1

Investigating Height Assignment Investigating Height Assignment Investigating Height Assignment Investigating Height Assignment

Type Errors in the NCEP Global Type Errors in the NCEP Global Type Errors in the NCEP Global Type Errors in the NCEP Global

Forecast SystemForecast SystemForecast SystemForecast System

James JungCooperative Institute for Meteorological Satellite Studies

John Le MarshallCentre for Australian Weather and Climate Research, Australia

Jaime DanielsNational Oceanic and Atmospheric Administration

NESDIS, Center for Satellite Applications and Research

Lars Peter RiishojgaardJoint Center for Satellite Data Assimilation

2

Outline

• Height Assignment types

• Definitions of Statistics used

− Speed

− Direction

• Height Assignment Statistics

− Water Vapor Images

− Infrared Images

• NCEP Future Work

• Comments and Conclusions

3

Height Assignment Types

• CO2 Slicing − GOES-12 and beyond

− Menzel et al 1983

• Water Vapor Intercept− Szejwach 1982

• Histogram− Nieman et al 1993

• IR Window− Nieman et al 1993

• Cloud Base− Le Marshall et al 1997

4

Wind Comparison Statistics

• Vector Difference

• Mean Vector Difference

• Standard Deviation

( ) ( )∑=

+= −−

N

i

mimi VVUUN

MVD1

221

( ) ( )VVUUVD mimi −+−=22

( ) ( )[ ]∑ −=

=

N

ii MVDVD

NSD

1

21

* Nieman et al 1997 i = observation, m = model

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• Root Mean Square Error

• Normalized Root Mean Square Error

• Speed Bias

Wind Comparison Statistics

( ) ( )SDMVDRMSE22

+=

SpeedRMSENRMSE =

∑=

= +−+

N

i

mmii VUVUBIASN

1

22221

* Nieman et al 1997 i = observation, m = model

6

New Directional Statistics

• Directional RMSE

• Directional Bias

B

A

C

(Xob,Yob)

(Xmod,Ymod)

∆Θ

∆X

∆Y

( )∆Θ−+= cos2222

ABBAC

∑=

=

N

i

iCBIASN

1

1

∑=

−=

N

i

iCDRMSEN

1

2

1

1

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Height Assignment Statistics

• Ocean only vectors used

• Monitored all height assignment types available for each observation.

• Separated by Satellite and Image type− GOES-11, GOES-12

− Water Vapor winds, Cloud-Drift IR winds

• Combined two seasons− Days 1-20 in July and December 2009

• Stratified by Latitude− NH (20N – 60N)

− Tropics (20N – 20S)

− SH (20S – 60S)

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Speed Bias

GOES-12

Water Vapor Winds

100

200

300

400

500

600

700

800

900

1000

-10 -5 0 5 10 15

Bias [m/s]

Pre

ssu

re [

hP

a]

CO2 H2O HIST WIN

Normalized MVD RMSE

GOES-12

Water Vapor Winds

100

200

300

400

500

600

700

800

900

1000

0 0.5 1 1.5 2 2.5

RMSE [m/s]

Pre

ssu

re [

hP

a]

CO2 H20 HIST WIN

Normalized MVD RMSE

GOES-11

Water Vapor Winds

100

200

300

400

500

600

700

800

900

1000

0 0.5 1 1.5 2 2.5

RMSE [m/s]

Pre

ssu

re [

hP

a]

H20 HIST WIN

Water Vapor Winds

Speed NRMSE and Bias

Speed Bias

GOES-11

Water Vapor Winds

100

200

300

400

500

600

700

800

900

1000

-10 -5 0 5 10 15

Bias [m/s]

Pre

ssure

[hP

a]

H2O HIST WIN

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Directional Bias

GOES-12

Water Vapor Winds

100

300

500

700

900

-10 -5 0 5 10 15

Bias [degrees]

Pre

ss

ure

[h

Pa

]

CO2 H2O HIST WIN

Directional RMSE

GOES-12

Water Vapor Winds

100

200

300

400

500

600

700

800

900

1000

0 20 40 60 80 100

RMSE [degrees]

Pre

ssu

re [

hP

a]

CO2 H2O HIST WIN

Directional Bias

GOES-11

Water Vapor Winds

100

200

300

400

500

600

700

800

900

1000

-10 -5 0 5 10 15

Bias [degrees]

Pre

ssu

re [

hP

a]

H2O HIST WIN

Directional RMSE

GOES-11

Water Vapor Winds

100

200

300

400

500

600

700

800

900

1000

0 20 40 60 80 100

RMSE [degrees]

Pre

ssu

re [

hP

a]

H2O HIST WIN

Water Vapor Winds

Directional RMSE and Bias

10

Speed Bias

GOES-12

Cloud-Drift IR Winds

100

200

300

400

500

600

700

800

900

1000

-10 -5 0 5 10

Bias [m/s]

