The
development of a prototype replacement data acquisition system for ISFF was
completed this past year. ISFF previously consisted of 2 different data
platforms, one designed in 1990 for ASTER and the second designed in 1995 for
FluxPam. The current goal is to create a single platform that can handle the
diverse variety of ISFF deployments. In the spring of 2004 a prototype of the
new platform was completed, and it was deployed successfully on two field projects
this past summer, CME04 (as
pictured at the left) and OHATS04 (links). A single data system has been ingesting
OHATS data from 19 sonics each running at 20
Hz.
Three systems were deployed in CME to collect data from a wide variety of serial
instruments, including data from a prototype ASA system. The hardware was designed
around the PC-104 standard, which offers a wide variety of vendors. The software
was developed under Linux to provide software portability. Another four data
systems have been used by Britt Stephens at RAF for the development of a new
CO2 sampling system (AIRCOA).
For its first field test of the prototype new data system, ISFF supported
a test by NCAR/HAO of scintillometers used to measure the ability of telescopes
to see through the atmosphere. Five sonic anemometer/thermometers were deployed
up to a height of 100m on NOAA's Boulder Atmospheric Observatory (BAO) tower.
The raw data were archived to allow computation of temperature power spectra
and thus structure functions. The comparison of these in situ high-frequency
turbulence observations with those from the scintillometers was quite good,
and led HAO to deploy the suite of sensors and data system to Big Bear, California
and Haleakala, Hawaii to evaluate sites for the new Advanced Technology Solar
Telescope. An ISS sodar was also deployed in support of the
BAO experiment.
Progress was made on the long-wave black-body calibration system. A variety of tests were conducted to determine the isothermal stability of the black-body cell and the best approach to measuring the “true” temperature of the black-body cell. The preferred solution was to mount 4 temperature reference probes around the exterior surface of the lower black-body cell. The inner surfaces of the black-body calibrator were then coated. The lower hemisphere of the cell, which can be held thermally uniform, was coated black and contributes almost 100% of the longwave emission. The upper section of the cell where the temperature varies most was coated in gold, providing high reflectance and thus a minimal contribution to the longwave radiation. A preliminary test was conducted with an Eppley pyrgeometer with good results.