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OceanCurrentWhat can it do for you?

OCEANS AND ATMOSPHERE

Madeleine CahillDavid Griffin Roger Scott15 February 2017

Acknowledgements

Edward King, CSIRO Helen Beggs, Bureau of MeteorologyChris Griffin, Bureau of MeteorologySusan Wijffels, CSIRO

OceanCurrent | Madeleine Cahill2 |

OceanCurrent - define

• Make IMOS data more accessible scientists but also to the public -the fishing industry, yachties and swimmers

• Facilitate the uptake of IMOS data

• Make physical oceanography accessible and relevant … to fisheries, biologists, the publicthe news items

• Core business started with single pass SST plotted with GSLA and surface velocities• Chlorophyll-a/Colour images• Daily images using composite SST to represent a single day• In-situ observations

• Current meter• Argo• Glider • And more recently SealCTDs

• SST Percentiles – a way of identifying extremes in SST and to help interpret the relevance of events


SealCTDs


Great Australian Bight Salinity time series 2015/2016


2016 – A year of extremes Monthly Mean SST Anomaly, April 2016


SST Percentiles

Objective – to be able to quantify events on a map of SST-> Percentiles

The need for a climatologyThe dataThe method The product

Estimating percentilesThe problems – cloud,Example location time seriesResulting maps


Climatology

• large spatial and temporal gradients in SST -> need a climatology to reference observations

• Previously we used CARS surface temperature - in-situ observations - 0.5 degree spatial resolution O(50km)- some regions poorly sampled

• a more recent climatology by Foster et al (2014) derived using CSIRO 1d SST composites- high resolution but cold bias

• New international standards in SST - GHRSST (Group for High Resolution SST)• Wijffels et al (in prep) ClimFit3• climatology based on BoM/IMOS SST 1-day night-only composites

Robust fit using 4 seasonal harmonics and trendable to reflect effects which modify the solar forcing


Foster et al (2014) Drifter-Satellite SSTMean cold bias 0.5 – 1° C


OceanCurrent | Madeleine Cahill

Satellite SST – Drifter SST (data used in Wijffels et al)

10 |

Data provided by Helen Beggs from Bureau of Meteorology

• NB only 2012-2016• All regions • Much smaller cold bias < 0.1°C• Improvements are due to

1. better cloud clearing and2. drifting buoys are used to

calibrate satellite SST to GHRSST standards

SW Australia - JanuaryMean Sea Level (OFAM) Mean SST (ClimFit3)


SW Australia - MarchMean Sea Level (OFAM) Mean SST (ClimFit3)


SW Australia - MayMean Sea Level (OFAM) Mean SST (ClimFit3)


SW Australia - JulyMean Sea Level (OFAM) Mean SST (ClimFit3)


SW Australia - SeptemberMean Sea Level (OFAM) Mean SST (ClimFit3)


SW Australia - NovemberMean Sea Level (OFAM) Mean SST (ClimFit3)


Tasmania January ClimFit3 SST


Tasmania February ClimFit3 SST


Tasmania March ClimFit3 SST


SST and Percentiles


Coral Sea SST, 20 March 2015


x

SST Anomaly, 20 March 2015


SST Percentiles


Time series of SST (L3S-1d) in Coral Sea


Coral SeaMarch SST Anomalies (10x10km region)


Mean SST in pink

OceanCurrent | Madeleine Cahill

Gulf of Carpentaria – L3S-6d SST

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SST Anomaly


Percentiles


Time series of SST in the Gulf of CarpentariaAnomalously high temperatures Jan-Apr 2016


ClimFit3 in pinkPercentiles calculated over 1993-2014

Gulf of CarpentariaMarch SST Anomalies (10x10km region)


Estimating Percentiles - February SST Anomalies149E 41.5S (off E Tas)

• Cloud and diurnal heating (afternoon effect) give problems at the extremes of the pdf/histogram

• Estimate the statistics using all SST anomalies for each month at every 2x2km location


Estimating Percentiles - February SST Anomalies149E 41.5S (off E Tas)

Same location but using data over 10x10km region around the same location


Eddy off Tasmania July 2016


x

Time series of SST in Eddy off Eastern Tasmania


Eastern Tasmania (eddy centre)May SST Anomalies (10x10km region)


January 2017 SST


January 2017Percentiles


SST and Percentiles are plotted daily on IMOS OceanCurrent

We will be updating the percentile calculation and bring back the pink dots

Ocean and AtmosphereMadeleine Cahillt +61 3 6232 5302E [email protected] www.csiro.au

OCEAN AND ATMOSPHERE

Thank you

OceanCurrent�What can it do for you?AcknowledgementsOceanCurrent - defineSealCTDsGreat Australian Bight Salinity time series 2015/20162016 – A year of extremes �Monthly Mean SST Anomaly, April 2016�SST PercentilesClimatologyFoster et al (2014) Drifter-Satellite SST�Mean cold bias 0.5 – 1° C Satellite SST – Drifter SST (data used in Wijffels et al) SW Australia - January� Mean Sea Level (OFAM) Mean SST (ClimFit3)� SW Australia - March� Mean Sea Level (OFAM) Mean SST (ClimFit3)� SW Australia - May� Mean Sea Level (OFAM) Mean SST (ClimFit3)� SW Australia - July� Mean Sea Level (OFAM) Mean SST (ClimFit3)� SW Australia - September� Mean Sea Level (OFAM) Mean SST (ClimFit3)� SW Australia - November� Mean Sea Level (OFAM) Mean SST (ClimFit3)�Tasmania January ClimFit3 SSTTasmania February ClimFit3 SSTTasmania March ClimFit3 SSTSST and PercentilesCoral Sea SST, 20 March 2015SST Anomaly, 20 March 2015SST PercentilesTime series of SST (L3S-1d) in Coral Sea Coral Sea�March SST Anomalies (10x10km region)Gulf of Carpentaria – L3S-6d SSTSST Anomaly PercentilesTime series of SST in the Gulf of Carpentaria�Anomalously high temperatures Jan-Apr 2016 �Gulf of Carpentaria�March SST Anomalies (10x10km region)Estimating Percentiles - February SST Anomalies� 149E 41.5S (off E Tas)Estimating Percentiles - February SST Anomalies� 149E 41.5S (off E Tas)Eddy off Tasmania July 2016� Time series of SST in Eddy off Eastern TasmaniaEastern Tasmania (eddy centre)�May SST Anomalies (10x10km region)January 2017 �SSTJanuary 2017�Percentiles�Thank you

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