Annual, orbital, and enigmatic variations in tropical oceanography recorded by the Equatorial Atlantic amplifier
Equatorial Atlantic surface waters respond directly to changes in zonal and meridional lower tropospheric winds forced by annual insolation. This mechanism has its maximum effect along the equatorial wave guide centered on 10 deg W. The result is to amplify even subtle tropical climate changes such...
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ftnasantrs:oai:casi.ntrs.nasa.gov:19930009781 2023-05-15T16:30:23+02:00 Annual, orbital, and enigmatic variations in tropical oceanography recorded by the Equatorial Atlantic amplifier Mcintyre, Andrew Unclassified, Unlimited, Publicly available Dec 1, 1992 http://ntrs.nasa.gov/search.jsp?R=19930009781 unknown http://ntrs.nasa.gov/search.jsp?R=19930009781 Accession ID: 93N18970 No Copyright Other Sources 46 NASA. Goddard Space Flight Center, Orbital, Rotational and Climatic Interactions; p 7 1992 ftnasantrs 2012-02-15T19:48:05Z Equatorial Atlantic surface waters respond directly to changes in zonal and meridional lower tropospheric winds forced by annual insolation. This mechanism has its maximum effect along the equatorial wave guide centered on 10 deg W. The result is to amplify even subtle tropical climate changes such that they are recorded by marked amplitude changes in the proxy signals. Model realizations, NCAR AGCM and OGCM for 0 Ka and 126 Ka (January and July), and paleoceanographic proxy data show that these winds are also forced by insolation changes at the orbital periods of precession and obliquity. Perhelion in boreal summer produces a strengthened monsoon, e.g., increase meridional and decrease zonal wind stress. This reduces oceanic Ekman divergence and thermocline/nutricline shallowing. The result, in the equatorial Atlantic, is reduced primary productivity and higher euphotic zone temperatures; vice versa for perihelion in boreal winter. Perihelion is controlled by precession. Thus, the dominant period in spectra from a stacked SST record (0-252 Ka BP) at the site of the equatorial Atlantic amplifier is 23 Ky (53 percent of the total variance). This precessional period is coherent (k = 0.920) and in phase with boreal summer insolation. Oscillations of shorter period are present in records from cores sited beneath the amplifier region. These occur between 12.5 and 74.5 Ka BP, when eccentricity modulation of precession is at a minimum. Within this time interval there are 21 cycles with mean periods of 3.0 plus or minus 0.5 Ky. Similar periods have been documented from high latitude regions, e.g., Greenland ice cores from Camp Century. The Camp Century signal in this same time interval contains 21 cycles. A subjective correlation was made between the Camp Century and the equatorial records; the signals were statistically similar, r = 0.722 and k = 0.960. Other/Unknown Material Greenland Greenland ice cores NASA Technical Reports Server (NTRS) Greenland |
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46 Mcintyre, Andrew Annual, orbital, and enigmatic variations in tropical oceanography recorded by the Equatorial Atlantic amplifier |
topic_facet |
46 |
description |
Equatorial Atlantic surface waters respond directly to changes in zonal and meridional lower tropospheric winds forced by annual insolation. This mechanism has its maximum effect along the equatorial wave guide centered on 10 deg W. The result is to amplify even subtle tropical climate changes such that they are recorded by marked amplitude changes in the proxy signals. Model realizations, NCAR AGCM and OGCM for 0 Ka and 126 Ka (January and July), and paleoceanographic proxy data show that these winds are also forced by insolation changes at the orbital periods of precession and obliquity. Perhelion in boreal summer produces a strengthened monsoon, e.g., increase meridional and decrease zonal wind stress. This reduces oceanic Ekman divergence and thermocline/nutricline shallowing. The result, in the equatorial Atlantic, is reduced primary productivity and higher euphotic zone temperatures; vice versa for perihelion in boreal winter. Perihelion is controlled by precession. Thus, the dominant period in spectra from a stacked SST record (0-252 Ka BP) at the site of the equatorial Atlantic amplifier is 23 Ky (53 percent of the total variance). This precessional period is coherent (k = 0.920) and in phase with boreal summer insolation. Oscillations of shorter period are present in records from cores sited beneath the amplifier region. These occur between 12.5 and 74.5 Ka BP, when eccentricity modulation of precession is at a minimum. Within this time interval there are 21 cycles with mean periods of 3.0 plus or minus 0.5 Ky. Similar periods have been documented from high latitude regions, e.g., Greenland ice cores from Camp Century. The Camp Century signal in this same time interval contains 21 cycles. A subjective correlation was made between the Camp Century and the equatorial records; the signals were statistically similar, r = 0.722 and k = 0.960. |
format |
Other/Unknown Material |
author |
Mcintyre, Andrew |
author_facet |
Mcintyre, Andrew |
author_sort |
Mcintyre, Andrew |
title |
Annual, orbital, and enigmatic variations in tropical oceanography recorded by the Equatorial Atlantic amplifier |
title_short |
Annual, orbital, and enigmatic variations in tropical oceanography recorded by the Equatorial Atlantic amplifier |
title_full |
Annual, orbital, and enigmatic variations in tropical oceanography recorded by the Equatorial Atlantic amplifier |
title_fullStr |
Annual, orbital, and enigmatic variations in tropical oceanography recorded by the Equatorial Atlantic amplifier |
title_full_unstemmed |
Annual, orbital, and enigmatic variations in tropical oceanography recorded by the Equatorial Atlantic amplifier |
title_sort |
annual, orbital, and enigmatic variations in tropical oceanography recorded by the equatorial atlantic amplifier |
publishDate |
1992 |
url |
http://ntrs.nasa.gov/search.jsp?R=19930009781 |
op_coverage |
Unclassified, Unlimited, Publicly available |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland Greenland ice cores |
genre_facet |
Greenland Greenland ice cores |
op_source |
Other Sources |
op_relation |
http://ntrs.nasa.gov/search.jsp?R=19930009781 Accession ID: 93N18970 |
op_rights |
No Copyright |
_version_ |
1766020110536933376 |