Led by scientists from the National Center for Atmospheric Research (NCAR), IHOP2002 (International H20 Project) will be based in central Oklahoma from May 13 to June 25. The National Science Foundation, NCAR's primary sponsor, is providing the bulk of the project’s $7 million funding, with additional support from other agencies, including the National Aeronautics and Space Administration (NASA), National Oceanic and Atmospheric Administration (NOAA), and U.S. Department of Energy (DOE).
Six aircraft from the United States and Germany will traverse the core study area, some flying as low as 100 feet above the surface. A futuristic, semi-autonomous research craft—the Proteus, sponsored by NASA—will carry instruments up to 45,000 feet. On the ground, an armada of 30 weather-tech vehicles, including four Doppler radars on flatbed trucks, will comb the rural roadways of Oklahoma, Kansas, and Texas. Over 100 scientists and technicians scattered across the plains will be aiming radars and other sensors at water vapor well ahead of the day's first raindrops.
Unlike many weather studies held in this region, IHOP is homing in on the water vapor that feeds showers and thunderstorms, rather than trying to capture episodic events like tornadoes or other severe weather.
"We're hoping to actually see how the water vapor moves," says NCAR's Tammy Weckwerth, one of IHOP's two lead scientists. "That's never been done before." Cloud cover may impede some of the more sensitive instruments, Weckwerth adds. "The ideal day will start out cloud free, yet humid."
Where, when, and how hard it will rain are the most difficult elements to nail down in weather forecasting, especially in spring and summer. Better precipitation outlooks are a key goal of the U.S. Weather Research Program, which has organized a number of agencies in support of IHOP. The study aims to improve forecasts from 1 to 12 hours ahead of heavy rain, which could help in flash-flood safety and other applications.
"Right now the lead time for flash-flood forecasts is well under an hour," says NCAR's David Parsons, co-lead scientist on the study. "If you can extend forecasts of heavy rainfall out a few hours, you’re doing great."
Heavy rain depends on an ample supply of moisture, so the lack of water-vapor data is a major forecast impediment. Currently, no device can track tiny molecules of water vapor minute by minute over large areas. Weather balloons (radiosondes) provide most of the water-vapor data used in forecasting; however, their high cost reduces the frequency and spacing of balloon launches. Lidar (laser-based radar) provides more detail than radiosondes, but it can only sample across a few miles, and clouds reduce that range further. Satellite sensors, which cover much of the globe, haven't yet furnished the high-resolution measurements needed in the lower atmosphere for storm prediction.
By mixing older and newer sensors, IHOP2002 will examine how the latest technology can bridge the gaps in water-vapor sensing. Four of the IHOP aircraft will carry state-of-the-art systems that produce vertical profiles of water vapor. These will be used to help calibrate new, higher-precision instruments aboard satellites. Other sensors on the ground will analyze signals from the Global Positioning System (GPS) and other sources. Special high-end radiosondes will be launched for comparison with other data.
Meanwhile, forecasters from several labs and universities will use a suite of high-performance computer models to predict each day’s weather. Rather than simply assigning a chance of rain, the meteorologists will specify rainfall amounts across the study area. Such forecasts are now limited in accuracy, but with the IHOP data at hand, scientists are hoping to improve their skills.
On the Web: http://www.atd.ucar.edu/dir_off/projects/2002/IHOP.html
Visuals: http://www.ucar.edu/communications/newsreleases/2002/IHOPimagery.html
Questions and answers about IHOP field activities
Where and when will aircraft be overhead?
Six aircraft (see below) will sample parts of the IHOP study area between May 13 and June 25. Flight days and locations will be determined by weather conditions; on operational days, aircraft will fly as early as 6:00 a.m. Most flights will take place by day, although a few could extend as late as midnight. One aircraft will fly at heights as low as 100 feet in limited areas to measure the effect of vegetation on low-level heat and moisture. Some of the low-level aircraft may fly over the same area several times in a single day. Three other planes will fly at middle altitudes, and NASA’s Proteus aircraft will fly as high as 45,000 feet.
