Who is the Mesoscale Group?

The Mesoscale Group in the Department of Atmospheric Sciences at the University of Washington is the graduate research group of Professor Robert A. Houze, Jr., who came to the department in 1972 immediately upon completing his Ph. D. in Meteorology at the Massachusetts Institute of Technology. He studied under Dr. Pauline Austin, one of the pioneers of radar meteorology. At the University of Washington he teaches undergraduate general meteorology courses and graduate courses in cloud physics and dynamics, and he leads the Mesoscale Group, which consists of 4-5 graduate students, occasional postdoctoral associates, a software engineer, and several undergraduate research aides.  Professor Houze first published his book Cloud Dynamics in 1973. A completely revised and updated 2nd Edition was published in 2014. This book grew out of his graduate courses and the Mesoscale Group's research on clouds and precipitation.

How the Mesoscale Group does its work

Professor Houze and his graduate students, staff, and postdoctoral associates have participated in field projects in Africa, India, Malaysia, Australia, the Solomon and Marshall Islands, the Maldives, the tropical Atlantic, Pacific, and Indian Oceans, the Gulf of Mexico, Florida, U.S. Great Plains, Switzerland, Italy, and the Pacific Northwest coast of North America. These projects have documented the characteristics of precipitation-producing clouds of some of the most important rainfall regimes in the world. The Mesoscale Group specializes in the collection and analysis of meteorological radar data from these projects, which have used meteorological research radars on land, ships, and aircraft. The approach of the group's research is to examine the radar data collected in these projects in the context of all other pertinent simultaneous observations to synthesize empirical conceptual models of the observed precipitating cloud systems. Atmospheric models are used to extend and explain the observations.

This research extended by Professor Houze's involvement in satellite programs in which radars have been deployed on spaceborne platforms. He has been a member of the Science Teams for the Tropical Rainfall Measuring Mission (TRMM) satellite and its follow-on the Global Precipitation Measurement satellite (GPM), which were the first precipitation radars (Ku and Ka band) in space. In addition, he has been on the Science Team for the CloudSat satellite, which carried a W-band cloud radar into space. These satellite radars have extended what has been learned in field programs. The Mesoscale group has used satellite data to study precipitating clouds in locations for which observations are especially difficult, such as the world's greatest mountain ranges, the Andes and Himalayas.

Tropical Convection and the Large-scale Atmospheric Circulation

One of the areas that the Mesoscale Group has focused on is tropical convection. Professor Houze has participated in all three tropical ocean field campaigns: GATE in the tropical Atlantic in 1974, TOGA COARE in the tropical Pacific in 1992-3, and DYNAMO in the Indian Ocean in 2011-2. In addition he has been a long time member of the TRMM satellite team 1985-2014 as well as the CloudSat and GPM teams. Studies based on these and other sources have documented the various forms taken by tropical convection, how the heating by the convection is distributed and affects the large-scale circulation. Several of these studies have examined convection in the Madden-Julian Oscillations.

Tropical Cyclones

Beginning in the 1980s, Professor Houze's group has been conducting studies of tropical cyclones, first he collaborated with the NOAA Hurricane Division, and several papers were done on Hurricane Norbert (1984). In 2005, he and Professor Shuyi Chen led the RAINEX project, which conducted flights into Hurricanes Katrina, Rita, and Ophelia. Several papers resulted on the nature of eyewalls, rainbands, and tropical cyclogenesis. The Mesoscale Group also used TRMM data to produce climatological studies of the structures of eyewalls and rainbands. The group also participated in NASA's GRIP and HS3 programs of flights into hurricanes. Currently the group is studying the landfall of Hurricane Karl (2010) in Mexico and its modification by passage over mountains.

Convection and Flooding in the Asian Monsoon

Ever since the MONEX field campaign of 1977-8, the mesoscale group has been studying how convection behaves and varies in the subregions of the Asian monsoon. The group's earlier studies focused on the South China Sea winter monsoon and how the mesoscale convection in that region varies diurnally owing to the complex of islands and intervening waterways. More recently the group's studies have focused on the South Asian summer monsoon and how the convection varies between the Bay of Bengal, Arabian Sea, and Himalayan region. In particular, using satellite data and modeling, we have examined the nature of the precipitating clouds producing the historic floods occurring in Pakistan and India since 2010.

Midlatitude Frontal Systems in Mountainous Regions

The group's earliest studies (in the 1970s-80s) were of frontal systems passing into the Cascade Mountains of the Pacific Northwest. In 1999, the group participated in the Mesoscale Alpine Programme (MAP) in the European Alps and in 2001 the group participated in IMPROVE II, a similar field study of frontal cloud systems passing over the Cascade Mountains. We used specialized dual-polarimetric radar in these studies to investigate the effects of mountains on frontal systems passing that mountain range. In 2015-6, Professor Houze and Dr. Lynn McMurdie let the OLYMPEX project, in which the NASA DC-8 and ER-2 aircraft, the University of North Dakota Citation aircraft, and four scanning dual-polarimetric radars were deployed with a host of specialized surface instruments and soundings to study fronts passing over the Olympic Mountains of Washington State.