Sodar Based Wind Profiles As Model Inputs: Understanding the Role of Atmospheric Conditions in Assessing the Quality of the Data

With the increased employment of sophisticated transport and dispersion models that require wind profiles, a greater emphasis has been placed on reliably acquiring these data. The recent release of updated guidance by the U. S. Environmental Protection Agency (EPA) on the quality assurance and quality control for Doppler sodars will lead to greater acceptance of this technology in regulatory-driven monitoring programs. As with any instrument used in a monitoring program, the independent audit process is essential for assessing the proper operation and performance of that particular sensor. In the case of a Doppler sodar, tethersondes, kites, or nearby towers are often used in that assessment. However, while the methodology and statistical techniques used for comparison purposes are well established, the expected scatter between wind measurements acquired by a sodar and audit instrument can vary widely as a function of atmospheric conditions and stability. Large scatter may be misinterpreted as erroneous data acquired by a sodar. This often occurs in a nonhomogeneous atmosphere. Data acquired during the 1995 Ground Based Remote Sensor Characterization Study at the Boulder Atmospheric Observatory demonstrates that this scatter can be due to horizontal inhomogeneities of the atmospheric boundary layer between the different measurement platforms. The results of the study help to understand the expected scatter that can occur when performing audits of such instrumentation and aid in the proper interpretation of the audit results.