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Aerosol Robotic Network (AERONET)
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SYSTEM DESCRIPTION
 
 

+ Overview
+ Measurement System
+ Operation
+ Calibration
+ Data Transfer
- Data Processing
+ Data Distribution

 
DATA PROCESSING
 
 
Step 1. Data Collection

All Cimel Automatic Sun photometers (SP) are separated by 3 main groups:

  1. SP connected to Data Collection Platforms (DCP)
  2. SP connected to PC that can go online
  3. SP not connected.

Group 1 sends the data automatically to 4 Satellites: GOES East, GOES West, Meteosat and GMS using DCP. Data are transferred from satellites to our processing server via several receiving stations: DAPS at NOAA facility in Wallops, Va., Eumetsat in Darmstadt, Germany, and Vitel receiving station at Pacific Tsunami Warning center in Ewa Beach, HI.

Group 2 automatically uploads the data to a PC using Cimel’s program astpwin.exe.

PC can be set up to submit the data to our processing server either automatically (usually every day) or the data can be submitted manually.

Group 3 needs to be periodically visited and data has to be collected and submitted manually.

 
Step 2. Preprocessing

After collection in processing server the data are converted to the unified format and the server generates reports about each instrument and DCP (if equipped). The reports are posted on the web site and also sent to parties responsible for instruments maintenance.

The converted SP data are placed in the database. Data are also copied to our backup system and cloned on several other workstations.

 
Step 3. Processing

The processing consists of several algorithms applied to the raw data:

  1. Aerosol Optical Depth (AOD) retrieval.
  2. AOD cloud screening.
  3. Seaprism processing.
  4. Sky Radiance data (Almucantars and Principal Planes) inversion.

As algorithm 4 is very processor intensive and time consuming it is made simultaneously on several smaller workstations (there are 4 right now with 13 CPU together). Each of them has a fully functional clone of the central database.

 
Step 4. Quality Assurance and Reprocessing
Once these data are manually inspected, they can be manually upgraded to the level 2 (Quality assured). These data can also be reprocessed to implement new parameters (e.g., calibration).
 
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NASA Official: Brent N. Holben
Last Updated: December 04, 2007