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Factors challenging our ability to detect long-term trends in ocean chlorophyll

Factors challenging our ability to detect long-term trends in ocean chlorophyll
Factors challenging our ability to detect long-term trends in ocean chlorophyll
Global climate change is expected to affect the ocean's biological productivity. The most comprehensive information available about the global distribution of contemporary ocean primary productivity is derived from satellite data. Large spatial patchiness and interannual to multidecadal variability in chlorophyll a concentration challenges efforts to distinguish a global, secular trend given satellite records which are limited in duration and continuity. The longest ocean color satellite record comes from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), which failed in December 2010. The Moderate Resolution Imaging Spectroradiometer (MODIS) ocean color sensors are beyond their originally planned operational lifetime. Successful retrieval of a quality signal from the current Visible Infrared Imager Radiometer Suite (VIIRS) instrument, or successful launch of the Ocean and Land Colour Instrument (OLCI) expected in 2014 will hopefully extend the ocean color time series and increase the potential for detecting trends in ocean productivity in the future. Alternatively, a potential discontinuity in the time series of ocean chlorophyll a, introduced by a change of instrument without overlap and opportunity for cross-calibration, would make trend detection even more challenging. In this paper, we demonstrate that there are a few regions with statistically significant trends over the ten years of SeaWiFS data, but at a global scale the trend is not large enough to be distinguished from noise. We quantify the degree to which red noise (autocorrelation) especially challenges trend detection in these observational time series. We further demonstrate how discontinuities in the time series at various points would affect our ability to detect trends in ocean chlorophyll a. We highlight the importance of maintaining continuous, climate-quality satellite data records for climate-change detection and attribution studies.
1726-4170
2711-2724
Beaulieu, C.
13ae2c11-ebfe-48d9-bda9-122cd013c021
Henson, S.A.
d6532e17-a65b-4d7b-9ee3-755ecb565c19
Sarmiento, J.L.
5887047e-92ac-47f7-a504-fb1699dd8d17
Dunne, J.P.
8ccd3d76-7ce1-41de-b8aa-c4ed36ab576e
Doney, S.C.
4c4985b2-bcb3-463a-9b4b-ead5b79ea9ac
Rykaczewski, R.R.
3d908a57-f11e-45fb-9ad9-7bc0f1fbaa1e
Bopp, L.
f3ec9518-4c47-471e-9da9-0476aaebdff6
Beaulieu, C.
13ae2c11-ebfe-48d9-bda9-122cd013c021
Henson, S.A.
d6532e17-a65b-4d7b-9ee3-755ecb565c19
Sarmiento, J.L.
5887047e-92ac-47f7-a504-fb1699dd8d17
Dunne, J.P.
8ccd3d76-7ce1-41de-b8aa-c4ed36ab576e
Doney, S.C.
4c4985b2-bcb3-463a-9b4b-ead5b79ea9ac
Rykaczewski, R.R.
3d908a57-f11e-45fb-9ad9-7bc0f1fbaa1e
Bopp, L.
f3ec9518-4c47-471e-9da9-0476aaebdff6

Beaulieu, C., Henson, S.A., Sarmiento, J.L., Dunne, J.P., Doney, S.C., Rykaczewski, R.R. and Bopp, L. (2013) Factors challenging our ability to detect long-term trends in ocean chlorophyll. Biogeosciences, 10 (4), 2711-2724. (doi:10.5194/bg-10-2711-2013).

Record type: Article

Abstract

Global climate change is expected to affect the ocean's biological productivity. The most comprehensive information available about the global distribution of contemporary ocean primary productivity is derived from satellite data. Large spatial patchiness and interannual to multidecadal variability in chlorophyll a concentration challenges efforts to distinguish a global, secular trend given satellite records which are limited in duration and continuity. The longest ocean color satellite record comes from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), which failed in December 2010. The Moderate Resolution Imaging Spectroradiometer (MODIS) ocean color sensors are beyond their originally planned operational lifetime. Successful retrieval of a quality signal from the current Visible Infrared Imager Radiometer Suite (VIIRS) instrument, or successful launch of the Ocean and Land Colour Instrument (OLCI) expected in 2014 will hopefully extend the ocean color time series and increase the potential for detecting trends in ocean productivity in the future. Alternatively, a potential discontinuity in the time series of ocean chlorophyll a, introduced by a change of instrument without overlap and opportunity for cross-calibration, would make trend detection even more challenging. In this paper, we demonstrate that there are a few regions with statistically significant trends over the ten years of SeaWiFS data, but at a global scale the trend is not large enough to be distinguished from noise. We quantify the degree to which red noise (autocorrelation) especially challenges trend detection in these observational time series. We further demonstrate how discontinuities in the time series at various points would affect our ability to detect trends in ocean chlorophyll a. We highlight the importance of maintaining continuous, climate-quality satellite data records for climate-change detection and attribution studies.

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Published date: 23 April 2013
Organisations: Ocean and Earth Science, Marine Biogeochemistry

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Local EPrints ID: 352323
URI: https://eprints.soton.ac.uk/id/eprint/352323
ISSN: 1726-4170
PURE UUID: 42b3893c-3d0a-49d3-9961-4ba2e15a02b5

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Date deposited: 09 May 2013 09:03
Last modified: 16 Jul 2019 21:34

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Contributors

Author: C. Beaulieu
Author: S.A. Henson
Author: J.L. Sarmiento
Author: J.P. Dunne
Author: S.C. Doney
Author: R.R. Rykaczewski
Author: L. Bopp

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