Central Facility Presentation

1
APPLICATIONS OF METEOSAT SECOND GENERATION (MSG)
FOG DETECTION Author Jochen Kerkmann
(EUMETSAT) (kerkmann_at_eumetsat.de) Contributo
rs H. J. Lutz (EUMETSAT), P. Pylkkö
(FMI), HP. Roesli (MeteoSwiss), D. Rosenfeld
(HUJ)
2
Day-time Fog over Southern Germany 24 February
2003
3
MSG-1 24 Feb 2003 1100 UTC Channel 09 (IR10.8)
1
2
2
1 low-level fog or stratus 2 snow 3
snow-free ground
1
3
1
1
1
3
IR10.8 channel not very useful for fog detection
4
MSG-1 24 Feb 2003 1100 UTC Channel 04 (IR3.9)
1
2
1 low-level fog or stratus 2 snow 3
snow-free ground
2
3
1
1
1
1
3
Detection of fog during day-time much better
with IR3.9 channel
5
MSG-1 24 Feb 2003 1100 UTC Channel 04r (IR3.9r)
1
2
1 low-level fog or stratus 2 snow 3
snow-free ground
2
3
1
1
1
1
3
Detection of fog during day-time also good with
solar component of IR3.9
6
MSG-1 24 Feb 2003 1100 UTC Difference IR3.9 -
IR10.8
1
2
1 low-level fog or stratus 2 snow 3
snow-free ground
2
3
1
1
1
1
3
or with the brightness temperature difference
IR3.9 - IR10.8
7
Detection of fog over snow surfaces with SEVIRI
NIR 1.6 channel 24 Feb 2003, 1100 UTC
1
2
1
3
1
2
1
3
1
8
Animation 1/5
Detection of fog over snow surfaces with SEVIRI
NIR 1.6 channel
2
1
2
1
1 low-level fog or stratus 2 snow 3 thin
mid-level cloud with water droplets (supercoole
d cloud) 4 lakes
2
3
4
MSG-1 24 Feb 2003 1100 UTC Channel 03 (NIR1.6)
9
Animation 2/5
Detection of fog over snow surfaces with SEVIRI
NIR 1.6 channel
2
1
2
1
1 low-level fog or stratus 2 snow 3 thin
mid-level cloud with water droplets (supercoole
d cloud) 4 lakes
2
3
4
MSG-1 24 Feb 2003 1115 UTC Channel 03 (NIR1.6)
10
Animation 3/5
Detection of fog over snow surfaces with SEVIRI
NIR 1.6 channel
2
1
2
1
1 low-level fog or stratus 2 snow 3 thin
mid-level cloud with water droplets (supercoole
d cloud) 4 lakes
2
3
4
MSG-1 24 Feb 2003 1130 UTC Channel 03 (NIR1.6)
11
Animation 4/5
Detection of fog over snow surfaces with SEVIRI
NIR 1.6 channel
2
1
2
1
1 low-level fog or stratus 2 snow 3 thin
mid-level cloud with water droplets (supercoole
d cloud) 4 lakes
2
3
4
MSG-1 24 Feb 2003 1145 UTC Channel 03 (NIR1.6)
12
Animation 5/5
Detection of fog over snow surfaces with SEVIRI
NIR 1.6 channel
2
1
2
1
1 low-level fog or stratus 2 snow 3 thin
mid-level cloud with water droplets (supercoole
d cloud) 4 lakes
2
3
4
MSG-1 24 Feb 2003 1200 UTC Channel 03 (NIR1.6)
13
MSG-1, 24 Feb 2004, 1100 UTC, VIS0.8
close-up viewover the Alps
Non-detection of fog over snow surfaces with
SEVIRI VIS0.6 amd VIS0.8 channels
14
MSG-1, 24 Feb 2004, 1100 UTC, HRV close-up
viewover the Alps
Non-detection of fog over snow surfaces with
SEVIRI HRV channel
15
1
MSG-1 24 Feb 2003 1100 UTC RGB Composite R
NIR1.6 G VIS0.8 B VIS0.6
1
2
2
1 low-level fog or stratus 2 snow 3 thin
mid-level cloud with water
droplets (supercooled cloud)
1
1
2
1
3
Recommended RGBs for Monitoring of Day-time Fog
16
1
MSG-1 24 Feb 2003 1100 UTC RGB Composite R
VIS0.8 G IR3.9r B IR10.8
1
2
2
1 low-level fog or stratus 2 snow 3 thin
mid-level cloud with water
droplets (supercooled cloud)
1
1
2
1
3
Recommended RGBs for Monitoring of Day-time Fog
17
