Data Information
Observation Frequency and Availability
Currently, two types of data have been made available via a forms interface: Data sampled at one minute intervals is available for the past seven days. It is updated upon request. Data sampled at fifteen minute intervals is available dating back to 1992. It is updated daily at 3 a.m. The forms allow both types of data to be returned either as raw data or graphed. Graphing of the 15 minute data is limited to 2 years at a time. One minute data from September 11 1995 to February 28 2002 has also been archived. These may be made available on request. 1 minute data from November 2004 will also be archived.
Datalogging and Transfer Information
Data Logging
A Campbell Scientific CR23X Logger records the output of the sensors at 10 second intervals, derives some other variables from this recorded data and calculates and stores 1 minute averages.
Data Transfer
The CR23X is connected to a Cynet 405U single frequency radio modem which transmits data to another 405U radio modem connected to a dedicated base station PC in the Atmospheric Instrument Laboratory in Building E5A. Data is transmitted from the field site to the base station every 5 minutes.
PC Recording and Processing
The PC is set up as a webserver using Apache. The data is stored in a MySQL database. The 1 and 15 minute interfaces are coded in PHP and the graphs are produced using JpGraph.
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