By Rebecca Fowler

This is part of a new series of posts that highlight the importance of Earth and space science data and its contributions to society. Posts in this series showcase data facilities and data scientists; explain how Earth and space science data is collected, managed and used; explore what this data tells us about the planet; and delve into the challenges and issues involved in managing and using data. This series is intended to demystify Earth and space science data, and share how this data shapes our understanding of the world.

On Friday, while many people were tracking the progress of the winter storm bearing down on the eastern United States, oceanographers were rummaging through their fieldwork photos for images of CTDs to share on Twitter in honor of #CTDAppreciationDay.

Today is #CTDAppreciationDay @teuta @rejectedbanana (Picture courtesy of C. Meinen) pic.twitter.com/1ye51A7GGA

— MotherAtSea (@MotherAtSea) January 22, 2016

What is a CTD? Why should it be appreciated? A CTD is a widely used oceanographic instrument. It’s a collection of sensors that measure conductivity (or salinity), temperature and depth, providing ocean scientists information about the physical characteristics of the water column. The most common arrangement for deploying a CTD sensor package is to affix it to a large metal frame called a rosette, which contains a set of bottles used to collect water samples, and often other sensors that measure additional physical or chemical properties of the water. The rosette is lowered into the ocean on a wire to different depths determined by scientists based on the type of data they wish to collect. Once the CTD is in the ocean, scientists receive real-time data on the characteristics of the water via a cable that connects the CTD to a computer on the ship.

“CTDs are to marine scientists perhaps like stethoscopes are to doctors. Generally rugged and reliable, part of basic training and you can use them to diagnose lots of different things,” said University of Southampton marine ecologist Jon Copley, who was motivated by the hashtag to post CTD images and video on Twitter.

CTD data is valuable because it enables scientists to quickly understand the physics of seawater in a given location. Scientists also combine CTD data with other data to learn about larger ocean processes, such as the flow of ocean currents, the distribution of and abundance of biological communities, and how in situ measurements compare to those modelled on computers.

The brain behind #CTDAppreciationDay belongs to Ivona Cetinić, an oceanographer at NASA Goddard Space Flight Center. “After seeing penguins being appreciated [on Twitter], and then squirrels, I decided that there should be a day where people appreciate something not so ordinary,” said Cetinić. “Honestly, I was quite surprised at how easily it got picked up. But at this time of year most oceanographers are stuck at their desks, dreaming of the ocean, so they all jumped at the opportunity to dig through their photo albums and recall cruises past.”

Renellys Perez, a University of Miami oceanographer working at NOAA, contributed images to the initiative and gave another explanation for the popularity of the hashtag: the poor quality internet available on many research vessels. “I wish that internet connectivity in the field was better so that more oceanographers would have the ability to communicate from sea,” she said. “I think hashtags are an excellent tool to communicate science and increase awareness about the joys and challenges of field and lab work.” 

Visit Twitter to see the full collection of #CTDAppreciationDay tweets, which show how CTDs are deployed, examples of CTD data, the history of the instrument and more. And mark January 22, 2017 on your calendar—Cetinić plans to make the CTD celebration an annual event.

— Rebecca Fowler is a science communicator and the Director of Communications and Outreach at the Federation of Earth Science Information Partners (ESIP).