IR10.8 - RTC, Regional Training Centre - Turkey

MSG Channels Overview 

(Introduction to Monitoring 

Convection with Satellite 

Images) 

Dr. Jochen Kerkmann 

Satellite Meteorologist, Training Officer 

EUMETSAT 

Collaborating: J. Prieto, M. Putsay, 

M. Setvak, HP. Roesli, R. Vazquez, 

S. Gallino

Course / Lesson objectives 

‣ Review the “ingredients approach” for nowcasting convection 

(conceptual models of convective storms lecture) 

‣ Overview of satellite image indicators for severe convection 

• Single channel view 

• Channel differences 

• Multi-spectral view 

• RGB View (Introduction to RGBs lecture) 

‣ Understand the importance of cloud particle size products 

(Cloud particle size products lecture) 

‣ Understand key water vapour features related to the environment of 

severe convection (Airmass RGB lecture) 

‣ Cloud analysis, precipitation, wind and stability products (NWC 

SAF, GII and cloud tracking products lectures)

METEOSAT SECOND GENERATION (MSG) 

‣ Spinning Enhanced Vis & IR Imager 

‣ 12 Spectral Channels 

‣ Images every 15 or 5 Minutes 

‣ 3 km horizontal ‘sampling distance’ at Sub- 

Satellite Point (SSP) 

‣ Hi-Res VIS-Channel 1 km sampling distance 

(SSP) 

MSG-1 Launch on 28 Aug 2002

MSG characterises the (pre-)convective environment 

Single channels: 

HRV, VIS0.6, NIR 1.6, IR3.9, WV 6.2, WV7.3, IR 10.8 

Channel differences: 

8.7 – 10.8 (cloud thickness) 

3.9 – 10.8 (cloud particle size) 

6.2 – 10.8 (cloud overshooting) 

RGB Composites: 

24-h Cloud Microphysics, Airmass 

Day Microphysics … 

Derived products: 

instability indices 

wind convergence 

humid areas 

HRV 15 June 2006 15:00 UTC

Monitoring convection with single MSG channels 

HRV 

VIS0.6 

NIR1.6 

IR3.9 

WV6.2 

WV7.3 

IR10.8 

fine-scale structures (high-res winds) 

optical thickness of clouds 

particle size and phase 

particle size and phase 

upper-level moisture, jets, PV anomalies 

mid-level moisture, jets, early convection 

top temperature 

HRV NIR 1.6 IR 3.9 IR 3.9r IR10.8

HRV Channel 

Broadband visible 

channel with an 

improved sampling 

interval of 1 km

Comparison HRV Channel vs AVHRR Channel 2 

MSG-1 HRV 

NOAA AVHRR Ch.2 

Shallow fog in the Po Valley as seen in the high-res. visible channel 

MSG-1, 19 November 2003, 13:00 UTC

Channel 12 (HRV): Optical Thickness 

Pretoria 

Maputo 

Swaziland 

Republic of 

South Africa 

Lesotho 

Thin Ci 

MSG-1, 6 November 2004, 12:00 UTC, Channel 12 (HRV)

Monitoring of 

Fine-Scale Structures with the HRV Channel 

Po Valley Fog 

MSG-1 

20 Nov 2003 

11:30 UTC 

Channel 12 

(HRV)

The Channel 

HRV 

Fine Scale Structures 

MSG-1 

8 June 2003 

13:00 UTC 

Channel 12 (HRV) 

Cloud Streets

Orographic Convection 

HRV 


Spain 

MSG-1 

8 June 2003 

15:00 UTC 


Orographic Convection

Single Cb 

Shadow 

Mesoscale 

Convective 

System 

HRV 


Lac Leman 

MSG-1 

7 August 2003 

16:30 UTC 

Channel 12 (HRV)

