From the Inconvenient Sceptic, word that the new Global Historical Climatological Network (GHCN) Version 3 may not have significant quality control.
I have been looking at tweaking the blended temperature set that I have been using. My intent has been to replace the Hadley data with the NCDC data (Global, Land & Sea). While I was looking through the data I found some bizarre discrepancies. The problem might be due to the presentation, but so far I have not found another source to get their data, so I cannot verify this.
The data from their site is tedious to extract as it is available by month from 1880-current. After I built my tables of data I did a comparison between the Beta-V3 and the V2 data. The primary difference I have found is that the difference between the two sets is not being calculated correctly. This problem is most evident in April, September and December. Sometimes enormous differences between the versions exist, but the differences are not being seen in the stated difference.
For example, April of 1996 has V2: 0.71 °C and Beta-V3: 0.24 °C. The calculated difference is 0.02 °C instead of the correct 0.47 °C difference. April and December are full of such errors. Above is a chart of the errors for these two months.
Needless to say it is difficult to trust the value of data that cannot even correctly state the difference between the two sets they are using.
Read more here
Here’s the announcement Monday for dataset availability of GHCN V3:
Date: Mon, 22 Nov 2010 09:05:05 -0600
From: CLIMLIST <email@example.com>
Subject: [CLIMLIST] Announcement: Global Historical Climatology
Network-Monthly (GHCNM) v3 beta dataset announcement
CLIMLIST Mailing Number 10-11-58
Origin: Byron.Gleason <Byron.Gleason [at] noaa.gov>
***** DO NOT USE REPLY FUNCTION *****
***** REPEAT – DO NOT USE REPLY! *****
The U.S. National Climatic Data Center in Asheville, NC has released
Version 3.0 beta of the Global Historical Climatology Network-Monthly
This dataset currently consists of monthly mean temperature data for
7280 stations and includes both raw and adjusted data. The dataset is
hosted at the following web sites:
Users are encouraged to provide feedback for this beta version at:
Climate Analysis Branch
National Climatic Data Center