Poster session
Over the past three years, tens of thousands of early African meteorological observations have been successfully digitised from the ACMAD collection. This is thanks to the Climate Data Rescue Africa Project (CliDaR-Africa) carried out by second year geography students as part of their Methods of Geographical Analysis module in Maynooth University. However, hundreds of millions of observations remain in image format from this collection, and billions more from numerous other archives around the world. To attain the quantum of rescue required the next logical step is to adapt the CliDaR-Africa Project for students at secondary level education across Europe and eventually the world. In this presentation we will outline what would be required to make this data rescue in the secondary school classroom a reality and some of the likely benefits for students. Students from Maynooth university who have already taken part in the CliDar-Africa Project have indicated that they have gained increased climate literacy and a range of useful skills from undertaking the activity. We are confident that, suitably tailored, it could benefit secondary level students in a similar way. Moreover, it is envisaged that the CliDar-Africa Project will directly make impactful social change by allowing young people to become involved in a real-world climate data project, allowing them to make a meaningful difference to others in less developed countries, while increasing their own knowledge on the challenges we face due to climate change. Novel participatory learning experiences should not be confined to the university sector alone. Suggestions and help in turning this from an ambition to a reality will be gratefully received.
How to cite: Healion, K., Noone, S., and Thorne, P.: Can we take student-based data rescue to the next level by engaging secondary school students across Europe and the world?, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2289, https://doi.org/10.5194/egusphere-egu25-2289, 2025.
ROPEWALK, funded by the AP Møller Mærsk Fund, is a joint initiative of the Danish National Archive and the Danish Meteorological Institute, which aims at digitizing and transcribing all weather observations in Danish ship journals and logbooks stored in the Danish National Archive, consisting of more than 750 shelf metres beginning as early as the 1680s. With the exception of the Napoleonic wars and Danish state bankruptcy in 1814, the data is complete.
Ship journals over large parts of the Northern Hemisphere are kept in the archive, with two regions of particular interest, Greenland and the Øresund:
The Greenlandic Trade Company had a monopoly for commerce with the colony of Greenland for nearly 200 years, and foreign ships would not be allowed to call a port. The company conducted these "Greenland Voyages" to western Greenland several times per year, starting as early as 1721 and through the 1930s. Weather observations from these voyages often include detailed sea ice observations.
Every ship passing the sound or belts in Denmark had to pay for passage between 1426 and 1857. To ensure payment, Danish war ships were placed at strategic locations near Copenhagen, Helsingør and Nyborg. Weather observations on board of these ships go back to the end of the Little Ice Age. In several cases, observations were conducted every time the ship bell was struck, resulting in as many as 48 observations in the course of a single day.
The scanning of the original logbooks and ship journals by the National Archive in highest possible resolution took 13 person-years, resulting in 2.1 million images covering more than 2.5 TB of data. Up to roughly 1750, the data consists of diary-like daily note in free text. Starting in the 1710s, observations are recorded as numbers in preprinted tables. We have transcribed this latter dataset, constructed a data model, trained a machine learning algorithm and conducted quality control. Free text data will be considered later.
First results will be presented. All transcribed data will be made publicly available and can be used for future research or as input for reanalysis projects.
How to cite: Stendel, M., Kronegh, A. J., and Skov, E. H.: First results from ROPEWALK (Rescuing Old data with People's Efforts: Weather and climate Archives from LogbooK records) - the digitization project for three centuries of weather observations on board of Danish ships, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2772, https://doi.org/10.5194/egusphere-egu25-2772, 2025.
In recent decades, numerous climate data digitization projects have been initiated in many countries worldwide. These projects aim to preserve data recorded in paper documents, which are vulnerable to deterioration, and to make them accessible to the scientific community to improve the accuracy of climatological studies and historical reconstructions for specific events. In this context, global reanalysis data sets play a crucial role, as their accuracy directly depends on the homogeneity and spatial distribution of the historical observational data on which they are based.
This study aims to design a new framework for the ReData (Recovery of Data) project, launched by the Meteonetwork Association in 2017. The project leverages the potential of Citizen Science, and it was upgraded in 2024 on the online platform Zooniverse, which engages volunteers in scientific research activities.
The project’s objective is to digitize the meteorological data collected by the Italian Royal Central Meteorological Office (RCMO) from 1879 to 1940 for issuing its daily meteorological bulletin. The network used for this bulletin started with 11 meteorological stations and rapidly expanded to approximately 70 within a few decades. By utilizing telegraph technology, real-time observations were transmitted to the Central Office in Rome, enabling the publication of the Daily Meteorological Bulletin, which also included observations from foreign stations, representing one of the earliest steps toward international atmospheric monitoring.