Cloud 

Streets 

Mesoscale 

Convective 

System 

HRV 


Coastal 

Convergence 

MSG-1 

13 June 2003 

12:00 UTC 


Po Valley 

Thin 

Cirrus

Gravity Waves, Thunderstorm, Mediterranean Sea 

Convergence 

Line 

MSG-1, 20 October 2005, 12:45 UTC, HRV

Gravity Waves & Overshooting Tops (morning) 

Gravity 

Waves 

Overshooting 

Top 

Po Valley 

MSG-1 

21 August 2006 

06:00 UTC 

Channel 12 (HRV)

Gravity Waves & Overshooting Tops (afternoon) 

- F2 Tornado Mallorca - 

Gravity 

Waves 

Overshooting 

Tops 

Spain 

MSG-2 

04 October 2007 

14:45 UTC 

Channel 12 (HRV)

Severe storm Mediterranean 15 October 2003 

Flanking / 

Convergence Line 

Enhanced IR10.8 

MSG-1 

15 October 2003, 

8:00 UTC 

HRV

Severe storm Yemen 5 May 2005 

Yemen 

Djibouti 

Severe Convection 

V / U-shape Storm 

MSG-1, 5 May 2005, 13:00 UTC, Channel 12 (HRV)

Seabreeze Convergence, Southern Italy (Salento) 

09:05 UTC 09:40 UTC 10:55 UTC 

12 June 2007, HRV Channel (Met-8 Rapid Scans)

Intersection of Boundaries, Burkina Faso 

Mali 

Niger 

Burkina Faso 

Ivory Coast 

Ghana 

Met-8, 5 April 2007, 11:00 UTC, VIS0.8 Channel


Mali 

Niger 

Burkina Faso 

Ivory Coast 

Ghana 



Mali 

Niger 

Burkina Faso 

Ivory Coast 

Ghana 


Exercise: Convergence Lines 

MSG-1 

5 June 2003 

12:00 UTC 

RGB Composite 

R = HRV 

G = HRV 

B = IR3.9


MSG-1, 5 June 2003, 14:45 UTC 

RGB HRV-HRV-IR10.8i

Outflow at high or low level 

Tropopause Outflow 

23-Apr-2003 17:00, HRV 

Surface Outflow 

Due to physical boundaries in the 

troposphere (ground and tropopause), 

the flow diverges out of the vertical column 

Day Microphysics 

14-Aug-2003 15:00

Convective Outflow Boundary, Corsica 

Met-8, 9 August 2006, 14:45 UTC, HRV Channel

Severe storm Cyprus 13 October 2006

Radial Cirrus, Hungary 

Met-8, 29 June 2006, 15:00 UTC, RGB HRV, HRV, IR10.8 

Source: M. Putsay

Radial Cirrus, Northern Italy 

Source: M. Setvak 

NOAA 6, 17 July 1982, 08:00 UTC, RGB VIS0.8, VIS0.8, IR11.0

Cirrus plume formation above thunderstorm anvil 

Pao Wang: cloud top gravity wave breaking theory 

Pre conditions: 

- strong winds at high levels (strong shear) 

- Stationarity of convective system 

MSG-1, 30 June 2008, 17:40 UTC, HRV

Overshooting tops as seen on 5- minute HRV data 

In case of 15-minute data we would have only the first and the last image! 

Typical life-time of overshooting tops is less than 15 minutes, about 5-10 minutes. 

With 15-minute imagery it is quite random whether we see the overshooting top or not and if 

yes in which developing phase do we see it. 

Source: M. Putsay & M. Setvak

A tiny cell could 

be presumed near 

to the big cell. 

The first tiny cell 

increased. Another 

is initiating. 

Both cells increased, a 

third one is presumed. 

One can see 

three cells. 

All three cells 

are increasing. 

On 5-minute 5 

imagery one can 

better follow the the initiation 

and growing of individual cells. 

