Influence of oceanic-atmospheric interactions on extreme events of daily rainfall in the Sub-basin 39 located in Northeastern Brazil

Salgueiro, João Hipólito Paiva de Britto; Montenegro, Suzana Maria Gico Lima; Pinto, Eber José de Andrade; Silva, Bernardo Barbosa da; Souza, Werônica Meira de; Oliveira, Leidjane Maria Maciel de

doi:10.1590/2318-0331.011616023

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Scientific/Technical Article • RBRH 21 (4) • Oct-Dec 2016 • https://doi.org/10.1590/2318-0331.011616023 copy

Influence of oceanic-atmospheric interactions on extreme events of daily rainfall in the Sub-basin 39 located in Northeastern Brazil

Influência da interação oceânico-atmosférica nos eventos extremos de precipitação diária na Sub-bacia 39, localizada no Nordeste do Brasil

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

Changes in extreme precipitation have been observed in regions where frequent rainfalls occur over short periods of time followed by prolonged droughts, creating, as a result, new watershed scenarios. Recent studies have attributed such occurrences to possible climate changes. This paper analyzes the correlation between extreme events recorded in the Sub-basin 39, located in Northeastern Brazil, and the anomalies caused by sea surface temperature - SST and the atmospheric systems operating in the region. Pearson correlation coefficients have been used combined with the variables analyzed. For such, trends in precipitation have been obtained by using the method of least squares together with linear regression and the Student's t test. The results obtained have demonstrated that due to the geographical position of the region investigated, both maximum extreme events (areas with positive trends) and minimum extreme events (areas with negative trends) are more dependent on the Dipole Atlantic than on the effects of El Niño Southern Oscillation - ENOS.

Keywords:
Climate change; Maximum precipitation; Minimum precipitation; Influence on TSM

Index	Definition / Unit
PRCPTOT	Total annual precipitation in wet days (mm)
RMedmm	Number of days with greater precipitation than or equal to the median (days)
RX1day	Maximum height precipitation in one day (mm)
RX5day	Maximum Height precipitation in five days (mm)
SDII	Simple index daily intensity (mm)
R10mm	Number of days with precipitation less than 10 mm (days)
R50mm	Number of days with precipitation less than 50 mm (days)
R99p	Total annual precipitation of extremely wet days (mm)
CWD	Maximum number of consecutive wet days (days)

Regionais index	El Niño / Southern Oscillation - Equatorial Pacific Ocean						Atlantic Ocean Dipole
Regionais index	Niño 1+2	Niño 3	Niño 3.4	Niño 4	ION	IOS	TNAI	TSAI
PRCPTOT	-0.167	-0.111	-0.087	-0.026	-0.169	+0.119	-0.227^* ***** Significance level 10%.	+0.213^ Significance level 5%;
RMedmm	-0.182	-0.139	-0.093	+0.012	-0.166	+0.211^* ***** Significance level 10%.	+0.027	+0.280^ Significance level 5%;
Rx1day	-0.125	-0.024	+0.040	+0.161	-0.054	+0.081	+0.113	+0.219^* ***** Significance level 10%.
Rx5day	-0.128	-0.052	+0.001	+0.076	-0.060	+0.124	+0.174	+0.134
SDII	-0.021	+0.026	+0.045	+0.093	-0.034	-0.049	-0.219^* ***** Significance level 10%.	+0.262^ Significance level 5%;
R10mm	-0.169	-0.136	-0.143	-0.090	-0.184	+0.203	-0.188	+0.334^* * Significance level 1%;
R50mm	-0.168	-0.156	-0.130	-0.066	-0.212^* ***** Significance level 10%.	+0.214^* ***** Significance level 10%.	-0.267^* ***** Significance level 10%.	+0.265^ Significance level 5%;
R99P	-0.225^* ***** Significance level 10%.	-0.191	-0.133	-0.031	-0.208	+0.192	-0.012	+0.285^ Significance level 5%;
CWD	+0.090	+0.156	+0.138	+0.244	+0.003	+0.025	+0.200	+0.442^* * Significance level 1%;

Regionais index	El Niño / Southern Oscillation - Equatorial Pacific Ocean						Atlantic Ocean Dipole
Regionais index	Niño 1+2	Niño 3	Niño 3.4	Niño 4	ION	IOS	TNAI	TSAI
PRCPTOT	-0.406^* * Significance level 1%;	-0.330^* * Significance level 1%;	-0.240^* ***** Significance level 10%.	-0.232^* ***** Significance level 10%.	-0.123	+0.188	-0.114	-0.234^* ***** Significance level 10%.
RMedmm	-0.239^* ***** Significance level 10%.	-0.184	-0.127	-0.121	-0.044	+0.076	+0.020	-0.231
Rx1day	-	-	-	-	-	-	-	-
Rx5day	-	-	-	-	-	-	-	-
SDII	-0.303^ Significance level 5%;	-0.262^ Significance level 5%;	-0.183	-0.259^ Significance level 5%;	-0.015	+0.216^* ***** Significance level 10%.	-0.133	-0.399^ Significance level 5%;
R10mm	-0.360^* * Significance level 1%;	-0.296_{* *}	-0.213^* ***** Significance level 10%.	-0.228^* ***** Significance level 10%.	-0.092	+0.120	-0.287^ Significance level 5%;	-0.301^ Significance level 5%;
R50mm	-0.218^* ***** Significance level 10%.	-0.185	-0.149	-0.151	-0.055	+0.106	+0.098	-0.196
R99P	-0.238^* ***** Significance level 10%.	-0.181	-0.130	-0.116	-0.040	+0.081	+0.109	-0.157
CWD	-0.285^ Significance level 5%;	-0.176	-0.097	-0.080	-0.067	+0.012	-0.200	-0.282

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[1] E-mails: joao.salgueiro@cprm.gov.br (JHPBS), suzanam.ufpe@gmail.com (SMGLM), eber.andrade@cprm.gov.br (EJAP), bbdasilva.ufpe@gmail.com (BBS), weronicameira@gmail.com (WMS), leidjaneoliveira@hotmail.com (LMMO)