GISS Surface Temperature Analysis (v3)
Updates to Analysis (2012-May 2019)
Note 1: This webpage describes v3 updates to the GISS analysis made in the period from December 2011 to May 2019, while the analysis was based mainly on the GHCN v3 data and various ocean data collections. GISTEMP v4 updates made after May 2019 and which use GHCN v4 data are listed here. GISTEMP v2 updates before December 2011 are detailed here.
Note 2: In spring 2015, NOAA's NCDC (mentioned in various entries below) was merged into NOAA's NCEI (National Center for Environmental Information), a new entity combining the three centers: NCDC, NGDC, and NODC (National Climate, Geophysical, and Oceanographic Data Center).
Graphs and tables are updated around the middle of every month using the current data files of NOAA/NCEI (GHCN: meteorological stations, ERSST: ocean) and SCAR (Antarctic stations) combined as described in our December 2010 publication (Hansen et al. 2010). These updated files incorporate reports for the previous month and late reports and corrections for earlier months. Here we list updates of the data or procedures that have occurred since our 2010 publication (Hansen et al. 2010).
September 16, 2019: NOAA is no longer providing updates to the GHCN v3 dataset. Consequently, updates to the GISTEMP v3 analysis concluded with the July 2019 update. Please see the current GISTEMP v4 for confinued updates and analysis.
June 14, 2019: The current GISS temperature analysis is now GISTEMP v4. We will continue to provide GISTEMP v3 analysis for as long as the necessary input datasets are available.
May 16, 2019: A globe version of the station locator was built that handles the increase in the number of stations eff iciently for most browsers. This option is added as an alternative to the leaflet version with its Mercator projection (and the need to move a station off the South pole to make it accessible).
The custom plotter was redesigned. The default smoothing was changed to using a 30-year window so that it better indicates the climate change, 30 years being the standard period to define the climate.
March 18, 2019: The History section was expanded to include the GHCN v4 based results in the comparison set. Further comparisons of GHCN v3/SCAR and GHCN v4 were prepared by Dr. Makiko Sato.
February 15, 2019: The GISTEMP v4 analysis was made available as a beta release. This new version uses the GHCN v4.0.0 collection of station data first made available by NOAA/NCEI on October 26, 2018. It includes reports from about 28,000 stations. Since SCAR reports are included in GHCNv4, in this version we are not using the original SCAR reports.
November 15, 2018: The new version of the collection of station data GHCN v4.0.0 was made available by NOAA/NCEI on October 26, 2018. It includes reports from about 28,000 stations. The current GISS analysis is still based on GHCN v3 and SCAR with reports from about 6000 stations. The October data from several countries were not available at the time of our latest update. Next month's update may show somewhat different values for October. In addition, future GISS analyses will be based on GHCN v4.
June 18, 2018: The netCDF file created with the zonal means versus time utility has been corrected.
February 15, 2018: The station report for January 2018 from Fada N'Gourma, Burkina Faso, seems too high compared to the reports of neighboring stations and other weather reports; it is added to our list of suspicious reports and currently not used in our analysis.
November 16, 2017: The station reports for September 2017 from the two stations mentioned in the October 16 note were replaced in GHCN v3 by reasonable looking data; hence they are now used in our current analysis.
October 16, 2017: Station reports for September 2017 from the two stations Dzardzan, Russia, and Askaniia-Nova, Ukraine, seemed inconsistent with reports from neighboring stations. Comparisons with other temperature reports confirmed that suspicion and we added those reports to the list of suspicious data; note that we don't use such data in our analysis.
August 15, 2017: Starting with today's update, the standard GISS analysis is no longer based on ERSST v4 but on the newer ERSST v5. Dr. Makiko Sato created some graphs and maps showing the effect of that change. More information may be obtained from NOAA/NCEI's website.
April 19, 2017: The separate pages for creating plots of "time series of zonal means" and "seasonal cycle of zonal means" were combined as a single page for making Plots of Zonal Means. The graphics code for creating the plots has also been updated.
January 20, 2017: Due to a typo in the modification of a program that creates the data base for the CSCI and station data graphs and tables, many of those graphs and tables for individual stations were incorrect. That typo has been fixed and the data base has been recreated. The GISTEMP analysis was not affected by this error, i.e. none of the results, tables, maps, graphs about global or regional means changed.
January 18, 2017: The legacy code, a mixture of Fortran/Python/C/sh routines was replaced by a pure Python code, an adaptation of the work done by the Clear Climate Code team. The results of the two codes are not identical, but the differences are well within the accuracy of the whole method. Global mean estimates e.g. may differ by an occasional ±0.01°C.
The new version of the code is made available on this site. A slightly modified version was made available at 6 PM EST to deal with the possibility that the switch to "https" might prevent a successful download of the input files.
