Chemical Sensor Program
In Situ Ultraviolet Spectrophotometer (ISUS)

Nitrate (µM - blue) and Temperature (°C - red) measured at the M1 mooring in Monterey Bay are plotted versus the Year Day over the previous 365 days.   As temperature goes down, the concentration of nitrate rises. Decreasing temperature indicates upwelling of cold deep water that is also rich in nutrients.  

The instrument has been turned around several times, after it was fouled or had a malfunction, creating the data gaps.