Currently, the daily RCMO bulletins available to the project cover the period from December 1879 to December 1934, while the remaining years still require scanning. In total, 55 years of data are accessible, encompassing 20,120 daily bulletins. Since the bulletins were scanned page by page, over 84,000 scans have been performed. Considering the number of meteorological variables recorded in the bulletins—which increased over time—it is possible to estimate the amount of data that could potentially be digitized through ReData. The result is impressive: over 20 million data points.
Following an in-depth analysis of the evolution of these bulletins, both in terms of the monitoring stations considered and the meteorological variables observed, this study presents the design of the project’s website, structured to facilitate the digitization process for users. In addition, the potential applications of the digitized data are explored, presenting a case study for the year 1882 that has already been entirely digitized: a synoptic reconstruction of the flood event that affected the Polesine area in northeastern Italy in September 1882. This disaster, caused by persistent heavy rainfall, led to severe flooding in the Veneto region, particularly along the Po and Adige rivers. This latter overflowed in Verona, causing extensive damage, including the collapse of the Ponte Nuovo bridge. The bulletins provide valuable information about the event, revealing particularly rainy conditions that worsened mid-month.
Such reconstruction demonstrates how the project has significant cultural and scientific value, offering benefits to students, researchers, institutions, and weather services. It addresses the lack of a comprehensive historical observational network of synoptic stations in Italy, adding critical data to reanalysis models and advancing studies of past and present climate trends.
How to cite: Ceppi, A., Brugnara, Y., Buccheri, G., Caruso, G., Cerri, L., Di Giovanni, M., Giazzi, M., Lapo Luperi, L., Manara, V., Ronca, L., and Maugeri, M.: The ReData project: involving citizen scientists in the recovery and digitization of historical daily weather bulletins, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8786, https://doi.org/10.5194/egusphere-egu25-8786, 2025.
Archives of observed weather data present unique opportunities for scientists to obtain long time series of the historical climate for many regions of the world. Unfortunately, most of these observational records are to-date available only on paper, and thus require digitization and transcription to facilitate analysis of climatic trends. Here we present a new open-source software, MeteoSaver, that uses machine learning (ML) algorithms to transcribe handwritten records of historical weather data. MeteoSaver version 1.0 processes images of tabular sheets alongside user-defined configuration settings, performing transcription through five sequential steps: (i) image pre-processing, (ii) table and cell detection, (iii) transcription, (iv) quality assessment and quality control, and (v) data formatting and upload. As an illustration and evaluation of the software, we apply MeteoSaver to ten pictured sheets of handwritten temperature observations from the Democratic Republic of the Congo. The results show that 95-100% of the records can be transcribed, of which a median of 74.4% reached the highest internal quality flag and 74% matches with the manually transcribed record, yielding a median mean absolute error of 0.3°C. These results illustrate that MeteoSaver can be applied to a range of handwriting styles and varying tabular dimensions, paper sizes, and maintenance conditions, highlighting its potential for transcribing tabular meteorological observations from multiple regions, especially if the sheets have a consistent format. Overall, our open-source software can help address the challenges of limited available hydroclimatic data within many regions of the world, by helping to save millions of handwritten records of historical weather data presently stored in archives, and expedite research on the climate and environmental changes in data scarce regions.
How to cite: Muheki, D., Vercruysse, B., Chandrasekar, K. K. T., Verbruggen, C., Birkholz, J. M., Hufkens, K., Verbeeck, H., Boeckx, P., Lampe, S., Hawkins, E., Thorne, P., Ntumba, D. K., Moulasa, O. K., and Thiery, W.: MeteoSaver: a new machine-learning based software for transcription of historical weather data, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9581, https://doi.org/10.5194/egusphere-egu25-9581, 2025.
Cli-DaRe@School is a citizen science project with the main goal of digitizing ancient and unexploited Italian meteorological observations still available only on paper or as scanned images of original records or published yearbooks. Launched in spring 2022 as a long-term coordinated initiative of the Italian Association of Atmospheric Sciences and Meteorology (AISAM) engaging a variety of researchers, as well as their affiliation Institutions, and high-school students and teachers.
