|Figure 1 Overview the ISTI comprehensive benchmarking system for assessing performance of homogenisation algorithms. (Fig. 3 of Willett et al., 2014)|
Monday, October 6, 2014
A framework for benchmarking of homogenisation algorithm performance on the global scale - Paper now published
Friday, September 12, 2014
So what data gets updated in our NRT system? We have determined four sources that have updated data within the first few days of the month. They are the CLIMAT streams from NCDC as well as the UK, the unpublished form of the monthly climatic data for the world (MCDW) and finally GHCN-D. Similar to the merge program, a hierarchy is placed determining which source its data appends to if there are conflicts. The hierarchy is here:
An overview of the system is shown here in this flow diagram (Click on image to enlarge):
Friday, August 29, 2014
ccc-gistemp is Climate Code Foundation‘s rewrite of the NASA GISS Surface Temperature Analysis GISTEMP. It produces exactly the same result, but is written in clear Python.
I’ve recently modified ccc-gistemp so that it can use the dataset recently released by the International Surface Temperature Initiative. Normally ccc-gistemp uses GHCN-M, but the ISTI dataset is much larger. Since ISTI publish the Stage 3 dataset in the same format as GHCN-M v3 the required changes were relatively minor, and Climate Code Foundation appreciates the fact that ISTI is published in several formats, including GHCN-M v3.
The ISTI dataset is not quality controlled, so, after re-reading section 3.3 of Lawrimore et al 2011, I implemented an extremely simple quality control scheme, MADQC. In MADQC a data value is rejected if its distance from the median (for its station’s named month) exceeds 5 times the median absolute deviation (MAD, hence MADQC); any series with fewer than 20 values (for each named month) is rejected.
So far I’ve found MADQC to be reasonable at rejecting the grossest non climatic errors.
Let’s compare the ccc-gistemp analysis using the ISTI Stage 3 dataset versus using the GHCN-M QCU dataset. The analysis for each hemisphere:
the published error bounds.
Zooming in on the recent period:
The additional data that ISTI has gathered is most welcome, and this analysis shows that the warming trend in both hemispheres was not due to choosing a particular set of stations for GHCN-M. The much more comprehensive station network of ISTI shows the same trends.
Thursday, July 24, 2014
(Update 5 August: the resolution which came out of the WMO Executive Council meeting is available at
Monday, July 21, 2014
http://video.ucar.edu/mms/image/samsi2014_jonathan_woody.mp4 - Jonathan Woody gave a talk on analyses of snow depth.
http://video.ucar.edu/mms/image/samsi2014_bo_li.mp4 - Bo Li provided a talk on model selection in the use of palaeodata analyses.
We hope to have a meeting report out within a matter of days to weeks. We will post this here.
Overall there was a lot of active participation and many new directions to be taken in the analysis of surface temperatures. Our thanks go out to both SAMSI and IMAGe for facilitating this meeting and to all the participants for being active. More details to appear soon ...
Friday, July 11, 2014
http://video.ucar.edu/mms/image/samsi2014_richard_smith.mp4 - Richard Smith provided an overview of the SAMSI program and their expectations for the workshop.
http://video.ucar.edu/mms/image/samsi2014_peter_thorne.mp4 - I provided an overview of the ISTI program and progress to date
http://video.ucar.edu/mms/image/samsi2014_peter_thorne_jared.mp4 - I deputized for Jared to provide an overview of the databank process
http://video.ucar.edu/mms/image/samsi2014_kate_willet.mp4 - Kate Willett provided an overview of progress with creation of benchmarks and remaining challenges.
http://video.ucar.edu/mms/image/samsi2014_lucie_vincent.mp4 - Lucie Vincent provided an overview of typical inhomogeneities found in station timeseries and some of their likely causes.
http://video.ucar.edu/mms/image/samsi2014_jaxk_reeves.mp4 - Jaxk Reeves provided an overview of at most one changepoint techniques.
http://video.ucar.edu/mms/image/samsi2014_colon_gallagher.mp4 - Colin Gallagher provided an overview of fitting regression models.
http://video.ucar.edu/mms/image/samsi2014_robert_lund.mp4 - Robert Lund provided an overview of multiple changepoint techniques.
http://video.ucar.edu/mms/image/samsi2014_enric_aguilar.mp4 - Enric Aguilar and http://video.ucar.edu/mms/image/samsi2014_victor_venema.mp4 Victor Venema provided an overview of several state of the art climate homogenization techniques.
http://video.ucar.edu/mms/image/samsi2014_matt_menne.mp4 - Matt Menne provided and overview of the Pairwise Homogenization Algorithm and Bayes Factor Analyses by NCDC and their benchmarking.
http://video.ucar.edu/mms/image/samsi2014_peter_thorne2.mp4 - I provided an overview of uncertainty quantification in climate datasets.
http://video.ucar.edu/mms/image/samsi2014_colin_morice.mp4 - Colin Morice provided an overview of the HadCRUT4 uncertainty estimation techniques.
http://video.ucar.edu/mms/image/samsi2014_doug_nychka.mp4 - Doug Nychka provided an overview of spatial statistical aspects.
http://video.ucar.edu/mms/image/samsi2014_jeff_whitaker.mp4 - Jeff Whitaker provided an overview of comparisons between surface temperature products and dynamical reanalyses driven solely by observed SSTs and surface pressure measurements.
http://video.ucar.edu/mms/image/samsi2014_enric_aguilar2.mp4 - Enric Aguilar gave a talk on problems in some typical data sparse non-N. American / European series.
http://video.ucar.edu/mms/image/samsi2014_finn_lindgren.mp4 - Finn Lindgren provided a talk on spatial statistical aspects.
