APPLICATIONS OFMETEOSAT SECOND
GENERATION (Meteosat-8)
AIRMASS RGB
Jochen KerkmannSatellite Meteorologist, Training Officer
Contributors: G. Bridge (EUM), C. Georgiev (Bulgaria)
P. Chadwick (Canada)
Learn how to generate the Airmass RGB (Recipe) Learn how to use/interpret the WV6.2 - WV7.3 and the
IR9.7 - IR10.8 brightness temperature difference (BTD) In particular, understand the relationship between the IR9.7 -
IR10.8 BTD and the total ozone content Short overview of WV image interpretation Interpretation of colours of the Airmass RGB Usage of the Airmass RGB composite for monitoring jet
streams, cyclogenesis, PV maxima etc.
Objectives
R = Difference WV6.2 - WV7.3G = Difference IR9.7 - IR10.8B = Channel WV6.2
THE "AIRMASS" RGB
Applications:Applications: Rapid Cyclogenesis, Jet Stream Analysis, PV AnalysisArea:Area: Full MSG Viewing AreaTime:Time: Day and Night
Airmass RGB: Recipe
Recommended Range and Enhancement:Recommended Range and Enhancement:
Beam Channel Range Gamma
Red WV6.2 - WV7.3 -25 … 0 K 1.0Green IR9.7 - IR10.8 -40 … +5 K 1.0Blue WV6.2 +243 … +208 K 1.0
Airmass RGB Example
MSG-1, 07 January 2005, 03:00 UTC, RGB CompositeWV6.2-WV7.3, IR9.7-IR10.8, WV6.2
combines the best three MSG features for the early detection of rapid
cyclogenesis !
Airmass RGB: Colour Inputs
Red = WV6.2 - WV7.3 Green = IR9.7 - IR10.8
Blue = WV6.2i RGB
Airmass RGB: Colour Inputs
Red = WV6.2 - WV7.3 Green = IR9.7 - IR10.8
Blue = WV6.2i RGB
Red Colour Beam: WV6.2 - WV7.3
Recommended Range and Enhancement:Recommended Range and Enhancement:
Beam Channel Range Gamma
Red WV6.2 - WV7.3 -25 … 0 K 1.0
Channel 05 (WV6.2)
MSG-1, 07 January 2005, 03:00 UTC, Channel 05 (WV6.2)Range: 253 K (black) to 213 K (white)
Channel 06 (WV7.3)
MSG-1, 07 January 2005, 03:00 UTC, Channel 06 (WV7.3)Range: 273 K (black) to 213 K (white)
MSG-1, 07 January 2005, 03:00 UTC, Difference WV6.2 - WV7.3Range: -35 K (black) to 0 K (white)
BTD WV6.2 - WV7.3
I. temperature and humidity profileII. satellite viewing angle
For cloud-free scenes, the BTD between WV6.2 and WV7.3 depends on (in order of priority):
BTD WV6.2 - WV7.3
I. temperature and humidity profile (above the cloud)II. satellite viewing angleIII. emissivity of cloud at WV6.2 and WV7.3
For cloudy scenes, the BTD between WV6.2 and WV7.3 depends on (in order of priority):
BTD WV6.2 - WV7.3
BTD WV6.2 - WV7.3
T(850 hPa)
6.2 m 7.3 mCase I:Very DryAtmospherevery small BTD
0
-10
-20
-25Moist Layer: opaque to the radiation at WV6.2 and
WV7.3(Planetary Boundary Layer)
BTD WV6.2 - WV7.3
T(850 hPa)
6.2 m 7.3 mCase II:Moist Layer at 700 hPasmall BTD
T(700 hPa)
0
-10
-20
-25
Moist Layer: opaque to the radiation at WV6.2 less opaque to the radiation at WV7.3
Moist Layer: opaque to the radiation at WV6.2 and WV7.3
(Planetary Boundary Layer)
BTD WV6.2 - WV7.3
T(850 hPa)
6.2 m 7.3 mCase III:Moist Layer at 500 hPalarge BTD
