APPLICATIONS OF METEOSAT SECOND GENERATION (Meteosat-8) AIRMASS RGB Jochen Kerkmann Satellite 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 - WV7.3 G = Difference IR9.7 - IR10.8 B = Channel WV6.2 THE "AIRMASS" RGB Applications: Applications:Rapid Cyclogenesis, Jet Stream Analysis, PV Analysis Area: Area:Full MSG Viewing Area Time: Time:Day and Night

Airmass RGB: Recipe Recommended Range and Enhancement: BeamChannelRangeGamma RedWV6.2 - WV … 0 K1.0 GreenIR9.7 - IR … +5 K1.0 BlueWV … +208 K1.0

Airmass RGB Example MSG-1, 07 January 2005, 03:00 UTC, RGB Composite WV6.2-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: BeamChannelRangeGamma RedWV6.2 - WV … 0 K1.0

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 - WV7.3 Range: -35 K (black) to 0 K (white) BTD WV6.2 - WV7.3

I.temperature and humidity profile II.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 angle III.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

T(850 hPa) 6.2  m7.3  m Case I: Very Dry Atmosphere very small BTD 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  m7.3  m Case II: Moist Layer at 700 hPa small BTD T(700 hPa) 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  m7.3  m Case III: Moist Layer at 500 hPa large BTD T(500 hPa) Moist Layer: quasi opaque to the radiation at WV6.2 quite transparent to the radiation at WV 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  m7.3  m Case IV: Moist Layer at 200 hPa small BTD T(200 hPa) 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 - WV7.3 Range: -30 K (black) to +5 K (white) BTD WV6.2 - WV7.3

Green Colour Beam: IR9.7 - IR10.8 Recommended Range and Enhancement: BeamChannelRangeGamma GreenIR9.7 - IR … +5 K1.0

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 - IR10.8 Range: -50 K (black) to 0 K (white) BTD IR9.7 - IR10.8

I.temperature difference between T(surf) and T(ozone) II.total ozone concentration III.satellite viewing angle IV.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 to T(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 concentration III.Satellite viewing angle IV.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)  m10.8  m

BTD IR9.7 - IR10.8 T(surf) T(ozone) 9.7  m10.8  m Case I: Rich Ozone Polar Airmass large BTD

BTD IR9.7 - IR10.8 T(surf) T(ozone) 9.7  m10.8  m Case II: Low Ozone Tropical Airmass smaller BTD

Difference IR9.7 - IR10.8 Range: -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 K 320 DU  -33 K 400 DU  -40 K Thumb rule: BTD IR9.7-IR10.8 [K] = -TOZ [DU]/10

BTD IR9.7-IR10.8: Effect of Ozone

Annual cycle of the total ozone amount 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 UTC Difference IR9.7 - IR10.8

Blue Colour Beam: WV6.2 Recommended Range and Enhancement: BeamChannelRangeGamma BlueWV … +208 K1.0

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 United Kingdom France

X X N 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 WV K -40 K IR9.7 - IR K -25 K WV6.2 - WV7.3 0 K 1 = high clouds (white) = mid-level clouds (light ochre) 3 = rich ozone tropical airmass with high tropopause (greenish) = low ozone polar airmass with low tropopause (bluish) = rich ozone airmass of dry air with a tropopause folding

Airmass RGB Example: Warm Airmass 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 clouds 2 = mid-level clouds 3 = warm airmass, high tropopause 4 = cold airmass, low tropopause 5 = dry descending stratospheric air Airmass RGB: Colour Interpretation MSG-1 07 January :00 UTC RGB Composite R = WV6.2 - WV7.3 G = IR9.7 - IR10.8 B = WV

1 = high cloud (severe convective storm) 2 = mid-level clouds 3 = hot land surface (high UTH) 4 = hot land surface (low UTH) Airmass RGB: Colour Interpretation MSG-1 21 August :00 UTC RGB Composite R = WV6.2 - WV7.3 G = IR9.7 - IR10.8 B = WV

Airmass RGB Global View MSG-1 19 April :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 hPaTotal Ozone

Comparison Airmass RGB vs PV/TOZ MSG-1, 08 January 2005, 06:00 UTC PV 300 hPaTotal Ozone

reddish areashigh 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: WV6.2, WV7.3, IR9.7 and IR10.8The "Airmass" RGB is a combination of 4 channels: WV6.2, WV7.3, IR9.7 and IR10.8 It helps to detect the position of jet streams and areas of dry descending stratospheric air with high PV (red areas)It helps to detect the position of jet streams and areas of dry descending stratospheric air with high PV (red areas) It also helps to discriminate airmasses (rich ozone tropical airmass, low ozone polar airmass)It also helps to discriminate airmasses (rich ozone tropical airmass, low ozone polar airmass) It is also useful to detect typical WV features like deformation zones and wave featuresIt is also useful to detect typical WV features like deformation zones and wave features At the same time, through the use of the IR channels, it allows to monitor cloud development at low, mid and high levelsAt the same time, through the use of the IR channels, it allows to monitor cloud development at low, mid and high levels