RGB Applications for Cloud Microphysical Analysis in NinJo

Victor Chung

SAAWSO Project Workshop

April 22-24, 2013

National Lab for Nowcasting and Remote Sensing MeteorologyMSC Ontario

Environment Canada

Objective

To demonstrate how to use RGB imageries in NinJo to perform

daytime cloud microphysical analysis

Why do we need RGB?

...because you can see more with an RGB.....

Role of 3.9 µm in RGB

http://www.meted.ucar.edu/satmet/goeschan/print/6_2_4_3.htm

The microphysics RGB in NinJoMicrophysics (day) [0.67, 3.7-10.7, 10.7i]

RGB examples to differentiate between water and ice clouds

Color enhanced imagery at 10.7 µm.

A

B

CD

E

F

Color enhanced imagery at 3.7 µm

A

B

CE

D

F

Let us look at cloud masses A, D, E, and B

Cloud mass AAppearance in channel 10.7 and 3.7 µm

cold at IR but quite warm at NIR super-cooled water droplets

10.7µm

3.7 µm

T_10.7: -23 to -29 C

T_3.9: 12 to 20 C

Cloud mass A

Cloud mass AAppearance in RGB

Super-cooledwater droplets

RGB

Cloud mass D & EAppearance in 10.7 and 3.7 µm

E (-20 to -25 C)

D (-20 to -25 C)

E (-13 to -15 C)

D (~15 C)

10.7 µm

3.7 µm

D: cold at IR, warm at NIR Super-cooled droplets

E: cold at IR, cold at NIR Ice particles

Histogram Plots for 10.7 and 3.7 µm Channels for a Line Across Cloud Masses D and E

10.7 µm (IR) 3.9 µm (NIR)

Small temperatureRange at IR

Two distinct peak atNIR

Ice

Water

Cloud masses D & EAppearance in RGB

E

D

RGB E: ice

D: super-cooled water

Let us look at cloud mass B evolution from 19 to 21z

Cloud mass B evolution from 19 to 21Z(at 19Z)

Ice or water?10.7 µm 3.7 µm

0.65 µm RGB2

It is water!

Scatter Plots of 3.7 versus 10.7 µm Channels for an Area over Cloud Mass B at 19Z

IR well below freezingNIR warm waterConclusion: super-cooledcloud droplets

Histogram Plots for 10.7 and 3.7 µm Channels for an Area over Cloud Mass B at 19Z

10.7 µ 3.7 µm

Cloud mass B at 20ZIce nucleation is

underway!10.7 µm (IR) 3.7 µm (NIR)

RGB0.65 µm

Scatter Plots of 3.7 vs 10.7 µm Channels for an Area over Cloud Mass B at 20Z

Small IRspread

Large NIRspread

Ice nucleation in process(water drops + ice crystals)

Histogram Plots for 10.7 and 3.7 µm Channels for an Area over Cloud Mass B at 20Z

10.7 µm 3.7 µm

Cloud mass B at 21Z

10.7 µm 3.7 µm

0.65 µm RGB

Clouds consists of mainly ice crystals

Scatter Plots of 3.7 vs 10.7 µm Channels for an Area over Cloud Mass B at 21Z

More pixels with NIRtemperature shift toThe colder side

Histogram Plots for 10.7 and 3.7 µm Channels for an Area over Cloud Mass B at 21Z

10.7 µm 3.7 µm

Conclusion• The special characteristics of the 3.7 um allows us to create a useful

RGB for cloud microphysical analysis

• Several examples have been used to demonstrate how to use this RGB operationally to differentiate between water and ice clouds

• This RGB can be applied for summer storm analysis, for example ice nucleation and lightning

• This RGB can be used in conjunction with other icing products for better cloud icing detection

Water Ice

Thank You!

Questions?

Outline --- this slide will not be shown

Objective- To demonstrate how to perform cloud

microphysical analysis using RGB imageries in NinJo

IntroductionOpener

- With RGB imagery, you can see things that can not be seen with a single channel imagery

- Characteristics of 3.9 um and its role on RGB imagery

Topic- Use of RGB in NinJo for cloud microphysics analysis

Thesis (idea convey)- RGB imagery helps forecasters to monitoring

cloud microphysical properties- Good microphysical analysis helps detecting

icing, and convective storm analysis

The Body- A list of examples for cloud microphysical analysis

ConclusionRestate the thesis

- RGB should be used more for cloud top microphysical analysis to improve our weather monitoring capabilityAction for future works

- Real-time applications for summer and winter storms

- Use in conjunction with icing product