During the first year the project focused on the target of four comprehensive monographs published by the Italian Hydrographic Service including about 6000 records of monthly temperature and precipitation data for the Italian territory. The temperature data cover the timespan 1926-1955 while the precipitation data refer to the years before 1950. A team of 334 students from 10 high schools in Italy was engaged. Each school was assigned pdf files containing the scanned pages to digitize, along with spreadsheet templates for data entry, and related tutorials. The person-hours dedicated to data digitization were about 4000, making about 4000 scanned pages digitized. Students had also the opportunity to join a training program offered by the project consisting of seminars explicitly meant for them. The goal of the seminar was to allow students to delve into various aspects of climate change and meteorology, and specific activities aimed to make them aware of the potentialities of the recovered data. Cli-DaRe@School is a remarkable citizen-science initiative for two main reasons: on one side it demonstrates the potentialities of high school students in providing an enormous contribution to rescue past meteorological data and making the freely available on open-access repositories, and on the other side bears a great educational added value, offering young students an easy hands-on experience with climate data and making them more aware of how science investigates past climatic trends.
At the end of the first year, we submitted a questionnaire to both students and teachers to probe their satisfaction with the project activities and gather suggestions for the following years. The questionnaire highlighted a good level of satisfaction for the teachers and a higher satisfaction for the students who explicitly chose to participate in the project with respect to those who participated as a class group and the most critical point resulted the number of hours dedicated to the digitization.
The quality check of the digitized data is performed partially automatically by means of an R code and partially manually and it is almost finished for the period 1921-1950, whereas it is still in progress for the previous years. Station metadata turned out to be a frequent source of errors, while the digitized precipitation and temperature data exhibited a very low fraction of errors. Currently, the activities to include the newly rescued records by populating already existing databases of long-term Italian precipitation and temperature series are in progress, and we aim to release the digitized data as open source in the next months.
How to cite: Manara, V., Brunetti, M., Beltrano, M. C., Bertoldi, G., Brugnara, Y., Cat Berro, D., Ceppi, A., Crespi, A., Stefanini, F. M., Sudati, F., Zardi, D., and Maugeri, M.: The citizen-science project Cli-DaRe@School: engaging high school students in digitizing data from historical meteorological observations in Italy, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10009, https://doi.org/10.5194/egusphere-egu25-10009, 2025.
Dieci e Lode is a cooperative project involving researchers from various affiliations under the umbrella of the Italian Association of Atmospheric Sciences and Meteorology (AISAM). The project aims to rescue and digitize data from meteorological observations made in former Italian colonies and territories.
Indeed, in the history of meteorology, Italy had a pivotal role in the development of observations, from the invention of some of the most important instruments to the establishment of the first international network of observations. Therefore, a huge heritage of enormously valuable data has been accumulated in many Italian archives over the past three centuries; however, despite many projects that have contributed to rescuing a significant part of this heritage, a substantial number of data archives remains available only on paper, which unfortunately is exposed to deteriorating over time, risking the loss of data and information of inestimable value for scientific research as well as for a variety of applications in the field of meteorology and climate, including the assessment of climate change.
Among those still to be recovered, a very significant fraction is represented by data from former Italian colonies or territories ruled by Italy, in different periods, between the late 19th century and the early 20th century (such as Eritrea, Somalia, Ethiopia, Libya, Dodecanese, Albania, Dalmatia, and Istria).
Hence, the present project aims to conduct a detailed search of meteorological information available for these regions during the periods mentioned above.
The main source will be the National Meteorological Archive of the Council for Research in Agricultural Economy (CREA) in Rome, specifically the Historical Central Library of Italian Meteorology.
The project will also pursue an extensive photographic scanning aimed at publishing online images of the data sheets and volumes; the overall number of pages expected to be scanned is approximately 40,000.
The project represents a significant step towards understanding the climate of the past in those Regions that still lack a large archive of past meteorological data. In particular, these data are of great importance for meteorological offices currently monitoring these territories to place meteorological observations in a longer-term context and, therefore, of greater significance in the study of ongoing climate change.
The investigation will be complemented by case studies aimed at evaluating possible implementations of citizen science activities aimed at extracting numerical series from digitized data sheets available for climatological research, in line with other works led by AISAM (Italian Association of Atmospheric Science and Meteorology), such as the Cli-DaRe@School project, which involves the participation of many Italian schools and hundreds of students. A feasibility study will also be conducted to assess how these activities can be supported by the latest Optical Character Recognition (OCR) technology.
