Table 1. IGRA quality assurance procedures and their impact.
Category QA Procedure Items Checked Items Deleted
Fundamental Sanity Checks Date Check Year, month, day, hour Sounding
Release Time Check Release time Release time
Observation Value Check p, z, T, d, ws, wd Individual values
Duplicate Level Check Pressure or height Levels
Station Elevation Checks Elevation Inspection (manual) Surface height Surface height
Internal Consistency Checks Hypsometric Check p, z Individual levels
Height Sequence Check z Levels
Multiple Surface Levels Check Level type indicator Levels
Surface Inspection (manual) p, T Level
Below-surface Level Check p, z Level
Obs Hour/Release Time Check Obs Hour - Release Time Sounding
Zero-speed Wind Check ws, wd ws, wd
Checks for Repetition of Values Temporal runs check (generic) p, z, T Levels or values
Temporal runs check (by hour) p, z, T Levels or values
Vertical runs check T

Values

Joint vertical runs check T Values
Frequent erroneous values check z, T Values
Fixed Geopotential Height z (Russian GTS only) Values
Climatological Checks Tier 1 p, z, T Levels or values
Tier 2 p, z, T Levels or values
Additional Checks on Temperature Crazy Profile Check T T-soundings
Generic vertical outlier check T Values
Vertical sore-thumb check T Values
Temporal sore-thumb check T Values
Data Completeness Checks Lone dewpoint depression check d, T Values
Lone wind value check ws, wd Values
Incomplete level check p, z, d, T, ws, wd Levels
Surface-only sounding check level-type indicator Sounding
Isolated sounding check data and time Sounding