1
MSG-1 24 Feb 2003 1100 UTC RGB Composite R
VIS0.8 G NIR1.6 B IR3.9r
1
2
2
1 low-level fog or stratus 2 snow 3 thin
mid-level cloud with water
droplets (supercooled cloud)
1
1
2
1
3
Recommended RGBs for Monitoring of Day-time Fog
18
MSG-1 24 Feb 2003 1145 UTC RGB Composite R
NIR1.6 G HRV B HRV
1
2
1
1 low-level fog or stratus 2 snow 3 thin
mid-level cloud with water droplets
(supercooled cloud)
2
Recommended RGBsfor Monitoring ofDay-time Fog
3
19
Night-time Fog over France 14 July 2003
20
Detection of fog at night (and day) with IR3.9 -
IR10.8 brightness temp. diff.
Animation 1/4
2
1 low-level fog or stratus 2 clear
ground 3 high-level clouds
1
3
MSG-1 14 July 2003 0300 UTC Difference
Image IR3.9 - IR10.8
21
Detection of fog at night (and day) with IR3.9 -
IR10.8 brightness temp. diff.
Animation 2/4
2
1 low-level fog or stratus 2 clear
ground 3 high-level clouds
1
3
MSG-1 14 July 2003 0400 UTC Difference
Image IR3.9 - IR10.8
22
Detection of fog at night (and day) with IR3.9 -
IR10.8 brightness temp. diff.
Animation 3/4
Detection of fog difficult at dawn/dusk !
2
1 low-level fog or stratus 2 clear
ground 3 high-level clouds
1
3
MSG-1 14 July 2003 0500 UTC Difference
Image IR3.9 - IR10.8
23
Detection of fog at night (and day) with IR3.9 -
IR10.8 brightness temp. diff.
Animation 4/4
2
1 low-level fog or stratus 2 clear
ground 3 high-level clouds
1
3
MSG-1 14 July 2003 0600 UTC Difference
Image IR3.9 - IR10.8
24
MSG-1, 14 July 2003
Difference IR3.9 - IR10.8, 200 UTC
HRVIS for comparison, 0845 UTC
25
Night-time Fog over S. Africa 24 April 2003
26
IR10.8 channel not useful for fog
detection during night-time
3
1 low-level fog or stratus 2 clear ground 3
thin mid-level clouds 4 thick high-level clouds
1
2
MSG-1 24 April 2003 0200 UTC Channel 09 (IR10.8)
4
27
IR8.7 channel also not useful for fog
detection during night-time
3
1 low-level fog or stratus 2 clear ground 3
thin mid-level clouds 4 thick high-level clouds
1
2
MSG-1 24 April 2003 0200 UTC Channel 07 (IR8.7)
4
28
IR3.9 channel also not useful for fog
detection during night-time
3
1 low-level fog or stratus 2 clear ground 3
thin mid-level clouds 4 thick high-level clouds
1
2
MSG-1 24 April 2003 0200 UTC Channel 04 (IR3.9)
4
29
Fog at night visible inIR3.9 - IR10.8 brightness
temperature difference images
3
1 low-level fog or stratus 2 clear ground 3
thin mid-level clouds 4 thick high-level clouds
1
2
MSG-1 24 April 2003 0200 UTC Difference
Image IR3.9 - IR10.8
4
30
Fog at night less visible in IR8.7 -
IR10.8 brightness temperature difference images
3
1 low-level fog or stratus 2 clear ground 3
thin mid-level clouds 4 thick high-level clouds
1
2
MSG-1 24 April 2003 0200 UTC Difference
Image IR8.7 - IR10.8
4
31
Fog at night not visible in IR12.0 -
IR10.8 brightness temperature difference images
3
1 low-level fog or stratus 2 clear ground 3
thin mid-level clouds 4 thick high-level clouds
1
2
MSG-1 24 April 2003 0200 UTC Difference
Image IR12.0 - IR10.8
4
32
MSG-1 24 April 2003 0200 UTC RGB Composite R
IR12.0 - IR10.8 G IR10.8 - IR3.9 B IR10.8
3
1
1 low-level fog or stratus 2 clear ground 3
thin mid-level clouds 4 thick high-level clouds
