Massachusetts Bay Physical Processes 2011 compared to 2012 Rocky Geyer Woods Hole Oceanographic Institution

River Discharge, 2011 Wet 68th 73rd 88th 93rd 98th 63rd 38th 93rd percentile 73rd 88th 93rd 98th 63rd percentile 38th Record Maximum* 93rd * 1992- 2011

River Discharge, 2012 Dry 36th 12th 26th 45th 21rd 21st 12th 31th percentile 12th 26th 45th 21rd percentile 21st 12th 31th

salinity Wow!

NERACOOS A Near-field

2011 was wet all year BIG discharge event in 2010

water temperature Upwelling event Mixing event Record near-bottom water temperature– end of august 2010. Why?

2011 Late spring winds and water temperature Strong upwelling

2012 late spring winds and water temperature NE wind mixing event surface 20 m 50 m

dissolved oxygen

2011 fall winds and water temperature Irene Peak stress same as Irene!

2012 fall winds and water temperature Hurricane Sandy

Generally warmer deep water means lower DO

Near-bottom Dissolved Oxygen Regression Model Dopredicted = - A T - B S

NERACOOS A East-West current at 50 m— Does it influence DO? Toward offshore 10 7.5 5 From offshore

summary Precipitation affects river flow, which affects salinity 2011 was wet, and 2012 was dry Winter temperature sets initial deep-water temperature 2012 had a warm winter, leading to warm bottom water Upwelling cools surface water and downwelling warms bottom water Dissolved oxygen co-varies with temperature and salinity warmer temperatures cause lower DO higher salinities cause lower DO (different from other systems) DO is a “regional” variable strong correlation between NERACOOS and near-field Bottom DO decreases steadily during the stratified period Fall wind mixing relieves near-bottom low DO