The OSNAP Challenge

We are excited to announce the OSNAP Challenge! Data from the OSNAP array is now in hand for the calculation of the meridional overturning circulation (MOC) from September 2014 to August 2016. Prior to the release of this time series, we invite the ocean community to submit their prediction of the MOC for this observational time period. The winning submission will be announced in spring of 2017.


For this challenge, the MOC is defined as the maximum of the overturning stream function (Sv) in density space across the whole OSNAP line. You can find the coordinates of the OSNAP mooring array here. More information on the OSNAP array and the data products can be found at

Submit your estimate

You can submit your MOC estimate – 24 monthly averages of the MOC from September 2014 through August 2016 – on the form located at the bottom of this page. Each person or group is allowed one estimate. The deadline for submissions is April 1st, 2017. We invite everyone who submits a prediction to post their methods on our blog. Please email Sarah Clem ( to submit a blog post.

How will the predictions be judged?

Submitted estimates will be compared to the 24-month OSNAP MOC time series, which will be released in spring of 2017. The winning submission will be the one that minimizes the root-mean-square-difference between the estimated and observed MOC. Winners will be awarded an OSNAP T-shirt and will have bragging rights until the next OSNAP challenge!

Follow the OSNAP Challenge

Follow us on the OSNAP blog and on Twitter at @osnap_updates for announcements of submissions and of the winner!