2
Recommended RGBfor Monitoring ofNight-time Fog
4
33
Night-time Fog over Central Europe 25 October 2003
34
IR10.8 channel not useful for fog
detection during night-time
3
1
1
2
2
1 low-level fog or stratus 2 clear ground 3
thin Cirrus clouds
MSG-1 25 October 2003 0200 UTC Channel
09 (IR10.8)
3
35
IR8.7 channel also not useful for fog
detection during night-time
3
1
1
2
2
1 low-level fog or stratus 2 clear ground 3
thin Cirrus clouds
MSG-1 25 October 2003 0200 UTC Channel 07 (IR8.7)
3
36
IR3.9 channel a bit better for fog
detection during night-time, but ...
3
1
1
2
2
1 low-level fog or stratus 2 clear ground 3
thin Cirrus clouds
MSG-1 25 October 2003 0200 UTC Channel 04 (IR3.9)
3
37
fog at nightvery well visible inIR3.9-IR10.8
temperature difference images
3
1
1
2
Fog -8/-10 K (black) Ground -4/-5 K (grey)
2
1 low-level fog or stratus 2 clear ground 3
thin Cirrus clouds
MSG-1 25 October 2003 0200 UTC Difference
Image IR3.9 - IR10.8
3
38
fog at nightalso well visible inIR8.7-IR10.8
temperature difference images
3
1
1
2
Fog -4 K (dark grey) Ground -2 K (light grey)
2
1 low-level fog or stratus 2 clear ground 3
thin Cirrus clouds
MSG-1 25 October 2003 0200 UTC Difference
Image IR8.7 - IR10.8
3
39
fog at nightnot visible inIR12.0-IR10.8
temperature difference images
3
1
1
2
2
1 low-level fog or stratus 2 clear ground 3
thin Cirrus clouds
MSG-1 25 October 2003 0200 UTC Difference
Image IR12.0 - IR10.8
3
40
3
MSG-1 25 Oct 2003 0200 UTC RGB Composite R
IR12.0-IR10.8 G IR10.8-IR3.9 B IR10.8
1
1
2
2
1 low-level fog or stratus 2 clear
ground 3 thin Cirrus clouds
3
Recommended RGB for Monitoring of Night-time Fog
41
Night-time Fog over Southern Finland 29 October
2003
42
Fog at nightnot visible inIR10.8 images
1
2
1
3
1 low-level fog or stratus 2 clear ground 3
high-level frontal clouds
3
MSG-1 29 October 2003 0200 UTC Channel
09 (IR10.8)
1
2
43
Fog at nightnot visible inIR8.7 images
1
2
1
3
1 low-level fog or stratus 2 clear ground 3
high-level frontal clouds
3
MSG-1 29 October 2003 0200 UTC Channel 07 (IR8.7)
1
2
44
Fog at nighthardly visible inIR3.9 images
1
2
1
3
1 low-level fog or stratus 2 clear ground 3
high-level frontal clouds
3
MSG-1 29 October 2003 0200 UTC Channel 04 (IR3.9)
1
2
45
Night-time fog is not well visible
inIR3.9-IR10.8 temperature difference images
over Scandinavia
1
2
1
3
1 low-level fog or stratus 2 clear ground 3
high-level frontal clouds
3
MSG-1 29 October 2003 0200 UTC Difference
Image IR3.9 - IR10.8
1
2
46
The IR8.7-IR10.8 temperature difference images
give better results for fog detection at high
latitudes
1
2
1
3
1 low-level fog or stratus 2 clear ground 3
high-level frontal clouds
3
MSG-1 29 October 2003 0200 UTC Difference
Image IR8.7 - IR10.8
1
2
47
MSG-1 29 Oct 2003 0200 UTC RGB Composite R
IR12.0-IR10.8 G IR10.8-IR8.7 B IR10.8
1
2
1
3
3
1 low-level fog or stratus 2 clear
ground 3 high-level frontal clouds
1
2
Recommended RGB for Monitoring of Night-time Fog
at high Latitudes
48
Night-time Fog over Central Europe 5 November
2003
49
3
3
Fog at nightnot visible inIR windowchannels
2
1 low-level fog or stratus 2 clear ground 3
