Weather charts are valuable historical resources for the history of meteorological observations in Japan, because they have been the key material to understand and predict weather based on the integration and visualization of meteorological observations of the ground and upper atmosphere. We therefore started the construction of a long-term data archive for weather charts that have been created by Japan Meteorological Agency (JMA) and its predecessors since March 1, 1883 for more than 130 years, and released a website called “Database of Weather Charts for Hundred Years.”
The core part of this database is weather charts purchased from Japan Meteorological Business Support Center. Weather charts were then uniformly extracted and converted, so that they can be searched by date. Continuous from the beginning is the surface weather chart around Japan or Asia Pacific, and the type of weather charts has been gradually increasing to reach eight at the latest. From the viewpoint of time series, a small number of weather charts are randomly missing, but as a whole it can be considered as continuous time series. But weather charts are significantly missing for twenty days in September 1923, which seems to be the result of fire at the Central Meteorological Observatory in Tokyo after Great Kanto Earthquake on September 1.
As of February 2016, we have 108,599 surface weather charts, and the total of 232,298 weather charts for all types, and the website was publicly released on November 2015, after experimental release on January 2014. The website shows a credit stating that this database is based on the usage of data from JMA according to the data policy of JMA.
The original plan of this database is to construct the database of weather charts that are geometrically corrected (georeferenced). The manual geometric correction of weather charts is infeasible for more than 100,000 weather charts, so the key is the development of an automated process for the geometric correction of surface weather charts. Weather charts after August 1958 can be processed to a satisfactory level, so we take advantage of geobrowsers such as Google Earth, Google Maps and Cesium to show the overlay of georeferenced weather charts. On the other hand, weather charts before July 1958 have a problem of low quality due to preservation and a larger variation of format, so we still do not have a fixed plan for georeferencing.
The next challenge is to improve the usability of the database. Search by date is the first method to implement in the database, but the problem here is the lack of advanced search due to the lack of metadata. We implemented four methods to improve the findability of weather charts.
The challenge for the future is the mining of information embedded within the weather chart. Automatic extraction of text by OCR is possible for text documents, but the same method does not work for weather charts on which lines are written multiple times. Hence we should take advantage of the methodology of crowd-sourcing or citizen science, where scientists and citizens can take part in the activity of information extraction from weather charts. Several successful projects have been reported in this direction, but the application to this project should solve the following issues. First, we need training for the proper interpretation of data such as different unit of pressure. Second, we need to clarify contribution to science about how historical weather charts can contribute to scientific discovery, because this is where citizens are motivated to contribute to the activity.
The archive of meterological observation data, the foundation of weather charts, is available on Digital Typhoon as AMeDAS Statistics - Analysis of Past AMeDAS Data and Information on AMeDAS Stations after 1976 when the ground observation has changed to AMeDAS system. On the other hand, the archive of meteorological satellite data was the original purpose of Digital Typhoon, and our database provides satellite data since December 1978, which is the longest archive in Japan as the archive of Himawari satellite series.
Created by National Institute of Informatics "Digital Typhoon" based on "Weather Charts" from Japan Meteorlogical Agency