How to cite: Brunetti, M., Baldi, M., Beltrano, M. C., De Vecchis, E., Leali, F., Giampietro, S., Iafrate, L., Manara, V., Pisani, S., Stefanini, F., Sudati, F., Zardi, D., Tadiello, A., Maugeri, M., and Ceppi, A.: Dieci e Lode: Climate Data from Former Italian Colonies and their Digitalization, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11077, https://doi.org/10.5194/egusphere-egu25-11077, 2025.
Scania is the most productive agricultural region in Sweden, located at the southernmost tip of the country, with a mild climate and including areas with very fertile soils. Historical research has shown how pre-industrial grain harvests in Scania benefitted from cooler and wetter summers, particularly during the months of June and July (Skoglund, 2022, 2024). This is in contrast to northern Sweden, where excessive dampness and, in particular, cold conditions during the growing season (April–September) have constituted the main agrometeorological constraints (Edvinsson et al. 2009; Skoglund, 2023).
The city of Lund, situated close to some of the most fertile plains of Scania, is also the location of some of the longest series of daily instrumental meteorological measurements (going back to 1748 for precipitation and 1753 for temperature). In addition, there is a relative abundance of digitized historical harvest data overlapping with the early instrumental period, c. 1750–1860, when many parts of Sweden, including Scania, experienced what has been described as an ‘agricultural revolution’. However, the early instrumental records from Lund have only been partially digitized and homogenized. This presentation focuses on recent and ongoing research to estimate the impact of drought on agriculture and society in southernmost Sweden during the 18th and 19th centuries using the early instrumental meteorological data from Lund in combination with other historical documentary evidence pertaining to harvests and demographic indicators and tree-ring based hydroclimate reconstructions.
References
Edvinsson, R., Leijonhufvud, L., and Söderberg, J.: Väder, skördar och priser i Sverige, in: Agrarhistoria på många sätt: 28 studier om människan och jorden. Festskrift till Janken Myrdal på hans 60-årsdag, edited by Liljewall, B., Flygare, I. A., Lange, U., Ljunggren, L., and Söderberg, J., pp. 115–136, The Royal Swedish Academy of Agriculture and Forestry, Stockholm, 2009.
Skoglund, M. K.: Climate variability and grain production in Scania, 1702–1911, Climate of the Past, 18, 405–433, 2022.
Skoglund, M. K.: Farming at the margin: climatic impacts on harvest yields and agricultural practices in central Scandinavia, c. 1560–1920, Agricultural History Review, 71, 203–233, 2023.
Skoglund, M. K.: The impact of drought on northern European pre-industrial agriculture, The Holocene, 34, 120–135, 2024.
How to cite: Skoglund, M.: Droughts and their impacts on agriculture and society in southernmost Sweden during the 18th and 19th centuries, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12823, https://doi.org/10.5194/egusphere-egu25-12823, 2025.
Maritime weather data contained in ship logbooks are used to assess historical changes in global surface wind and precipitation patterns since the early 19th century. We focus on unexploited caches of archival documentation, namely U.S. whaling logbooks of voyages spanning the period 1820 to 1890 from New England archives housed by the New Bedford Whaling Museum, Nantucket Historical Association, and Providence Public Library. The logbooks, often covering multi-year voyages around the globe, contain systematic weather observations (e.g., wind strength/direction, sea state, precipitation, cloudiness) at (sub-)daily temporal resolution. The qualitative, descriptive wind and precipitation recordings by the whalers are quantified and compared with reanalysis products where applicable.
Following extensive quality control, we find overall good agreement in wind strength and direction for the whaling logbook wind records with reanalysis products for mean and seasonal climatologies around the world. Interannual variations in North Atlantic wind fields associated with the North Atlantic Oscillation or changes in characteristics of the Azores High subtropical pressure system are also captured by the whaling ship recordings. Predominant precipitation patterns around the world oceans can be captured and variations across a range of timescales are assessed.
Our results demonstrate that the historical records provide an important long-term context for changing maritime wind and rainfall patterns in remote ocean regions lacking observational records during the 19th century. Challenges and opportunities for data rescue and digitization of maritime weather records in these under-utilized historical ship logbooks for climate purposes will be discussed.
How to cite: Ummenhofer, C., Sander, N., Giacoppo, T., Wimberly, F., Muench, B., and Walker, T.: Nineteenth century maritime weather data from historical New England whaling ship voyages (1820-1890), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13448, https://doi.org/10.5194/egusphere-egu25-13448, 2025.
