IHOP: The International H2O Project

International H2O Project

Map of Oklahoma and Kansas showing location of data collection sensors

IHOP_2002 domain area

IHOP, an NCAR-led experiment, took place in May and June over the Southern Great Plains. In one of the largest-ever field experiments in North America, scientists from the U.S. and several foreign countries teamed to improve characterization of the four-dimensional distribution of water vapor and its application to improving the understanding and prediction of thunderstorms. Airflow, temperature, and humidity data were collected with a large armada of aircraft and ground-based mobile sensors and fixed-base remote and in-situ sensors.

Drylines and fronts were a key focus of the experiment. Scientists from Canada, France, Germany and the U.S. hoped to enhance their understanding of the process of convection initiation and boundary evolution, and learn what types of data are needed to make forecasts of thunderstorms and rainfall amounts more specific.

The number of mobile facilities involved in IHOP and the coordination of their movement was unprecedented. To investigate the atmosphere, IHOP used six research aircraft carrying in-situ and remote sensors, including an array of airborne Doppler and water-vapor sensing lidars. A large groundbased array of mobile mesonet vehicles, mobile sounding systems, profilers, and radiometers nested within the aircraft sampling areas. Four mobile radars, never before used in concert with each other, spent many hours scanning the atmosphere. A field coordination vehicle was located in the center of the target area and served as the hub of the mobile digital network. Weather data from remote probes was transmitted to the FC by radio frequencies, and for the first time, the field coordinator was able to communicate with the Norman Operations Center by satellite broadband Internet and satellite phone.

NSSL's ground-based platforms focused on mesoscale boundaries and convection initiation on a total of 12 mission days. Of these 12 cases, cumulonimbus clouds developed within the intensive observing region along a boundary on 2 days, towering cumuli on 5 days, and no significant convection on 5 days. An additional 3 days were spent sampling boundary layer evolution from sunrise to early afternoon around a cluster of fixed IHOP sensors in the Oklahoma Panhandle. The 24 May case featured the first known observed evolution of a dryline, cold front, and their triple point intersection using highresolution mobile sensors. Valuable data were also collected on sharply defined drylines, slow moving cold fronts, and the triple point intersection of an outflow boundary and a convergence line.

Predicting rainfall amounts continues to be a mystery -- flash floods caused by heavy thunderstorm rainfall are responsible for more deaths than hurricanes, tornadoes, windstorms or lightning. Annual property damage from flash floods alone exceeds $5 billion. Data gathered from IHOP will detail the thunderstorm initiation process and provide the groundwork for new forecast rules in the prediction of heavy rainfall.

Support for IHOP_ 2002

NSSL scientist Conrad Ziegler, in collaboration with then-CIMMS scientist Erik Rasmussen and Penn State scientist Paul Markowski, led NSSL's ground-based mobile data collection effort. NSSL's contribution to the armada included a SMART Radar, a mobile CLASS ballooning vehicle, a camera vehicle, 9 mobile mesonets, an NSSL field coordination vehicle, an NSSL scout vehicle, and a technicians vehicle to provide in-field maintenance. This contribution received significant external support from the National Science Foundation (NSF), the NOAA United States Weather Research Program (USWRP), the NOAA High Performance Computing and Communications (HPCC) program, and the NSSL Director's Discretionary Fund.

In addition to coordinating the ground-based mobile data collection effort, NSSL provided trailers to house additional computers needed for field coordination and data management. NSSL, CIMMS scientists, graduate students, undergraduate and other paid assistants and volunteers, and REU students visiting for the summer got the chance of a lifetime to participate in the project.

NSSL, SPC, CIMMS and NWSFO provided critical forecasting support. A morning outlook was issued each day around 9 a.m. in the Science Support Area of NSSL/SPC facilities. An early afternoon briefing followed, including a forecast for the remainder of the day and the forecast for Day 2. Long-range guidance was used to forecast out to ten days. Nowcasting (0-3 hours) operations ran during the day until early evening.