@InProceedings{ObregónNobr:2006:RaVaEn,
               author = "Obreg{\'o}n, Guillermo Oswaldo and Nobre, Carlos fonso",
          affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto 
                         Nacional de Pesquisas Espaciais (INPE)}",
                title = "Rainfall variability at the end of the dry season over the 
                         Southern Amazon Basin",
            booktitle = "Proceedings...",
                 year = "2006",
               editor = "Vera, Carolina and Nobre, Carlos",
                pages = "679--682",
         organization = "International Conference on Southern Hemisphere Meteorology and 
                         Oceanography, 8. (ICSHMO).",
            publisher = "American Meteorological Society (AMS)",
              address = "45 Beacon Hill Road, Boston, MA, USA",
             keywords = "Southern Amazon Basin, rainfall variability, Amazonian forest 
                         fires.",
             abstract = "The last few years witnessed a lively discussion about the 
                         meteorological impact of the observed smoke from Amazonian forest 
                         fires along the smoke plumes. It seems that biomass burning 
                         aerosol impact on cloud formation and microphysical processes may 
                         be of importance mostly at the end of the dry season and beginning 
                         of the wet season. The aim of this study is to analyze daily and 
                         weekly historical rainfall time series for stations located along 
                         the smoke plume over Southern Amazonia in search of trends that 
                         could be attribute to biomass burning effects. Daily rainfall time 
                         series longer than 30 years of records for August- September from 
                         four rainfall gauges distributed around southern Amazon basin are 
                         analyzed. During the earlier part of the record, biomass burning 
                         was not extensive as opposed to the later part of the record. The 
                         Empirical Mode Decomposition (EMD) and their related marginal 
                         spectrum are used to determine oscillatory components of the 
                         rainfall variability that would help finding possible mechanisms 
                         related to large scale global circulation or to the impact of the 
                         smoke from Amazon fires on rainfall. An interesting observation 
                         made in this regard that shed some light on the way precipitation 
                         pattern has behaved in terms of both the wet spells and the 
                         frequency intensities from small to intense ones, along the period 
                         studied, is the strong inter-annual modulation. The cumulative 
                         rainfall during the two months of each year along all the recorded 
                         data shows similar pattern. Other analyses reveal a rather low 
                         reliability of rainfall in all the rainfall stations and in both 
                         months August and September. The oscillatory components of the 
                         monthly rainfall reveal common features of inter-annual 
                         variability. The first mode appears as a mixture of quasi-biennial 
                         oscillation and frequencies related to the ENSO phenomenon. Other 
                         modes are related to the quasi-decadal and bi-decadal 
                         oscillations. The slowest varying mode (residue) seems to 
                         represent the rainfall long term trend. With exception of 
                         Jaragu{\'a} in September, the rainfall trend for all the rainfall 
                         stations and in both months August and September is positive. 
                         Notwithstanding the small number of stations utilized in the 
                         analysis, the results indicate that, if biomass burning smoke 
                         effects are present in Southern Amazonia at the end of the dry 
                         season inhibiting rainfall, those effects may be masked by large 
                         scale controls over rainfall producing mechanisms. That would call 
                         for detailed experimental plans to single out the possible effect 
                         of smoke on rainfall over Amazonia.",
  conference-location = "Foz do Igua{\c{c}}u",
      conference-year = "24-28 Apr. 2006",
           copyholder = "SID/SCD",
             language = "en",
         organisation = "American Meteorological Society (AMS)",
                  ibi = "cptec.inpe.br/adm_conf/2005/10.31.20.51",
                  url = "http://urlib.net/ibi/cptec.inpe.br/adm_conf/2005/10.31.20.51",
           targetfile = "679-682.pdf",
                 type = "Human influences on climate",
        urlaccessdate = "30 abr. 2024"
}