Satellite observations of SW oceanography in 2013, and using fronts to describe ecological interactions

Peter Miller

South West Marine Ecosystems Conference 2014

4th April 2014

Plymouth Marine Laboratory

Satellite oceanography and fronts

• SW oceanography from space in 2013

• Algal blooms in 2013

• Satellite detection of ocean fronts

• Ecological applications, conservation and MPAs

MultiView composites

2001 vs 2007 vs 2013 SST

°C

Feb

Oct.

Cooler than

usual

Warmer than

usual

Earlier onset of stratification

April 2001 Apr 2013

Miller, P.I. (2009) Composite front maps for improved visibility of dynamic sea-surface features

on cloudy SeaWiFS and AVHRR data. Journal of Marine Systems, 78(3), 327-336.

A “typical” July – amazingly not stormy

Jul 2001 Jul 2013

Later breakdown of stratification

Oct. 2001 Oct. 2013

Chlorophyll-a in a ‘typical’ year

Chlorophyll-a in 2013 – lower than typical?

Longer Spring bloom

Lack of summer

dinoflagellate

blooms

Algal bloom news

• In June 2013, there was an

extensive Phaeocystis bloom

along the south Devon & Cornwall

coast.

• Could this have depleted the

nutrients to reduce later blooms?

• In early 2014, we observed

species normally associated with

warm temperate/tropical water:

• Dinophysis tripos – Toxic

• Trichodesmium – brought by

Gulf Stream

Satellite oceanography and fronts

• SW oceanography from space in 2013

• Algal blooms in 2013

• Satellite detection of ocean fronts

• Ecological applications, conservation and MPAs

Introduction to ocean fronts

• Ocean fronts delineate the

boundary between water masses.

• Analogous to atmospheric fronts.

• Where interesting things happen…

• Areas of enhanced mixing.

• Many pelagic fish and megafauna

distributions are related to fronts.

SST map

Local window

Histogram bimodality

test and threshold

Cohesion test

Cayula, J.-F., and Cornillon, P., (1992), Edge detection algorithm for SST

images. Journal of Atmospheric and Oceanic Technology, 9, 67-80.

Front detection method

Front map

Contour following

Advantages of front detection

SST Fcomp

• Does not blur dynamic features.

• Highlights persistent or strong gradient fronts.

Miller, P.I., (2009) Composite front maps for improved visibility of dynamic oceanic fronts on cloudy AVHRR and SeaWiFS data, Journal of Marine Systems.

Satellite oceanography and fronts

• SW oceanography from space in 2013

• Algal blooms in 2013

• Satellite detection of ocean fronts

• Ecological applications, conservation and MPAs

Jul. 1982

Frequently observed ocean fronts

Dec.1998

Nov. 2008

• Huge unique archive: >30,000

AVHRR passes 1999-2008

• Developed and tested methodology

to analyse persistent fronts in time

series

• Percentage of months in which strong

front observed = Frequent fronts

%

Summer

Miller, P.I. & Christodoulou, S. (2014) Frequent locations of ocean fronts as an

indicator of pelagic diversity: application to marine protected areas and

renewables. Marine Policy. 45, 318–329.

• Front maps were used to

prioritise candidate MPAs:

10 out of 46 offshore MPAs.

Areas of Pelagic Ecological Importance

%

Summer

Frequent fronts

Warm S

trong

Weak

Cold

Key May

2008 May

2008

Ocean fronts: from spaghetti to synoptic chart

Miller, P.I., (in preparation), A line clustering algorithm with application to simplifying ocean front maps derived from satellite data, Remote Sensing of Environment.

Warm S

trong

Weak

Cold

Key

Low High

Front distance

Low High

Front density

May

2008

Ocean front metrics

May

2008

Front side

Studying marine animal use of fronts

• Gaining evidence on different marine taxa Pirotta, E., et al. (2014) Scale-dependent foraging ecology of a marine top predator modelled using

passive acoustic data. Functional Ecology, 28(1), 206-217.

Oppel, S., et al. (2012) Comparison of five modelling techniques to predict the spatial distribution

and abundance of seabirds. Biological Conservation, 156, 94-104.

Schabetsberger, R., et al. (2013) Oceanic migration behaviour of tropical Pacific eels from Vanuatu.

Marine Ecology Progress Series, 475, 177-190.

Edwards, E.W.J., et al. (2013) Fine-scale linkage between coastally breeding seabirds and mid-

Atlantic Ridge prey communities. Deep Sea Res. II, 98B, 438-444.

• Kylie Scales

– PhD project on ocean front metrics for improving

understanding of marine animal distribution.

Scottish marine protected areas

• Advancing the methodology to

detect fronts closer to the coast

– Ocean colour fronts at 300m resolution

– Compare thermal and colour fronts

• Used to support the development of

Scotland's MPA network

– Identify areas of wider functional

importance

Hot off

the press

www.snh.gov.uk

Miller, P.I., Xu, W. & Carruthers, M. (submitted) Seasonal shelf-sea front mapping using satellite ocean colour

and temperature to support development of a marine protected area network. Deep Sea Research II.

