Ahoy! Old ships' logs help forecast the future
These days we can find out the temperature anywhere in the world by clicking on our closest device, so why do we need weather observations from over 100 years ago? Kylie Andrews explains how old ship logs can help us predict the future.
Data in the logs of old ships such as the Himalaya could help scientists predict future weather patterns (Source: State Library of Victoria)
Clement Wragge understood the importance of keeping weather records.
The colourful 19th century Queensland meteorologist saw the possibility of forecasting and tracking the path of tropical cyclones using weather observations from ships' logs.
The convention of naming tropical cyclones was begun by him — although he got in trouble once he started naming them for politicians he didn't like!
He collected log books from ships that traversed the immediate Australasian region as well as the Atlantic, Indian and Pacific oceans from 1882-1903.
Now you can help scientists decipher the data in the log books kept by Wragge — you'll notice his letterhead at the top of many of the log book pages — as part of Weather Detective, ABC Science's new citizen science project.
How could weather records written down by a 19th century sea captain possibly be useful in the 21st century?
Anyone who's prepared for a cyclone or made farming decisions based on long-term weather forecasts will understand the value of accurate predictions on what the weather will do in the future.
And while these long-term weather predictions may appear definitive and insightful, they're only as good as the past data that they're based on. That's how forecasting works, it's predicting — or modelling — the future using what's happened in the past.
So gaining as much information about past weather is really useful.
We have a good idea of the Earth's climatic history over thousands of years — mostly from geological sources — but this doesn't provide the level of detail required for forecasting weather.
"The quality and quantity of the data that you're putting in is essential to the sort of product you're putting out, because if you don't have enough you're not going to be able to produce anything meaningful," says Rob Allan, meteorologist with the UK Met Office, and and co-creator with Philip Brohan of Old Weather, the UK version of Weather Detective.
Sea surface temperatures are important
Sea surface temperature is actually a measurement of the temperature of the ocean, not the temperature on board the boat. It's measured by sticking a thermometer into a bucketful of ocean water.
Because the ocean is more homogenous than land, a single sea temperature reading can give an excellent indication of the sea temperature for a large area. Since the oceans cover 70 per cent of our planet, observations at sea are very important for understanding and predicting weather.
Land-based temperature records are also important. However, microclimates on land can lead to large variations in temperatures within a small area — for example, a shaded valley may be cooler than an open plain — which means that historical records can be unrepresentative.
That doesn't mean the scientists won't use the land surface temperatures — they will! Just that sea surface temperature is particularly valuable.
"There had been quite an ongoing effort for a long time in developing sea surface temperature sets," says Allan, "and we have a long set of sea surface temperatures so this project is to see if we could recover more sea surface temperature data."
The power of citizen science
The amount of work involved in delving into the logbooks to uncover the weather observations is huge! The work involved is way too much for a small team, but with the power of citizen science, the information can be unlocked by sharing the load.
Unfortunately, it's not the sort of thing that a computer can be trained to do. Reading handwritten text is a skill that people and not computers excel in. Humans are also better at identifying important information.
The weather observations found by our citizen science weather detectives will add to our understanding of our planet's weather history.
They'll go into a database called Atmospheric Circulation Reconstructions over the Earth (ACRE) which will be available to anyone.
"The idea was to get a bigger better database of the weather, where we pick up more events like El Niño, La Niña or storms," says Allan.
"So instead of 40 or 50 years of recent data you could get 150 maybe longer years of data. And then you suddenly get this much more valuable tool to feed into whatever you want to use it for."
Ambitiously, ACRE aims to put together a full history of our planet's weather back to 1850 — providing weather details all over the globe for 200 kilometre by 200 kilometre resolutions for every three to six hours. The weather details will then be used to reconstruct a 3D picture of what was happening with air masses and air pressure systems at the time. It's really like something out of a science fiction film!
It's an incredibly ambitious project that is well underway and should reap some very useful results — from improving weather forecasting, to understanding climate change to re-analysing serious past weather events, such as the Knickerbocker Storm of 1922.
A significant use, and one of the reasons the project was started — is to verify seasonal forecast models which are used by farmers and primary producers for crop production.
On a regional level, it could be really useful for understanding how particular climatic phenomena — such as El Niño — may respond to climate change. And that extra length of records may give us more information about how likely extreme events, such as heatwaves or floods, are to occur in the future.
How you can help
Can you volunteer some time to be a citizen scientist? Visit Weather Detective and read through old ships' log books looking for weather observations from the 1890s and 1900s as part of a real research project. Get involved in August and you could win a tablet device!
Published 11 August 2014
