author = "Wu, Huanyu and Zou, Yong and Alves, Lincoln Muniz and Macau, 
                         Elbert Einstein Nehrer and Sampaio, Gilvan and Marengo, Jos{\'e} 
          affiliation = "{East China Normal University} and {East China Normal University} 
                         and {Instituto Nacional de Pesquisas Espaciais (INPE)} and 
                         {Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto 
                         Nacional de Pesquisas Espaciais (INPE)} and {Centro Nacional de 
                         Monitoramento e Alertas de Desastres Naturais (CEMADEN)}",
                title = "Uncovering episodic influence of oceans on extreme drought events 
                         in Northeast Brazil by ordinal partition network approaches",
              journal = "Chaos",
                 year = "2020",
               volume = "30",
               number = "5",
                month = "May",
             abstract = "Since 2012, the semiarid region of Northeast Brazil (NEB) has been 
                         experiencing a continuous dry condition imposing significant 
                         social impacts and economic losses. Characterizing the recent 
                         extreme drought events and uncovering the influence from the 
                         surrounding oceans remain to be big challenges. The physical 
                         mechanisms of extreme drought events in the NEB are due to varying 
                         interacting time scales from the surrounding tropical oceans 
                         (Pacific and Atlantic). From time series observations, we propose 
                         a three-step strategy to establish the episodic coupling 
                         directions on intraseasonal time scales from the ocean to the 
                         precipitation patterns in the NEB, focusing on the distinctive 
                         roles of the oceans during the recent extreme drought events of 
                         2012-2013 and 2015-2016. Our algorithm involves the following: (i) 
                         computing drought period length from daily precipitation anomalies 
                         to capture extreme drought events; (ii) characterizing the 
                         episodic coupling delays from the surrounding oceans to the 
                         precipitation by applying the Kullback-Leibler divergence (KLD) of 
                         complexity measure, which is based on ordinal partition transition 
                         network representation of time series; and (iii) calculating the 
                         ratio of high temperature in the ocean during the extreme drought 
                         events with proper time lags that are identified by KLD measures. 
                         From the viewpoint of climatology, our analysis provides 
                         data-based evidence of showing significant influence from the 
                         North Atlantic in 2012-2013 to the NEB, but in 2015-2016, the 
                         Pacific played a dominant role than that of the Atlantic. The 
                         episodic intraseasonal time scale properties are potential for 
                         monitoring and forecasting droughts in the NEB in order to propose 
                         strategies for drought impacts reduction.",
                  doi = "10.1063/5.0004348",
                  url = "http://dx.doi.org/10.1063/5.0004348",
                 issn = "1054-1500",
             language = "en",
           targetfile = "wu_uncovering.pdf",
        urlaccessdate = "17 jan. 2021"