Going global with EBSAs

• In a project with the US Duke University,

we are providing large-scale front frequency

maps to guide definition of Ecologically or

Biologically Significant Areas (EBSAs) in the

high seas. East Pacific

North Pacific NW Atlantic

Workshops to define high-seas MPAs

• Intergovernmental meetings

organised by the Convention on

Biological Diversity.

• The front maps contributed to

East Pacific EBSAs for:

– Costa Rica Dome

– Carnegie Ridge and Equatorial front

Satellite oceanography and fronts

• SW oceanography from space in 2013

• Algal blooms in 2013

• Satellite detection of ocean fronts

• Ecological applications, conservation and MPAs

Peter Miller pim@pml.ac.uk

Extra slides

Thermal and chlorophyll front fusion

Thermal fronts

Dilated 6 pixels Chl-a fronts

Dilated 6 pixels

Front fusion

mask

Front fusion map:

• bright/faded (fusion)

• red/blue (thermal),

• green/blue (chl-a),

• magenta/blue (overlap)

Sep.

2010

Biophysical interactions

• Co-location of many

fronts in March on Malin

Shelf.

• Notice the outer front at

the shelf-break is only a

chl-front - water may be

stratified.

Mar. 2010

Front metrics for marine ecology

Frequent fronts

Global front map

Synoptic front chart

Peter Miller, pim@pml.ac.uk

Composite front map

Fusion / integration

Satellite detection of oceanic fronts

26 Jun.

2009

06:37

27 Jun.

2009

19:58

Composite front maps: revealing strong fronts

Fmean Fcomp

X

Fpersist

X

Pfront Fprox

Miller, P.I., (2009) Composite front maps for improved visibility of dynamic oceanic fronts on cloudy AVHRR and SeaWiFS data, Journal of Marine Systems.

Mean gradient

Persistence Advection / proximity

Basking shark track vs. synoptic fronts

Warm

Str

ong

Weak

Cold

Key

Acknowledgements to Prof David Sims and his shark-tagging team at MBA, Plymouth 24 Aug. – 15 Oct. 2002

Kittiwake foraging radii

Acknowledgements to Natural England; RSPB staff and

volunteers (mainland), Vickie Heaney (Scilly) and Nicola

Saunders and Sophie Wheatley (Lundy).

Kittiwake productivity vs fronts

Fronts and marine biology

• Bakun’s triad: enrichment, concentration and

retention – Bakun (2006) Fronts and eddies as key structures in the

habitat of marine fish larvae. Scientia Marina.

Priede, I.G. & Miller, P.I. (2009) A basking shark tracked by satellite

with simultaneous remote sensing: reveals orientation to a

thermal front. Fisheries Research, 95(2-3), 370-372.

5.5°W 5.0°W

55.5°N

55.0°N

Firth of

Clyde,

Scotlan

d

Basking

shark

track Front

• Many pelagic fish distributions related to fronts – E.g. tuna: Worm et al. (2005)

Global patterns of predator diversity in the open oceans. Science.

– E.g. basking sharks: Fronts influence zooplankton diel migration and hence prey behaviour (Sims et al., 2005).

Front metrics for marine ecology

• Introduction to ocean fronts

• Satellite detection of ocean fronts

• Front metrics and ecological applications

• Nuts and bolts

Matchup input data format

• A text file with space-separated values (can be multiple spaces or

tabs), in these columns in this order (or Excel spreadsheet)

– latitude: decimal degrees, north positive.

– longitude: decimal degrees, east positive.

– value: any numeric value, could be the measurement for that position, or

some numeric sample identifier.

– date: in format dd/mm/yyyy.

– time: in format hh:mm. Use '12:00' if the time is unimportant or unknown.

50.5905 -2.9153 2.394 13/06/2005 12:00

50.6817 -2.9817 1.8967 27/06/2005 12:00

50.6750 -2.9817 0.945 29/06/2005 12:00

50.6613 -2.8433 1.7388 13/07/2005 12:00

50.7008 -2.7535 0.0436 30/04/2007 12:00

50.5667 -3.4200 0.2091 30/01/2008 12:00

50.4500 -3.4700 1.1 09/09/2009 12:00 . . .

Matchup output format

lat lon value EO_value st_dev offset[day] date time match_filename

54.24310 -4.76190 12.11600 -999.00000 0.00000 -999.00000 10/08/2012 14:57 Missing

54.24940 -4.79160 12.11500 -999.00000 0.00000 -999.00000 10/08/2012 10:23 Missing

54.27150 -4.74900 12.11400 -999.00000 0.00000 -999.00000 10/08/2012 07:45 Missing

54.16240 -4.79490 12.11300 0.00300 0.00000 -0.80208 09/08/2012 07:15 M2012218-

54.22490 -4.70270 12.11200 0.00220 0.00000 -1.10417 09/08/2012 14:30 M2012218-