ARM

SuomiNet-type Instruments Tested and Ready for Tropics

The SuomiNet software integrates a network of global positioning systems to distribute spatially and temporally dense atmospheric data in real-time from broad and diverse regions. ARM file photo.
The SuomiNet software integrates a network of global positioning systems to distribute spatially and temporally dense atmospheric data in real-time from broad and diverse regions. ARM file photo.

ARM Program scientists are concentrating on developing techniques for obtaining the best possible water vapor measurements under a wide range of conditions (clear/cloudy, day/night, etc.). In 2001, 15 SuomiNet systems were installed at selected facilities at the ARM Climate Research Facility Southern Great Plains (SGP) site to obtain these measurements (see photo at right). SuomiNet is an international network of global positioning system (GPS) receivers and meteorological instrument packages, configured and managed to generate near real-time estimates of precipitable water vapor in the atmosphere, total electron content in the ionosphere, and other meteorological and geodetic information. To acquire total column water vapor measurements at its Tropical Western Pacific (TWP) sites, the ARM Climate Research Facility is deploying a similar system developed by COSMIC, including GPS and meteorological packages (from Paroscientific).

The COSMIC system is based on the Trimble netRS receiver, which incorporates a linux system that permits the receiver to be connected directly to the network, eliminating the need for a separate dedicated computer for communication and data transfer. ARM file photo.
The COSMIC system is based on the Trimble netRS receiver, which incorporates a linux system that permits the receiver to be connected directly to the network, eliminating the need for a separate dedicated computer for communication and data transfer. ARM file photo.

To ensure compatibility with the existing SuomiNet data processing systems, ARM Climate Research Facility operations staff began working with COSMIC representatives in July to configure and test the systems at SGP prior to deployment to the tropics. Siting requirements, such as a clear view of the sky down to an elevation angle of 5 degrees, the need to be away from metal structures, etc., were considered in the testing. Testing was successfully completed, and installation at TWP will occur once the final setup designs and necessary operations and maintenance documents are delivered to site operations staff.

Approximately one megabyte of data for each SuomiNet site will be delivered with the new system each day. These additional data will help ARM researchers quantify improvements to clear sky radiative transfer, which are currently limited by the uncertainty in atmospheric water vapor distribution profiles.

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