Extreme windstorms are associated with high wind speeds and are a major source of natural hazard risk with considerable socio-economic impacts. Reported socio-economic impacts include damage to infrastructure, agriculture, forestry, coastal areas, flooding, and loss of lives. Due to the environmental and socio-economic impacts of extreme windstorms, there is broad interest in understanding the potential impact of climate change on extreme extratropical windstorm activity in the North Atlantic.
One of these severe extratropical windstorms with hurricane-force winds took place on 6 – 7 January 1839, known as ‘Night of the Big Wind’, and is one of the strongest in the instrumental record for Ireland.
Ireland and the UK have a rich heritage of historical documentary (e.g. newspapers, weather diaries) and instrumental meteorological observations, which allows a detailed reconstruction of the impacts of this severe extratropical windstorm. Additionally, a detailed analysis of the documentary sources are important to understand vulnerability, exposure and adaptation to severe extratropical windstorms.
It is crucial to understand how the consequences of this historical windstorm could have been different had it occurred in a warmer present-day and projected warmer climate.
Better knowledge and understanding of such severe historical extratropical windstorms will allow observed trends in windstorms to be put into a longer-term context and improve our understanding of the risks from such events today and in the future in the context of a warmer climate.
How to cite: Mateus, C. and Hawkins, E.: Documentary analysis of the impacts of the storm ‘Night of the Big Wind’ on the 6 – 7 January 1839 in Ireland and the UK, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13736, https://doi.org/10.5194/egusphere-egu25-13736, 2025.
Before the establishment of a weather station network in Japan, European and U.S. naval ships sailed along the region’s coastal waters during the 18th and 19th centuries. Weather records observed using meteorological instruments onboard these ships provide valuable insights into the climate studies before the network’s establishment. These ship log weather records are stored in libraries and archives across various countries. In this study, we focus on the ship log weather records made on vessels sailing along Japan waters during this period. The earliest weather records in the vicinity of Japan were documented aboard the ship of Jame Cook’s third expedition in 1779. Historical tropical cyclone (TC) tracks for the 1850s and 1860s were also identified from these records. We focus on three tropical cyclone (TC) events in the vicinity of Japan during the period from 21 to 25 July 1853 observed by seven US Naval ship of Perry’s Japan Expedition fleet, on 23 and 24 September 1856 observed by Dutch Navy ship Medusa, and on 15 and 16 August 1863 during the bombardment of Kagoshima in Japan observed by eleven UK Navy ships. This research is part of the international data rescue efforts known as the Atmospheric Circulation Reconstructions over the Earth (ACRE) initiative. Data rescue activities in Asia are conducted under ACRE Japan, one of the regional branches of ACRE.
How to cite: Kubota, H., Tsukahara, T., and Matsumoto, J.: Data rescue of instrumental meteorological data records of European and US Naval ship logs sailing along Japan waters during the 1850s and 1860s, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14354, https://doi.org/10.5194/egusphere-egu25-14354, 2025.
This study analyzes temperature and precipitation observations recorded by the network of the Spanish Meteorological Agency (AEMET) in the Segura River Basin (DHS), located in the southeast of the Iberian Peninsula, during the winter of 1944/45. A torrential precipitation event between December 24 and 28 was followed by a snow and extreme cold event between January 11 and 14, with some stations recording over 250 mm during both episodes. Between these events, unusually cold temperature anomalies were observed. This accumulation of extreme weather phenomena had significant socioeconomic impacts, which we documented using regional press sources. These reports describe large areas isolated by snow for weeks, river overflows, disrupted communications, and substantial impacts on economic activities. Using the ERA5 reanalysis, we evaluated the uniqueness of these extreme events, identifying their analogs since 1940 based on surface pressure anomaly patterns, 500 mb geopotential height, and 850 mb temperature. The results show that warmer climatic conditions have reduced the frequency of these events, while intensifying winter precipitation extremes and decreasing the duration and magnitude of cold episodes in the region. This finding aligns with climate change projections for the region during the current century. Through this study, we characterize the dynamics of past extreme weather events in the Mediterranean, contributing to an improved understanding of present and future extreme events.
How to cite: Halifa-Marín, A., Calvo-Sancho, C., Gil-Guallar, M., Royo-Aranda, A., Beguería, S., and Vicente-Serrano, S. M.: Reconstructing Extreme Weather Events in the Southeastern Iberian Peninsula: Lessons from the Winter of 1944/45, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18487, https://doi.org/10.5194/egusphere-egu25-18487, 2025.