high-level clouds
1
1
3
MSG-1 5 November 2003 0300 UTC Channel 04 (IR3.9)
1
2
50
3
3
Fog at nightnot visible inIR windowchannels
2
1 low-level fog or stratus 2 clear ground 3
high-level clouds
1
1
3
MSG-1 5 November 2003 0300 UTC Channel 07 (IR8.7)
1
2
51
3
3
Fog at nightnot visible inIR windowchannels
2
1 low-level fog or stratus 2 clear ground 3
high-level clouds
1
1
3
MSG-1 5 November 2003 0300 UTC Channel
09 (IR10.8)
1
2
52
Fog at nightwell visible inIR3.9 - IR10.8
difference images
3
3
2
Fog -7/-10 K (black) Ground -4 K (grey)
1 low-level fog or stratus 2 clear ground 3
high-level clouds
1
1
3
MSG-1 5 November 2003 0300 UTC Difference
Image IR3.9 - IR10.8
1
2
53
3
3
Fog at nightalso well visible inIR3.9 - IR12.0
difference images
2
Fog -8/-10 K (black) Ground -5 K (grey)
1 low-level fog or stratus 2 clear ground 3
high-level clouds
1
1
3
MSG-1 5 November 2003 0300 UTC Difference
Image IR3.9 - IR12.0
1
2
54
3
Fog at nightalso visible inIR8.7 - IR10.8
difference images
3
2
Fog -3/-4 K (dark grey) Ground -1 K (light grey)
1 low-level fog or stratus 2 clear ground 3
high-level clouds
1
1
3
MSG-1 5 November 2003 0300 UTC Difference
Image IR8.7 - IR10.8
1
2
55
Fog at nightnot visible indifferenceIR12.0 -
IR10.8
3
3
2
Fog 0/1 K (light grey) Ground 0/1 K (light
grey)
1 low-level fog or stratus 2 clear ground 3
high-level clouds
1
1
3
MSG-1 5 November 2003 0300 UTC Difference
Image IR12.0 - IR10.8
1
2
56
3
3
MSG-1 5 November 2003 0300 UTC RGB Composite R
IR12.0-IR10.8 G IR10.8-IR3.9 B IR10.8
2
1
1
1 low-level fog or stratus 2 clear
ground 3 high-level clouds
3
1
2
Recommended RGB for Monitoring of
Night-time Fog
57
Day-time Fog over Central Europe 5 November 2003
58
River Valley Fog as seen by Meteosat First
Generation (MFG) Met-7, 5 November 2003, 0800
UTC, VIS channel
59
River valley fog can be better detected with the
MSG HRV channel
Mosel Valley
Danube Valley
MSG-1 5 November 2003 0845 UTC Channel 12 (HRV)
60
and the MSG HRV channel gives more details
MSG-1 5 November 2003 0845 UTC Channel 12 (HRV)
61
MSG-1 5 November 2003 0900 UTC RGB Composite R
NIR1.6 G VIS0.8 B VIS0.6
3
2
1
1
1 low-level fog or stratus 2 clear
ground 3 high-level clouds 4 snow
1
4
2
4
Recommended RGBs for Monitoring of
Day-time Fog
62
MSG-1 5 November 2003 0900 UTC RGB Composite R
VIS0.8 G IR3.9r B IR10.8
3
2
1
1 low-level fog or stratus 2 clear
ground 3 high-level clouds 4 snow
1
2
4
1
4
Recommended RGBs for Monitoring of Day-time
Fog
63
MSG-1 5 November 2003 0900 UTC RGB Composite R
VIS0.8 G NIR1.6 B IR3.9r
3
2
1
1 low-level fog or stratus 2 clear
ground 3 high-level clouds 4 snow
1
2
4
1
4
Recommended RGBs for Monitoring of Day-time
Fog
64
3
MSG-1 5 November 2003 0845 UTC RGB Composite R
HRV G HRV B IR3.9i
2
1 low-level fog or stratus 2 clear ground 3
high-level clouds 4 snow
1
1
4
Recommended RGBsfor Monitoring ofDay-time
Fog
2
4
1
65
Night-time Fog over Europe 9 November 2003
66
Fog at nightnot visible inIR windowchannels
1
3
1
2
1 low-level fog or stratus 2 cold clear
ground 3 warm clear ground (mountains) 4
thin, high-level clouds
3
4
1
MSG-1 09 November 2003 0315 UTC Channel
04 (IR3.9)
67
