Recovered WWII Pearl Harbor ship data aids climate study

The new dataset comprised nearly 630k records, including over three million individual observations. 

The weather observations were collected mainly in the Pacific Ocean, with some coming from the Atlantic and Indian Oceans. The logbooks emanated from the U.S. Navy Pacific Fleet stationed in Hawai'i during the Second World War.

To ensure the accuracy and reliability of the data, scientists employed quality control by deploying individual assessors to check the data. 

The dataset includes hourly weather observations, including air temperature, sea surface temperature, atmospheric pressure, wind speed, and wind direction, which were inter-compared for quality with independent ship measurements and compared with the 20th-century examined data.

The vast data helped scientists understand how the global climate behaved during World War II, particularly whether those years were abnormally warm due to changes in observation practices caused by wartime disruptions.

Observations to aid climate research

Dr. Praveen Teleti, the University of Reading research scientist who led the research, stated: 

“Disruptions to trade routes in World War II led to a significant reduction in marine weather observations. Until recently, records from that time were still only available in classified paper documents. The scanning and rescuing of this data provides a window into the past, allowing us to understand how the world's climate was behaving during a time of tremendous upheaval.”

Dr. Teleti added, “The greatest respect must go to the brave servicemen who recorded this data. War was all around them, but they still did their jobs with such professionalism. It is thanks to their dedication and determination that we have these observations 80 years on.”  

The logbooks' documented information was derived from different ships that played imperative roles during the events of the Second World War. These included battleships, aircraft carriers, destroyers, and cruisers. 

The recovered information during wartime showed how servicemen recording the data made changes in the way they observed the weather. They took more observations during the day to avoid being seen by enemy ships. 

These changes may have made temperatures seem slightly warmer, which is why history books might mention a period of unusual warmth during World War II. Former studies have also reported that the war years were abnormally warm. According to the statement, the new data will help clear up this uncertainty. 

Data from that period usually is not digitized; however, the rescued details could help scientists rectify and fill gaps in current datasets, enhancing understanding of how the global climate has changed since the early 20th century.

The study was published on September 18 in the journal RMets.

Study abstract:

The number and coverage of weather observations over the oceans were considerably reduced during World War II (WW2) due to disruptions to normal trade routes. The observations that do exist for this period are often unavailable to science as they are still only available as paper records or scanned images. We have rescued the detailed hourly weather observations contained in more than 28,000 logbook images of the US Navy Pacific Fleet stationed at Hawai'i during 1941–1945 to produce a dataset of more than 630,000 records. Each record contains the date and time, positional information and several meteorological measurements, totalling more than 3 million individual observations. The data rescue process consisted of a citizen science project asking volunteers to transcribe the observations from the available images, followed by additional quality control processes. This dataset not only contains hourly weather observations of air temperature, sea surface temperature, atmospheric pressure, wind speed and wind direction, mainly in the Pacific Ocean but also includes some observations from the Atlantic and Indian Oceans. The new observations are found to be of good quality by inter-comparing independent measurements taken on ships travelling in convoy and by comparing with the 20th-Century Reanalysis. This dataset provides invaluable instrumental weather observations at times and places during WW2, which fill gaps in existing reconstructions.