Basics Satellite Meteorology ( An Introduction to RS of MSG) Joseph Kagenyi Kenya Meteorological Department.

Basics Satellite Meteorology(An Introduction to RS of MSG)

Joseph Kagenyi Kenya Meteorological Department

Objective

• Channel properties• Signal source• Discrimination of Ice / Water/ clouds• Summary of channels applications

SEVIRI CHANNELS

Channel Gases Application

HRV 0.7 Broad band VIS Surface, aerosol, cloud detail (1 km)

VIS 0.6 Narrow band Ice or snow

VIS 0.8 Narrow band Vegetation

NIR 1.6 Window Aerosols, snow<>cloud

IR 3.8 Triple window SST, fog<>surface, ice cloud

WV 6.2 Water vapour Upper troposphere 300 Hpa humidity

WV 7.3 Water vapour Mid-troposphere 600 Hpa humidity

IR 8.7 Almost window Water vapour in boundary layer, ice<>liquid

IR 9.7 Ozone Stratospheric winds

IR 10.8 Split window CTH, cloud analysis, PW

IR 12.0 Split window Land and SST

IR 13.4 Carbon dioxide +10.8: Semitransparent-cloud top, air mass analysis

Properties

Cloud

Abs

orpt

ion

<--

----

----

----

----

----

----

> S

catt

erin

g

1 --

----

----

--<

----

----

----

E

mis

sivi

ty

----

->--

---

0

12 channels data RGBs

• Exploiting channel combinations to understand the observation products

• Making multichannel approach relevant and applicable: – (MFG) 3 channels,– (MSG) 12 channels and – (MTG) 39 channels

PART 3:

RECOMMENDEDRED-GREEN-BLUE (RGB) COLOUR COMPOSITESFOR MONITORING CONVECTION

DAY-TIME

Recommended RGBs Daytime

Red: Cloud depth and amount of cloud water and ice,provided by the visible reflectance at 0.6 mm.

Green: Cloud particle size and phase, approximated by the1.6 mm or 3.9 mm solar reflectance component.

Blue: Temperature, provided by the 10.8 mm channel.

Recommended RGBs Daytime - HRVIS

Red: Cloud optical depth and detailed cloud top structures,

provided by the HRVIS channel.

Green: Cloud optical depth and detailed cloud top structures,

provided by the HRVIS channel.

Blue: Temperature, provided by 10.8 mm, or cloud particle size

and phase, provided by the NIR1.6 or IR3.9 channel.

Typical Convective Development- Daytime -

VIS0.6 NIR1.6 IR3.9IR10.8

I. Very early stage white white whitelight grey(low, warm water cloud) opt thick water waterwarm

II. First convection* white white whitedark grey(first convective towers) opt thick supercooled supercooledcold

water water

III. First icing white light grey greyblack(transformation in Cb) opt thick small ice small ice very cold

IV. Large icing white dark grey blackblack(Cb anvils) opt thick large ice large ice very cold

*This phase is more frequent in Africa, i.e. it is more easy to find examples for this phase in tropical convection

Red Green BlueVIS0.6 IR3.9 IR10.8 RGB

I. Very early stage 255 255 200 white-light yellow

II. First convection 255 255 100 yellow

III. First icing 255 150 0 orange

IV. Large icing 255 0 0 red

RGB 01-04-09

RGB 0.6 / 3.9 / 10.8

I. Very early stagewhite-light yellow

II. First convection yellow

III. First icing orange

IV. Large icing red

I

II

III

IV

RGB 01-04-09

Red Green BlueVIS0.6 NIR1.6 IR10.8 RGB

I. Very early stage 255 255 200 white-light yellow

II. First convection 255 255 100 50 yellow

III. First icing 255 200 0 orange

IV. Large icing 255 100 0 red-orange

RGB 01-03-09

II. First Convection (Supercooled Clouds)

MSG-1, 5 June 2003, 10:00 UTC, RGB 01-03-09

Supercooled Water Clouds

III. First Icing

MSG-1, 5 June 2003, 10:30 UTC, RGB 01-03-09

Cb Icing

IV. Large Icing

MSG-1, 5 June 2003, 11:30 UTC, RGB 01-03-09

Large Ice

Small Ice

V. Very Large Icing

MSG-1, 5 June 2003, 13:30 UTC, RGB 01-03-09

Large Ice

PART 2:

CHANNEL DIFFERENCESUSEFUL TOMONITOR CONVECTION

NIGHT-TIME

Recommended Differences

IR3.9 - IR10.8 particle size, phaseIR8.7 - IR10.8 optical thicknessIR12.0 - IR10.8 optical thicknessWV6.2 - IR10.8 overshooting topsWV6.2 - WV7.3 overshooting tops

PART 3:

RECOMMENDEDRED-GREEN-BLUE (RGB) COLOUR COMPOSITESFOR MONITORING CONVECTION

NIGHT-TIME

Recommended RGBs Night-time

Red: Cloud optical depth, approximated by the12.0 - 10.8 mm or 10.8 - 8.7 brightness temperature.

Green: Cloud particle size and phase, approximated by the10.8 - 3.9 mm brightness temperature.

Blue: Temperature, provided by 10.8 mm brightness temperature.

Typical Convective Development- Nighttime -

12.0-10.8 10.8-8.7 10.8-3.9 10.8

I. Very early stage white white white light grey(low, warm water cloud) opt thickopt thicklow water warm

II. First convection* white white light greydark grey

(first convective towers) opt thicksupercooled supercooled coldwater water

III. First icing white grey b/w noiseblack

(transformation in Cb) opt thickice cloud very cold very cold

IV. Large icing white grey b/w noiseblack

(Cb anvils) opt thickice cloud very cold very cold

*This phase is more frequent in Africa, i.e. it is more easy to find examples for this phase in tropical convection

Red Green Blue12.0-10.8 10.8-3.9 10.8 RGB

I. Very early stage 255 255 200 white-light yellow

II. First convection 255 200 100 light brown

III. First icing 255 100/255 0 red-yellow

IV. Large icing 255 100/255 0 red-yellow

RGB 10-09 / 09-04 / 09

summary

• RGB for deep convection during day time– Day RGB149 or RGB139

• Deep Convection is also visible on -– Day Convection RGB(5-6,4-9,3-1)

• At night Deep convection we use complex differencing:– Night Convection RGB (5-6,8-9, 9i)– Rgb10-9,9-4,9

• The Airmass RGB (5-6,8-9,5i) is also useful in extratropical regions