T(500 hPa) Moist Layer: quasi opaque to the radiation at WV6.2 quite transparent to the radiation at WV7.3
0
-10
-20
-25Moist Layer: opaque to the radiation at WV6.2 and
WV7.3(Planetary Boundary Layer)
BTD WV6.2 - WV7.3
T(850 hPa)
6.2 m 7.3 mCase IV:Moist Layer at 200 hPasmall BTD
T(200 hPa)
0
-10
-20
-25
Moist Layer: quite transparent to the radiation at WV6.2 transparent to the radiation at WV7.3
Moist Layer: opaque to the radiation at WV6.2 and WV7.3
(Planetary Boundary Layer)
MSG-1, 07 January 2005, 03:00 UTC, Difference WV6.2 - WV7.3Range: -30 K (black) to +5 K (white)
BTD WV6.2 - WV7.3
Green Colour Beam: IR9.7 - IR10.8
Recommended Range and Enhancement:Recommended Range and Enhancement:
Beam Channel Range Gamma
Green IR9.7 - IR10.8 -40 … +5 K 1.0
Channel 08 (IR9.7)
MSG-1, 07 January 2005, 03:00 UTC, Channel 08 (IR9.7 (ozone channel))Range: 263 K (black) to 213 K (white)
Channel 09 (IR10.8)
MSG-1, 07 January 2005, 03:00 UTC, Channel 09 (IR10.8)Range: 293 K (black) to 213 K (white)
MSG-1, 07 January 2005, 03:00 UTC, Difference IR9.7 - IR10.8Range: -50 K (black) to 0 K (white)
BTD IR9.7 - IR10.8
BTD IR9.7 - IR10.8
I. temperature difference between T(surf) and T(ozone)II. total ozone concentrationIII. satellite viewing angleIV. emissivity of surface at IR9.7 and IR10.8
(e.g. desert surface has a 3% difference in emissivity,water has a difference of 0.3 %)
==> strong diurnal/seasonal cycle due toT(surf) variation
For cloud-free scenes, the BTD between IR9.7 and IR10.8 depends on (in order of priority)*:
*neglecting WV absorption
BTD IR9.7 - IR10.8
I. temperature difference between T(cloud) and T(ozone)II. total ozone concentrationIII. Satellite viewing angleIV. emissivity of cloud at IR9.7 and IR10.8
For cloudy scenes, the BTD between IR9.7 and IR10.8 depends on (in order of priority)*:
*neglecting WV absorption
For high-level clouds: T(cloud) T(ozone)For mid/low-level clouds: T(cloud) > T(ozone)
BTD IR9.7 - IR10.8
T(surf/cloud)
T(ozone)
(surf/cloud)9.7 (surf/cloud)10.8
9.7 m 10.8 m
BTD IR9.7 - IR10.8
T(surf)
T(ozone)
9.7 m 10.8 m +5
-20
-40
Case I:Rich OzonePolar Airmasslarge BTD
BTD IR9.7 - IR10.8
T(surf)
T(ozone)
9.7 m 10.8 m +5
-20
-40
Case II:Low OzoneTropical Airmasssmaller BTD
Difference IR9.7 - IR10.8Range: -45 K (black) to +5 K (white)
23 June 2004, 12:00 UTC
BTD IR9.7 - IR10.8: Effect of T(surf)
07 January 2005, 12:00 UTC
BTD IR9.7-IR10.8: Effect of Ozone
260 DU -25 K320 DU -33 K400 DU -40 K
Thumb rule:BTD IR9.7-IR10.8 [K] = -TOZ [DU]/10
BTD IR9.7-IR10.8: Effect of Ozone
BTD IR9.7-IR10.8: Effect of Ozone
Annual cycle of the total ozoneamount above Arosa (CH)
Source: MeteoSwiss
BTD IR9.7-IR10.8: Effect of Ozone
Source: MeteoSwiss
BTD IR9.7-IR10.8: Effect of Viewing Angle
The larger the satellite viewing angle, the stronger the ozone absorption effect(limb cooling) !