October 21, 2016: While restructuring the "Station Data" site in April 2016, a bug was introduced in the utility creating the text and CSV tables of the station data. It caused the skipping of some years. That bug was fixed. It had no impact on the graph or any other part of the analysis. Thanks to David Appell for bringing it to our attention.
September 12, 2016: The gridding process was slightly modified at the poles: Rather than treating the 40 sub-boxes ending at the North pole and at the South pole as individual boxes with centers at 84N and 84S respectively, they are now combined into a single box centered at the pole. The impact of this change on the global means is insignificant; however the maps look somewhat more realistic in the polar regions.
May 13, 2016: Some temperature series from GHCN and the various SCAR sources turned out to be identical, but we treated them as separate stations, giving too much weight to such a series compared to neighboring stations during the gridding process. Now we are only using one of these series; if possible we select the SCAR READER/surface data, else the GHCN data; we use the remaining two SCAR sources only if no other data are available for that location. The impact on the results was minimal (less than 0.01°C for the global monthly means). This was done by including these duplicate stations into the list of discarded records. The downloadable source package was updated correspondingly.
January 20, 2016: Some tables are now presented in human-readable as well as machine-readable CSV format. Unfortunately, the wrong files were used. That mishap was corrected at 5:30 PM; however, the replacement files were created by a newer version of the GISS analysis. On 1/21/2016 they were replaced by the proper files.
The currently used SCAR data are made available from the main GISTEMP site. The animations were updated to include the most recent data.
The maps page has been updated and uses a rewritten program to generate the map and the zonal line plot. Plots for the most recent available month are displayed when the page is first loaded. We anticipate making related updates to the station data and graphs pages in the coming weeks.
July 19, 2015: The data and results put on the public site on July 15 were affected by a bug in the ERSST v4 part of the automated incremental update procedure. The analysis was re-done after recreating the full version of SBBX.ERSSTv4 separately. We would like to acknowledge and thank Nick Stokes for noticing that there might be a problem with these data.
July 15, 2015: Starting with today's update, the standard GISS analysis is no longer based on ERSST v3b but on the newer ERSST v4. Dr. Makiko Sato created some graphs and maps showing the effect of that change. More information may be obtained from NOAA/NCDC's website. Furthermore, we eliminated GHCN's Amundsen-Scott temperature series using just the SCAR reports for the South Pole.
June 13, 2015: NOAA's NCEI (formerly NCDC) switched from v3.2.2 to the new release v3.3.0 of the adjusted GHCN, which is our basic source. This upgrade included filling some gaps in a few station records and fixing some small bugs in the homogenization procedure. NCEI's description of those changes is available here. One of the impacts was removing some data that the GISS procedure had always eliminated and the list of GISS corrections was correspondingly reduced. Hence the (insignificant) impact on the GISS analysis was slightly different from the impact described in that document. The changes produced a decrease of 0.006°C/decade for the 1880 to 2014 trend of the annual mean land surface air temperature rather than the 0.003°C/decade increase reported by NCEI. Both are substantially less than the margin of error for that quantity (±0.016°C/decade). Impacts on the changes of the annual Land-Ocean temperature index (global surface air temperature) were about 5 to 10 times smaller than the margin of error for those estimates.
Please note that neither the land data nor the ocean data used in this analysis are the ones used in the NCEI paper "Possible artifacts of data biases in the recent global surface warming hiatus" that appeared on June 4, 2015. For the ocean data, GISS still uses ERSST v3b rather than the newer ERSST v4, but will switch to that file next month, when we add the June 2015 data; the collection of land station data used in that paper includes many more sources than GHCN v3.3.0 and will probably be incorporated into a future GHCN v4.
May 15, 2015: Due to an oversight several Antarctic stations were excluded from the analysis on May 13, 2015. The analysis was repeated today after including those stations.
February 14, 2015: UK Press reports in January 2015 erroneously claimed that differences between the raw GHCNv2 station data (archived here) and the current final GISTEMP adjusted data were due to unjustified positive adjustments made in the GISTEMP analysis. Rather, these differences are dominated by the inclusion of appropriate homogeneity corrections for non-climatic discontinuities made in GHCN v3.2 in 2011/2012. See the earlier notes from December 14, 2011 and September 26, 2012; more details are provided in the FAQ.
December 29, 2014: The title on the US temperature graph was corrected by replacing "Continental US" by "Contiguous US". References to the corresponding graphs in the literature were updated.
September 15, 2014: Color maps using the Robinson projection or polar projection are now presented without contour smoothing, since that process occasionally results in skipping some color bands. It seems however to work fine for the equirectangular projection.
July 14, 2014: The missing China May 2014 reports became available and are now part of our analysis. That correction increased the global May 2014 anomaly by a statistically insignificant 0.002°C.
