airmass rgb r = difference wv6.2 - wv7.3 g = …oisidds/html/doc/airmass_interpretation.pdf ·...
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R = Difference WV6.2 - WV7.3G = Difference IR9.7 - IR10.8B = Channel WV6.2 (inverted)
Airmass RGB
ApplicationsApplications:: Rapid Cyclogenesis, Jet Stream Analysis, PV AnalysisArea:Area: Full MSG Viewing AreaTime:Time: Day and Night
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RangesRanges and and Enhancements:Enhancements:
Beam Channel Range Gamma
Red WV6.2 - WV7.3 -25 … 0 1.0Green IR9.7 - IR10.8 -40 … +5 1.0Blue WV6.2 +243 … +208 1.0
Airmass RGB
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Red Moisture content at roughly 700-400 hPaand 500-200 hPa levels, approximated byBT difference of split WV window.
Green Total ozone concentration (tropopauseheight) approximated by the BT differencebetween 9.7µm (O3 channel) and 10.8µm.[to distinguish between ozone-rich polarand ozone-poor (sub) tropical airmasses]
Blue Upper level moisture content provided bythe BT at 6.2µm.
Physical Interpretation
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Interpretation of Colours
Thick, high-level clouds
Thick, mid-level clouds
Thick, low-level clouds
(warm airmass)
Thick, low-level clouds
(cold airmass)
Jet (high PV) Cold Airmass Warm Airmass Warm Airmass
High UTH Low UTH
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Example 1: Clouds
MSG-1, 7 January 2005, 22:00 UTC
Mid-level cloudHigh-level cloud
Low-level cloud (warm airmass)
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Example 2: Jet Streak
05 - 06
08 - 09
05i
In airmass RGB images, dry descending stratospheric air relatedto jet streaks appears in reddish colours !
The RGB values shown above (in the red box) correspond tothe location (shown by an arrow) on the next slide !
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MSG-1, 7 January 2005, 22:00 UTC
Example 2: Jet Streak
Advection jet
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05 - 06
08 - 09
05i
In airmass RGB images, warm ozone-poor airmasses with hightropopause appear in greenish colours !
The RGB values shown above (in the red box) correspond tothe location (shown by an arrow) on the next slide !
Example 3: Warm Airmass
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MSG-1, 7 January 2005, 22:00 UTC
Example 3: Warm Airmass
Warm Airmass(ozone-poor)
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Example 4: Cold Airmass
05 - 06
08 - 09
05i
In airmass RGB images, cold airmasses with low tropopauseappear in bluish colours !
The RGB values shown above (in the red box) correspond tothe location (shown by an arrow) on the next slide !
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MSG-1, 7 January 2005, 22:00 UTC
Example 4: Cold Airmass
Cold Airmass(ozone-rich)
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MSG-1, 23 June 2004, 12:00 UTC
Example 5: Effect of Surface Temperature
Very hot land surfaces(appear dark)
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MSG-1, 04 November 2005, 10:00 UTC
Example 6: Effect of Limb Cooling
Limb effect - bluish colours(large BTD IR9.7-IR10.8)
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1 = high clouds2 = mid-level clouds3 = warm airmass, high tropopause4 = cold airmass, low tropopause5 = dry descending stratospheric air
15
3
2
4 MSG-122 March 200505:00 UTC
South Africa Example 7:Southern
Hemisphere
5
1
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reddish areas high PV values19 January 2005, 06:15 UTC
Example 8: Comparison withPotential Vorticity (PV)
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Example 9: Comparison with PV/OzoneMSG-1, 08 January 2005, 06:00 UTC
PV 300 hPa Total Ozone
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Global View
MSG-119 April 200510:00 UTC
Note: warm airmasses seen at ahigh satellite viewing angleappear with a bluish colour(limb cooling effect) !