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USGS R/V Polaris Retires: We reflect on what she taught us
USGS R/V Polaris Retires: We reflect on what she taught us
Erica Nejad, Charles Martin, Tara Schraga, Jim CloernUS Geological Suvey
Fivedecadesand1100researchcruisesaboardtheR/VPolarishavedocumentedaremarkablerangeof
SanFranciscoBaycondi;onsJan Apr Aug
9
10
11
12
12
14
16
18
18
20
22
0 10 20 30 0 10 20 30 0 10 20 30Salinity
Tem
pera
ture
(° C
)
1969−2013
2014−2015
Recordhighwatertemperaturesin2014-15,yearsofthewarmblob
MeanJanuary,AprilandAugusttemperaturealongthesalinitygradientfortwoeras:1969-2013and2014-2015
LowestduringElNiñoyearfloodsandhighestduringprolongeddroughts
Monthlymonitoringincludesmeasurementsof:• Salinity• Temperature• DissolvedOxygen• Chlorophyll-a• Nutrients• SuspendedPar;culatemaVer• LightPenetra;on• PhytoplanktonComposi;on• PhytoplanktonToxins
What extreme highs and lows have we
recorded over this period and what are
the physical and ecological
circumstances surrounding them?
WATERTEMPERATURE&CLIMATEANOMALIES
SALINITYINSOUTHBAYTIEDTODELTAOUTFLOW
FRESHWATERATTHEGOLDENGATE
SUPERSATURATEDOXYGEN
Lower South Bay South Bay Central Bay
Large phytoplankton bloom in South Bay (up to 480ug/L)
Super saturated DO up to 140% extending from Lower South Bay
to almost Central Bay. (long term average = 90%)
March1998oxygensupersatura;oneventcausedbyahugebloomofdiatomsintheSouthBay.
1965 1970 1975 1980 1990 1995 2000 2005 2010 20150
5
10
15
20
25
30
35
Salin
ity
HIGHESTCHL-A,SACRAMENTORIVER
1975 1980 1990 1995 2000 2005 2010 2015
0
10
20
30
40
50
60
70
Cal
cula
ted
Chl
orop
hyll
(ug/
L)
10
30
50
70
Yolo Bypass Dry Yolo Bypass Flooded
LargestphytoplanktonbloomdetectedinSacramentoriversta;onswasMay2016,likelyproducedintheYoloBypasswhenitwasfloodedbyalargeElNiñostorm
Sta;on25-30surfacesalinityandyearlyaverageddeltaoublowfromhVp://www.water.ca.gov/dayflow/
NearfreshwateratthesurfaceofSta;on18duringtheFebruary1998ElNiñoflood
Inservicefrom:1969-2015
• Longtermresearchallowsustoviewextremesinthecontextofahistoricbaseline• Allexamplesofextremeeventshighlightthebayrespondingtoclimateevents
CONCLUSIONS
Lower South Bay South Bay Central Bay
sday.wr.usgs.gov/access/wqdata/index.htmlContact:EricaNejad([email protected])
Photos:hVp://earthobservatory.nasa.gov/IOTD/view.php?id=87719
+
PROLONGEDDROUGHT(1987-92)
DROUGHT(2007-09)
ELNIÑO(1982-83)
EXTREMEDROUGHT(1976-77)
DROUGHT(2014-15)
ELNIÑO(1997-98)