ARM/GCIP Near Surface Observation Data Set (NESOB)

Introductory Notes for the ARM/GCIP Near Surface Observation Data Set

A special data set is being compiled for the geographical area which includes both the ARM/CART site and the Little Washita Watershed as shown in Figure 1. The vertical dimension includes from 3000 meters above the surface to two meters below the surface. The specific types of observations are listed in Table 1 which is divided into three parts:

This special data set is designated the ARM/GCIP Near-Surface Observation (NESOB) data set and is designed to serve at least the following types of research:

Land surface process studies
Validation and verification of land surface processing schemes
Detailed validation and verification of model output from regional land atmosphere coupled models.
Derivation of surface energy and water budgets.

The land surface studies and models can use the data at point locations to force land surface models or can make use of the observations to complete an area analysis for different size areas within the ARM/CART site and the Little Washita Watershed. The difficulty in achieving a consensus on the techniques for an area analysis has necessitated a decision to compile data as close as possible to an observational measurement. This will enable an investigator to use whatever analysis techniques are deemed appropriate for their specific research.

A two-phased approach to compiling the NESOB data set was designed in late 1995. Phase I includes the six month period of 1 April through 30 September 1996 and is being used as a proof of concept for this multiple-use data set. Also, the full complement of enhanced observations were not yet operating during this period.

Phase II - The full complement of observing systems needed for the ARM/GCIP NESOB composite data set began operating by the end of March 1997. We will start the full year ARM/GCIP NESOB data set on 1 April 1997 and continue through 31 March 1998.

Most of the data types for the Phase I NESOB data set were compiled along with the data for the GCIP Enhanced Seasonal Observing Period for the Arkansas-Red River which also took place from 1 April through 30 September 1996. However, the calibration of the Soil Moisture/Soil Temperature profile data has been delayed. We are informed that the last step in the calibration of these profile data, i.e the transformation of the soil water matric potential to volumetric soil water content is now completed. The efforts to complete the Phase I data set are being restarted. We are planning a period of experimental use of the Phase I data before finalizing the plans, schedule and procedures for the one-year Phase II data set..