Data

Data File Format

The EOL format is an ASCII text format that includes a header, containing detailed project information and sounding information, and seventeen columns of high resolution data. The temporal resolution of the data is quarter second. The thermdynamic data (presssure, temperature and humidity) are only available at half-second resolution and the wind data is available at a quarter-second resolution.

For a description of parameters provided in the quality controlled dropsonde data files visit: Drosponde Data Parameters

Data Quality Control

Quality control of the sounding data is an extensive, multi-step process that includes evaluating the data products using a variety of visualization tools and statistical methods to identify and correct data quality issues caused by launch detect errros, sensor offsets or bias, accelerated descent rates, and failure of the sensors to accurately transmit data from flight level altitude to the ocean's surface. The variables, pressure, temperature, and relative humidtity are calibrated values from measurements made directly by the dropsonde and all are subjected to quality control. The dew point is calculated from the quality cotrolled relative humidity and temperature. The geopotential altitude is calculated from the hydrostatic equation, typically from the ocean's surface upward. The descent rate of the dropsonde is computed using the time-differentiated hydrostatic equation. Wind speed and wind direction are quality controlled, GPS position is not.

Performing the quality control procedures outlined below allows us to identify and, in many cases, resolve issues that could potentially impact research performed using the dropsonde data.

1. Evaluate raw data profiles
2. Categorize files according to data quality issues
3. Determine appropriate ASPEN QC configuration
4. Identify soundings that did not to transmit useful data to the surface
5. Apply geoid height correction to aircraft flight level altitude (for files identified in step 4)
6. Apply 'ground check' pressure correction
7. Evaluate fast fall soundings and set winds to missing if appropriate
8. Evaluate soundings with increased surface winds
9. Process through Batch ASPEN
10. Create QCed waterfall/timeseries plots
11. Create histograms to examine range and distribution of P,T,U and Wspd
12. Evaluate individual QC profiles
 

For a more details description of the dropsonde data QC procedures, please visit Dropsonde Data QC

 

Data Archival (CODIAC)