Sept 13, 2002
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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 |
Hongbing Zhang
Phone number: 1-765-494-0650
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.
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