Development of Instability Index of GEO-KOMPSAT-2A

Sung-Rae Chung1, Myoung-Hwan Ahn2, Su-Jeong Lee2

1 KMA/NMSC, 2 Ewha Womans University

2014 Convection Working Group Workshop, 7-11 April 2014, Zagreb, Croatia

2

Geo-KOMPSAT-2 Program

GK-2A for the next generation Meteorological Imager and Space Weather

monitoring

GK-2B for the Ocean Color and Atmospheric Trace Gas monitoring

Meteorological Sensor

Space weather Sensor

Ground Segment

Data Processing System

KMA

Ocean /Environmental

Sensor

Geo-KOMPSAT-2B

2012 ~ 2017 (6 years)

Geo-KOMPSAT-2A

3

AMI (Geo-KOMPSAT-2A)

[Source: Konig, 2002]

<Basic Spectral Bands>

BandsBand Name

Center Wavelength Band Width

(Max, um)

Resolution (km)

SNRNEdT(K)

(240/300K)Radiometric

AccuracyMin(um) Max(um)

VNIR

1 VIS0.4 0.431 0.479 0.075 1 250 5%

2 VIS0.5 0.5025 0.5175 0.0625 1 250 5%

3 VIS0.6 0.625 0.66 0.125 0.5 120 5%

4 VIS0.8 0.8495 0.8705 0.0875 1 210 5%

5 NIR1.3 1.373 1.383 0.03 2 300 5%

6 NIR1.6 1.601 1.619 0.075 2 300 5%

MWIR

7 IR3.8 3.74 3.96 0.5 2 3/0.2 1K8 IR6.3 6.061 6.425 1.038 2 0.4/0.1 1K9 IR6.9 6.89 7.01 0.5 2 0.37/0.1 1K

10 IR7.3 7.258 7.433 0.688 2 0.35/0.12 1K11 IR8.7 8.44 8.76 0.5 2 0.27/0.1 1K

LWIR

12 IR9.6 9.543 9.717 0.475 2 0.35/0.15 1K13 IR10.5 10.25 10.61 0.875 2 0.4/0.2 1K14 IR11.2 11.08 11.32 1.0 2 0.19/0.1 1K

15 IR12.3 12.15 12.45 1.25 2 0.35/0.2 1.1K16 IR13.3 13.21 13.39 0.75 2 0.48/0.3 1.1K

AMI (Advanced Meteorological Imager)• 16 spectral bands

4

Satellite observed radi-ances

Stability Indices (e.g. CAPE)

• Good at estimating non-linear relations

• Once the statistical relations are established, the retrieval can be made computationally very fast (Konig, 2002), often with surprising accuracy (Gardner & Dorling, 1998)

• Training dataset should be complete (large enough to cover a variety of atmospheric phenomena, seasons, and locations) (Blackwell & Chen, 2009)

Artificial Neural Network (ANN)

setup rela-tion

[Source: Konig, 2002]

Statistical Retrieval of Instability Index

T, q profiles (radiosonde, satellite,..)

Work Process Flow

5

CAPE

Final set ofObjective

selectionprofiles

CAPE

Simulated Radiance (I)

MODTRAN run

band-averaged Radiance ()

SRF (SEVIRI for AMI)

Theoretical TB

Inverse of Planck eq.

(establish relations)

Best ANN Parameters

determine

Measured ra-diance (TB)

Real Application: CAPE

direct estima-tionfrom GK2A AMI

ANN training

CAPE Range TOTALselecte

d 0 <= CAPE <1000

133,194

1,375

1000 <= CAPE <2000

6,360 1,375

2000 <= CAPE 1,375 1,375

TOTAL140,9

294,125

IASI (SEVIRI coverage)

6

cir_day

CAPE

INPUTTotal

weights ( WIHxWHO )

circular day 0.09circular

time0.22

Latitude 0.02

Longitude 0.32

Sat. zenith -0.18

Tb6.2 -0.71

Tb7.3 1.56

Tb8.7 6.79

Tb9.6 4.63

Tb10.8 -0.38

Tb12.0 -7.04

Tb13.4 -4.17strongest weight

cir_time

latitude

longitude

sat_zenith

TB6.2

TB7.3

TB8.7

TB9.6

TB10.8

TB12.0

TB13.4

n 1

n 2

n 3

n 4

n 5

n 6

n 7

n 8

n 9

n 10

n 11

n 12

Input layer Hidden layer

Output layer

2nd strongest weight* thickness of the arrows: relative magni-

tude of connection weights

Combination of weights for the best ANN per-formance

Algorithm Validation

7

Radiosonde

IASI(SEVIRI cover-

age)

CAPEANN

training

CAPE re-trieved

CAPE measured

ANN withbest parame-

ter

Radiances from SEVIRI 2.5min (super) rapid

scan

direct es-timation

Validation

compareFuture work

CAPE derived using ANN algorithm(20 June 2013)

8

09:02:14 11:02:13 13:02:12

15:02:15 17:02:14 20:02:13

Significant features- During the afternoon hours (at around 13:02 UTC) several convective clouds begin

to pop up over the regions where the CAPE values are relatively high (marked with arrows and circles at 09:02 UTC image) and developed to the severe convective clouds (at 15:02 UTC)

- High CAPE values around the leading edges of clouds induce a further develop-ment, while weaker CAPE values around the trailing edges result in weakened convective activities. Significance will be assessed with more case studies and quantitative validation.

- No significant convection occurs over high CAPE areas in the morning images (at around 11:02 UTC marked with dashed blue arrows) which requires further inves-tigation.

1,000 2,000 4,000 (J / kg)

0 3,000

CAPE derived using ANN algorithm(20 June 2013 09~21 UTC)

9

1,000 2,000 4,000 (J / kg)

0 3,000

Thank you!