Monday, June 30, 2014
This release is the culmination of three years effort by an international group of scientists to produce a truly comprehensive, open and transparent set of fundamental monthly data holdings. The databank has been previously available in beta form, giving the public a chance to provide feedback. We have received numerous comments and have updated many of our sources.
This release consists of:
- Over 50 distinct sources, submitted to the databank to date in Stage 0 (hardcopy / image; where available), Stage 1 (native digital format), and Stage 2 (converted to common format and with provenance flags).
- All code to convert the Stage 1 holdings to Stage 2.
- A recommended merged product and several variants which have all been built off the Stage 2 holdings. 2 ASCII formats are provided (ISTI format, GHCN format), along with a CF Compliant netCDF format.
- All code used to process the data merge, along with statistical auxiliary files.
- Documentation necessary to understand at a high level the processing of the data, including the location of the manuscript published in Geoscience Data Journal.
- For more information, please visit our website: www.surfacetemperatures.org
- General Comment? Please email email@example.com
|Location of all stations in the recommended version of the Stage Three component of the databank. The color corresponds to the number of years of data available for each station.|
|Station count of the recommended merge by year from 1850-2010. Databank stations in red compared to GHCN-M, version 3 in black.|
Saturday, June 28, 2014
The work itself was led by Peter Pavlasek of the Slovak Institute of Metrology. His introduction is reproduced below:
Temperature is one of the main quantities measured in meteorology and plays a key role in weather forecasts and climate determination. The instrumental temperature recordings now spans well over a century, with some records extending back to the 17th century, and represents an invaluable tool in evaluating historic climatic trends. However, ensuring the quality of the data records is challenging, with issues arising from the wide range of sensors used, how the sensors were calibrated, and how the data was recorded and written down. In particular, the very definition of the temperature scales have evolved. While they have always been based on calibration of instruments via a series of material phase transitions (fixed points), the evolution of sensors, measuring techniques and revisions of the fixed points used has introduced differences that may lead to difficulties when studying historic temperature records. The conversion program here presented deals with this issue for 20th century data by implementing a proposed mathematical model to allow the conversion from historical scales to the currently adopted International Temperature Scale of 1990 (ITS-90). This program can convert large files of historical records to the current international temperature scale, a feature which is intended to help in the harmonisation processes of long historic series. This work is part of the project “MeteoMet” funded by the EURAMET, the European association of National Institutes of Metrology, and is part of a major general effort in identifying the several sources of uncertainty in climate and meteorological records.
Michael de Podesta, who has served on the steering committee since ISTI's inception, reviewed the software for ISTI and had the following summary:
Assuming that calibration procedures immediately spread throughout the world – homogenisation algorithms might conceivably see adjustments in 1968, with smaller adjustments in 1990.
If undetected, the effect would be to create a bias in the temperature record. This is difficult to calculate since the bias is temperature dependent, but if the mean land-surface temperature is ~10°C and if temperature excursions are typically ±10 °C then one might expect that the effect to be that records prior to 1968 were systematically overestimated by about 0.005 °C, and records between 1968 and 1990 by about 0.003 °C.
Michael's full summary which includes some graphical and tabular summaries can be found here.
The code package is a windows operating system based package. It is available here.
Wednesday, June 4, 2014
Also, watch this space at the end of this month for exciting developments on the first pillar of the ISTI framework - the databank.
Finally, we are rapidly hurtling towards the SAMSI/IMAGe/ISTI workshop on surface temperatures and their analyses. Its going to be a busy few weeks so expect this blog to be somewhat less moribund than of late ...
Friday, April 4, 2014
Thursday, February 6, 2014
As one such activity, the Initiative put forward a proposal for a SAMSI (Statistical and Applied Mathematical Sciences Institute) summer program activity - which got selected. Over the past few months we have been working with colleagues from SAMSI and NCAR IMAGe (Institute for Mathematics Applied to Geosciences) who joined as substantive co-sponsors to arrange the meeting logistics. We are now in a position to announce the workshop.
So, without further ado ...
Applications are invited for participation in a workshop to be held in Boulder, Colorado July 8th-16th. The aim of the workshop is to develop new and novel techniques for the homogenisation of land surface air temperature data holdings. The workshop participants will have access to the almost 32,000 stations held in the first version databank release (which will be publicly available by then) and also to several of the benchmark datasets. The workshop will mainly be practically based - with few talks and lots of coding and discussions either in plenary or in smaller breakout groups. A final agenda will be forthcoming nearer the time.
