Rob Allan leads the international ACRE initiative within the Climate Monitoring and Attribution Group of the Met Office. ACRE provides an umbrella that links together a variety of projects, institutions, organisations, and activities related to data rescue and climate applications around the globe.
Why is data rescue important for the ERA-CLIM project?
Data rescue is important to all reanalyses, especially those such as ERA-CLIM and the ACRE-facilitated 20th Century Reanalysis (20CR). These are the longest historical reanalyses that exist – ERA-CLIM 20C going back to 1900 and 20CRv2c extending back to 1850.
With the international ACRE initiative we provide historical, digitised surface instrumental terrestrial and marine weather observations to all reanalyses, and make known to our ERA-CLIM colleagues and partners any upper-air data we find in our efforts.
Before the Second World War, we estimate that there are something like as many observations that have not been digitised as have been, and are currently in the international repositories and holdings, and reanalyses have so far assimilated.
What are the sources of data and what difficulties are encountered in acquiring the data?
There are many sources of data needed by reanalyses, not just those held by the archives and repositories of National Meteorological and Hydrological Services (NMHS). Many parts of old colonial administrations made meteorological observations, as did a wide range of bodies, organisations and individuals ranging from observatories, lighthouses, missionaries, the military, ships (logbooks), doctors etc.
With such a diversity of sources, we have found that it is important to work with a wide range of disciplines beyond climate science – social sciences and humanities, historians, geographers, archivists, libraries and such. Just engaging with such a range of personnel and organisations is a major task in itself and, although it can be time consuming, it is vital to successful data rescue endeavours.
Who is involved in data rescue?
Under ERA-CLIM2, a number of partners are undertaking data rescue for the project. These are augmented by the ACRE initiative which has over 100 projects, institutions, organisations and bodies around the world which are contributing vital historical weather observations to reanalyses. So it is a major undertaking, and is integral to the production of the long reanalyses that ERA-CLIM2 and 20CR are producing and working to improve and extend.