Application of GPS data on Severe Weather Forecasting

To investigate correlation between PWV and VIL, and hence its role in lightning/damaging winds monitoring/nowcasting

Summer Internship at the Hong Kong Observatory 2006

Law Ka Hei (CUHK/PHY/3)

Supervisor: Linus Yeung

Motivation

Project Goal Use PWV for severe weather nowcasting

PWV - Precipitable Water Vapor Represent amount of water vapor in an atmospher

ic column VIL - Vertically Integrated Liquid

Represent amount of liquid water in an atmospheric column

Highly related to rainfall

Calculation of PWV

GPS SignalDelay

IonosphericDelay

TroposphericDelay

HydrostaticDelay

Wet Delay

PWV

Selection of Data

PWV PWV Error Raw Data Source

Latest

Best AccuracyCenter

04a

Visualization Tool – Web

PWV http://openlab3/~swirls/2005.html

VIL http://openlab3/~swirls/vil.cgi?id=0507201200-hks

l Radar Image

http://openlab3/~swirls/radar_js.html

PWV Climatology

Diurnal PWV Mean in Spring

52.00

53.00

54.00

55.00

56.00

57.00

58.00

59.00

0 5 10 15 20

Hour

PW

V M

ea

n (

mm

) hkfn

hkkt

hklt

hksc

hksl

hkst

MeanDiurnal PWV Mean in Summer

43.00

48.00

53.00

58.00

63.00

0 5 10 15 20

Hour

PW

V M

ean

(mm

) hkfn

hkkt

hklt

hksc

hksl

hkst

Diurnal PWV Mean in Autumn

42.00

47.00

52.00

57.00

62.00

0 5 10 15 20

Hour

PW

V M

ean

(mm

) hkfn

hkkt

hklt

hksc

hksl

hkst

Diurnal PWV Mean in Winter

20.00

25.00

30.00

35.00

40.00

0 5 10 15 20

Hour

PW

V M

ean

(mm

) hkfn

hkkt

hklt

hksc

hksl

hkst

Diurnal PWV Mean in Spring

43.00

48.00

53.00

58.00

63.00

0 5 10 15 20

Hour

PW

V M

ean

(mm

) hkfn

hkkt

hklt

hksc

hksl

hkst

Standard DeviationDiurnal PWV Standard Deviation in Summer

5.00

6.00

7.00

8.00

9.00

10.00

11.00

12.00

13.00

14.00

15.00

0 5 10 15 20

Hour

PW

V S

D (m

m)

hkfn

hkkt

hklt

hksc

hksl

hkst

Diurnal PWV Standard Deviation in Winter

5.00

6.00

7.00

8.00

9.00

10.00

11.00

12.00

13.00

14.00

15.00

0 5 10 15 20

Hour

PW

V S

D (m

m)

hkfn

hkkt

hklt

hksc

hksl

hkst

Diurnal PWV Standard Deviation in Spring

5.00

6.00

7.00

8.00

9.00

10.00

11.00

12.00

13.00

14.00

15.00

0 5 10 15 20

Hour

PW

V S

D (m

m)

hkfn

hkkt

hklt

hksc

hksl

hkst

Diurnal PWV Standard Deviation in Autumn

5.00

6.00

7.00

8.00

9.00

10.00

11.00

12.00

13.00

14.00

15.00

0 5 10 15 20

Hour

PW

V S

D (m

m)

hkfn

hkkt

hklt

hksc

hksl

hkst

PWV before Rainstorm

0

0.5

1

1.5

2

2.5

3

3.5

-10 -8 -6 -4 -2 0

Time Before (Hour)

Ave

rag

e P

WV

Tim

e D

iffe

ren

ce (

mm

)

Scatter Plot: VIL vs PWV

50 52 54 56 58 60 62 64 66 68 70 72 74 76 78

PWV

-2

0

2

4

6

8

10

12

14

16

18

7km V

IL

VIL vs PWV Time Change

-6 -4 -2 0 2 4 6

PWV Time Difference (-2, -6) Anomaly

-2

0

2

4

6

8

10

12

14

16

18

7km V

IL

VIL vs PWV Time Change

-5 -4 -3 -2 -1 0 1 2 3 4 5 6

PWV Time Difference (-8, -15) Anomaly

-2

0

2

4

6

8

10

12

14

16

18

7km V

IL

Thank You

Any Questions?