Surface Data Sources

Historical instrumental climatic data perspectives and potential

Internationally, the development and maintenance of long historical climatic data series and data sets is an expensive, and often poorly funded, undertaking. Only a few centres and institutions around the world have the capacity, infrastructure and personnel to take on such tasks as an ongoing operation. Although significant international bodies under WMO patronage exist to facilitate many of these activities, they have little or no funding support for data recovery, digitisation or quality control activities. As a consequence, the ongoing development of many long historical data compilations and products is in a finely balanced, or even precarious, state. In fact, such initiatives tend to be either supported by finite research projects, funded by contracts with specific short-term customer needs, or can only respond to the prospect of residual monies from budgets needing to be spent before the financial year ends.

Ironically, with growing concern about climatic change and variability, there is an equally growing demand for more information about the nature of the climate system over longer periods of time. This material is not only potentially incisive in itself, but is needed to assess the veracity of state-of-the-art model simulations of the climate system over past and recent times. One recent, and potentially powerful, way in which such historical climatic data can contribute to our understanding of climatic variability and change, is through their use in reanalyses of the global climate.

Pioneering reanalysis techniques using only surface observations are underway, and promise to produce a 100-year reanalysis product covering the 20th Century. The potential also exists for a reanalysis product covering the globe over the last 150 years (SIRCA) and across the North Atlantic-European sector on 200 to 250-year time scales. However, the success of these new reanalysis approaches depends heavily on the availability of sufficient historical daily to sub-daily surface observations over the earth. At present, systematic data archaeology and retrieval of such observations is limited by funding and personnel constraints.

ACRE surface data activities supporting surface-observations-only reanalyses

ACRE is recovering, extending, quality controlling and consolidating global historical instrumental (MSLP, SST and sea-ice) daily to sub-daily meteorological observations extending back into the 18th Century. These data are being archived by the GCOS AOPC/OOPC Working Group on Surface Pressure (WG-SP) in a repository called the International Surface Pressure Data Bank (ISPD). This effort is being channelled through WG-SP Regional Data Co-ordinators in various countries and regions world-wide. The ISPD data will extend circulation indices and gridded mean sea level pressure (MSLP) data sets to cover the last 200-250 years, and provide the basis for a series of surface observations-based reanalysis projects from the mid-18th to early 19th century to the present.

Station map for every year of the ISPDv2.1.2 at http://www.esrl.noaa.gov/psd/data/ISPD/v2.0/

Data from ISPDv2 can be accessed courtesy of NCAR at http://rda.ucar.edu/datasets/ds132.0/

Station map for every year of the ISPDv3.0 at http://www.esrl.noaa.gov/psd/data/ISPD/

Marine and Terrestrial Data needs for the ISPD

Marine-based data required for the ACRE initiative have generally been more easily obtained than those from land-based stations. This has occurred because a major repository for these data exists in the form of the International Comprehensive Ocean-Atmosphere Data Set (ICOADS) data set, which has an ongoing funding commitment and an infrastructure that supports its activities. Nevertheless, there are still a wealth of ship-based instrumental climatic data that need to be retrieved and digitised for both projects outlined here, and for other projects aiming to improve the historical climatic data base underpinning studies of climatic variability and change. In this capacity, the RECovery of Logbooks And International Marine data (RECLAIM Project) is playing a vital international role in the recovery and quality control of new marine data from ship logbooks. These RECLAIM activities need to be more closely linked with the ISPD and the above reanalyses.

In the absence of an equivalent to ICOADS for the land-based data activities, these have frequently required novel or extraordinary efforts to secure the necessary funding to support the retrieval and digitisation of the daily to sub-daily observations. In general, such initiatives have had to focus on those data deemed to be of high priority in relatively data sparse regions of the globe. This need is particularly acute in Asia, Africa, South America and across the Southern Hemisphere, especially at high latitudes. Thus the development of the ISPD's capacity to engender a strong and ongoing commitment to the funding of land-based data recovery, imaging, digitisation and quality control in support of the ACRE initiative is a particular imperative.

Bibliography of early European pressure observations

Rob Allan has produced a bibliography listing sources of long timeseries of monthly to sub-daily pressure observations for the European region. It will form the basis of the terrestrial pressure data component of the really long surface-input-only reanalyses that ACRE's US partners are leading.

• Data sources

• Preliminary reanalysis products

ACRE is managed by Rob Allan