author = "Oliveira J{\'u}nior, Jos{\'e} Francisco de and Gois, Givanildo 
                         de and Terassi, Paulo Miguel de Bodas and Silva J{\'u}nior, 
                         Carlos Antonio da and Blanco, Cl{\'a}udio Jos{\'e} Cavalcante 
                         and Sobral, Bruno Serafini and Gasparini, Kaio Allan Cruz",
          affiliation = "{Universidade Federal de Alagoas (UFAL)} and {Universidade Federal 
                         Fluminense (UFF)} and {Universidade de S{\~a}o Paulo (USP)} and 
                         {Universidade do Estado de Mato Grosso (UNEMAT)} and {Universidade 
                         Federal do Par{\'a} (UFPA)} and {Universidade Federal Fluminense 
                         (UFF)} and {Instituto Nacional de Pesquisas Espaciais (INPE)}",
                title = "Drought severity based on the SPI index and its relation to the 
                         ENSO and PDO climatic variability modes in the regions North and 
                         Northwest of the State of Rio de Janeiro - Brazil",
              journal = "Atmospheric Research",
                 year = "2018",
               volume = "212",
                pages = "91--105",
                month = "Nov.",
             keywords = "Drought monitoring, Statistical indexes, Precipitation, Climatic 
                         extremes, Interannual variability, Oceanic Niño index.",
             abstract = "Drought severity in regions North and Northwest of Rio de Janeiro 
                         state (SRJ) was evaluated using the Standardized Precipitation 
                         Index (SPI) for the monthly (SPI-1) and annual (SPI-12) scales, as 
                         well as its relationship with El Niño - Southern Oscillation 
                         (ENSO) and Pacific Decadal Oscillation (PDO). Data of 14 rainfall 
                         stations from a time series considering the period of 19672013 was 
                         used. The SPI calculation was based on the SCI package available 
                         at R software version 3.4.2 library. SPI categories used are Very 
                         Dry, Moderately Dry and Extremely Dry associated with the hot and 
                         cold phases of the PDO, followed by ENSO events according to the 
                         Oceanic Niño index (ONI) in El Niño region 3.4 using an 
                         interaction matrix. The matrix was evaluated by the coefficients 
                         of Kendall (\τ), Sperman (\ρ), Pearson (r) and R2 
                         determination, followed by Willmott's concordance index (d), 
                         Standard Error of Estimation (SEE) and Student's t-test. The 
                         intense activity of La Niña in the cold 1st phase of the PDO 
                         increased rainfall with greater intensity in the Northwest region 
                         compared to the North. In the 2nd cold phase of the PDO, the 
                         events of El Niño, La Niña and Neutral years of the ENSO mutually 
                         contribute to the changes in rainfall regime of both regions. The 
                         most frequent SPI categories are Moderately Dry and Extremely Dry. 
                         SPI-1 was efficient in perceiving extreme droughts, while SPI-12 
                         results were not significant in the revealing of extreme droughts. 
                         In addition, there was no relational pattern through statistical 
                         indexes between droughts detected by SPI, ENSO and PDO. 
                         Nevertheless, when ENSO cycles were persistent within both phases 
                         of the PDO, droughts occurred, mainly on the monthly scale.",
                  doi = "10.1016/j.atmosres.2018.04.022",
                  url = "http://dx.doi.org/10.1016/j.atmosres.2018.04.022",
                 issn = "0169-8095",
             language = "en",
           targetfile = "oliveira_drought.pdf",
        urlaccessdate = "29 nov. 2020"