1. Introduction

1.1. Scope and Objectives

CASES-97 is the first of several anticipated field efforts under the umbrella of the Cooperative Atmosphere Surface Exchange Study (CASES). The objective of CASES is to understand and parameterize the interactions between the earth's surface and its vegetation and the atmosphere, from turbulence time scales to years. The needed observations and their interpretation will be obtained through the cooperation of scientists from diverse fields with support and instrumentation from several organizations.

CASES-97 is a confederation of loosely coordinated complimentary experiments (Table 1.1). CASES-1 focuses on features of the fair-weather boundary and its evolution, CASES-2 focuses on radar precipitation algorithm verification and development. This document focuses on the efforts labeled CASES-97-1a and CASES-97-1b, because they require tight coordination. Coordination with CASES-2 PIs, will focus on obtaining fair-weather radar scans to supplement CASES 1a and 1b measurements. The low-level Jet Experiment (JETEX) PIs may coordinate some of their IOP's with CASES-1. Little coordination will be required with CASES-1c, whose concentrated effort will follow drydown after rainfall events, but we will consult them on soil moisture conditions. CASES-97-1c involves a post-field phase data-analysis effort.

The GEWEX Continental Scale International Project (GCIP) Enhanced Observing Period (EOP) immediately preceded the CASES -97 experiment.

We envision linkages will all these efforts as data are analyzed. In addition, comparison analyses are anticipated with the Southern Great Plains Experiment, to be conducted June 18-July 18.

The objectives of CASES 1a are:

The objectives of CASES-1b are to:

There is considerable overlap between the objectives of CASES-97-1a and CASE-97-1b.

1.2. Location and Duration

CASES 1a and 1b will be focused on the lower part of the Walnut River watershed located east of Wichita, Kansas (Fig. 1.1), from 22 April through 22 May 1997. Supporting Synoptic data will be collected over the central U.S. (Fig. 1.2).

1.3. Instrumentation

The objectives will be met through continuous measurements at the surface from

There will be five 24-hour Intensive Operations Periods. Decisions to have IOPs will require daily monitoring of instrumentation and weather, and a formal decision process. During IOPs,

 Large-scale meteorological and surface context for later analysis and modeling studies will include data from satellite, the U.S. synoptic network, and model (Eta and Eta/RUC) analyses and forecasts (Table 7.1).


Table 1.1. Experiments related to CASES 97

Experiment PI's Affliation Times Objectives
CASES-97-1a Grossman CU 22 April-
22 May 97
  1. Perform budgets of PBL heat, moisture, momentum
  2. Quantify effect sfc properties on PBL evolution
  3. Test BATS and CCM3 PBL scheme and link them
  4. Test techniques to examine mesoscale eddies
  5. Evaluate Argonne Boundary Layer Experiments instrumentation, what measurements really needed for (a) and (b) using model, or just observations
Pielke CSU
Zeng Ariz.
Wesely Argonne
Coulter Argonne
CASES-97-1b Hicks NOAA/ARL 22 April-
22 May 97
    Use tower and aircraft data to study air-surface exchanges in patchy surface wetness conditions
Grossman CU
Wesely Argonne
CASES-97-1c Marht Ore. State 22 April-
22 May 97
  1. Determine effect entrainment events on sfc fluxes
  2. Investigate effects of winds vs radiation on nocturnal PBL
  3. nvestigate use of sfc radiation temperature in bulk formula for fluxes in nonhomogeneous terrain.
Sun CU
Grossman CU
CASES-97-1d Cuenca Ore. State April 1997-
April 2000
    Determine relevant length scales for soil moisture content, soil hydraulic processes, and precipitation
Kelly Ore. State
CASES-97-2 Wilson NCAR May 1997
  1. Improve existing WSR-88D rainfall estimation
  2. Evaluate dual-polarization rainfall estimation
Brandes NCAR
Zrnic NSSL
Vivekanandan NCAR
Duchon Oklahoma
Chandrasekar CSU
JETEX-97 Arritt Iowa State 20 April-
May 97
  1. Investigate the interaction of the low-level jet with boundary-layer processes and turbulent exhange
  2. Evaluate contamination of wind profiler data by birds
Segal Iowa State
Ojima CSU post expt
    Run CENTURY model with historical and CASES-97 data to study ecosystem controls on water, carbon, and other trace gases

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Last Modified: 20 Aug 1997