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Spatial and temporal variability of rainfall in eastern Amazon during the rainy season.

Ferreira DB, de Souza EB, de Moraes BC, Meira Filho LG - ScientificWorldJournal (2015)

Bottom Line: Empirical orthogonal functions (EOF) and composites analysis were employed on pentad data in order to investigate the tropical atmospheric-ocean patterns over the Atlantic Ocean and the spatial-temporal characteristics of the rainfall in eastern Amazon during the peak of the rainy season (February to April).The EOF results evidenced that the Intertropical Convergence Zone (ITCZ) is the main rainfall-producing system in eastern Amazon during the rainy season.Conditions associated with the southward SST gradient in the intertropical Atlantic formed the dynamic patterns that favored the position of the ITCZ to south of the equator, thus explaining the predominance of positive precipitation anomalies in eastern Amazon, especially in the state of Maranhão and northeastern Pará during the February and April months.

View Article: PubMed Central - PubMed

Affiliation: Vale Institute of Technology, Boaventura da Silva Street 955, 66055-090 Belém, PA, Brazil ; Post-Graduate Program in Environmental Sciences, Federal University of Pará, Augusto Corrêa Street 1, 66075-110 Belém, PA, Brazil.

ABSTRACT
Empirical orthogonal functions (EOF) and composites analysis were employed on pentad data in order to investigate the tropical atmospheric-ocean patterns over the Atlantic Ocean and the spatial-temporal characteristics of the rainfall in eastern Amazon during the peak of the rainy season (February to April). The EOF results evidenced that the Intertropical Convergence Zone (ITCZ) is the main rainfall-producing system in eastern Amazon during the rainy season. Conditions associated with the southward SST gradient in the intertropical Atlantic formed the dynamic patterns that favored the position of the ITCZ to south of the equator, thus explaining the predominance of positive precipitation anomalies in eastern Amazon, especially in the state of Maranhão and northeastern Pará during the February and April months.

No MeSH data available.


Related in: MedlinePlus

As in Figure 4, but for April composites, corresponding to the objectively selected events in the EOF1.
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fig6: As in Figure 4, but for April composites, corresponding to the objectively selected events in the EOF1.

Mentions: The OLR anomalies and the streamlines at 200 hPa are shown in Figure 6(a). It is observed that BH appears further northward compared to the previous months composites (anticyclonic circulation over Mato Grosso in 15°S and 058°W) and a diffluence wind at 05°S latitude, connected to the ITCZ movement in high levels. The OLR pattern shows an area of deep convection in the subtropical Atlantic, containing negative anomalies ranging between −15 W/m2 and −30 W/m2 (blue colors). Associated with these dynamic conditions, the trend is that there is greater amount of convective clouds; consequently, most of the significant volumes of rainfall are observed in eastern Amazon. Looking at Figure 6(b), the 925 hPa wind, a convergence region can be seen between 00° and 05°S latitudes. Regarding the composite of the SST anomalies, it is verified negative values over the subtropical North Atlantic, which were responsible for intensifying the northeast trade winds and, thus, move the ITCZ band to the Southern Hemisphere. On the other hand, the positive anomalies positioned over the south subtropical Atlantic weaken the southeastern trade winds.


Spatial and temporal variability of rainfall in eastern Amazon during the rainy season.

Ferreira DB, de Souza EB, de Moraes BC, Meira Filho LG - ScientificWorldJournal (2015)

As in Figure 4, but for April composites, corresponding to the objectively selected events in the EOF1.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4352512&req=5

fig6: As in Figure 4, but for April composites, corresponding to the objectively selected events in the EOF1.
Mentions: The OLR anomalies and the streamlines at 200 hPa are shown in Figure 6(a). It is observed that BH appears further northward compared to the previous months composites (anticyclonic circulation over Mato Grosso in 15°S and 058°W) and a diffluence wind at 05°S latitude, connected to the ITCZ movement in high levels. The OLR pattern shows an area of deep convection in the subtropical Atlantic, containing negative anomalies ranging between −15 W/m2 and −30 W/m2 (blue colors). Associated with these dynamic conditions, the trend is that there is greater amount of convective clouds; consequently, most of the significant volumes of rainfall are observed in eastern Amazon. Looking at Figure 6(b), the 925 hPa wind, a convergence region can be seen between 00° and 05°S latitudes. Regarding the composite of the SST anomalies, it is verified negative values over the subtropical North Atlantic, which were responsible for intensifying the northeast trade winds and, thus, move the ITCZ band to the Southern Hemisphere. On the other hand, the positive anomalies positioned over the south subtropical Atlantic weaken the southeastern trade winds.

Bottom Line: Empirical orthogonal functions (EOF) and composites analysis were employed on pentad data in order to investigate the tropical atmospheric-ocean patterns over the Atlantic Ocean and the spatial-temporal characteristics of the rainfall in eastern Amazon during the peak of the rainy season (February to April).The EOF results evidenced that the Intertropical Convergence Zone (ITCZ) is the main rainfall-producing system in eastern Amazon during the rainy season.Conditions associated with the southward SST gradient in the intertropical Atlantic formed the dynamic patterns that favored the position of the ITCZ to south of the equator, thus explaining the predominance of positive precipitation anomalies in eastern Amazon, especially in the state of Maranhão and northeastern Pará during the February and April months.

View Article: PubMed Central - PubMed

Affiliation: Vale Institute of Technology, Boaventura da Silva Street 955, 66055-090 Belém, PA, Brazil ; Post-Graduate Program in Environmental Sciences, Federal University of Pará, Augusto Corrêa Street 1, 66075-110 Belém, PA, Brazil.

ABSTRACT
Empirical orthogonal functions (EOF) and composites analysis were employed on pentad data in order to investigate the tropical atmospheric-ocean patterns over the Atlantic Ocean and the spatial-temporal characteristics of the rainfall in eastern Amazon during the peak of the rainy season (February to April). The EOF results evidenced that the Intertropical Convergence Zone (ITCZ) is the main rainfall-producing system in eastern Amazon during the rainy season. Conditions associated with the southward SST gradient in the intertropical Atlantic formed the dynamic patterns that favored the position of the ITCZ to south of the equator, thus explaining the predominance of positive precipitation anomalies in eastern Amazon, especially in the state of Maranhão and northeastern Pará during the February and April months.

No MeSH data available.


Related in: MedlinePlus