Source: M. Putsay

Earth Surface Channel 01 (VIS0.6) Clouds 

Sun Glint 

Snow 

High reflectance 

Very thick 

clouds 

Desert 

Bare Soil 

Very thin clouds 

over land 

Forest 

Ocean, Sea 

31 October 2003, 11:30 UTC 


over ocean 

Low reflectance

Earth Surface Channel 02 (VIS0.8) Clouds 

Sun Glint 

Snow 


Very thick 

clouds 

Desert 

Gras, Rice fields 

Forest 

Bare Soil 


over land 

Ocean, Sea 

31 October 2003, 11:30 UTC 


over ocean 

Low reflectance

Thick Cb Cloud 

Thin Cirrus Anvil 

VIS0.6 

Optical Thickness 

MSG-1 

5 June 2003 

14:45 UTC 

Channel 01 

(VIS0.6)

D. Jolivet & A. Feijt, KNMI, 2003 

Water 

Ice 

Reflectivity at 

1.6 micron in 

function of 

optical thickness 

for various 

classes of 

effective droplet 

radius and ice 

particle size 

C1 = 30 m 

C2 = 60 m 

C3 = 130 m 

(max. crystal dimension)

Earth Surface Channel 03 (NIR1.6) Clouds 

Sun Glint 

Sand Desert 


Water clouds 

with small 

droplets 

Gras, Rice fields 

Forest 

Bare Soil 

Water clouds 

with large 

droplets 

Ice clouds with 

small particles 

Snow 

Ocean, Sea 

31 October 2003, 11:30 UTC 

Ice clouds with 

large particles 

Low reflectance

Channel 03 (NIR1.6): cloud phase 

VIS0.6 

VIS 0.6 and 0.8 m: 

thick ice and water 

clouds appear both 

white - difficult to 

discriminate 

NIR1.6 

NIR 1.6 m: 

ice clouds appear 

darker than water 

clouds 

MSG-1, 5 June 2003, 14:45 UTC

Channel 03 

(NIR1.6): 

Particle Size 

Small ice 

particles 

(40-50%) 

Large ice 

particles 

(30%) 

MSG-1 

5 June 2003 

14:45 UTC 

Channel 03 

(1.6 m)

Channel 03 (NIR1.6): cloud optical thickness 

Thick Cb 

Thin Ci 

NIR1.6 

MSG-1, 14 August 2003, 12:00 UTC 

RGB VIS0.6, NIR1.6, IR10.8

Reflection of Solar Radiation 

EUMETSAT Meteorological Satellite Conference, Helsinki 

2006 

41 

• Reflection at NIR1.6 and IR3.9 

is sensitive to cloud phase and 

very sensitive to particle size 

• Higher reflection from water 

droplets than from ice particles 

• During daytime, clouds with 

small water droplets (St, Sc) are 

much darker than ice clouds 

(inverted image) 

Figure by 

COMET

Channel 04 (IR3.9): Cloud Phase & Particle Size 

IR3.9 shows much more cloud top structures than IR10.8 

1 3 1 

1 

1 

1 3 

1 

3 

1 

1 

3 

2 3 

2 

3 

Channel 04 (IR3.9) 

1= ice clouds with very small particles 

2= ice clouds with small particles 

3= ice clouds with large ice particles 

MSG-1, 20 May 2003, 13:30 UTC 

Channel 09 (IR10.8)

Channel 04r (IR3.9r): Cloud Phase & Particle Size 

Water Clouds (20/25%) 

Maputo 

Water Clouds 

(16/20%) 

Large Ice Particles 

(1/2%) 

Small Ice Particles 

(8/11%) 

MSG-1, 6 November 2004, 12:00 UTC, Channel 04r (IR3.9r) 

Range: 0 % (black) to +60 % (white), Gamma = 2.5

Channel 09 (IR10.8): Top Temperature 

Warm Tops 

Maputo 

Cold Tops 

MSG-1, 6 November 2004, 12:00 UTC, Channel 09i (IR10.8i) 

