55  m) –(Against) Most heritage retrievals do not use green Smoke Depiction –(For) Quantitative smoke product possible –(Against) Red/blue provides better contrast with green vegetation Fire Product: Quick look imagery –(For) ‘True-color‘ readily understood –(Against) Might be good enough synthesized via LUT, etc. method Active, smoldering, burn-scar better with NIR/SWIR Snow & Ice Extent –(For) Brightest surface –(Against) Contrast better with NIR

Green-8 9/17/2015 RGB: True and Synthetic Color (It is all about visual) Justification for replacing G with 860 nm –NDVI uses 860 and 680 nm (chlorophyll based), not 550 nm (relatively low reflection) Success criteria for “Visual” –Green vegetation –White clouds, snow –Bright whitish sand, desert –Aqua (blue/green) ocean –Correct representation for smoke, fire –Grey culture features Additionally, the color combination (weights) has to be “universally set”, continuous re-adjusting is not possible in real applications

Green-9 9/17/2015 Three examples follow 1.Florida Coast Land, ocean, clouds 2.Narragansat Bay Vegetation, culture feature, water 3.Middle East/Persian Gulf Desert, dust storm, water

Green-10 9/17/2015 R-G-BR-G-B R-(R+B)/2-B Replacing Green with Average Red and Blue (Tim Schmit)

Green-11 9/17/2015 This is as good as can be reproduced, since the image used the 0.55 um from the same image to build the LUT.

Green-12 9/17/2015

Green-13 9/17/2015 RGB True Color Image (Narragansat Bay, AVIRIS Data)

Green-14 9/17/2015 G= (R+B)/2 RGB Image without the Green Band

Green-15 9/17/2015 G= NIR RGB Image without the Green Band

Green-16 9/17/2015 G= NIR/5, if NIR/5> (R+B)/2 and G=(R+B)/2, if NIR/5<(R+B)/2 RGB Image without the Green Band (A more sophisticated color combination)

Green-17 9/17/2015 RGB Image with and without the Green Band (Middle East/Persian Gulf, MODIS Data) G=GG=(R+B)/2

Green-18 9/17/2015 RGB Image without the Green Band G=NIRG=NIR/5 if NIR/5>(R+B)/2, else G=(R+B)/2

Green-19 9/17/2015 Observations Green band substitution requires some level of algorithm development –Simple substitution with NIR, or average of red and blue does not work for all cases Combined use of NIR, blue and red shown to work for a variety of backgrounds

Green-20 9/17/2015 Dust Enhancement Technique Reference: Steve Miller, NRL-Monterey, AMS Conference 2003 Challenge: Detection of dust storm over desert Approach: Utilize normalized difference between NIR and blue Red Gun = (R NIR -R BLUE )/ (R NIR +R BLUE ) Data: MODIS

Green-21 9/17/2015 Dust Enhancement Product Red Gun = (R NIR -R BLUE )/ (R NIR +R BLUE ) Green gun = GreenGreen gun =(R+B)/2

Green-22 9/17/2015 Dust Enhancement Product G=(R+B)/2 Red Gun = (R NIR -R BLUE )/ (R NIR +R BLUE ) Red Gun = Red

Green-23 9/17/2015 Summary Green is a highly desirable band –High demand for RGB imagery key reason However, it is not crucial for ABI because 1.For some applications, another band or band combinations will do (algorithm development required) 2.For some applications, other sensors either from HES or VIIRS will do Looking at satellite instrument synergy opportunities, if ABI had green band, it could be more effective in helping to task HES-CW Looking at the trend of future remote sensing systems, it is strongly recommend that the green band be considered –as “goal” for ABI –for systems beyond GOES-R