AOC conducted statistical analysis as the starting point for development of automated quality control routines. The initial data set used in the statistical analysis was all HDOBs from tasked tropical research or reconnaissance missions for NOAA WP-3D flights into tropical waves up to Category 5 hurricanes from 2005 through July 2010. Analysis was performed on a representative number of flight-level parameters across the full range of tropical systems treated as a single universal data set. The initial results confirmed that statistically flagging outlying parameter values plus or minus three standard deviations beyond a normal statistical density distribution may be feasible and useful. The data were then stratified with respect to the strength of tropical system (tropical wave, tropical storm, Category 1 hurricane, etc.) for further analysis.
The operational objective of this effort is to develop and implement quality control algorithms that flag anomalous data before the HDOBs are transmitted from the aircraft. Flagging, rather than removal of outlier data, allows the Flight Meteorologist the discretion to identify instances where there is a valid meteorological reason for extreme values, e. g., very warm 700 millibar flight level ambient temperatures in the eye of an intense hurricane, and allow them to be included in the HDOB. While all AOC flight level data are carefully examined in post-flight analysis before finalized data sets are forwarded to researchers, this real-time quality control methodology will improve HDOB data validity for hurricane forecasters and researchers utilizing these observations in an operational mode.