There is growing evidence of worldwide increases in magnitude and frequency of large rainstorms driven by global warming-related rises in atmospheric temperature and moisture content and sea surface temperature – and with major consequences for flooding, landslides, soil erosion and sediment transport. Assessments of the magnitude of recent change, however, are often constrained via comparisons with short periods of pre-1980 daily rainfall data that may not be representative of the pre-global warming era. Assessment of change in tropical areas is particularly hampered not only by the short and patchy nature of daily records (in terms of continuity, quality and availability), but also by the localized nature of many tropical rainstorm events and the strong influence of locally variant factors (such as coastal and topographic aspect and associated, often diurnally variant, local wind circulations) on large event occurrence. This paper focuses on methods used in the assembly and analysis of changes in magnitude-frequency, seasonality, areal extent and other characteristics of large ( >50 mm) daily rainstorms in Sabah, Malaysian Borneo, over the past 120 years. Archival search, detection and transcription of daily data for 1906-1959, together with Malaysian Meteorological Department data since 1960, enabled continuous daily data series to be constructed for three stations of contrasting coastal aspect (Sandakan – N-facing; Kota Kinabalu - W-facing; and Tawau - S-facing). The only gap was during and immediately following the Japanese Occupation during WWII. Shorter daily rainfall series at other Sabah stations – notably Labuan, Kudat and the inland stations of Danum Valley and Keningau - were also derived and used. A previous paper (Walsh et al. 2013) analysed changes up to 2012 at individual stations using > 50mm and >100 mm threshold daily rainfall series and extreme value analysis. The current paper uses novel approaches to refine and extend analysis in four ways. First, combined data series of the three key stations are used to derive separate datasets of “local” and “multi-site/regional” events for assessment of changes in their frequencies. Second, it uses the N-facing Sandakan and Kudat records to identify (and assess changes in magnitude-frequency) of “Cold Wave” events - characterized by 4-10 successive days of very high rainfall in December or January and affecting N/NE-facing coastal areas of Sabah and Peninsular Malaysia. The very recent December 2024 event had particularly severe flooding consequences. Third, changes in seasonality of large events are explored via (1) monthly frequency regimes for 1906-40, 1947-79, 1980-99 and 2000-24 and (2) running means of monthly frequencies. Fourth, when exploring seasonal and annual changes in frequency, the focus is on change in frequencies of different size categories of rainstorm (50-74, 75-99, 100-124, 125-149, 150-174, 175-199 and >200 mm) rather than the hitherto cruder > 50 mm and 100 mm threshold data. Results demonstrate that rises in magnitude-frequency since 1980 are continuing, but where the magnitudes of change vary with season (NE Monsoon, SW Monsoon and Transition Phases}, between stations of different coastal and topographic aspect, between different storm-size categories, and between localized and regional storm types.
How to cite: Walsh, R., Safjankova, A., Bidin, K., Los, S., and Nainar, A.: Novel approaches in assembling and analysing multi-archive datasets to assess changes in frequency, seasonality and areal extent of large rainstorms in Sabah, Malaysian Borneo 1906-2024 , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19442, https://doi.org/10.5194/egusphere-egu25-19442, 2025.
Global climate datasets portray an asymmetrical collection of historical observations, a selected few regions and time-periods contribute more than others. For example, observations from Western Europe and North America in the 20th Century are more numerous than all other regions of the globe combined over the same period. Estimation of return period (probability) of any extreme weather events depends on the observation of similar events in the past. Also, observations of past extreme weather events are necessary to understand the severity and scope of future extreme events. Regions newly liberated from colonisation since the end of World War II suffer from much sparser data collection. Here, we present a comprehensive plan to discover, transcribe, and analyse historical weather observations from Singapore, West Malaysia, and northern Sumatra from 1900 to 1960s.Our primary objective is to construct a long time-series of historical instrumental meteorological data and understand extreme climate-induced events, their impacts and associated societal responses in the region. To do so, we utilise varied and diverse sources of information such as weather journals-records, missionary documents and newspapers from the study period. We transform qualitative descriptions of extreme weather conditions into continuous quantitative ordinal-scale climate indices using novel transfer functions for historical climatological data. Finally, these indices will be used to assess resilience of society and local economy to the shocks of prolonged adverse weather events, helping policy makers calibrate policy interventions in the event of extreme weather induced disasters
How to cite: Teleti, P. R. and Williamson, F.: Roadmap to discover, transcribe, and analyse early 20th Century weather observations from Singapore, West Malaysia, and northern Sumatra, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-21784, https://doi.org/10.5194/egusphere-egu25-21784, 2025.
