IHOP 2002 Mobile GPS Water vapor measurement campaign

Sept 13, 2002

Contact information

Dr. Jennifer S. Haase

Research Scientist

Dept. of Earth & Atmospheric Sciences

Purdue University

CIVL 1397, Room 3263A

West Lafayette, IN 47907-1397, USA

Phone number: 1-765-494-1643

Department Fax: 1-765-496-1210

email: jhaase@purdue.edu

Eric Calais, Associate Professor

Dept. of Earth & Atmospheric Sciences

Purdue University

West Lafayette, IN 47907-1397, USA

Voice: 765-496-2915

Fax: 765-496-1210

ecalais@purdue.edu

http://www.eas.purdue.edu

Data Contact

Hongbing Zhang

zhanghb@purdue.edu

Phone number: 1-765-494-0650

Overview

 

The International H20 Project (IHOP)was focussed on investigating the role water vapor plays in convective initiation through dense targeted campaign measurements from ground and airborne platforms. We used this opportunity to test a new technique under development to derive integrated water vapor from a GPS receiver on a moving platform. The technique of deriving integrated water vapor from stationary GPS receivers has been demonstrated to provide data with high accuracy ( 1 kg/m2). The problem is more difficult when using a moving receiver, because of the correlation between errors in receiver height determination and zenith delay. New processing techniques are being developed with additional constraints to solve this problem.

 

During the IHOP campaign, measurements were made with three objectives 1) to test different observation strategies, 2) provide data near other independent sources of water vapor measurements for validation, 3) to describe the ability to reconstruct lateral humidity variations that are relatively well defined, and 4) to the extent possible, to contribute additional moisture measurements to the IHOP project.

 

Of the three IHOP objectives, this type of measurement is expected to make the greatest contribution to the study of convective initiation and the targeted boundaries that are thought to play a strong role therein.

 

This report describes the measurements that were taken during the IHOP campaign for these objectives.

 

Measurement Campaign

 

The general strategy of the mobile GPS measurement campaign was to take advantage of the location of other measurement platforms to provide validation of the GPS measurements. The measurements were made from June 2, 2002 to June 11, 2002 at the western IHOP region in the Oklahoma Panhandle near the S-Pol Homestead site south of Liberal, Kansas.

 

The general strategy during convective initiation missions was to deploy one GPS station as a fixed site either at the Homestead site or at the site occupied by the MIPS Mobile Integrated Profiling System to serve as a reference site for the GPS data processing. A second mobile GPS was deployed usually following the MMR Mobile Microwave Radiometer. A third mobile GPS was usually deployed following one of the mobile radiosonde units (GLASS). With this geometry, we expected to provide sampling across the target boundary with high contrasts in integrated water vapor.

 

The general strategy during boundary layer missions was to provide control data sets near Homestead with one or two fixed GPS stations, and a third mobile GPS that traveled on trajectories near the fixed GPS. Trajectories were planned to get coincident data sets with the surface flux profiles, the MIPS, MMR, and the fixed instruments at Homestead.

 

Fixed sites that were repeatedly measured were the Homestead site, HOME, and the garage in Liberal, GARA/GAR2.

 

IWV values during any time indicated with �fixed� for any receiver will be made available. IWV values during any time indicated with �mobile� for any receiver will be processed depending on priorities and data quality. The data has not yet been processed to IWV as of this date.

 

The start and end times and approximate locations of the data recorded for each deployment are described in Table 1. Raw GPS data (not IWV) were sampled at 1 second sampling rate except for June 12, 2002, where data were sampled at 5 Hz, and for the overnight periods on June 2 and June 5.

 

The GPS receivers were dual frequency Ashtech micro-Z receivers with Ashtech choke-ring antennas. They were deployed with surface meteorological equipment to record local pressure, temperature, and relative humidity. Receivers TM01 was mounted on a tripod at fixed sites, and receivers TM02 and TM03 were mounted on the roof of a vehicle.


 

Table 1 Start and end times and approximate locations of recorded data.

Date

Mission

Receiver 1

start-end times

Receiver 2

start-end times

Receiver 3

start-end times

June 2 (153)

no mission

setup reference site

TM01 fixed HOME

21:45-154:16:00*

 

 

June 3 (154)

CI Mission

3 mi S of Turpin

9 mi S of Turpin

TM01 fixed

16:45-18:58

with MIPS

TM01 fixed2

20:20-23:00

no MIPS

TM02 mobile

17:48-22:42

TM03 mobile

15:30-00:45

with GLASS2

June 4 (155)

aborted CI mission

Map HOME to GARA

TM01 fixed HOME

20:15-23:32

TM02 fixed GARA

with MMR

20:35-24:00

TM03 mobile

15:35-156:02:00

June 5 (156)

(overnight)

no mission

compare with MMR

TM01 fixed HOME

00:00-22:15*

TM02 fixed

GARA

with MMR

00:00-20:09

 

June 5 (156)

no mission

laps around HOME

TM01 fixed HOME

22:15-157:00:44

TM02 mobile

20:09-157:01:04

TM03 mobile

20:22-157:00:46

June 6 (157)

BL mission

laps around HOME and on SSF transect

TM01 fixed at SSF2

14:45-24:06

TM02 mobile

14:26-23:50

TM03 fixed GAR2

14:32-158:03:02

June 7 (158)

BLH mission

near SSF

TM01 fixed HOME

15:42-22:37

TM02 mobile

15:13-21:23

with MMR

TM03 mobile

14:30-16:36

TM03 fixed with MIPS

17:04-21:45

June 8 (159))

no mission

(overnight)

TM01 fixed HOME

00:00-15:55

 

TM03 fixed GAR2

00:00-15:55

June 8 (159)

no mission

map MMR route and HOME to Liberal

TM01 fixed at HOME

15:55-24:00

TM02 mobile

14:22-20:40

TM02 fixed at GAR2

20:56-23:19

TM03 mobile

15:55-23:30

June 9 (160)

no mission

(overnight)

TM01 fixed HOME

00:00-12:15

 

TM03 fixed GAR2

03:48-15:36

June 9 (160)

CI Mission null case W of Guymon

TM01 fixed

20:15-22:18

with MIPS

TM02 mobile

16:04-161:02:04

TM03 mobile

15:51-161:01:03

June 10 (161)

CI Mission

5 mi NE of Ness City

TM01 fixed

19:37-22:30

with MIPS

TM02 mobile

18:37-22:27

with MMR

TM03 mobile

18:41-22:21

with GLASS2

June 11 (162)

CI Mission

E of Homestead

 

TM02 mobile

15:28-23:32 with MMR

TM02 mobile

15:26-18:48

TM02 fixed

18:48-21:01

TM02 fixed2

21:15-00:00

June 12 (163)

CI Mission near Laverne

0.2 sec data

 

TM02 mobile

17:00-22:11**

with MMR

TM03 fixed

17:50-22:22**

with GLASS2

* 30 sec raw data sampling�������� ** 0.2 sec (5 Hz) raw data sampling