The data you show is from the Annapolis buoy, which is NOAA’s. We help manage the water quality aspect of the buoy, however, and post data on our website. Water quality data on the buoys is collected once every hour. Since the salinity dips for just one reading, it is likely an error with the sensor. It is unlikely the sensor would have left the water since it’s mounted on a sturdy buoy. This would be more likely to happen on some of our continuous monitoring sites where waters are more shallow. I hope this helps. Best regards, Mark Trice Program Chief, Water Quality InfomaticsWe will take another look at the salinity level at the Annapolis buoy during our January 17 meeting. Learning how to weigh things Scientifically We also practiced weighing things scientifically. Mr. Paul showed us how to use a knife edge balance and Miss Linda and Miss Debbie explained how to use the "tare" function on the electronic scale to remove the weight of a container from our measurements.