MSG-1, 31 October 2003, 11:30 UTCDifference IR9.7 - IR10.8
Blue Colour Beam: WV6.2
Recommended Range and Enhancement:Recommended Range and Enhancement:
Beam Channel Range Gamma
Blue WV6.2 +243 … +208 K 1.0
Channel 05 (WV6.2)
MSG-1, 07 January 2005, 03:00 UTC, Channel 05 (WV6.2)Range: 253 K (black) to 213 K (white)
Met-7, 26 December 1999, 06:00 UTC, WV Channel(Storm "Lothar")
Features seen in WV Images
Dry intrusion
Source: DWD
UnitedKingdom
France
X
XN
N
GOES-12, 14 February 2004, 00:15 UTC, WV Channel
Features seen in WV Images
Convex Deformation Zone
Saddle Point
Source: NOAA & P. Chadwick
MSG-1, 21 January 2005, 12:15 UTC, Channel 05 (WV6.2)
Features seen in WV Images
Stau cloud
Foehn
Mountain waves in cloud-free areas
with possible Clear Air Turbulence (CAT)
Italy
MSG-1, 25 June 2005, 14:15 UTC, Channel 05 (WV6.2)
Features seen in WV Images
High-level gravity waves caused by thunderstorms
Algeria
Mali
Airmass RGB: Colour Interpretation
243 K WV6.2 208 K
-40 K IR9.7 - IR10.8 +5 K
-25 K WV6.2 - WV7.3 0 K
1 = high clouds (white)
1
1
12
2
2
2 = mid-level clouds (light ochre)3 = rich ozone tropical airmass with high tropopause (greenish)
3
3
3 4
4
4
4 = low ozone polar airmass with low tropopause (bluish)
5
5
5
5 = rich ozone airmass of dry air with a tropopause folding
Airmass RGB Example: Warm Airmass
MSG-1, 7 January 2005, 22:00 UTC
MSG-1, 7 January 2005, 22:00 UTC
Airmass RGB Example: Cold Airmass
MSG-1, 7 January 2005, 22:00 UTC
Airmass RGB Example: Advection Jet
Airmass RGB: 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
1 = high clouds2 = mid-level clouds3 = warm airmass, high tropopause4 = cold airmass, low tropopause5 = dry descending stratospheric air
Airmass RGB: Colour Interpretation
MSG-107 January 200515:00 UTCRGB CompositeR = WV6.2 - WV7.3G = IR9.7 - IR10.8B = WV6.2
2 1
54
3
1 = high cloud (severe convective storm)2 = mid-level clouds3 = hot land surface (high UTH)4 = hot land surface (low UTH)
Airmass RGB: Colour Interpretation
MSG-121 August 200612:00 UTCRGB CompositeR = WV6.2 - WV7.3G = IR9.7 - IR10.8B = WV6.2
2
1
4
3
2
Airmass RGBGlobal View
MSG-119 April 200510:00 UTC
Note: warm airmasses seen at a high satellite viewing angle appear with a bluish colour (limb cooling effect) !
Comparison Airmass RGB vs PV 300 hPa
MSG-1, 8 January 2005, 06:00 UTC
Comparison Airmass RGB vs TOZ
MSG-1, 8 January 2005, 06:00 UTC
Comparison Airmass RGB vs PV/TOZ
MSG-1, 08 January 2005, 06:00 UTC
PV 300 hPa Total Ozone
Comparison Airmass RGB vs PV/TOZ
MSG-1, 08 January 2005, 06:00 UTC
PV 300 hPa Total Ozone
reddish areas high PV values
19 January 2005, 06:15 UTC
Comparison Airmass RGB vs PV 300 hPa
SUMMARY
• The "Airmass" RGB is a combination of 4 channels: The "Airmass" RGB is a combination of 4 channels: WV6.2, WV7.3, IR9.7 and IR10.8WV6.2, WV7.3, IR9.7 and IR10.8
• It helps to detect the position of jet streams and areas of It helps to detect the position of jet streams and areas of dry descending stratospheric air with high PV (red areas)dry descending stratospheric air with high PV (red areas)
• It also helps to discriminate airmasses (rich ozone tropical It also helps to discriminate airmasses (rich ozone tropical airmass, low ozone polar airmass)airmass, low ozone polar airmass)
• It is also useful to detect typical WV features like It is also useful to detect typical WV features like deformation zones and wave featuresdeformation zones and wave features
• At the same time, through the use of the IR channels, it At the same time, through the use of the IR channels, it allows to monitor cloud development at low, mid and high allows to monitor cloud development at low, mid and high levelslevels
