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Carmen E. Morales - Samuel Hormazabal Isabel Andrade - Marco Correa-Ramírez Universidad de Concepción P. Universidad Católica de Valparaíso CHILE (FONDECYT.

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Presentation on theme: "Carmen E. Morales - Samuel Hormazabal Isabel Andrade - Marco Correa-Ramírez Universidad de Concepción P. Universidad Católica de Valparaíso CHILE (FONDECYT."— Presentation transcript:

1 Carmen E. Morales - Samuel Hormazabal Isabel Andrade - Marco Correa-Ramírez Universidad de Concepción P. Universidad Católica de Valparaíso CHILE (FONDECYT ) Bathymetry (m) High resolution time-space variability of satellite chlorophyll-a in the coastal and coastal transition zones off central-southern Chile (33-42ºS) PERU-CHILE CURRENT SYSTEM

2 BACKGROUND COASTAL ZONE OFF CENTRAL-SOUTHERN CHILE CHARACTERIZED BY HAVING A STRONG SEASONALITY IN WIND-DRIVEN UPWELLING PROCEESES, CHLOROPHYLL-a CONCENTRATION AND PHOTOSYNTHETIC PRIMARY PRODUCTION. NEW TOY TO PLAY WITH: HIGHER RESOLUTION SATELLITE DATA DATA SETS FOR CHLOROPHYLL-a: -IN SITU SNAPSHOTS FROM DIFFERENT STUDIES -IN SITU FIXED TIME SERIES STATION (ST. 18 OFF CONCEPCION) SINCE REGIONAL SATELLITE TIME SERIES (100, 9, AND 4 km)

3 CONSIDERING A HIGHER RESOLUTION DATA, WHICH ARE THE MOST SIGNIFICANT SCALES OF TIME-SPACE VARIABILITY IN PHYTOPLANKTON BIOMASS ALONG THE COAST AND ACROSS- SHORE? MEAN VALUES Chl-a (mg m-3) SST (ºC) Wind stress (N m-2) wind stress curl (10-7 N m-3) MOTIVATION ******

4 APPROACHES AND METHODS DATA - Time series satellite data: Chlorophyll-a (OC3 algorithm, Werdell 2009) and SST: daily and 1X1 km resolution, MODIS Aqua mission (http://oceancolor.gsfc.nasa.gov/).http://oceancolor.gsfc.nasa.gov/ Note: 5 d average and DINEOF interpolation (Alvera-Azcárate et al. 2007) Surface wind: wind stress and wind stress curl: daily and 25x25 km resolution, Cross-Calibrated Multi-Platform Surface Ocean Wind product (CCMP); (ftp://podaac-ftp.jpl.nasa.gov/allData/ccmp/L3.0/). ANALYSIS Multi-Taper Method - Singular Value Decomposition- (MTM-SVD)*  Time-space variability of the main frequencies of Chl-a or other: graphs of local fractional variance (LFV) and their significance percentage of the variance explained by each frequency in different areas within the region of study (spatial reconstruction of the variance) oscillation patterns in each frequency (phases and signal propagation) * Correa-Ramírez & Hormazabal, 2012 (doi:103856/vol40-issue4-fulltext-19)

5 MAIN FREQUENCIES OF VARIABILITY OF CHL-a Dominant frequencies of variability in Chl-a: semi-annual, annual, and inter-annual Similarities in the variability of frequencies between the coastal band (<100 km) and the whole region (coast + CTZ)

6 CONTRIBUTION OF THE DOMINANT FREQUENCIES OF CHL-a VARIABILITY IN THE SPACE DOMAIN INTER-ANNUAL ANNUAL SEMI-ANNUAL

7 ANNUAL CYCLE OF CHL-a (anomalies) WINTER SPRING SUMMER AUTUMN

8 MAIN FREQUENCIES OF VARIABILITY CHL-a, SST, AND WIND Coastal Chl-aCoastal SST

9 ANNUAL CYCLE OF (anomalies) WIND STRESS (color) AND WIND STRESS CURL (grey line) WINTER SPRINGSUMMER AUTUMN

10 PATTERNS OF CHL-a, SST, Wind VARIABILITY - COASTAL Chl-a SST Wind forcing NIÑO NIÑA NIÑO NIÑA EL NIÑO 3.4

11 Dominant frequency of Chl-a variability in the region: annual – associated with wind and SST variability Higher (inter-annual) and lower (semi-annual) frequencies also important but beyond the coastal band. In the coastal band, the patterns of the annual phytoplankton cycle: i)An alongshore propagation of the Chl-a increase ii)a strong latitudinal zonation of the Chl-a  2 breaks in continuity (at ~37 and 40°S, two main upwelling centers). CONCLUSIONS In the CTZ, the highest mean Chl-a (>0.5 mg/m3) extended out to ~200 km offshore in the northern region (33-38°S) whereas it was about half that width in the southern region (38-42°S) associated to a change in wind stress and wind stress curl.

12 Offshore annual cycle of Chl-a in opposite phase with coastal Chl-a (Yuras et al., 2005). Between the coast and the offshore, a band of ~60-80 km with no significant annual variability  annual increase in Chl-a in the coastal band does not propagates to offshore waters. PUZZLE Implications: Chl-a increases in the CTZ depend on in situ growth of phytoplankton (no advection from coast) -- a process most likely linked to eddy pumping via mesoscale eddies. Assumption: eddy generation has no annual frequency! IS THAT TRUE ??? OTHER EXPLANATIONS?????

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