author = "Moreira, Andreise and Fontana, Denise Cybis and Kuplich, Tatiana 
          affiliation = "{Universidade Federal do Rio Grande do Sul (UFRGS)} and 
                         {Universidade Federal do Rio Grande do Sul (UFRGS)} and {Instituto 
                         Nacional de Pesquisas Espaciais (INPE)}",
                title = "Wavelet approach applied to EVI/MODIS time series and 
                         meteorological data",
              journal = "ISPRS Journal of Photogrammetry and Remote Sensing",
                 year = "2019",
               volume = "147",
                pages = "335--344",
                month = "Jan.",
             abstract = "The aim of this study was to describe the phenology of different 
                         types of grasslands from the Pampa and Mata Atl{\^a}ntica biomes 
                         in the southern region of Brazil and its relation with 
                         meteorological variables, in a time series of EVI/MODIS data using 
                         the Wavelet approach (Transform WT - and Coherence - WC). There is 
                         a lack of studies focusing on how climate variability influences 
                         the phenology of different Brazilian Pampa grassland typologies. 
                         This information is essential to describe the spatio-temporal 
                         dynamics of grasslands and contribute to actions of sustainable 
                         management and conservation strategies, threatened by crops, 
                         forestry, and expansion of overgrazed cattle farms. A series of 
                         EVI/MODIS acquired from February 2000 to December 2014, totaling 
                         342 images, were sampled for each of the 10 grassland typologies 
                         at the study area. Mean EVI data and the WT indicated when and 
                         where changes in the grassland phenological dynamics occurred. The 
                         WC, applied to the EVI/MODIS time series with (i) rainfall and 
                         (ii) air temperature, helped to identify the correlation between 
                         the data. Two well - defined cycles were identified: annual, 
                         ranging from 1 to 23 observations, and interannual, from 92 to 184 
                         observations. The different grassland typologies showed similar 
                         phenological patterns, although some spatial dependency was 
                         observed and related to the different soil and terrain morphometry 
                         at the study area. The influence of those abiotic factors on the 
                         grassland vegetation, phenological events and their expression on 
                         the EVI was also spatially dependent and strongly linked to 
                         weather conditions (e.g., the permanence of humidity after 
                         rainfall in shallow soils) and climate. The correlation between 
                         EVI and air temperature was stronger in the annual cycle for all 
                         grassland typologies. For the interannual cycles, El Niņo and La 
                         Niņa events caused higher correlation between EVI data and 
                  doi = "10.1016/j.isprsjprs.2018.11.024",
                  url = "http://dx.doi.org/10.1016/j.isprsjprs.2018.11.024",
                 issn = "0924-2716",
             language = "en",
           targetfile = "moreira_wavelet.pdf",
        urlaccessdate = "28 nov. 2020"