Last night we deployed our first Argo float of the trip, a core float that measures the basic physical properties necessary to understand the ocean state: temperature, salinity, and pressure. Liz, one the marine techs on the R/V Thompson, woke me up around 2 am to let me know that we were approaching the location that had been chosen for the first deployment (latitude, longitude). I pulled on my steel-toed rubber boots, courtesy of the Woods Hole Oceanographic Institution’s (WHOI) stockroom, and headed down to the main lab where the floats are being held. The ship slowed to a gentle 5 knots from its cruising speed of about 12 knots.
Although thousands of Argo floats have been deployed over the last two and a half decades, Argo programs around the world are always trying to improve the deployment process to make it as foolproof as possible. The WHOI Argo team typically packs core floats inside cardboard boxes held together with water soluble tape, which protect the float as it’s lowered into the water and biodegrade quickly once in the ocean. These carefully-packed floats are attached to straps that are secured with a small mechanism called a water release. The water release contains a tiny starch component that dissolves on contact with the water, thereby releasing the float gently into the sea. This is how it’s supposed to work, anyway – the WHOI Argo team has been vexed by their water releases not triggering properly and decided to use a new type of water release on the floats they sent to the Thompson. The header image above shows the new water release and straps after the deployment (photo credit: Cora Hersh). I was happy to report back to Woods Hole that the new type of release worked just fine, this time anyway! With the help of AB (“Able Seaman”) Sophie, Liz and I sent the float off to explore the depths of the North Pacific. My fingers are crossed that our water release luck holds for the rest of the core float deployments! Unfortunately I didn’t take any good pictures of the deployment as it was the middle of the night and raining, so you’ll have to just imagine for now.
The whole process took probably under half an hour – my bunk was still warm by the time I crawled back in. Deployments for the BGC floats will be a little more involved, as I’ll be taking some surface water samples at the same time. Check back in soon for more!