Interannual Variability of Boreal Summer Rainfall in the Equatorial Atlantic
Tropical Atlantic rainfall patterns and variation during boreal summer [June-July-August (JJA)] are quantified by means of a 28-year (1979-2006) monthly precipitation dataset from the Global Precipitation Climatology Project (GPCP). Rainfall variability during boreal spring [March-April-May (MAM)] i...
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ftnasantrs:oai:casi.ntrs.nasa.gov:20080045467 2023-05-15T17:30:42+02:00 Interannual Variability of Boreal Summer Rainfall in the Equatorial Atlantic Adler, Robert F. Gu, Guojun Unclassified, Unlimited, Publicly available August 2007 application/pdf http://hdl.handle.net/2060/20080045467 unknown Document ID: 20080045467 http://hdl.handle.net/2060/20080045467 Copyright, Distribution as joint owner in the copyright CASI Meteorology and Climatology 2007 ftnasantrs 2019-07-21T06:40:45Z Tropical Atlantic rainfall patterns and variation during boreal summer [June-July-August (JJA)] are quantified by means of a 28-year (1979-2006) monthly precipitation dataset from the Global Precipitation Climatology Project (GPCP). Rainfall variability during boreal spring [March-April-May (MAM)] is also examined for comparison in that the most intense interannual variability is usually observed during this season. Comparable variabilities in the Intertropical Convergence Zone (ITCZ) strength and the basin-mean rainfall are found during both seasons. Interannual variations in the ITCZ's latitudinal location during JJA however are generally negligible, in contrasting to intense year-to-year fluctuations during MAM. Sea surface temperature (SST) oscillations along the equatorial region (usually called the Atlantic Nino events) and in the tropical north Atlantic (TNA) are shown to be the two major local factors modulating the tropical Atlantic climate during both seasons. During MAM, both SST modes tend to contribute to the formation of an evident interhemispheric SST gradient, thus inducing anomalous shifting of the ITCZ and then forcing a dipolar structure of rainfall anomalies across the equator primarily in the western basin. During JJA the impacts however are primarily on the ITCZ strength likely due to negligible changes in the ITCZ latitudinal location. The Atlantic Nino reaches its peak in JJA, while much weaker SST anomalies appear north of the equator in JJA than in MAM, showing decaying of the interhemispheric SST mode. SST anomalies in the tropical central-eastern Pacific (the El Nino events) have a strong impact on tropical Atlantic including both the tropical north Atlantic and the equatorial-southern Atlantic. However, anomalous warming in the tropical north Atlantic following positive SST anomalies in the tropical Pacific disappears during JJA because of seasonal changes in the large-scale circulation cutting off the ENSO influence passing through the mid-latitudes. Hence the anomalies associated with the tropical Pacific during JJA are forced through an anomalous Walker circulation primarily working on the western basin, and likely a lagged oceanic response in the equatorial region. Other/Unknown Material North Atlantic NASA Technical Reports Server (NTRS) Pacific Western Basin |
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Open Polar |
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NASA Technical Reports Server (NTRS) |
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ftnasantrs |
language |
unknown |
topic |
Meteorology and Climatology |
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Meteorology and Climatology Adler, Robert F. Gu, Guojun Interannual Variability of Boreal Summer Rainfall in the Equatorial Atlantic |
topic_facet |
Meteorology and Climatology |
description |
Tropical Atlantic rainfall patterns and variation during boreal summer [June-July-August (JJA)] are quantified by means of a 28-year (1979-2006) monthly precipitation dataset from the Global Precipitation Climatology Project (GPCP). Rainfall variability during boreal spring [March-April-May (MAM)] is also examined for comparison in that the most intense interannual variability is usually observed during this season. Comparable variabilities in the Intertropical Convergence Zone (ITCZ) strength and the basin-mean rainfall are found during both seasons. Interannual variations in the ITCZ's latitudinal location during JJA however are generally negligible, in contrasting to intense year-to-year fluctuations during MAM. Sea surface temperature (SST) oscillations along the equatorial region (usually called the Atlantic Nino events) and in the tropical north Atlantic (TNA) are shown to be the two major local factors modulating the tropical Atlantic climate during both seasons. During MAM, both SST modes tend to contribute to the formation of an evident interhemispheric SST gradient, thus inducing anomalous shifting of the ITCZ and then forcing a dipolar structure of rainfall anomalies across the equator primarily in the western basin. During JJA the impacts however are primarily on the ITCZ strength likely due to negligible changes in the ITCZ latitudinal location. The Atlantic Nino reaches its peak in JJA, while much weaker SST anomalies appear north of the equator in JJA than in MAM, showing decaying of the interhemispheric SST mode. SST anomalies in the tropical central-eastern Pacific (the El Nino events) have a strong impact on tropical Atlantic including both the tropical north Atlantic and the equatorial-southern Atlantic. However, anomalous warming in the tropical north Atlantic following positive SST anomalies in the tropical Pacific disappears during JJA because of seasonal changes in the large-scale circulation cutting off the ENSO influence passing through the mid-latitudes. Hence the anomalies associated with the tropical Pacific during JJA are forced through an anomalous Walker circulation primarily working on the western basin, and likely a lagged oceanic response in the equatorial region. |
author |
Adler, Robert F. Gu, Guojun |
author_facet |
Adler, Robert F. Gu, Guojun |
author_sort |
Adler, Robert F. |
title |
Interannual Variability of Boreal Summer Rainfall in the Equatorial Atlantic |
title_short |
Interannual Variability of Boreal Summer Rainfall in the Equatorial Atlantic |
title_full |
Interannual Variability of Boreal Summer Rainfall in the Equatorial Atlantic |
title_fullStr |
Interannual Variability of Boreal Summer Rainfall in the Equatorial Atlantic |
title_full_unstemmed |
Interannual Variability of Boreal Summer Rainfall in the Equatorial Atlantic |
title_sort |
interannual variability of boreal summer rainfall in the equatorial atlantic |
publishDate |
2007 |
url |
http://hdl.handle.net/2060/20080045467 |
op_coverage |
Unclassified, Unlimited, Publicly available |
geographic |
Pacific Western Basin |
geographic_facet |
Pacific Western Basin |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
CASI |
op_relation |
Document ID: 20080045467 http://hdl.handle.net/2060/20080045467 |
op_rights |
Copyright, Distribution as joint owner in the copyright |
_version_ |
1766127591007191040 |