Range: +50°C (black) to -70°C (white), Gamma = 1.0

Channel 09 (IR10.8): Top Temperature 

Warm Tops 

Maputo 

Cold Tops 

Coldest 

Tops 

MSG-1, 6 November 2004, 12:00 UTC, Channel 09 (IR10.8)

“Block” Colour Enhancement 

Detection of Mesoscale Convective Systems in color-enhanced 

Meteosat-7 IR image (6 Jul 2001, 19.00 UTC) 

Lines: surface observations (isallobars) 

Source: DWD

Channel 09 (IR10.8): Cloud Top Temperature 

Probably the best known (and documented) cloud top 

feature is the “cold-U” or “cold-V”, with warmer embedded 

area inside. 

18 August 1986 13:30 UTC, NOAA 9, Czech Republic 

Source: M. Setvak

Cold-ring storm over Czech Republic & Austria 

‣ When overshoting tops descend back 

to EL they warm up adiabatically, 

and mix to some extent with the 

warmer environment of the lower 

stratosphere 

‣ The warm cores (or warm embedded 

areas) of ring shaped storms should 

not be interpreted as “depressions” or 

“holes” within the storm, but just the 

opposite, that is, as quasi-steady 

elevated regions 

MSG-1, IR10.8 

25 June 2006, 14:00 UTC 

Source: M. Setvak

Cold-ring storm over Czech Republic & Austria 


Enhanced IR10.8 at 14:00

28 June 2005 

17:45 UTC 

IR 10.8 

M. Setvak: “The most violent updrafts create overshooting tops (often called 

penetrating towers) which keep on cooling, because of their rapid ascent, down 

to temperatures which can be by about 20 K (or even more) lower than the lowest 

temperature at the tropopause level !” 

Source: M. Setvak

28 June 2005 

17:45 UTC 

HRV 

Source: M. Setvak

Cold-U Storm over Bulgaria 


Tornadic storm over Bulgaria (cold-U shape) 

22 April 2008, MSG, IR10.8

Cold-ring storms over Hungary & Serbia 

Tornadic storm over Hungary (cold-ring shape) 

20 May 2008, MSG, IR10.8 

Source: M. Putsay

Cold-U storm over Hamburg/Germany 

MSG-1, 9 May 2004, 07:00 UTC, IR10.8

RGB Convective Storms

Different appearance of convective storms when observing 

these by weather radars and satellites: 

27 August 2001 1545 UTC, NOAA 14 

enhanced AVHRR ch 4 > radar reflectivity (max Z) 

Source: Martin Setvak

Merged IR10.8 + HRV Product (Martin Setvak)

Stereo HRV Product (Jan Kanak)

Estofex Criteria for Organised Convection

Monitoring convection with MSG channel differences 

IR3.9 - IR10.8 


IR10.8 - IR12.0 

WV6.2 - IR10.8 

particle size, top temperature 

cloud phase, opt. thickness, (humidity) 

opt. thickness, (humidity) 

overshooting tops 

VIS0.8-VIS0.6 NIR1.6-VIS0.8 IR3.9-IR10.8 IR8.7-IR10.8 IR10.8-IR12.0

- 

VIS0.8 

VIS0.6 

large difference 

= 

Principle of 

Image 

Difference 

VIS0.8 - VIS0.6 

small difference

Difference IR3.9 - IR10.8: Cloud Particle Size 

Maputo 

Large Ice Particles 

(+26/+35 K) 

Small Ice Particles 

(+65/+73 K) 

MSG-1, 6 November 2004, 12:00 UTC, Difference IR3.9 - IR10.8 

Range: -5 K (black) to +70 K (white), Gamma = 0.5

MSG-1 

5 June 2003 

14:45 UTC 

Difference Image 

IR3.9 - IR10.8

Differences IR8.7 - IR10.8 and IR10.8 – IR12.0 

IR10.8 IR8.7 - IR10.8 IR10.8 - IR12.0 

[-80 / +25°C] [-3 / +10 K] [0 / +7 K] 

top temperature phase + optical thickness optical thickness 

MSG-1, 8 September 2003, 12:00 UTC 

Hurricane "Isabel"

