REQUEST FOR GLASS, ISS & ISFF SUPPORT
COOPERATIVE ATMOSPHERE-SURFACE EXCHANGE STUDY1999 (CASES-99)
NCAR/ATD - April 1999 OFAP Meeting
Submitted on December 15, 1998
Corresponding Principal Investigator
Name:
Institution:
Address:
Phone:
FAX:
email:
William Blumen
University of Colorado
Program in Atmospheric and Oceanic Sciences
(PAOS)
Campus Box 311
Boulder, CO 80309
(303) 492-8770
(303) 492-3524
blumen@paradox.colorado.edu
Project Description
Project Title:
Co-Investigator(s) and Affiliation(s):
Location of Project:
Start and End Dates of Project:
CASES-99
Larry Mahrt, Oregon State University
David Fritts, Colorado Research Associates
(CoRA)
Jielun Sun, University of Colorado, Boulder,
National Center for Atmospheric Research
Gregory Poulos, CoRA
Near Leon, KS (~ 40 km southeast of
Wichita, KS), on the east side of the
Walnut River Watershed
10/1/99-10/31/99
Abstract of Proposed Project
The purpose of the Cooperative Atmosphere-Surface Exchange Study (CASES) site
is to “provide a long-term facility for scientists to study the mesoscale processes of
meteorology, hydrology, climate, chemistry, ecology and their complex linkages, and to
serve as a focal point to provide field experience for students of the natural sciences.”
(Pflaum, 1995) The CASES program in autumn 1999 (CASES-99) will focus on
exchanges in the soil/biosphere/atmosphere interface, specifically those during statically
stable, and therefore primarily nocturnal, atmospheric conditions.
The field program will use the CASES site within the Walnut River Watershed east of
Wichita, Kansas, near which there are already several sets of instrumentation in place
(the Department of Energy ARM-CART Great Plains site, the Argonne National
Blumen - CASES-99 - ISFF, ISS, GLASS
Laboratory Atmospheric Boundary Layer Experiments (ANL ABLE) sites, and the
NOAA Wind Profiler Network), together with enhanced instrumentation, for one month
of extensive measurements during October 1999. The experimental site is a watershed,
but a relatively shallow one with typical slopes of 0.5o or less, and is climatologically
favored for clear sky and weakly stable (0.25 < Ri <1.0) to very stable (Ri > 1.0)
conditions during autumn.
CASES-99 will combine measurements and data analyses with state-of-the-art
numerical modeling to investigate five areas of scientific interest. The choice of these
scientific topics is motivated by both the need to delineate physical processes that
characterize the stable boundary layer, which are as yet not clearly understood (see
Nappo and Johansson, 1998), and the specific scientific goals of the investigators. The
scientific areas addressed in this request are: 1) Intermittent turbulent transfer of
momentum, moisture and sensible heat, and sensible and radiative flux divergences of
heat in the surface layer of the stable nighttime boundary layer (including, specifically,
characterization of the heterogeneity and relevant scales of these fluxes); 2)
Nonstationarity and momentum, heat and moisture flux divergence associated with
vertical shear flow instabilities near the ground and aloft, the overturning of KelvinHelmholtz billows and internal gravity waves; 3) Enhanced dissipation of kinetic energy
associated with small-scale density fronts and synoptic-scale cold fronts and; 4) The
specific source mechanisms for the generation of inertial oscillations, with emphasis on
the evening boundary layer transition and on frontal passages.
Effective research in these scientific areas relies heavily on high-quality
measurements of temperature, moisture, and momentum fluxes over horizontal and
vertical scales and on knowledge of the meso--scale atmospheric environment within
which events occur that cause the fluxes. The instruments requested in this LAOF
proposal will provide the core measurements upon which testing of many of the
associated scientific hypotheses will depend. Furthermore, if this request is granted, the
entire multi-agency, multi-nation plan for deployment of instruments for CASES-99 will
center upon the LAOF group of reliable, high-quality, measurement systems.
A summary of requested instrumentation is as follows:
1) 1 GLASS (to be co-located with the 40-meter tower);
2) 3 ISS (to be place in a triangular, meso--scale array surrounding the main
CASES-99 site);
3) 9 ISFF (3 to be placed on one 40-meter tower, 6 to be distributed in concentric
triangles);
4) 8 extra PRTs, preferably with 5 Hz or better sampling, to be placed on the 40meter tower (5 m intervals);
5) The Wyoming King Air (addressed through a separate request);
6) Multiple radiative flux divergence instruments accurate to ~ 1 Wm-2 and water
vapor flux with the ISFFs;
7) A 40-meter tower (to have 3 ISFF sets, plus a number of other investigator
supplied instruments).
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