Satellite Observations Of SW Oceanography, And Using Fronts To Describe Ecological Interactions
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Transcript of Satellite Observations Of SW Oceanography, And Using Fronts To Describe Ecological Interactions
![Page 1: Satellite Observations Of SW Oceanography, And Using Fronts To Describe Ecological Interactions](https://reader031.fdocuments.in/reader031/viewer/2022020417/55cf929e550346f57b980a3e/html5/thumbnails/1.jpg)
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
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Satellite oceanography and fronts
• SW oceanography from space in 2013
• Algal blooms in 2013
• Satellite detection of ocean fronts
• Ecological applications, conservation and MPAs
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MultiView composites
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2001 vs 2007 vs 2013 SST
°C
Feb
Oct.
Cooler than
usual
Warmer than
usual
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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.
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A “typical” July – amazingly not stormy
Jul 2001 Jul 2013
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Later breakdown of stratification
Oct. 2001 Oct. 2013
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Chlorophyll-a in a ‘typical’ year
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Chlorophyll-a in 2013 – lower than typical?
Longer Spring bloom
Lack of summer
dinoflagellate
blooms
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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
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Satellite oceanography and fronts
• SW oceanography from space in 2013
• Algal blooms in 2013
• Satellite detection of ocean fronts
• Ecological applications, conservation and MPAs
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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.
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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
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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.
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Satellite oceanography and fronts
• SW oceanography from space in 2013
• Algal blooms in 2013
• Satellite detection of ocean fronts
• Ecological applications, conservation and MPAs
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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.
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• Front maps were used to
prioritise candidate MPAs:
10 out of 46 offshore MPAs.
Areas of Pelagic Ecological Importance
%
Summer
Frequent fronts
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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.
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Warm S
trong
Weak
Cold
Key
Low High
Front distance
Low High
Front density
May
2008
Ocean front metrics
May
2008
Front side
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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.
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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.
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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
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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
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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 [email protected]
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Extra slides
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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
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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
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Front metrics for marine ecology
Frequent fronts
Global front map
Synoptic front chart
Peter Miller, [email protected]
Composite front map
Fusion / integration
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Satellite detection of oceanic fronts
26 Jun.
2009
06:37
27 Jun.
2009
19:58
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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
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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
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Kittiwake foraging radii
Acknowledgements to Natural England; RSPB staff and
volunteers (mainland), Vickie Heaney (Scilly) and Nicola
Saunders and Sophie Wheatley (Lundy).
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Kittiwake productivity vs fronts
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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).
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Front metrics for marine ecology
• Introduction to ocean fronts
• Satellite detection of ocean fronts
• Front metrics and ecological applications
• Nuts and bolts
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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 . . .
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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-