How transparent are thin ice clouds 

= 3.9 = 8.7 = 10.8 = 12.0 

T(cloud) = 200 K 

T(surf) = 300 K 

Picture from Bernhard Muehr

Effect on Brightness Temperatures 

= 3.9 = 8.7 = 10.8 = 12.0 

BT(3.9) >> BT(8.7) > BT(10.8) > BT(12.0) 

(neglecting other effects) 


How transparent are thick ice clouds 

= 3.9 = 8.7 = 10.8 

= 12.0 

Note: not considering other effects, 

BT(8.7) BT(10.8) BT(12.0) 


Difference IR10.8 - IR12.0: Optical Thickness 

Thin Ice Cloud 

Maputo 

Thick Ice Cloud 

MSG-1, 6 November 2004, 12:00 UTC, Difference IR10.8 - IR12.0 


Channel 02 (VIS0.8): Optical Thickness 


Maputo 


MSG-1, 6 November 2004, 12:00 UTC, Channel 01 (VIS0.6) 

Range: 0 % (black) to 100 % (white), Gamma = 1.0

Difference IR8.7 - IR10.8: Optical Thickness 

MSG-1 

14 July 2003 

02:00 UTC 



[BTD in K] 

Desert 

(cloud-free) 

Thick Ice 

Clouds 

Thin Ice 

Clouds 

Thin Ice Clouds 

(very high) 

Ocean/Land 

(cloud-free) 

Desert Dust 

or Water Clouds

Difference IR10.8 - IR12.0: Optical Thickness 

Desert 

Dry 

Ocean/Land 

Moist 

MSG-1 

26 January 2004 

10:00 UTC 


IR10.8 - IR12.0 

[BTD in K] 

Thick High 

Clouds 

Thick Low 

Clouds 

Thin Clouds 

(water or ice) 

Extremely High, 

Thin Clouds (ice)


Thick Ice Clouds 

MSG-1 

5 June 2003 

14:45 UTC 


IR8.7 - IR10.8

Difference IR8.7 - IR10.8: Optical Thickness & Phase 


Maputo 


MSG-1, 6 November 2004, 12:00 UTC, Difference IR8.7 - IR10.8 


Difference IR10.8 - IR12.0: Contrails 

Contrails 

MFG IR Channel 

MSG-1, 26 Sep 2003, 08:00 UTC 

MSG Diff. IR10.8 - IR12.0

Cloud Phase not visible in VIS0.6, VIS0.8 Channels 

8 November 2005, 12:00 UTC, Channel 02 (VIS0.8)

Cloud Phase in IR8.7 - IR10.8 

8 November 2005, 12:00 UTC, BTD IR8.7 - IR10.8 

Water clouds: BTD IR8.7 - IR10.8 < -1 K 

Ice clouds: BTD IR8.7 - IR10.8 >= -1 K

Cloud Phase in IR8.7 - IR10.8 

Ice clouds 

Water clouds 

8 November 2005, 12:00 UTC, BTD IR8.7 - IR10.8 

Water clouds: BTD IR8.7 - IR10.8 < -1 K 

Ice clouds: BTD IR8.7 - IR10.8 >= -1 K

VIS0.8 Channel 

ice clouds 

IR8.7 – IR10.8 

water clouds 

IR10.8 – IR12.0

Overshooting Tops in Difference WV6.2 - IR10.8 

Negative BTD values for 

most of the image (IR 

warmer than WV band) 

MSG-1, 14 July 2003, 02:00 UTC

Overshooting Tops in Difference WV6.2 - IR10.8 

Maputo 

Overshooting 

Tops 

MSG-1, 6 November 2004, 12:00 UTC, Difference WV6.2 - IR10.8

MSG-1 

5 June 2003 

14:45 UTC 


WV6.2 - IR10.8

Possible Explanations for Positive BTD 

- presence of warmer moisture layer in the lower 

stratosphere, detectable by this method only above 

cold storm tops (Schmetz et al., 1997); 

- emissivity/transparency differences of frozen cloud 

tops in WV6.2 and IR 10.8 bands (cloud top 

microphysics). 

