Easterly Wave Disturbances over Northeast Brazil: An Observational Analysis
This paper aims to identify the circulation associated with Easterly Wave Disturbances (EWDs) that propagate toward the Eastern Northeast Brazil (ENEB) and their impact on the rainfall over ENEB during 2006 and 2007 rainy seasons (April–July). The EWDs identification and trajectory are analyzed usin...
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| Format: | Article |
| Language: | English |
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Wiley
2015-01-01
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| Series: | Advances in Meteorology |
| Online Access: | http://dx.doi.org/10.1155/2015/176238 |
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| author | Helber Barros Gomes Tércio Ambrizzi Dirceu Luís Herdies Kevin Hodges Bruce Francisco Pontes da Silva |
| author_facet | Helber Barros Gomes Tércio Ambrizzi Dirceu Luís Herdies Kevin Hodges Bruce Francisco Pontes da Silva |
| author_sort | Helber Barros Gomes |
| collection | DOAJ |
| description | This paper aims to identify the circulation associated with Easterly Wave Disturbances (EWDs) that propagate toward the Eastern Northeast Brazil (ENEB) and their impact on the rainfall over ENEB during 2006 and 2007 rainy seasons (April–July). The EWDs identification and trajectory are analyzed using an automatic tracking technique (TracKH). The EWDs circulation patterns and their main features were obtained using the composite technique. To evaluate the TracKH efficiency, a validation was done by comparing the EWDs number tracked against observed cases obtained from an observational analysis. The mean characteristics of EWDs are 5.5-day period, propagation speed of ~9.5 m·s−1, and a 4500 km wavelength. A synoptic analysis shows that between days −2 d and 0 d, the low level winds presented cyclonic relative vorticity and convergence anomalies both in 2006 and 2007. The EWDs signals are strongest at low levels. The EWDs propagation is associated with relative humidity and precipitation positive anomalies and OLR and omega negative anomalies. The EWDs tracks are seen over all ENEB and their lysis occurs between the ENEB and marginally inside the continent. The tracking captured 71% of EWDs in all periods, indicating that an objective analysis is a promising method for EWDs detection. |
| format | Article |
| id | doaj-art-6d0e1fa5d4914ac7ab1e16f9612d0b22 |
| institution | Kabale University |
| issn | 1687-9309 1687-9317 |
| language | English |
| publishDate | 2015-01-01 |
| publisher | Wiley |
| record_format | Article |
| series | Advances in Meteorology |
| spelling | doaj-art-6d0e1fa5d4914ac7ab1e16f9612d0b222025-02-03T00:59:28ZengWileyAdvances in Meteorology1687-93091687-93172015-01-01201510.1155/2015/176238176238Easterly Wave Disturbances over Northeast Brazil: An Observational AnalysisHelber Barros Gomes0Tércio Ambrizzi1Dirceu Luís Herdies2Kevin Hodges3Bruce Francisco Pontes da Silva4Institute of Astronomy, Geophysics and Atmospheric Sciences, University of São Paulo, 05508-090 São Paulo, SP, BrazilInstitute of Astronomy, Geophysics and Atmospheric Sciences, University of São Paulo, 05508-090 São Paulo, SP, BrazilCPTEC-INPE, 12630-000 Cachoeira Paulista, SP, BrazilNERC Centre for Earth Observation, University of Reading, Reading RG6 6BB, UKCapixaba Institute of Research, Technical Assistance and Rural Extension, 29052-010 Vitoria, ES, BrazilThis paper aims to identify the circulation associated with Easterly Wave Disturbances (EWDs) that propagate toward the Eastern Northeast Brazil (ENEB) and their impact on the rainfall over ENEB during 2006 and 2007 rainy seasons (April–July). The EWDs identification and trajectory are analyzed using an automatic tracking technique (TracKH). The EWDs circulation patterns and their main features were obtained using the composite technique. To evaluate the TracKH efficiency, a validation was done by comparing the EWDs number tracked against observed cases obtained from an observational analysis. The mean characteristics of EWDs are 5.5-day period, propagation speed of ~9.5 m·s−1, and a 4500 km wavelength. A synoptic analysis shows that between days −2 d and 0 d, the low level winds presented cyclonic relative vorticity and convergence anomalies both in 2006 and 2007. The EWDs signals are strongest at low levels. The EWDs propagation is associated with relative humidity and precipitation positive anomalies and OLR and omega negative anomalies. The EWDs tracks are seen over all ENEB and their lysis occurs between the ENEB and marginally inside the continent. The tracking captured 71% of EWDs in all periods, indicating that an objective analysis is a promising method for EWDs detection.http://dx.doi.org/10.1155/2015/176238 |
| spellingShingle | Helber Barros Gomes Tércio Ambrizzi Dirceu Luís Herdies Kevin Hodges Bruce Francisco Pontes da Silva Easterly Wave Disturbances over Northeast Brazil: An Observational Analysis Advances in Meteorology |
| title | Easterly Wave Disturbances over Northeast Brazil: An Observational Analysis |
| title_full | Easterly Wave Disturbances over Northeast Brazil: An Observational Analysis |
| title_fullStr | Easterly Wave Disturbances over Northeast Brazil: An Observational Analysis |
| title_full_unstemmed | Easterly Wave Disturbances over Northeast Brazil: An Observational Analysis |
| title_short | Easterly Wave Disturbances over Northeast Brazil: An Observational Analysis |
| title_sort | easterly wave disturbances over northeast brazil an observational analysis |
| url | http://dx.doi.org/10.1155/2015/176238 |
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