Applications are welcome from all. The final meeting is space limited to 44 people. Participants from non-traditional backgrounds, early career scientists and members of under-represented groups are particularly encouraged to apply.
Further meeting details and application form are availble at https://www2.image.ucar.edu/event/summerprog.surfacetemps
Wednesday, January 29, 2014
The coming year promises an upward shift in apparent momentum as a result of significant work over the past three years with the release of databank holdings and benchmarks and an exciting workshop to be held in the summer - for more details on the latter watch this space in a few days time.
We will also continue to work with partner activities to further mutual aims.
Thursday, January 16, 2014
- Release of the version 1 databank which will consist of c.32,000 stations
- Development and release of benchmarks
- A workshop held jointly with SAMSI and NCAR on developing novel approaches to dataset homogenization
Friday, January 10, 2014
The abstract is:
Surface temperature is a key aspect of weather and climate, but the term may refer to different quantities that play interconnected roles and are observed by different means. In a community-based activity in June 2012, the EarthTemp Network brought together 55 researchers from five continents to improve the interaction between scientific communities who focus on surface temperature in particular domains, to exploit the strengths of different observing systems and to better meet the needs of different communities. The workshop identified key needs for progress towards meeting scientific and societal requirements for surface temperature understanding and information, which are presented in this community paper. A "whole-Earth" perspective is required with more integrated, collaborative approaches to observing and understanding Earth's various surface temperatures. It is necessary to build understanding of the relationships between different surface temperatures, where presently inadequate, and undertake large-scale systematic intercomparisons. Datasets need to be easier to obtain and exploit for a wide constituency of users, with the differences and complementarities communicated in readily understood terms, and realistic and consistent uncertainty information provided. Steps were also recommended to curate and make available data that are presently inaccessible, develop new observing systems and build capacities to accelerate progress in the accuracy and usability of surface temperature datasets.If you are interested in broader aspects of the surface temperatures problems and issues than just land surface air temperatures or how ISTI may fit into the whole I would encourage you to read the paper (caveat emptor: I am a co-author). The paper is available at
Wednesday, December 18, 2013
Following last year's success, the EarthTemp Network is again organising a session at the EGU 2014 and are looking for abstract submissions. The deadline is 16 Jan., and the EGU Assembly is 27 April - 2 May 2014.
The session "Taking the temperature of the Earth: Temperature Variability and Change across all Domains of Earth's Surface" is motivated by the need for better understanding of in-situ measurements and satellite observations to quantify surface temperatures and invites contributions that emphasize sharing knowledge and make connections across different domains and sub-disciplines. They can include, but are not limited to, topics such as:
- How to improve remote sensing of ST in different environments
- Challenges from changes of in-situ observing networks over time
- Current understanding of how different types of ST inter-relate
- Nature of errors and uncertainties in ST observations
- Mutual/integrated quality control between satellite and in-situ observing systems.
- What do users of surface temperature data require for practical applications (e.g. in environmental or health sciences)?
In practice, this means that there will not be the traditional split between oral presentations and poster session. Each author will get her/his 2 minutes of oral presentation in front of the whole audience. Once this general presentation is over, each author gets their "own" screen and can show the complete presentation, with plenty of time for discussions.
We are thrilled to try out this new format, as it supports the vision of the EarthTemp Network to experiment with new ways of encouraging dialogue and collaborations.
We hope you will help us making this session again a big success with your submissions. The convener is happy to answer all questions about the new PICO format and help with technical issues,
so that your contribution will have an impact.
Abstracts can be submitted (deadline 16 January 2014) through the session website.
Some more information on the EarthTemp Network can be found on the EarthTemp Network Website. We have also just published the final version of the EarthTemp position paper, arising from the first workshop in Edinburgh, in the EGU open access journal Geoscientific Instrumentation, Methods and Data Systems:
Merchant, C. J., Matthiesen, S., Rayner, N. A., Remedios, J. J., Jones, P. D., Olesen, F., Trewin, B., Thorne, P. W., Auchmann, R., Corlett, G. K., Guillevic, P. C., and Hulley, G. C.: The surface temperatures of Earth: steps towards integrated understanding of variability and change, Geosci. Instrum. Method. Data Syst., 2, 305-321, doi:10.5194/gi-2-305-2013, 2013.
Thursday, November 7, 2013
Thanks to the many contributors we now have an overview for a number of countries:
There is always room for more. If you come across any useful information or would just like to see what is there so far please go to:
This is an online editable document so please do add info. A static version will be scraped once a month.
Tuesday, October 29, 2013
- Confirming the holdings for stations under the auspices of the national service;
- Sharing any metadata that is associated with these holdings;
- Help in sharing any other national data either collected by the national service or not held directly by the national service; and
- Making available any parallel measurement holdings undertaken by the service as part of their network operations to manage / understand change.
While we are discussing the databank ... we are now very much in the final stretch of the development of a stable release. The methods paper has been accepted and as soon as it is available in AOP (probably in the next week or two) we will announce so here. In the meantime i's are being dotted and t's crossed to enable us to go out of beta to a release candidate version concurrent with the paper appearance. Barring discovery of major issues in process forensics the release candidate will become version 1 as soon as due processes have been undertaken.