9.6 Quality Assurance and Quality Control

This section provides information on QAQC procedures unique to upper-air measurement systems. Generic material on QAQC procedures for meteorological systems and definitions of terms used in QAQC is presented in Section 8.

With some exceptions (e.g., rawinsonde measurements of pressure, temperature, and humidity) upper-air monitoring systems provide indirect measurements of the meteorological variables used in dispersion modeling. This presents a unique challenge to the quality assurance and quality control (QAQC) of these systems; for example, there is no upper-air counterpart to the bench top calibration of a wind vane. The alternative to the bench-top calibration is a calibration using a collocated transfer standard; this involves locating an identical instrument as close as practical to the instrument being calibrated (see Section 8.3) - again, as with the bench-top procedure, there is no upper-air counterpart to the collocated transfer standard for a wind vane. Similarly, there is no upper-air counter part to the performance audit of a wind vane (as explained in Section 8, calibrations and audits are one and the same as far as "what" takes place; the difference has to do with the independence of the person conducting the audit).  Given the inability to conduct a true performance audit, the onus for claims of data validity for most upper-air measurements falls on the systems audit - this, as explained in Section 8.4, is essentially a challenge to the QAPP and provides an overall assessment of the commitment to data validity. 

Alternative procedures for calibrations and performance audits of upper-air measurement systems are based on inter-comparisons with other measurement systems - these alternatives are discussed in Sections 9.6.1 (Calibration Methods) and 9.6.2 (Systems and Performance Audits).

Before discussing quality assurance programs, it is useful to explain the difference between quality control (QC) and quality assurance (QA). For the purposes of this document, QC refers to the operational procedures used to ensure that a measurement process is working properly. QC procedures include periodic instrument calibrations, site checks, data examination for reasonableness, and data validation. QC procedures produce quantitative documentation upon which claims of accuracy can be based. QA refers to all the planned or systematic actions necessary to provide adequate confidence that the entire measurement process is producing data that meets the data quality objectives established for a monitoring program. These actions include routine evaluation of how the QC procedures are implemented (system audits) and assessments of instrument performance (performance audits). Summarized below are details on the preparation of a Quality Assurance Project Plan (QAPP) and key elements that are unique to upper-air measurement methods.

9. UPPER-AIR MONITORING 
9.1 Fundamentals  
      9.1.1 Upper-Air Meteorological Variables  
     9.1.2 Radiosonde Sounding System  
     9.1.3 Doppler Sodar 
     9.1.4 Radar Wind Profiler 
     9.1.5 RASS  
 9.2 Performance Characteristics  
     9.2.1 Definition of Performance Specifications  
     9.2.2 Performance Characteristics of Radiosonde Sounding Systems 
     9.2.3 Performance Characteristics of Remote Sensing Systems  
 9.3 Monitoring Objectives and Goals  
     9.3.1 Data Quality Objectives  
 9.4 Siting and Exposure
 9.5 Installation and Acceptance Testing 
 9.6 Quality Assurance and Quality Control 
     9.6.1 Calibration Methods  
     9.6.2 System and Performance Audits  
     9.6.3 Standard Operating Procedures 
     9.6.4 Operational Checks and Preventive Maintenance  
     9.6.5 Corrective Action and Reporting  
     9.6.6 Common Problems Encountered in Upper-Air Data Collection 
 9.7 Data Processing and Management (DP&M) 
      9.7.1 Overview of Data Products  
     9.7.2 Steps in DP&M 
     9.7.3 Data Archiving  
 9.8 Recommendations for Upper-Air Data Collection