Global Land Air Temperature methodology
- -- BobReuschlein <earlwal@...> wrote:
Does someone have a US temperature average year by year for the last century plus? back to 1880 or maybe 1850's? What is meant by the average temperature? For Earth? For Land? For US? I have US up to 1988, and the nineties were very hot, but not quadruple hot.
The GLT data used in the graph on ClimateArchive
was from NOAA NCDC, which I copied to:
The post I made below to energyresources provides additional explanation that I hope is helpful. pat
Tue Dec 30, 2003 4:09 pm
Subject: Global Land Temperature figure on ClimateArchive -
I did a copy-paste from NOAA URL, below. Earlier in 2003 I did extensive
analysis of NWS cooperative climate station data, many of the tables are on ClimateArchiveTwo. In addition, I authored articles that were based on the temperature and dewpoint data from ClimateArchiveTwo. May latest reports are on the Minnesotan's for Sustainability website. The easiest way to get there (shortest URL) is to use:
I have created Excel spread sheets for three stations with annual temperature data at non-urban or small town locations, for use with my article presented in Reno, Nevada at the NOAA NWS Climate Prediction Center Workshop 20-23 October 2003. The stations are at Jamestown, ND, Leech Lake Dam, MN and Spooner Experimental Farm, WI. I plan to create figures for those three stations showing annual temperatures from 1898 through 2003 later this week.
NOAA URL for Global Land Temperature methodology:
Overview NCDC's long-term mean temperatures for the Earth were calculated by processing data from thousands of world-wide observation sites on land and sea for the entire period of record of the data. Many parts of the globe are inaccessible and therefore have no data. The temperature anomaly time series presented here were calculated in a way that did not require knowing the actual mean temperature of the Earth in these inaccessible areas such as mountain tops and remote parts of the Sahara Desert where there are no regularly reporting weather
stations. Using the collected data available, the whole Earth long-term mean temperatures were calculated by interpolating over uninhabited deserts, inaccessible Antarctic mountains, etc. in a manner that takes into account factors such as the decrease in temperature with elevation. By adding the long-term monthly mean temperature for the Earth to each anomaly value, one can create a time series that approximates the temperature of the Earth and how it has been changing through time.
An Operational Near Real Time Global Temperature Index
Robert G. Quayle, Thomas C. Peterson, Alan N. Basist, and Catherine S. Godfrey National Climatic Data Center (NCDC), NOAA/NESDIS, Asheville N.C.
Abstract. To capture the global land surface temperature signal in a timely way, a blend of traditional long-term in situ climatic data sets, combined with real time Global Telecommunications System monthly CLIMAT summaries is employed. For the global sea surface, long-term ship data climatologies are combined with a blend of ship, buoy, and satellite data to provide the greatest possible coverage over the oceans. The result is a global century-scale surface temperature index that closely parallels other widely published global surface temperature measurements and can be updated monthly a week or two after the end of a data month.
The Third Session of the Conference of the Parties to the U.N. Framework
Convention on Climate Change in Kyoto, Japan, was but one client of NOAA that needed quick and authoritative information on century scale climate perspectives in a near-real-time mode. NCDC was able to offer help, and this work documents the methodology which has been used since that time. It seems paradoxical that we need near-real-time data for a system that responds as slowly as climate, but recent paleoclimatic evidence and the recent warmth of the globe suggest that this paradigm is not always justified. Moreover, as nations struggle to develop
effective environmental policies, the observed data become a critical part of these ongoing discussions; and the meteorological infrastructure of the globe is also geared to real-time operation. Therefore, both the need for, and the capability for delivering near-real-time climatic analyses are quite real. In fact, timely climatic information (provided when there is a maximum of interest) may be the best way to provide the most reliable information to the greatest
number of people.
Surface Land Temperatures
Surface land air temperature (LAT) climatology (at instrument shelter height) is derived from the Global Historical Climatology Network version 2 data set (GHCN, Peterson and Vose 1997). GHCN v.2 includes previously unavailable Colonial Era data that fill in data sparse times and places (Peterson and Griffiths 1997).
All data are processed via the Climate Analysis System (CAS) developed at NCDC. The update system subjects the most recent data to a rigorous quality control (Peterson et al. 1998a). Its unique duplicate preservation scheme preserves the integrity of the input data streams (Peterson and Vose 1997). The First-Difference area averaging technique thrives on these duplicates and maximizes the global data available for analysis (Peterson et al. 1998b). Homogeneity adjustment procedures developed over several years assures objective, reproducibly homogeneous time series (Peterson and Easterling 1994, Easterling and Peterson 1995, Peterson et al. 1998c). Data volume varies from several hundred stations per year to several thousand (Peterson and Vose, 1997).
For 1997, over 14,000 individual station monthly records are used in the
analysis to produce 5x5 degree grid box data that are summarized into
hemispheric and global averages.
Sea Surface Temperatures
The Global Ocean Surface Temperature Atlas (GOSTA, Bottomley et al. 1990), provides a century+ global record of 5x5 degree grid box in situ Sea Surface Temperature (SST) means by year through 1996. For this application, we use the U. K. Meteorological Office version, called UKMO HSST in the form of anomalies with respect to a 1961-90 averaging period (Folland et al. 1993). For near real time updates, the most timely and geographically complete data available are the National Centers for Environmental Prediction - Optimum Interpolation (NCEP OI)
blended satellite, ship and buoy SST data set (Reynolds and Smith 1994), also in monthly 5x5 degree grid box format, available for all years since 1982. NCDC produced global averages and the accompanying anomaly series from both data sets. To produce a long time series (beginning in 1880) with maximum contemporary coverage, these two SST data sets are combined.
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