J. Van Baelen IHOP Workshop, Boulder, CO 24-26 March 2003

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IHOP 2002 GPS/H20

Water Vapor Investigations with Ground-Based GPS

J. Van Baelen IHOP Workshop, Boulder, CO 24-26 March 2003

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Contributions

GPS/H20 France: J. Van Baelen, J-P. Aubagnac, CNRM, Toulouse

O. Bock, J. Tarniewicz, SA, Paris

A. Walpersdorf, LGIT, Grenoble

E. Doerflinger, F. Masson, LDL, Montpellier

Field Deployment: J. Van Baelen, E. Doerflinger, J-P. Aubagnac, Ph. Collard, O. Bock

OK Mesonet: J. Basara, OU / OKmesonet team

UCAR/GST: J. Braun

IHOP/DATA BASE: JOSS, NOAA/FSL, ARM/SGP

J. Van Baelen IHOP Workshop, Boulder, CO 24-26 March 2003

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GPS derived IWV

HH

dzzNdzznZTD 6101

ZWDZHDZTD

HPZHD H733 108.22cos1066.21102768.2

4221.1610719.31051.461 55 mT

HH

m dzzTzedzzTzeT 2 sGPSm TKT 72.02.70

HHH

dzzTzedzzTzedzzTzezpZTD 56 10719.37.6462.7710

ZWDIWV

J. Van Baelen IHOP Workshop, Boulder, CO 24-26 March 2003

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IHOP objectives for GPS/H20 teams

Methodology Aspects Mapping functions and antenna modeling errors,

Low elevation angles and slant tropospheric delays

Tomographic inversion algorithms, constraints and resolution,

Effect of WV heterogeneity on precise positionning,

Spatial and temporal correlations in ZTD’s and STD’s and covariance matrix determination

J. Van Baelen IHOP Workshop, Boulder, CO 24-26 March 2003

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IHOP objectives for GPS/H20 teams

Scientific Objectives GPS water vapor retrieval validation,

Study of spatial and temporal variability and dynamics of IWV,

Study of WV convergence as CI precursor,

3-D water vapor distribution through tomography both local (L1 with few L2 constraints) and synoptic,

Data assimilation (slant delays),

J. Van Baelen IHOP Workshop, Boulder, CO 24-26 March 2003

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Field Deployment: Objectives vs Logistics

Légende:

• Parc INSU

• SuomiNet

• NOAA/FSL

• ARM/CART

J. Van Baelen IHOP Workshop, Boulder, CO 24-26 March 2003

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GPS deployment at OKmesonet sites

J. Van Baelen IHOP Workshop, Boulder, CO 24-26 March 2003

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E p o c h s w / O b se rv a tio n s (ma x :

1 7 2 7 9 )

0

2 0 0 0 0

I O P d a y s ( 1 3 3 - 1 7 6 )

B L

A C

B R

E C

B U

R B

G U

T H

M E

D F

O IL

T

IHOP 2002 : GPS deployment and observation statistics

Observations

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44

IOP days (133-176)

BLAC

BREC

BURB

GUTH

MEDF

OILT

REDR

J. Van Baelen IHOP Workshop, Boulder, CO 24-26 March 2003

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E p o c h s w / O b se rv a tio n s (ma x :

1 7 2 7 9 )

0

2 0 0 0 0

I O P d a y s ( 1 3 3 - 1 7 6 )

B L

A C

B R

E C

B U

R B

G U

T H

M E

D F

O IL

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IHOP 2002 : GPS deployment and observation statistics

0

1000000

2000000

3000000

4000000

5000000

6000000

7000000

1 2 3 4 5 6 7

BLAC BREC BURB GUTH MEDF OILT REDR

Summary per Station

EPS

OBS

DEL

J. Van Baelen IHOP Workshop, Boulder, CO 24-26 March 2003

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GPS Data Analysis Status

Use of GAMIT / GLOBK software package Implemented at CNRM late fall 2002.

First pass analysis Preliminary work on the 11-12 June case (!),

10° cut off angle, 30 seconds epochs, Saastamoinen hydrostatic model, Dry and wet Niel mapping functions, Three-hourly ZTD calculations and a single

gradient per day, All stations non-constrained.

J. Van Baelen IHOP Workshop, Boulder, CO 24-26 March 2003

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GPS Data Analysis Status

Next step Kalman filter to positionning and precise

calculation of (half-)hourly ZTD’s,

Automated processing for entire campaign,

Determination of IWV for all stations of interest to IHOP,

Results provided to IHOP Data Base in final form.

J. Van Baelen IHOP Workshop, Boulder, CO 24-26 March 2003

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GPS Analysis Stations

J. Van Baelen IHOP Workshop, Boulder, CO 24-26 March 2003

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Preliminary Results:

June 11-12 Case Study

ZTD and IWV Comparisons: NOAA half-hourly ZTD’s from IHOP D.B. French processed data (GAMIT) UCAR/GST processed data (Bernese)

Combined results: NOAA + French stations IWV’s UCAR/GST – French stations ZTD’s

Field Differences

J. Van Baelen IHOP Workshop, Boulder, CO 24-26 March 2003

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J. Van Baelen IHOP Workshop, Boulder, CO 24-26 March 2003

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J. Van Baelen IHOP Workshop, Boulder, CO 24-26 March 2003

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J. Van Baelen IHOP Workshop, Boulder, CO 24-26 March 2003

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J. Van Baelen IHOP Workshop, Boulder, CO 24-26 March 2003

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J. Van Baelen IHOP Workshop, Boulder, CO 24-26 March 2003

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J. Van Baelen IHOP Workshop, Boulder, CO 24-26 March 2003

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J. Van Baelen IHOP Workshop, Boulder, CO 24-26 March 2003

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J. Van Baelen IHOP Workshop, Boulder, CO 24-26 March 2003

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J. Van Baelen IHOP Workshop, Boulder, CO 24-26 March 2003

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IHOP Data Base [JOSS] Imagery

J. Van Baelen IHOP Workshop, Boulder, CO 24-26 March 2003

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French GPS Station ZTD’s

J. Van Baelen IHOP Workshop, Boulder, CO 24-26 March 2003

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GPS vs Radiosondes ZTD’s

J. Van Baelen IHOP Workshop, Boulder, CO 24-26 March 2003

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AIRS Campaign at CNRM (Fall ’02)

Comparison IWV

GPS - Radiosondes

27IHOP Workshop, Boulder, CO 24-26 March 2003

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Conclusions

First results of GAMIT single pass processed French GPS data consistent with other results,

Addition of French GPS stations seems to provide finer resolution to the central area of interest in the 11-12 June case,

In this case, higher humidity contents shown,

However, all solutions appear sensitive to single station ‘peculiar’ values => data or artifact ?

28IHOP Workshop, Boulder, CO 24-26 March 2003

J. Van Baelen

Ongoing WorkComplete processing of French GPS stations and others of the IHOP area with GAMIT soon to be available with (half-)hourly ZTD’s and gradients,

Methodology and Scientific studies to be undertaken following the topics specified,

Each topic is under the principal interest of various members of the French GPS/H2O teams, all of them are ready to collaborate and share their expertise with interested parties,

Contact joel.van-baelen@meteo.fr or the corresponding team directly