Fog at nightnot visible inIR windowchannels
1
3
1
2
1 low-level fog or stratus 2 cold clear
ground 3 warm clear ground (mountains) 4
thin, high-level clouds
3
4
1
MSG-1 09 November 2003 0315 UTC Channel
07 (IR8.7)
68
Fog at nightnot visible inIR windowchannels
1
3
1
2
1 low-level fog or stratus 2 cold clear
ground 3 warm clear ground (mountains) 4
thin, high-level clouds
3
4
1
MSG-1 09 November 2003 0315 UTC Channel
09 (IR10.8)
69
Animation 1/6
Fog at night visible inIR3.9 - IR10.8 difference
images
1
Fog -7/-10 K (black) Ground -4/-5 K (grey)
3
1
2
1 low-level fog or stratus 2 cold clear
ground 3 warm clear ground (mountains) 4
thin, high-level clouds
3
4
1
MSG-1 09 November 2003 0315 UTC Difference
Image IR3.9 - IR10.8
70
Animation 2/6
Fog at night visible inIR3.9 - IR10.8 difference
images
1
Fog -7/-10 K (black) Ground -4/-5 K (grey)
3
1
2
1 low-level fog or stratus 2 cold clear
ground 3 warm clear ground (mountains) 4
thin, high-level clouds
3
4
1
MSG-1 09 November 2003 0415 UTC Difference
Image IR3.9 - IR10.8
71
Animation 3/6
Fog at night visible inIR3.9 - IR10.8 difference
images
1
Fog -7/-10 K (black) Ground -4/-5 K (grey)
3
1
2
1 low-level fog or stratus 2 cold clear
ground 3 warm clear ground (mountains) 4
thin, high-level clouds
3
4
1
MSG-1 09 November 2003 0515 UTC Difference
Image IR3.9 - IR10.8
72
Animation 4/6
Fog at dawn/dusk not visible in IR3.9 - IR10.8
difference images
1
Fog -3/-4 K (grey) Ground -4/-5 K (grey)
3
1
2
1 low-level fog or stratus 2 cold clear
ground 3 warm clear ground (mountains) 4
thin, high-level clouds
3
4
1
MSG-1 09 November 2003 0615 UTC Difference
Image IR3.9 - IR10.8
73
Animation 5/6
Fog at daytime visible in IR3.9 -
IR10.8 difference images
1
Fog 2/6 (light grey) Ground -4/-5 K (dark
grey)
3
1
2
1 low-level fog or stratus 2 cold clear
ground 3 warm clear ground (mountains) 4
thin, high-level clouds
3
4
1
MSG-1 09 November 2003 0715 UTC Difference
Image IR3.9 - IR10.8
74
Animation 6/6
Fog at daytime visible in IR3.9 -
IR10.8 difference images
1
Fog 6/12 (light grey) Ground -2/-3 K (dark
grey)
3
1
2
1 low-level fog or stratus 2 cold clear
ground 3 warm clear ground (mountains) 4
thin, high-level clouds
3
4
1
MSG-1 09 November 2003 0815 UTC Difference
Image IR3.9 - IR10.8
75
Fog at night also visible in differenceIR8.7 -
IR10.8
1
Fog -3/-4 K (black) Ground -1/-2 K (grey)
3
1
2
1 low-level fog or stratus 2 cold clear
ground 3 warm clear ground (mountains) 4
thin, high-level clouds
3
4
1
MSG-1 09 November 2003 0315 UTC Difference
Image IR8.7 - IR10.8
76
Fog at night not visible in differenceIR12.0 -
IR10.8
1
Fog 0/1 K Ground 0/1 K Ocean -1 K
3
1
2
1 low-level fog or stratus 2 cold clear
ground 3 warm clear ground (mountains) 4
thin, high-level clouds
3
4
1
MSG-1 09 November 2003 0315 UTC Difference
Image IR12.0 - IR10.8
77
MSG-1 9 November 2003 0315 UTC RGB Composite R
IR12.0-IR10.8 G IR10.8-IR3.9 B IR10.8
1
3
1
2
3
1 low-level fog or stratus 2 cold clear
ground 3 warm clear ground
(mountains) 4 thin, high level clouds
4
1
Recommended RGB for Monitoring of
Night-time Fog
78
Day-time Fog over Europe 9 November 2003
79
Low Stratus and River Valley Fog as seen by