June 17, 2014: Analysis was delayed hoping the missing reports from China would become available. Unfortunately, this has not been the case yet. Please note, that the current May 2014 data are therefore not directly comparable to previous records.
Febuary 14, 2014: Two January 2014 reports from Greenland (Godthab Nuuk and Angmagssalik) and one from Mongolia (Dauunmod) were disregarded since they seemed unusual and proved to be inconsistent with other reports.
January 21, 2014: The GISS analysis was repeated this morning based on today's status of the GHCN data. The changes were well within the margin of error, e.g. the L-OTI mean for 2013 changed from 0.6048±0.02°C to 0.6065±0.02°C, a change of less than 0.002°C. However, rounding to 2 digits for the L-OTI table changed the 0.60°C used in some documents prepared last week to 0.61°C. This minuscule change also moved year 2013 from a tie for the 7th place to a tie for the 6th place in the GISS ranking of warmest years, demonstrating how non-robust these rankings are.
January 21, 2014: The GISTEMP maps webpage now defaults to using the Robinson map projection. The previous default "regular" projection is labeled as Equirectangular.
August 14, 2013: The July 2013 report from Jaskul (46.2N, 45.4E) is inconsistent with its June 2013 report unlike the reports from neighboring stations. In that region, the July mean has been consistently higher than the June mean and not 4.3°C colder as the current report would indicate. Hence that report was not used in our analysis.
May 24, 2013: The time series and seasonal cycle website plotting tools were restored, which completes the return of the interactive features disabled in January. A problem with porting graphics software between servers led to a longer delay than expected. (Note: These two plotting tools were combined in the update of Apr. 19, 2017.)
May 15, 2013: The 3/3013 report from Dushanbe was corrected and the 3/3013 report from Kuwait was deleted in GHCN v3, so that these two GISS deletions were dropped.
April 15, 2013: Two March 2013 reports, one from Kuwait International Airport and one from Dushanbe (38.5N, 68.8E), did not agree with neighboring reports or with Weather Underground data. Hence they were not used in our analysis. The faulty February 2013 report from Nema was replaced by a corrected report in GHCN v3.
April 1, 2013: A comparison of our global analysis using NOAA ERSST (our current approach) for ocean temperature as opposed to NOAA OISST concatenated with HadSST1 is available on Dr. Sato's webpage.
March 21, 2013: This update was delayed by an investigation of some unrealistic looking reports from various stations in Mongolia. NCDC eliminated the reports today. In addition, the February 2013 report from Nema also seems unrealistic and has been eliminated. Finally, from now on we will incorporate into our analysis the reconstructed Byrd station data provided by Prof. David Bromwich.
February 24, 2013: The GISTEMP maps and station data website plotting tools were restored.
January 16, 2013: Starting with the January 2013 update, NCDC's ERSST v3b data will be used to estimate the surface air temperature anomalies over the ocean instead of a combination of Reynold's OISST (1982 to present) and data obtained from the Hadley Center (1880-1981).
January 14, 2013: Due to technical problems with the webserver onto which the GISTEMP webpages were recently migrated, interactive plotting tools such as making maps of the surface temperature anomaly and line plots of station data were disabled as the site was migrated onto newer hardware.
November 19, 2012: The machine which hosted the GISTEMP web pages will be decommissioned shortly, and all files and utilities have been moved to a new server. As the new machine uses a different architecture and OS, many utilities required some adjustment. Please send email to reto.a.ruedy@nasa.gov if you notice any problems.
September 26, 2012: NOAA/NCDC replaced GHCN v3.1 by GHCN v3.2. Hence the GISS analysis is based on that product starting 9/14/2012. Version v3.2 differs from v3.1 by minor changes in the homogenization of the unadjusted data. A description of the modifications in the adjustment scheme and their effects are available here.
February 17, 2012: The analysis was redone on Feb 17 after learning from NOAA/NCDC that the operational version of GHCN v3 was only made available that afternoon.
February 12, 2012: The reported December 2011 data for the stations LIEPAJA, ALEKSANDROVSK, and ST.PETERSBURG were replaced by corrected reports and the strange Dec 1991 report from MALAKAL is no longer part of the adjusted GHCN v3. The corresponding entries in the GISS list of suspicious data were removed.
January 18, 2012: The reported December 2011 data for the stations LIEPAJA, ALEKSANDROVSK, and ST.PETERSBURG were clearly incorrect and were discarded. Also, a likely artificial discontinuity for the station record of SHIQUANHE was eliminated by disregarding the data for 2005-present.
December 14, 2011: GHCN v2 and USHCN data were replaced by the adjusted GHCN v3 data. This simplified the combination procedure since some steps became redundant (combining different station records for the same location, adjusting for the station move in the St. Helena record, etc). See related figures.
