RGB Airmass and Dust products

NASA SPoRT

CIRA

RGB Air Mass

RED (6.2 – 7.3) –vertical moisture distributionGREEN (9.7 -10.7) – tropopause height based on ozone concentrationBLUE (6.2) – upper level moisture

Tropical air masses are green to tan colors while polar air masses are purple. Jet streaks appear bright red due to stratospheric intrusions they cause.

• Primary Applications:– Identify boundary of polar and tropical air masses– Locate areas of large potential vorticity due to jet streaks

Warm, moist upper levels

Warm, moist mid levels

Cool, moist upper levels

Cold, dry upper levels

Cool, moist upper levels

Pot. Vorticity, Jet Streak

RGB Air Mass DetailsColor Band / Band

Diff.Physically Relates to…. Little contribution to

composite indicates…..Large contribution to composite indicates …..

Red 6.7 – 7.3 Vertical water vapor difference

Moist conditions high levels

Dry conditions at high levels

Green 9.7- 10.7 Estimate of tropopause height based on ozone.Polar (tropical) air has higher (lower) ozone concentrations

Tropopause height is low. Typically indicates a polar air mass, where 9.7 has very cold brightness temperature compared to 10.7

Tropopause height is high.Likely a tropical air mass where the two channels will have similar brightness temperature values

Blue 6.7 (inverted, meaning warm to cold scale)

Water Vapor in layer from ~200 – 500 mb

Dry at upper levelsWarm brightness temperatures have little blue

Moist at upper levelsCold brightness temperatures result in lots of blue

Above are details from SPoRT’s RGB Quick Guide to help understand color contributions to resulting composite. It can be found at:http://weather.msfc.nasa.gov/sport/training/rgb_airmass/RGB%20Air%20Mass%20Reference%20Guide.pdf

EUMETSAT has developed color interpretation guides for RGBs. See: http://oiswww.eumetsat.int/~idds/html/product_description.html

Hurricane Philippe (2011)RGB Air Mass

Applications for extratropical transition monitoring • Stratospheric intrusion and

associated jet streak shown in red coloring

• Helps to indicate when transition is beginning to occur

• Blue indicating cooler air resulting from more baroclinic activity to the southwest (i.e. there’s less green here so less tropical in nature)

Hurricane Philippe (2011)RGB Air Mass Training Module

RGB, GFS 500mb Height and Vorticity00Z on 10/8

RGB is better than WV to compare to model forecasts/analysis of

Dust Event from 07/20/12RGB Dust Product

RED (12 – 10.8) –Optical ThicknessGREEN (10.8 – 8.7) – Particle PhaseBLUE (10.8) – Object surface temperature

Dust areas are in magenta shades. Over water, magenta dust is influenced by thermal signature of SST. Over land, intense magenta from storm outflows show dust initiation transport.

• Primary Applications:– Identify airborne dust (magenta coloring) from cloud features– Highlights moisture boundaries

Note more blue vs magenta shades in areas where tropical

storms are located.

DustLack of Dust

RGB Dust DetailsColor Band / Band

Diff.Physically Relates to…. Little contribution to

composite indicates…..Large contribution to composite indicates …..

Red 12.0 – 10.8 Optical thickness Thin clouds. Difference is negative. Less of the 12um channel passes through the clouds (colder brightness temperature) than the 10.8um channel

Thick clouds or dust. Difference is positive. More of the 12um channel passes through the clouds (Warmer brightness temperature) than the 10.8um channel

Green 10.8 – 8.7 Particle phase (ice vs water) or com

Ice particles or particles of similar characteristics have small difference

High clouds over desert regions – emission from surface overwhelms the relationship

Blue 10.8 Temperature of surface Cold surface Warm surface

Color Physical Meaning

Red Green Blue

Dust at 400mb at night

255 79 150

Dust at 700mb at night

160 80 210

Dust at 900mb at night

136 80 239

Dust (Day time)

Dust (Day time)

Above are details from SPoRT’s RGB Quick Guide to help understand color contributions to resulting composite. It can be found at:http://weather.msfc.nasa.gov/sport/training/rgb_dust/RGB%20Dust%20Reference%20Guide.pdf

EUMETSAT has developed color interpretation guides for RGBs. See: http://oiswww.eumetsat.int/~idds/html/product_description.html