MFG Met-7, 9 November 2003, 0800 UTC, VIS channel
80
MSG HRV channel gives more details on the fog ...
Fog/low stratus
MSG-1 9 November 2003 0815 UTC Channel 12 (HRV)
River Valley Fog
81
closer look at Denmark
MSG-1 9 November 2003 0815 UTC Channel 12 (HRV)
Fog/Low stratuswith Gravity Waves
82
MSG-1 9 November 2003 0815 UTC RGB Composite R
NIR1.6 G VIS0.8 B VIS0.6
1
3
1
2
1
1 low-level fog or stratus 2 clear
ground 3 high-level thick clouds 4
high-level thin clouds 5 snow
4
4
5
4
3
1
2
Recommended RGBs for Monitoring of
Day-time Fog
83
MSG-1 9 November 2003 0815 UTC RGB Composite R
VIS0.8 G IR3.9r B IR10.8
1
3
1
2
1 low-level fog or stratus 2 clear
ground 3 high-level thick clouds 4
high-level thin clouds 5 snow
1
4
4
5
4
3
1
2
Recommended RGBs for Monitoring of
Day-time Fog
84
MSG-1 9 November 2003 0815 UTC RGB Composite R
VIS0.8 G NIR1.6 B IR3.9r
1
3
1
2
1
1 low-level fog or stratus 2 clear
ground 3 high-level thick clouds 4
high-level thin clouds 5 snow
4
4
5
4
3
1
2
Recommended RGBs for Monitoring of
Day-time Fog
85
3
MSG-1 9 November 2003 0815 UTC RGB Composite R
HRV G HRV B IR3.9 - IR10.8
1
1
2
1
4
4
2
1 low-level fog or stratus 2 clear
ground 3 high-level thick clouds 4
high-level thin clouds 5 snow
5
1
4
1
2
Recommended RGBs for Monitoring of
Day-time Fog
86
Night-time Fog over Central Europe 11 November
2003
87
MSG-1 11 Nov 2003 0300 UTC RGB Composite R
IR12.0 - IR10.8 G IR10.8 - IR3.9 B IR10.8
1
2
4
5
3
3
1. Sea surface 2. Land surface 3. Warm fog 4.
Cool fog stratus (-3oC) 5. Supercooled water
stratus (-13oC) 6. Highly supercooled water
stratus (-18oC) 7. Cb with lightning 8. Thick
cirrus 9. Thin cirrus
6
1
7
8
7
9
Recommended RGB for Monitoring of
Night-time Fog
88
MSG-1 11 Nov 2003 0300 UTC Difference Image R
IR12.0 - IR10.8
1. Sea surface 2. Land surface 3. Warm fog 4.
Cool fog stratus (-3oC) 5. Supercooled water
stratus (-13oC) 6. Highly supercooled water
stratus (-18oC) 7. Cb with lightning 8. Thick
cirrus 9. Thin cirrus
Recommended RGB for Monitoring of
Night-time Fog
89
MSG-1 11 Nov 2003 0300 UTC Difference Image G
IR10.8 - IR3.9
1. Sea surface 2. Land surface 3. Warm fog 4.
Cool fog stratus (-3oC) 5. Supercooled water
stratus (-13oC) 6. Highly supercooled water
stratus (-18oC) 7. Cb with lightning 8. Thick
cirrus 9. Thin cirrus
Recommended RGB for Monitoring of
Night-time Fog
90
MSG-1 11 Nov 2003 0300 UTC Difference Image B
IR10.8
1. Sea surface 2. Land surface 3. Warm fog 4.
Cool fog stratus (-3oC) 5. Supercooled water
stratus (-13oC) 6. Highly supercooled water
stratus (-18oC) 7. Cb with lightning 8. Thick
cirrus 9. Thin cirrus
Recommended RGB for Monitoring of
Night-time Fog
91
Day-time Fog over the Po Valley 20 November 2003
92
MSG-1, 20 November 2003, 1100 UTC, HRV Channel
93
MSG-1, 20 November 2003 Difference IR3.9 - IR10.8
Night Fog darker than clear ground
Dawn Fog and clear ground equal
Day Fog brighter than clear ground
1 to 2 critical slots at dawn/dusk
94
Click on the icon tosee the animation(0000-150
0 UTC,AVI, 15068 KB) !
MSG-1, 20 November 2003, 0000 UTC, IR3.9 - IR10.8
95
SUMMARY
96
Detection of Fog/Low Stratus during Daytime

