Data are stored in the datalogger's internal 124k memory as samples are taken (at 1 second intervals.) At the end of a measurement period (this is currently 1 hour) the data are processed and written to final storage within the datalogger memory and to an external 716k or 4 MB storage module.
Some of the data are converted to engineering units (example: °C) by datalogger software before storage, and other data (from sensor types whose calibrations differ from instrument to instrument) are stored unconverted (as a voltage for example). This is done so instruments that require unique calibrations can be replaced in the field without the necessity of changing calibrations within the datalogger software. These calibrations are then applied in the office after the data are retrieved.
Data are retrieved by disconnecting the storage module from the datalogger, and replacing it with another. The removed module then can be taken to a field office where the data is downloaded, or can be mailed to a central location to be downloaded. The module contains a lithium battery that maintains power and keeps the data intact. Data retrieval software (Campbell Scientific) is used to copy data from the module. The data are read from the module, converted to comma delimited ASCII, and stored to another medium or hard drive. Once the copied data are confirmed as good, the module is erased and is ready to be used again. This operation takes only a few minutes.
Mojave sites transmit data to a field - base station computer via a system of 900 MHz radio transceivers. Data at these sites is written to external storage modules as well.
The datalogger at each site is connected to a radio transceiver and antenna. There is also one transceiver and antenna connected to a computer at a local desert studies center. Software on this computer makes scheduled connections to the sites in the field via radio transmission. The data is collected and stored on the computer. The data are then transmitted to the USGS home office through an automated ftp server and satellite internet service. This system allows researchers to access the data in near real time.
Next, the data is read into a custom data processing package (written in MATLAB). See the schematic below that outlines the different modules we have developed to quality check, process, and archive the data.
Processed data are distributed as ASCII text through this website, making it quickly and readily available to cooperators and others.
U.S. Department of the Interior | U.S. Geological Survey
URL: http://esp.cr.usgs.gov/info/sw/clim-met/storage.html
Page Contact Information: ESP Web Team
Page Last Modified: Wed 15-Mar-2006 14:40:38 MST
