Low-Latitude Western North Atlantic Climate Variability During the Past Millennium: Insights from Proxies and Models
Estimates of natural climate variability during the past millennium provide a frame of reference in which to assess the significance of recent changes. This thesis investigates new methods of reconstructing low-latitude sea surface temperature (SST) and hydrography, and combines these methods with t...
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ftdtic:ADA510965 2023-05-15T17:28:53+02:00 Low-Latitude Western North Atlantic Climate Variability During the Past Millennium: Insights from Proxies and Models Saenger, Casey P. WOODS HOLE OCEANOGRAPHIC INSTITUTION MA 2009-09 text/html http://www.dtic.mil/docs/citations/ADA510965 http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA510965 en eng http://www.dtic.mil/docs/citations/ADA510965 Approved for public release; distribution is unlimited. DTIC Physical and Dynamic Oceanography Atmospheric Physics *VARIATIONS *HYDROGRAPHY *ATLANTIC OCEAN *CLIMATE *OCEAN SURFACE CALIBRATION OCEANS OSCILLATION CIRCULATION GULF STREAM STRONTIUM ATMOSPHERE MODELS COMPUTERIZED TOMOGRAPHY PATTERNS HEATING COOLING ATMOSPHERIC MOTION CORAL THESES SST(SEA SURFACE TEMPERATURE) Text 2009 ftdtic 2016-02-22T22:30:23Z Estimates of natural climate variability during the past millennium provide a frame of reference in which to assess the significance of recent changes. This thesis investigates new methods of reconstructing low-latitude sea surface temperature (SST) and hydrography, and combines these methods with traditional techniques to improve the present understanding of western North Atlantic climate variability. A new strontium/calcium (Sr/Ca) - SST calibration is derived for Atlantic Montastrea corals. This calibration shows that Montastrea Sr/Ca is a promising SST proxy if the effect of coral growth is considered. Further analyses of coral growth using Computed Axial Tomography (CAT) imaging indicate growth in Siderastrea corals varies inversely with SST on interannual timescales. A 440-year reconstruction of low-latitude western North Atlantic SST based on this relationship suggests the largest cooling of the last few centuries occurred from ~1650-1730 A.D., and was ~1 deg C cooler than today. Sporadic multidecadal variability in this record is inconsistent with evidence for a persistent 65-80 year North Atlantic SST oscillation. Volcanic and anthropogenic radiative forcing are identified as important sources of externally-forced SST variability, with the latter accounting for most of the 20th century warming trend. An 1800-year reconstruction of SST and hydrography near the Gulf Stream also suggests SSTs remained within about 1 deg C of modern values. This cooling is small relative to other regional proxy records and may reflect the influence of internal oceanic and atmospheric circulation. Simulations with an atmospheric general circulation model (AGCM) indicate that the magnitude of cooling estimated by proxy records is consistent with tropical hydrologic proxy records. The original document contains color images. Sponsored in part by NSF grant ATM-033746. Text North Atlantic Defense Technical Information Center: DTIC Technical Reports database |
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Open Polar |
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Defense Technical Information Center: DTIC Technical Reports database |
op_collection_id |
ftdtic |
language |
English |
topic |
Physical and Dynamic Oceanography Atmospheric Physics *VARIATIONS *HYDROGRAPHY *ATLANTIC OCEAN *CLIMATE *OCEAN SURFACE CALIBRATION OCEANS OSCILLATION CIRCULATION GULF STREAM STRONTIUM ATMOSPHERE MODELS COMPUTERIZED TOMOGRAPHY PATTERNS HEATING COOLING ATMOSPHERIC MOTION CORAL THESES SST(SEA SURFACE TEMPERATURE) |
spellingShingle |
Physical and Dynamic Oceanography Atmospheric Physics *VARIATIONS *HYDROGRAPHY *ATLANTIC OCEAN *CLIMATE *OCEAN SURFACE CALIBRATION OCEANS OSCILLATION CIRCULATION GULF STREAM STRONTIUM ATMOSPHERE MODELS COMPUTERIZED TOMOGRAPHY PATTERNS HEATING COOLING ATMOSPHERIC MOTION CORAL THESES SST(SEA SURFACE TEMPERATURE) Saenger, Casey P. Low-Latitude Western North Atlantic Climate Variability During the Past Millennium: Insights from Proxies and Models |
topic_facet |
Physical and Dynamic Oceanography Atmospheric Physics *VARIATIONS *HYDROGRAPHY *ATLANTIC OCEAN *CLIMATE *OCEAN SURFACE CALIBRATION OCEANS OSCILLATION CIRCULATION GULF STREAM STRONTIUM ATMOSPHERE MODELS COMPUTERIZED TOMOGRAPHY PATTERNS HEATING COOLING ATMOSPHERIC MOTION CORAL THESES SST(SEA SURFACE TEMPERATURE) |
description |
Estimates of natural climate variability during the past millennium provide a frame of reference in which to assess the significance of recent changes. This thesis investigates new methods of reconstructing low-latitude sea surface temperature (SST) and hydrography, and combines these methods with traditional techniques to improve the present understanding of western North Atlantic climate variability. A new strontium/calcium (Sr/Ca) - SST calibration is derived for Atlantic Montastrea corals. This calibration shows that Montastrea Sr/Ca is a promising SST proxy if the effect of coral growth is considered. Further analyses of coral growth using Computed Axial Tomography (CAT) imaging indicate growth in Siderastrea corals varies inversely with SST on interannual timescales. A 440-year reconstruction of low-latitude western North Atlantic SST based on this relationship suggests the largest cooling of the last few centuries occurred from ~1650-1730 A.D., and was ~1 deg C cooler than today. Sporadic multidecadal variability in this record is inconsistent with evidence for a persistent 65-80 year North Atlantic SST oscillation. Volcanic and anthropogenic radiative forcing are identified as important sources of externally-forced SST variability, with the latter accounting for most of the 20th century warming trend. An 1800-year reconstruction of SST and hydrography near the Gulf Stream also suggests SSTs remained within about 1 deg C of modern values. This cooling is small relative to other regional proxy records and may reflect the influence of internal oceanic and atmospheric circulation. Simulations with an atmospheric general circulation model (AGCM) indicate that the magnitude of cooling estimated by proxy records is consistent with tropical hydrologic proxy records. The original document contains color images. Sponsored in part by NSF grant ATM-033746. |
author2 |
WOODS HOLE OCEANOGRAPHIC INSTITUTION MA |
format |
Text |
author |
Saenger, Casey P. |
author_facet |
Saenger, Casey P. |
author_sort |
Saenger, Casey P. |
title |
Low-Latitude Western North Atlantic Climate Variability During the Past Millennium: Insights from Proxies and Models |
title_short |
Low-Latitude Western North Atlantic Climate Variability During the Past Millennium: Insights from Proxies and Models |
title_full |
Low-Latitude Western North Atlantic Climate Variability During the Past Millennium: Insights from Proxies and Models |
title_fullStr |
Low-Latitude Western North Atlantic Climate Variability During the Past Millennium: Insights from Proxies and Models |
title_full_unstemmed |
Low-Latitude Western North Atlantic Climate Variability During the Past Millennium: Insights from Proxies and Models |
title_sort |
low-latitude western north atlantic climate variability during the past millennium: insights from proxies and models |
publishDate |
2009 |
url |
http://www.dtic.mil/docs/citations/ADA510965 http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA510965 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
DTIC |
op_relation |
http://www.dtic.mil/docs/citations/ADA510965 |
op_rights |
Approved for public release; distribution is unlimited. |
_version_ |
1766122024224161792 |