For both explanations, the BTD strongly depends on actual 

temperature profile near and above the tropopause !

Severe Convection France 

BTD = + 5.7 K 

Overshooting tops 

HRV 

BTD WV6.2-IR10.8 

IR10.8 channel 

28 June 2005, 18:45 UTC, France 

Source: M. Setvak

Severe Convection France 

Here the shape of BTD maximum 

begins to resemble a plume 


IR10.8 channel 

28 June 2005, 19:30 UTC, France 

Source: M. Setvak

Multispectral view of convective storms 

VIS 0.8 NIR 1.6 MIR 3.9 MIR 3.9r IR10.8 

VIS0.8-VIS0.6 NIR1.6-VIS0.8 MIR3.9-IR10.8 IR8.7-IR10.8 IR10.8-IR12.0 

20 May 2008, Tornadic storms over Hungary

RGB Day Microphysics: Colour Inputs 

Red = VIS0.8 

Green = IR3.9r 

Blue = IR10.8 

RGB

Cold-ring storm over Poland 

MSG-1, 2 July 2007, 15:15 UTC, IR10.8



HRV channel 

2 July 2007, 17:45 UTC, Severe Convection Poland 

Source: P. Struzik


29 June 2006, by A. Manzato

Plume, Severe Convection, Poland 

IR10.8 

HRV 

MSG-1, 31 May 2005, 17:15 UTC 

NIR1.6

BT IR 10.8 

12:00 UTC 

Severe 

Storm CZ 

13 June 2003 

BTD WV6.2 - IR 10.8 

IR 3.9 

Source: M. Setvak


20 May 2008 

by M. Putsay

Combination of satellite & radar data 

29 June 2006 

by M. Putsay

Combination of satellite, radar & lightning data 

20 May 2008 

by M. Putsay

Summary: possible satellite indicators for severe convection (if many of 

them come together then the likelihood of severe weather increases) 

• cold cloud tops (enhanced IR10.8 image) 

• explosive cooling & growth (enhanced IR10.8 and HRV image) 

• cold-ring / cold-U shape (enhanced IR10.8 image) 

• other cloud top textures (e.g. MCS) (IR10.8 image, ASII product) 

• long-living storm system (more than 10 hours, IR10.8 and HRV image) 

• right-moving storm (IR10.8 and HRV image) 

• radial Cirrus clouds (IR10.8 image) 

• above-anvil Cirrus plume (HRV image) 

• low-level inflow jet (HRV image) 

• convergence line, flanking line, intersection of convergence lines (HRV image) 

• convective outflow boundaries top/bottom of troposphere (HRV image) 

• upper level divergence (HRV winds) 

• gravity waves on Cb anvil (HRV image, WV6.2 image) 

• strong overshooting of the tops of convective cells (HRV+IR image and WV6.2 - IR10.8 difference) 

• small ice particles (Convection RGB, IR3.9r effective radius (Reff) product) 

• retrieved vertical profiles of cloud particle effective radius and thermodynamic phase (T-Reff plots) 

• left-exit region of upper level jet (WV6.2 image, Airmass RGB) 

• east side of PV anomaly (WV6.2 image, Airmass RGB) 

• high low-level moisture (Dust RGB); upper level moisture flow (WV6.2 and WV7.3 images) 

• unstable environment (GII product) 

• high precip rate (MPE & CRR products)

IR10.8 - RTC, Regional Training Centre - Turkey

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