Pre

ssu

re [

hP

a]

CO2 H20 HIST WIN

Normalized MVD RMSE

GOES-12

Cloud-Drift IR Winds

100

200

300

400

500

600

700

800

900

1000

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

RMSE [m/s]

Pre

ssu

re [

hP

a]

CO2 H20 HIST WIN

Speed Bias

GOES-11, IR Window

100

200

300

400

500

600

700

800

900

1000

-10 -5 0 5 10

Bias [m/s]

Pre

ssu

re [

hP

a]

H20 HIST WIN

Normalized MVD RMSE

GOES-11

Cloud-Drift IR Winds

100

200

300

400

500

600

700

800

900

1000

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

RMSE [m/s]

Pre

ssu

re [

hP

a]

H20 HIST WIN

Cloud-Drift IR Winds

Speed NRMSE and Bias

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Directional Bias

GOES-12

Cloud-Drift IR Winds

100

200

300

400

500

600

700

800

900

1000

-10 -5 0 5 10 15

Bias [degrees]

Pre

ssu

re [

hP

a]

CO2 H2O HIST WIN

Directional RMSE

GOES-12

Cloud-Drift IR Winds

100

200

300

400

500

600

700

800

900

1000

0 10 20 30 40 50 60 70 80

RMSE [degrees]

Pre

ssu

re [

hP

a]

CO2 H2O HIST WIN

Directional Bias

GOES-11

Cloud-Drift IR Winds

100

200

300

400

500

600

700

800

900

1000

-10 -5 0 5 10 15

Bias [degrees]

Pre

ssu

re [

hP

a]

H2O HIST WIN

Directional RMSE

GOES-11

Cloud-Drift IR Winds

100

200

300

400

500

600

700

800

900

1000

0 10 20 30 40 50 60 70 80

RMSE [degrees]

Pre

ssu

re [

hP

a]

H2O HIST WIN

Cloud-Drift IR Winds

Directional RMSE and Bias

12

Speed Bias

GOES-12, H2O Intercept

Water Vapor Winds

100

200

300

400

500

600

700

-6 -4 -2 0 2 4 6 8 10

Bias [m/s]

Pre

ssu

re [

hP

a]

SH Trop NH

Normalized MVD RMSE

GOES-12, H2O Intercept

Water Vapor Winds

100

200

300

400

500

600

700

0 0.5 1 1.5 2

RMSE [m/s]

Pre

ssu

re [

hP

a]

SH Trop NH

Speed Bias

GOES-11, H2O Intercept

Water Vapor Winds

100

200

300

400

500

600

700

-6 -4 -2 0 2 4 6 8 10

Bias [m/s]

Pre

ssu

re [

hP

a]

SH Trop NH

Normalized MVD RMSE

GOES-11, H2O Intercept

Water Vapor Winds

100

200

300

400

500

600

700

0 0.5 1 1.5 2

RMSE [m/s]

Pre

ssu

re [

hP

a]

SH Trop NH

Latitude error dependence

Water Vapor Winds

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Speed Bias

GOES-12, H2O Intercept

Cloud-Drift IR Winds

100

200

300

400

500

600

700

-12 -10 -8 -6 -4 -2 0 2 4

Bias [m/s]

Pre

ssu

re [

hP

a]

SH Trop NH

Normalized MVD RMSE

GOES-12, H2O Intercept

Cloud-Drift IR Winds

100

200

300

400

500

600

700

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

RMSE [m/s]

Pre

ssu

re [

hP

a]

SH Trop NH

Speed Bias

GOES-11, H2O Intercept

Cloud-Drift IR Winds

100

200

300

400

500

600

700

-12 -10 -8 -6 -4 -2 0 2 4

Bias [m/s]

Pre

ssu

re [

hP

a]

SH Trop NH

Normalized MVD RMSE

GOES-11, H2O Intercept

Cloud-Drift IR Winds

100

200

300

400

500

600

700

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

RMSE [m/s]

Pre

ssu

re [

hP

a]

SH Trop NH

Latitude Error Dependence

Cloud-Drift IR Winds

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NCEP Continuation Work

• Modify analysis code to process all height

assignment types

• Generate O-B/O-A statistics for each height

assignment type

• Derive assimilation techniques specific to

height assignment type

− Investigate QC techniques using multiple height

assignments

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Comments and Conclusions

• The cloud-drift IR winds have a slow speed bias not found in the water vapor winds.

− Why, how can this be resolved?

• Are improvements possible to the CO2 and H2O intercept methods?

− What are the upper and lower limits of the techniques?

• O-B errors in the tropics are greater than at mid-latitudes

− This is a model problem. How can data providers help?

• Can other data providers include height assignment type in the BUFR file?

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Questions ?