How will the weather balloons (radiosondes) be launched and retrieved?
Some 800 radiosondes will be launched during IHOP2002, many twice each day from National Weather Service offices in Dodge City, KS, Oklahoma City, OK, and Wichita, KS, and from Liberal, KS. Others will be launched from vehicles positioned in and near regions of expected storm development. Some of the balloons are specially enhanced "reference radiosondes". After these fall to earth, they will be retrieved by IHOP technicians in vans. The other radiosondes will have labels with phone numbers; please call the number for details on how to return the sondes.
What other IHOP activities will be noticeable?
Several mobile radars (see below) will canvass the study region, scanning the skies from off-road positions or while driving. Other vehicles will have roof-mounted weather stations that monitor local conditions. The presence of an IHOP vehicle doesn't necessarily mean that a given location will get severe weather. All IHOP vehicles will be clearly marked as being affiliated with NOAA/NSSL or one of the other participating institutions (see list below).
More on IHOP instruments and participants
| Aircraft (all based at Will Rogers World Airport, Oklahoma City) | Period of study | Typical altitudes during IHOP |
| NASA Proteus | May 25–June 14 | 45,000 ft. |
| Flight Int’l Learjet | May 13–June 25 | 14,000–22,000 ft. |
| DLR Falcon (Germany) | May 17–June 14 | 10,000–23,000 ft. |
| NASA DC-8 | May 25–June 13 | 25,000 ft. |
| Naval Research Lab P-3 | May 17–June 25 | 300–14,000 ft |
| U. of Wyoming King Air | May 13–June 25 |
100–4,000 ft. |
Doppler radar
Four mobile Doppler radars from several institutions will travel aboard flatbed trucks. Each one has a compartment for technicians and a rotating transmitter/receiver unit, several feet wide, that can operate while the truck is in motion or parked off road. NCAR’s fixed S-Pol radar will be located near Bryan’s Corner in the eastern Oklahoma Panhandle. Another NCAR-developed Doppler radar will be on board the P-3 aircraft. Together, these radars will provide details on rainfall location and intensity, as well as the air motion before thunderstorms form.
Other instruments
4 fixed and 4 airborne lidars (laser-based radars that profile moisture and wind across short distances)
1 advanced wind profiler (upward-pointing radar that senses wind direction and speed aloft)
2 sodars (sonic-based radars that sense wind direction and speed aloft)
3 interferometers (devices that detect radiation emitted by water vapor)
1 mobile and 3 profiling radiometers (devices that sense radiation emitted by water vapor)
400 dropsondes (instrument packages that parachute to earth from airplanes)
1 tethersonde system (weather station on a line tethered to a balloon floating as high as 3,000 feet)
52 GPS receivers (sensors that infer moisture from changes in a GPS signal)
15 fixed and 9 mobile weather stations, all specially tailored for IHOP
800 radiosondes (instrumented weather balloons), plus special launches
Data will also be provided by the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) network, the Oklahoma Mesonet, and standard observing networks.
Participating institutions from the U.S., Canada, France, and Germany
Agencies
National Aeronautics and Space Administration o National Center for Atmospheric Research o National Oceanic and Atmospheric Administration
- National Science Foundation
- U.S. Department of Energy
- French National Center for Scientific Research
- Météo-France
Universities
- University of Alabama in Huntsville
- University of California, Los Angeles
- University of Colorado
- University of Connecticut
- University of Maryland at Baltimore County
- University of Massachusetts
- University of Minnesota
- University of Nevada and its Desert Research Institute
- University of Oklahoma and its Cooperative Institute for Mesoscale Meteorological Studies
- Pennsylvania State University
- University of Wisconsin–Madison
- University of Wyoming
- McGill University (Canada)
- University of Hohenheim (Germany)
Other participants
- Colorado Research Associates o German Aerospace Center
Note to Editors: Reporters are invited to the IHOP2002 media day on Monday, May 13. A press briefing will take place at Oklahoma City’s Will Rogers World Airport, where the project aircraft are based. A separate advisory with more details on IHOP media day will be issued later this month.