UNDERSTANDING CONVECTIVE CLOUDS THROUGH THE EYES OF (MSG) Cloud Particle Size
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UNDERSTANDING CONVECTIVE CLOUDS THROUGH THE EYES
OF (MSG)
Cloud Particle Size
Jochen KerkmannSatellite Meteorologist, Training [email protected]: D. Rosenfeld (HUJ), I. Lensky (HUJ)
J. Prieto (EUM), D. Lindsey (CIRA) K. Kollath & M. Putsay (HMS) P. Watts & M. Koenig (EUM)
Observing Cloud Particle Size
MFG: not possible ( only cloud thickness and cloud top temperature)
MSG: possible ( 2 window channels)
• NIR1.6 and IR3.9r channels (day)• IR3.9 - IR10.8 BTD (day & night (warm clouds))
• IR8.7 – IR10.8
Figure by COMET
Reflection of Solar Radiation
• 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)
Difference IR3.9 - IR10.8: Cloud Particle Size
Maputo
MSG-1, 6 November 2004, 12:00 UTC, Difference IR3.9 - IR10.8Range: -5 K (black) to +70 K (white), Gamma = 0.5
Large Ice Particles(+26/+35 K)
Small Ice Particles(+65/+73 K)
Observed IR3.9 - IR10.8 BTD for Opaque Ice Clouds
78 68 56 72 62 50 65 55 43 58 47 35 47 37 25 0 0 0
IR3.9 - IR10.8 brightness temperature difference depends on both:cloud particle size and cloud top temperature
(and sun/satellite viewing angles)
IR3.9Refl.
10 8 6 4 2 0
Cloud Top Temperature -70°C -60°C -50°C
Where do small ice particles form ?
in Cb clouds with strong updrafts in Cb clouds with cold (high) cloud base (short
time from cloud base to spontaneous freezing level)
in mountain wave and Pileus clouds in highly “polluted” clouds generally: in ice clouds that form rapidly
“Updraft” Effect
This idea follows from results from multiple papers by D. Rosenfeld, and Heymsfield et al. (2005)
Updraft Effect
„Cloud Depth“ Effect
This idea follows from results from multiple papers by D. Rosenfeld, and Heymsfield et al. (2005)
Maputo
MSG-1, 6 November 2004, 12:00 UTC
Thick Ice Cloud(small ice)
Thick Ice Cloud(large ice)
Particle Size seen in Day Convective Storms RGB
Recommended Range and Enhancement:Recommended Range and Enhancement:
Beam Channel Range Gamma
Red WV6.2 - WV7.3 -35 … +5 K 1.0Green IR3.9 - IR10.8 -5 … +60 K 0.5Blue NIR1.6 - VIS0.6 -75 … +25 % 1.0
RGB 05-06, 04-09, 03-01 ("Day Convective Storms")
devised by: J. Kerkmann
Deep precipitating cloud(precip. not necessarily reaching the ground)
- high-level cloud- large ice particles
Ocean Land
Thin Cirrus cloud
(large ice particles)
Thin Cirrus cloud
(small ice particles)
Deep precipitating cloud(Cb cloud with strongupdrafts and severeweather)*
- high-level cloud- small ice particles
*or thick, high-level lee cloudiness with small ice particles
Colour Interpretation
MSG-1, 29 June 2006, 12:00 UTC
1
2
1. Large ice (dissipating storm)2. Small ice (strong updrafts, large hail)
RGB Convection RGB Nat. Colours
Comparison RGB Convection vs RGB Nat. Colours
12:00 UTC(animation 1/7)
12:15 UTC(animation 2/7)
• Small ice (high IR3.9r of 6-7%)
• Long-living storm system• Convective outflow boundary• Overshooting tops• Gravity waves• Radial Ci
12:30 UTC(animation 3/7)
12:45 UTC(animation 4/7)
13:00 UTC(animation 5/7)
13:15 UTC(animation 6/7)
13:30 UTC(animation 7/7)
IR10.8 IR3.9refl
HRV +radar Convective Storms RGB: G=IR3.9-IR10.8
IR3.9-IR10.8 depends on both
IR10.8 IR3.9refl
HRV +radar Convective Storms RGB: G=IR3.9-IR10.8
IR3.9-IR10.8 depends on both
MSG-1, 13 June 2003, 12:00 UTC
RGB 02, 04r ,09 RGB 05-06, 04-09, 03-01 better identification of young, severe storms
Comparison RGB 02,04r,09 vs RGB 05-06,04-09,03-01
MSG-2, 3 April 2008, 12:30 UTC
Cb Cloud(small ice,
IR3.9r=16%)
Small Ice Particles in Clouds with Cold Base
MSG-1, 22 February 2007, 12:00 UTC
Thick Ice Cloud(small ice)
dust outbreak
Small Ice Particles in “Polluted” Clouds
Small Ice Particles in High-level Lee Cloudiness
MSG-1, 19 March 2007, 08:00 UTCRGB WV6.2-WV7.3, IR3.9-IR10.8, NIR1.6-VIS0.6
(RGB Convection)
Very cold clouds(lee cloudiness) with
small ice particles
Small Ice Particles in isolated High-level Wave Cloud
MSG-2, 11 April 2008, 11:00 UTC Metop-A, AVHRR, 8:49 UTC
Mountain wave cloud withsmall ice particles
Balatonalmádi
Pileus cloud15:27 UTC
André Simon, Mária Putsay, Ákos Horváth:
Is the appearance of this Is the appearance of this yellow spot connected to the yellow spot connected to the
Pileus?Pileus?
Small Ice Particles in Pileus Clouds
SmallSmall LargeLarge
NIR1.6 high Refl. (40-50%) low Refl. (30%)
IR3.9r high Refl. (5-10%) low Refl. (1-2%)
IR3.9 - IR10.8 large pos. (40-75 K) pos. (20-30 K)
Day Microphys. RGB
Convection RGB
Summary (for thick, cold ice clouds, day)