Robert A. Baxter, Certified Consulting Meteorologist

Speaker element check on AV4000 sodar

Sodars provide measurements of wind and turbulence in the lower atmospheric boundary layer. The sodar technology has been commercially available for several decades and has endured significant scrutiny from the scientific community. As the sounding technique became more popular for regulatory monitoring (as opposed to the research programs) in the 1980s and 1990s, the need for independent verification of the operations increased in importance to assure that the data being generated by the instruments was useable for the intended purpose. To aid this effort, audit instrumentation and procedures were developed and implemented to independently assess the performance of sodars. Summarized below are papers I prepared on sodar related quality assurance. Additional details on the papers can be found on my publications page.  You are also referred to the most recent guidance prepared by the USEPA entitled Meteorological Monitoring Guidance for Regulatory Modeling Applications (2000). This document contains the most recent updates to upper-air QA guidance as it relates to sodars used in regulatory monitoring and modeling programs. I participated in the workshops leading up to the release of the guidance and feel it is a good summary of what is needed to best assure data of known quality.  

Selected publications I have authored or co-authored relating specifically to sodar quality assurance include:

• Sodar Based Wind Profiles as Model Inputs:  Understanding the Role of Atmospheric Conditions in Assessing the Quality of the Data, 2000
  
• Quality Assurance Methods for Ground-Based Meteorological Remote Sensors, 1999
• Quality Assurance of Remote Wind Profilers During the 1995 EPA Sodar Characterization Study, 1996
• Draft Guidelines for the Quality Assurance and Management of PAMS Upper-Air Meteorological Data, 1995
• Quality Assurance of Data Produced from Sodars -- Application of a New Instrument for Field Performance Auditing, 1995
• Performance Auditing of Sodars Under the New USEPA Guidance -- Applications of a New Instrument to Quantitatively Assess Sodar Performance, 1995
• Development of a Universal Acoustic Pulse Transponding System for Performance Auditing Sodars, 1994
• Performance of Sodar Audits Under the New USEPA Guidance, 1994

I provided QA services on a variety of programs using a multitude of sodars. The sodars  have included those manufactured by AeroVironment (models 2000, 3000 and 4000), Metek (MODOS), Radian (models 600, 600PA and 300), Remtech (P0, PA2) and NOAA/ETL. The services provided included monitoring plan reviews, audits, data validation and training. One unique specialty I have is the development and implementation of a new instrument, the Acoustic Pulse Transponder (APT), for performance auditing of sodars. This instrument simulates the Doppler shifted acoustic “echoes” produced by atmospheric motion and allows the validation of wind, and mixing height calculations by sodars. Two different configurations allow the auditing of either phased array or multi-axis antenna sodars. More details can be found on my APT page.