The coastal impact of the 2015-2016 and 2017 “El Niño” events off Peru: analysis of in-situ measurements, satellite data
and regional model experiments
Vincent Echevin, F. Colas, P. Testor (LOCEAN)
H. Demarcq (MARBEC),
D. Correa, D. Espinoza, M. Campos, M. Graco, D. Gutierrez (IMARPE)
J.-L. Fuda, H. Benabdelmoumene (DT INSU)
Support of GMMC, INSU, IRD, IMARPE in 2016-2017 for CIENPERU (Coastal Impact of El Nino in Peru)
Deployment of 2 gliders : 2 x 1.5 months (Nov-Dec 2015 ; March-April 2016, DT INSU)
Deployment of 6 ARGO floats (Olaya, IMARPE RV)
3 T/S (Nov-Dec 2015)
1 TS, 1 TS/DO (did not work) , 1 BGC (March 2016)
Regional modelling using CROCO-PISCES
and ORCA12 (global-analysis-forecast-phys-001-002) as boundary conditions
The coastal impact of the 2015-2016 and 2017 “El Niño” events off Peru: analysis of in-situ measurements, satellite data
and regional model experiments
Profiles from 15/03/2017to 15/06/2017
SST/Precip anomaly Mars 2017
SST/Precip anomaly Jan 2016
SST anomaly JFM 2017 (“El Niño costero”)
SST anomaly JFM 2016 (El Niño)
Two anomalous events in 2015-2016 and 2017 off Peru
A A AB B
Temp
O2
Chl-a
C
A
B
C
Figure 3
Glider measurements during the 2015-2016 El Niño
Coastal SST (7°S) SST Nino3.4
0
200
Evolution of SST anomaly
Comparison with regional model results
temperature
oxygen
Regional model : CROCO-PISCES (1/9°) + offline zoom (1/27°) Atmospheric forcing: ASCAT wind stress/ climatological heat fluxes (COADS) Boundary conditions : ORCA12 (phys), CARS climatology (biogeochemistry)
Impact of the 2015-2016 El Niño on surface chlorophyll concentration
Nov 2015
Dec 2015
Nov clim 2003-15
Dec clim 2003-15
Anomaly Nov 2015
Anomaly Dec 2015
Also true for other Nino events (1997, 2002, 2009, 2015)
Figure 2
x
Model (1/27°)surface Chl in Dec 2015 (mgChl/m3)
Impact of El Niño on surface chlorophyll concentration
Phosphate (μmol/l)
Distance to coast (nautical miles)
Silicate (μmol/l) Nitrate (μmol/l)0
200
Oxygen (ml/l)
Distance to coast (nautical miles)
Distance to coast (nautical miles)
Distance to coast (nautical miles)Figure 5
SST coast(7°S) SST Nino3.4
Nutrient concentration on the shelf during El Niño
17-18 dec2015
(IMARPE)100
Norm of bottom velocity
dec 2015
Model alongshoreVelocity (28nov-5dec2015)
Potential processes driving the upwelling of nutrients during EN
Alongshore wind stress anomaly off Peru (7S-13S, 100km)
Impact of the « El Niño costero » 2017 eventThe “El Niño costero” event in 2017
Lima, March 2017
SST/Precip anomaly March 2017
Coastal SST(7°S) SST Nino3.4
Precipitation off North Peru
March 2017
March 2017
EN EN 82-83EN 97-98
EN 2015-16
EN 97-98
SSS anomaly off North Peru
35.0
33.4
SSS anomaly JFM 2017 (2013-2017 orca12 clim)
Impact of the “El Niño costero” off Peru in JFM2017
EN 15-16
March 2017
Jan 2017 Feb 2017 Mar 2017
Impact of the “El Niño costero” off Peru in JFM2017
Sections 8°S (Chicama) IMARPE
Sections 8°S (Chicama) Model
Temperature anomalies
AVHRR ROMS ROMS clim wind
ASCAT / ASCAT climatology
Role of the wind stress in the developpment the “El Niño costero”
SST JFM2017
Alongshore wind stress (N m-2)
Precip anomaly in JFM2017, GPCP correlation precip/ poleward surface wind off Peru, JFM, NCEP2
Large scale forcing of “El Niño costero”
SPA
Precip anomaly in JFM2017, GPCP correlation precip/ poleward surface wind off Peru, JFM, NCEP2
Large scale forcing of “El Niño costero”
Coastal El Nino index, Quinn(92)
Another coastal EN event in.. 1925 (Takahashi and Martinez, ClimDyn 2017)
SST/wind anomaly in equatorial Pacific in Feb-Apr 1925
SPA
Surface chlorophyll during EN 2015-2016 and “EN costero » 2017
● Negative anomalies caused by depressed nutricline
● Negative anomalies caused by reduced wind-driven upwelling
Conclusions and perspectives
El Nino 2015-2016 :
relatively weak impact on the Peru upwelling system in comparison with
Expected deepening of the thermocline/oxycline/nutricline
Maintenance of high chlorophyll nearshore
Potential role of the sediment (to be confirmed)
« El Nino Costero » 2017 :
● Strong temperature anomaly in JFM 2017 off Peru in spite of weak La Nina conditions in EqPac
Surface warming due to weak winds in late 2016/early 2017 and possibly enhanced insolation
Rare event (1925)
● Regional model allows to investigate local processes (wind,heat fluxes,equatorial waves)
Perspectives :
Implementation of biogeochemical sediment model in CROCO-PISCES
Sensitivity experiments with more realistic heat flux products, mixed layer schemes
Alongshore wind stress in Nov-Dec Sea level anomaly in nov-Dec 2015
Phosphate (17-18 dec 2015)
Distance to coast (nautical miles)
Silicate (17-18 dec 2015)
Nitrate (17-18 dec 2015)
0
200
Oxygen (17-18 dec 2015)
Distance to coast (nautical miles)
Distance to coast (nautical miles)
Distance to coast (nautical miles)
Figure 4
Figure 5
Distribución vertical de Temperatura del Mar (ATM) en la sección oceanográfica de Chicama (0 – 100 millas), los días 16-17/12/2016, 25-26/01/2017, 18-19/02/2017, 27-28/03/2017, 11/04/2017 y 17-18/05/2017.
Jan 2017 Feb 2017 Mar 2017
Distribución vertical de anomalía de Temperatura del Mar (ATM) en la sección oceanográfica de Chicama (0 – 100 millas), los días 16-17/12/2016, 25-26/01/2017, 18-19/02/2017, 27-28/03/2017, 11/04/2017 y 17-18/05/2017.
Jan 2017 Feb 2017 Mar 2017
Temperature 8.5°S Jan 2017 Feb 2017 Mar 2017
Jan clim (2003-2016) Feb clim Mar clim
Temperature 8.5°S Jan 2017
Feb 2017
Mar 2017
Jan 2017 Feb 2017 Mar 2017
Norm of bottom velocity
dec 2015
Model alongshoreVelocity (28nov-5dec2015)
Bottom stress averagedbetween 7S-8S on shelf
Bottom boundary layer depthand mixed layer depth (m)
mld
bbl
The 2015-2016 El Niño off Peru: impact on surface chlorophyll
