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The importance of unresolved biases in 20th century sea-surface temperature observations

The importance of unresolved biases in 20th century sea-surface temperature observations
The importance of unresolved biases in 20th century sea-surface temperature observations
A new analysis of sea surface temperature (SST) observations indicates notable uncertainty in observed decadal climate variability in the second half of the twentieth century, particularly during the decades following World War II. The uncertainties are revealed by exploring SST data binned separately for the two predominant measurement types: “engine-room intake” (ERI) and “bucket” measurements. ERI measurements indicate large decreases in global-mean SSTs from 1950 to 1975, whereas bucket measurements indicate increases in SST over this period before bias adjustments are applied but decreases after they are applied. The trends in the bias adjustments applied to the bucket data are larger than the global-mean trends during the period 1950–75, and thus the global-mean trends during this period derive largely from the adjustments themselves. This is critical, since the adjustments are based on incomplete information about the underlying measurement methods and are thus subject to considerable uncertainty. The uncertainty in decadal-scale variability is particularly pronounced over the North Pacific, where the sign of low-frequency variability through the 1950s to 1970s is different for each measurement type. The uncertainty highlighted here has important—but in our view widely overlooked—implications for the interpretation of observed decadal climate variability over both the Pacific and Atlantic basins during the mid-to-late twentieth century.
0003-0007
621-629
Davis, Luke L. B.
4a6a9540-fefa-4ad2-9d4f-d8784282c575
Thompson, David W. J.
19fa8700-3917-452c-8669-511698eaccd3
Kennedy, John J.
36c4828b-1d5a-4810-97a3-fb2d48c87410
Kent, Elizabeth C.
59bfb484-c094-43a7-8d2a-4d0a4357eeeb
Davis, Luke L. B.
4a6a9540-fefa-4ad2-9d4f-d8784282c575
Thompson, David W. J.
19fa8700-3917-452c-8669-511698eaccd3
Kennedy, John J.
36c4828b-1d5a-4810-97a3-fb2d48c87410
Kent, Elizabeth C.
59bfb484-c094-43a7-8d2a-4d0a4357eeeb

Davis, Luke L. B., Thompson, David W. J., Kennedy, John J. and Kent, Elizabeth C. (2019) The importance of unresolved biases in 20th century sea-surface temperature observations. Bulletin of the American Meteorological Society, 100 (4), 621-629. (doi:10.1175/BAMS-D-18-0104.1).

Record type: Article

Abstract

A new analysis of sea surface temperature (SST) observations indicates notable uncertainty in observed decadal climate variability in the second half of the twentieth century, particularly during the decades following World War II. The uncertainties are revealed by exploring SST data binned separately for the two predominant measurement types: “engine-room intake” (ERI) and “bucket” measurements. ERI measurements indicate large decreases in global-mean SSTs from 1950 to 1975, whereas bucket measurements indicate increases in SST over this period before bias adjustments are applied but decreases after they are applied. The trends in the bias adjustments applied to the bucket data are larger than the global-mean trends during the period 1950–75, and thus the global-mean trends during this period derive largely from the adjustments themselves. This is critical, since the adjustments are based on incomplete information about the underlying measurement methods and are thus subject to considerable uncertainty. The uncertainty in decadal-scale variability is particularly pronounced over the North Pacific, where the sign of low-frequency variability through the 1950s to 1970s is different for each measurement type. The uncertainty highlighted here has important—but in our view widely overlooked—implications for the interpretation of observed decadal climate variability over both the Pacific and Atlantic basins during the mid-to-late twentieth century.

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e-pub ahead of print date: 7 May 2019

Identifiers

Local EPrints ID: 432366
URI: https://eprints.soton.ac.uk/id/eprint/432366
ISSN: 0003-0007
PURE UUID: 2bc33e85-f066-4f4f-a426-8763c7d6e31f

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Date deposited: 11 Jul 2019 16:30
Last modified: 10 Dec 2019 05:01

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Author: Luke L. B. Davis
Author: David W. J. Thompson
Author: John J. Kennedy
Author: Elizabeth C. Kent

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