Instruments Added and Upgraded at Tropical Western Pacific Sites
![Challenges presented by the remoteness and environmental conditions at ACRF's Tropical Western Pacific locale are offset by the unique climatological data collected by the measurement instruments located at its sites, including Nauru Island shown above.](https://webarchive.library.unt.edu/eot2008/20090508205121im_/http://www.arm.gov/images/twp_visit.jpg)
Located about 8,000 miles from the United States along the equator near northern Australia, the Tropical Western Pacific (TWP) locale is far more difficult to maintain than ACRF’s other two locales—Southern Great Plains (SGP) in Oklahoma and the North Slope of Alaska (NSA). In a concerted effort to upgrade the TWP sites on Darwin, Australia; Nauru Island; and Manus Island, Papua New Guinea; infrastructure staff recently completed a number of notable instrument installations and upgrades, with more on the way in the coming months.
In the first week of December, ACRF operations personnel installed an atmospheric emitted radiance interferometer (AERI) at the Darwin site. This instrument measures the absolute infrared spectral radiance in the sky, and provides key data for a number of parameters used in cloud and radiative transfer models. Soon after the AERI installation, technicians replaced the Digicora systems at Nauru and Manus islands. The Digicora receives signals from radiosondes launched into the sky every 12 hours at the TWP sites. Though helium is typically used to fill radiosondes, procuring this gas is prohibitively expensive in the tropics. Instead, hydrogen is used at the TWP sites, and the generators used to produce the gas received important preventative maintenance during the recent round of upgrades.
Next in line for the TWP sites are newly re-engineered total sky imagers (TSIs). Design modifications to the new TSIs will reduce the potential for failure and down-time resulting from the adverse operating conditions in the tropics. Installation of the TSIs should be completed in Darwin in January, Nauru in February, and Manus in March. In addition to new measurement capabilities and improving routine data collection efforts at the TWP sites, these upgrades—particularly at Darwin—will be very important for the Tropical Warm Pool International Cloud Experiment scheduled to occur in early 2006.