• VIS0.6 and HRVIS to disciminate between fog and
  ground (fog white, ground dark)
• VIS0.8 less useful because of less contrast to
  vegetated areas
• NIR1.6 and IR3.9 to discriminate between fog and
  snow (fog high reflectivity, snow low
  reflectivity)
• IR3.9 - IR10.8 fog large positive values clear
  ground around 0 K (-5 K to 5 K)

97
Detection of Fog/Low Stratus during Daytime

• RGB 03-02-01 fog white-pinkish clear ground
  greenish or reddish (depending in vegetation)
• RGB 03-12-12 fog white-pinkish clear ground
  reddish
• RGB 02-04r-09 fog white-pinkish clear ground
  blueish
• RGB 02-03-04r fog whitish, clear ground
  greenish-bluish

98
Detection of Fog/Low Stratus during Nighttime
(Low and Mid Latitudes)

• IR3.9-IR10.8 fog -10/-7 K clear ground around
  -4 K(difficulties at high latitudes)
• RGB 10-09 / 09-04 / 09 fog light
  greenish-yellowish clear ground dark pinkish

99
Detection of Fog/Low Stratus during Nighttime
(High Latitudes)

• IR8.7-IR10.8 fog -4 K, clear ground around -1/-2
  K
• RGB 10-09 / 09-07 / 09 fog light
  greenish-yellowish clear ground dark pinkish

100
Detection of Fog/Low Stratus atDawn/Dusk

• IR3.9-IR10.8 fog detection difficult because of
  compensating effects (fog colder in IR3.9 than in
  IR10.8 because of lower emissivity, but
  reflection of solar radiation)
• IR8.7-IR10.8 fog -4 K, clear ground around -1/-2
  K(only small difference between fog and clear
  ground, but works also at dawn/dusk)

101
Detection of Fog/Low Stratus Conclusion
In operational applications, the difference
IR8.7-IR10.8may be the best to detect fog/low
stratus (day- and night), because of

• Less noisy than the difference IR3.9 -
  IR10.8(works well also over Scandinavia)
• 24-hour capability with "constant" colour for
  fog/low stratus (unlike IR3.9-IR10.8 difference)
• High-level Cirrus above fog/low stratus can also
  be detected (combined with IR12.0-IR10.8
  difference)

102
MSG-1, 9 November 2003, 0015 UTC, Difference
Image, IR8.7 - IR10.8
Click on the icon to see the animation
(0015-0815 UTC, AVI, 10550 KB) !