RESEARCH PROJECTS THAT THEY ARE CURRENTLY WORKING ON OR HAVE RECENTLY COMPLETED

Simpson:

Dr. LeMone's latest research project was CASES-97, which she coordinated with Bob Grossman. The boundary layer is the region closest to the ground (the lowest few thousand feet). While researchers understand how the boundary layer and the ground interact with one another, they do not have mathematical equations based on these interactions that can be used in forecasting. Certain variables, such as heating and evaporation rates at the surface and the mixing rate between lower and upper air in the boundary layer, must be measured in order to come up with mathematical equations. This project took place from April 22 to May 22 in the Walnut River watershed, which is east of Wichita, Kansas. Two airplanes, the University of Wyoming's King Air and the NOAA Twin Otter (a twin otter is seen in the picture above), were used to take measurements over the test area.

Dr. Yanai is currently involved with the Tropical Meteorology Project at UCLA.  This project is researching different tropical motion systems and their interactions by using the data taken during different field experiments, including GATE.  This study took place in June 1992 off the North Africa coast, where the Azores and Madeira Islands are located.

One of Dr. Albrecht's most recent studies was ASTEX.  This experiment was designed to study large-scale clouds and how they are affected by aerosols, cloud microphysics, and chemistry.

OVERALL IMPRESSIONS OF GATE

Simpson:

Convective clouds produce significant amounts of anvil and stratiform precipitation. In GATE the amount of stratiform precipitation was comparable to the convective precipitation. Bob Houze was the person whose papers first made this an important recognized feature of tropical convective systems.

There are two main types of cloud systems, namely 1) slow moving cloud clusters and 2) fast moving arc-shaped squall lines. These latter are oriented approximately normal to the wind shear and can move faster than the strongest wind, which has a low-level jet structure when they occur. Ed Zipser's publications probably did the most to explain the structure and motion of GATE squall lines. There were several other strange cloud patterns mapped in GATE that may represent two features that have collided. (Unfortunately all the GATE data have not been worked up and published).

The downdrafts associated with GATE cloud clusters brought down into the lower boundary layer midlevel air which was cooler and drier than that of the undisturbed subcloud layer, thus shutting off convection for 4 to 8 hours and sometimes longer. These "wakes" of convection were first studied and reported, I believe, by Mike Garstang.
 

By the mid-1970's there were a number of sophisticated single-cloud models. The three-dimensional models had been designed for understanding mesocyclones and the formation of tornadoes. There were also two-dimensional models that could be used for weather modification studies. However, GATE clouds could not be easily simulated by 2-D models. Gary Van Helvoirt, a graduate student of Dr. Simpson's at the University of Virginia, used Dr. Schlesinger's Midwest cloud model and applied it to the GATE data. He examined how well this model worked on the GATE data. "...the model worked amazingly well and simulated the GATE clouds using the nearest GATE sounding without any tinkering or adjustment. The model worked equally well on some more modest sized GATE clouds and revealed some very interesting insights into the entrainment process which had been murky for nearly three decades."

From this same model (Gary Van Helvoirt's), it was discovered that "the motions inside the cloud were vortical (vorticity about the vertical axis)." When the researchers went back to the mesocyclone models from which this model came, they saw that the same reasoning applied. They then recalled that a funnel had been sighted near the tallest cloud being mapped. Waterspouts were also reported on Day 186. Studies of these waterspouts yielded "interesting relationships between the low-level cloud and boundary layer and the production of waterspouts which we believe shed some light on a class of tornadoes." This information was later applied to a waterspout over Great Salt Lake where a similar waterspout occurred.

"It was the GATE experience that was a guiding force in many of the research activities I've been involved with over the last 25 years.  During my participation in projects like FIRE and ASTEX, I've always tried to ensure that students were heavily involved."

Simpson:

"Before I started my graduate studies at Colorado State University, I knew of GATE even though I didn't know it by that name.  In the spring of 1972 I was applying to graduate schools and had been accepted for admission and offered assistantships at both the University of Arizona and Colorado State University.  Just as I had made a decision to go to Arizona, I received a letter from Professor Stephen Cox at Colorado State describing an exotic field program in Africa scheduled for the summer of 1974.  I took the bait and made plans to attend CSU.  When I arrived that fall, Dr. Cox's first question to me was 'Do you have an aversion to flying?'  Although I was initially a bit puzzled by this question, I later learned why this question was so critical for my participation in GATE."

"During my first two years at CSU I was involved with the evaluation and development of radiation instrumentation for airborne applications in GATE while I worked on my M.S. thesis on the effects of differential radiative heating on the dynamics of tropical waves."

"we spent almost four months flying as observers in aircraft carrying radiometers to support Professor Cox's project to develop radiative budgets for the GATE study area....  During each intensive phase of GATE, the students working with Dr. Cox were on a schedule of two days of flying followed by a day off.  Since the aircraft flights were as long as 10-12 hours on the DC-6, we not only got an excellent first-hand look at tropical weather, but also lots of flying time.  Although the excitement of being in a foreign country and spending hours flying over the tropical eastern Atlantic was a remarkable experience in its own right, our daily interactions with scientists from all over the world was a unique aspect of the GATE experience."

Simpson:

"GATE provided me with an appreciation of the role of observations as a reality check for my modeling work."

In my research of some of the scientists involved in GATE, I have found that GATE served as a major part of their careers.  Working with scientists from around the world did cause difficulties in some instances, but the leaders of the project managed to keep any hostilities to a minimum and the environment one in which all could learn and thrive.  I find it quite amazing that each of the four scientists that I talked to have been involved in very different projects since GATE, but their experiences 25 years ago have helped them all in various ways.  I would like to thank Dr. Simpson, Dr. LeMone, Dr. Yanai, and Dr. Albrecht  for taking the time to answer my questions and help me with this in-depth look at how GATE affected the lives and careers of those individuals who were a part of it. Without their help, none of this would have been possible.