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  • Author or Editor: D. H. Lenschow x
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Edward G. Patton
,
Thomas W. Horst
,
Peter P. Sullivan
,
Donald H. Lenschow
,
Steven P. Oncley
,
William O. J. Brown
,
Sean P. Burns
,
Alex B. Guenther
,
Andreas Held
,
Thomas Karl
,
Shane D. Mayor
,
Luciana V. Rizzo
,
Scott M. Spuler
,
Jielun Sun
,
Andrew A. Turnipseed
,
Eugene J. Allwine
,
Steven L. Edburg
,
Brian K. Lamb
,
Roni Avissar
,
Ronald J. Calhoun
,
Jan Kleissl
,
William J. Massman
,
Kyaw Tha Paw U
, and
Jeffrey C. Weil

The Canopy Horizontal Array Turbulence Study (CHATS) took place in spring 2007 and is the third in the series of Horizontal Array Turbulence Study (HATS) experiments. The HATS experiments have been instrumental in testing and developing subfilterscale (SFS) models for large-eddy simulation (LES) of planetary boundary layer (PBL) turbulence. The CHATS campaign took place in a deciduous walnut orchard near Dixon, California, and was designed to examine the impacts of vegetation on SFS turbulence. Measurements were collected both prior to and following leafout to capture the impact of leaves on the turbulence, stratification, and scalar source/sink distribution. CHATS utilized crosswind arrays of fast-response instrumentation to investigate the impact of the canopy-imposed distribution of momentum extraction and scalar sources on SFS transport of momentum, energy, and three scalars. To directly test and link with PBL parameterizations of canopy-modified turbulent exchange, CHATS also included a 30-m profile tower instrumented with turbulence instrumentation, fast and slow chemical sensors, aerosol samplers, and radiation instrumentation. A highresolution scanning backscatter lidar characterized the turbulence structure above and within the canopy; a scanning Doppler lidar, mini sodar/radio acoustic sounding system (RASS), and a new helicopter-observing platform provided details of the PBL-scale flow. Ultimately, the CHATS dataset will lead to improved parameterizations of energy and scalar transport to and from vegetation, which are a critical component of global and regional land, atmosphere, and chemical models. This manuscript presents an overview of the experiment, documents the regime sampled, and highlights some preliminary key findings.

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David A. R. Kristovich
,
George S. Young
,
Johannes Verlinde
,
Peter J. Sousounis
,
Pierre Mourad
,
Donald Lenschow
,
Robert M. Rauber
,
Mohan K. Ramamurthy
,
Brian F. Jewett
,
Kenneth Beard
,
Elen Cutrim
,
Paul J. DeMott
,
Edwin W. Eloranta
,
Mark R. Hjelmfelt
,
Sonia M. Kreidenweis
,
Jon Martin
,
James Moore
,
Harry T. Ochs III
,
David C Rogers
,
John Scala
,
Gregory Tripoli
, and
John Young

A severe 5-day lake-effect storm resulted in eight deaths, hundreds of injuries, and over $3 million in damage to a small area of northeastern Ohio and northwestern Pennsylvania in November 1996. In 1999, a blizzard associated with an intense cyclone disabled Chicago and much of the U.S. Midwest with 30–90 cm of snow. Such winter weather conditions have many impacts on the lives and property of people throughout much of North America. Each of these events is the culmination of a complex interaction between synoptic-scale, mesoscale, and microscale processes.

An understanding of how the multiple size scales and timescales interact is critical to improving forecasting of these severe winter weather events. The Lake-Induced Convection Experiment (Lake-ICE) and the Snowband Dynamics Project (SNOWBAND) collected comprehensive datasets on processes involved in lake-effect snowstorms and snowbands associated with cyclones during the winter of 1997/98. This paper outlines the goals and operations of these collaborative projects. Preliminary findings are given with illustrative examples of new state-of-the-art research observations collected. Analyses associated with Lake-ICE and SNOWBAND hold the promise of greatly improving our scientific understanding of processes involved in these important wintertime phenomena.

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