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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

Time series of the PC coefficients associated with (a) EOF1 February, (b) EOF2 March, and (c) EOF1 April. The PCs in black with threshold below −1 standard deviation for February and March and above +1 standard deviation for April represent ITCZ events selected for each pentad.
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fig3: Time series of the PC coefficients associated with (a) EOF1 February, (b) EOF2 March, and (c) EOF1 April. The PCs in black with threshold below −1 standard deviation for February and March and above +1 standard deviation for April represent ITCZ events selected for each pentad.

Mentions: Figure 3 shows the PC time series corresponding to the EOF1 for February, EOF2 for March, and EOF1 for April, in which high temporal variability of the EOF patterns during 1981 to 2010 period is observed. Black bars in Figure 3 show significant PC values. The area with positive eigenvectors in February and March with significant negative PC (less than −1 standard deviation) represents events OLR associated with intensified ITCZ convective activity, while in April the negative eigenvectors with significant positive PC (greater than +1 standard deviation) represent the same events. Thus, it was possible to select objectively the events associated with the ITCZ in each month of the years studied. Table 1 enumerates the pentads in each month selected by the criteria abovementioned with total of 29 events for February and also in March and 35 events for April. These events will be used in the composites analyses to follow.


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)

Time series of the PC coefficients associated with (a) EOF1 February, (b) EOF2 March, and (c) EOF1 April. The PCs in black with threshold below −1 standard deviation for February and March and above +1 standard deviation for April represent ITCZ events selected for each pentad.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig3: Time series of the PC coefficients associated with (a) EOF1 February, (b) EOF2 March, and (c) EOF1 April. The PCs in black with threshold below −1 standard deviation for February and March and above +1 standard deviation for April represent ITCZ events selected for each pentad.
Mentions: Figure 3 shows the PC time series corresponding to the EOF1 for February, EOF2 for March, and EOF1 for April, in which high temporal variability of the EOF patterns during 1981 to 2010 period is observed. Black bars in Figure 3 show significant PC values. The area with positive eigenvectors in February and March with significant negative PC (less than −1 standard deviation) represents events OLR associated with intensified ITCZ convective activity, while in April the negative eigenvectors with significant positive PC (greater than +1 standard deviation) represent the same events. Thus, it was possible to select objectively the events associated with the ITCZ in each month of the years studied. Table 1 enumerates the pentads in each month selected by the criteria abovementioned with total of 29 events for February and also in March and 35 events for April. These events will be used in the composites analyses to follow.

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