4 October 2010: More than 1,000 temperature stations of the United States Historical Climatology Network (USHCN), are meant to be the high quality network used to determine surface temperature trends in the U.S. The USHCN is part of the National Oceanic and Atmospheric Administration (NOAA), and is a subset of a system of approximately 12,000 data collection sites across the country. "To be included in USHCN, a station had to be active in 1987, have at least 80 years of mean monthly temperature and precipitation data, and have experienced few station changes (e.g., changes in location). Numerous concerns have been documented regarding NOAA's data collection and processing within the USHCN.
Interestingly, the U.S. Department of Commerce's own Office of the Inspector General (OIG) weighed in with a letter to U.S. Representatives Joe Barton and Dana Rohrabacher recently made public. We quote:
NOAA acknowledges that there are problems with the USHCN data due to biases introduced by such means as undocumented site relocation, poor siting, or instrument changes. The agency has taken steps to improve data quality by implementing enhanced quality control steps and algorithms (referred to as USHCN Version 2) and having them peer reviewed. According to the peer reviews we examined, the resulting dataset improved upon the algorithms in the prior Version 1 data.
NOAA has also embarked on an effort to modernize 1,000 stations in the Historical Climatology Network (HCN). NOAA’s goal was to have several of its climate monitoring networks "work in tandem to feed consistently accurate, high-quality data to scientists studying climate trends."
The full OIG report (only 12 pages, limited references) was supposed to be a review of the USHCN "to determine whether NOAA has taken appropriate steps to ensure quality climate data." It advocates for Congress to fund the new network sites. The report also supports historical procedures with regarding to data collection and manipulation, publication reviews, etc. Interestingly, the report notes that evidence that such procedures (e.g., the formerly required peer-review process for articles being published) was not generally available, and that the new electronic process was not reviewed.
What remains to be seen is if NOAA will ever release details of its "adjustment" algorithms and the justifications for how those are applied and when. Of course, another challenge will be that we now have a new network being implemented, if NOAA can get Congress to give it the money it's seeking, a process that will take until 2020. Meanwhile data known to have gaps and other problems, stations with historical influence of an Urban Heat Island effect, and other complications will remain in use. Finally, unless NOAA or NASA create a time machine, the old data are going to always remain a subject of debate, at least until NOAA can fully explain why its adjustments are correct.
Full OIG report: (http://www.oig.doc.gov/oig/reports/correspondence/2010.07.29_IG_to_Barton_Rohrabacher_STL-19846.pdf), which includes a breakdown of budgeting expenses for the requested $100,000.
"NOAA/NCDC – USHCN is broken please send 100 million dollars" H/T WattsUpWithThat.com (Sept. 2010)
"What the modernized USHCN will look like" H/T WattsUpWithThat.com (April 2008)
A few links regarding UHI: