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@Article{CostaMachKumm:2018:ExMiRa,
               author = "Costa, Izabelly Carvalho da and Machado, Luiz Augusto Toledo and 
                         Kummerow, Christian",
          affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto 
                         Nacional de Pesquisas Espaciais (INPE)} and {Colorado State 
                         University}",
                title = "An examination of microwave rainfall retrieval biases and their 
                         characteristics over the Amazon",
              journal = "Atmospheric Research",
                 year = "2018",
               volume = "213",
                pages = "323--330",
                month = "Nov.",
             keywords = "Satellite rainfall estimation, Passive microwave rainfall 
                         estimation, Satellite rainfall estimation errors.",
             abstract = "Estimates of surface precipitation obtained from passive microwave 
                         sensors over land are closely related to the ice path present in 
                         the clouds. However, there are cloud types without any ice or with 
                         an ice layer not thick enough to justify the associated rainfall. 
                         For these cloud types, the precipitation is not estimated 
                         correctly, causing an underestimation of the precipitation. On the 
                         other hand, there are cases of deep clouds, in which the signal 
                         produced by ice scattering is not effectively associated with 
                         precipitation, producing, in turn, an overestimate of rainfall. 
                         This study analyzes cases that have large errors in the rainfall 
                         estimates obtained from passive microwave data to better 
                         understand and potentially mitigate these biases. This study uses 
                         data from the Tropical Rainfall Measuring Mission (TRMM) 
                         satellite, specifically the Precipitation Radar (PR), TRMM 
                         Microwave Imager (TMI) and Lightning Imaging Sensor (LIS). Ten 
                         years of TRMM data (2002\−2011) are used in the analysis. 
                         The study area is approximately 1,110,000\ km2, centered on 
                         the city of Manaus in the Amazon region. The error distribution 
                         resembled a Gaussian distribution. The error population was then 
                         divided into three categories, one class denominated as 
                         consistent, in the center of the distribution (20 percentile to 80 
                         percentile), and the others two, as under- and over-estimated 
                         populations, representing the tails of the distribution. For 
                         under- and over-estimated categories, the vertical structure of 
                         the clouds was evaluated. The underestimation error is correlated 
                         with almost all cloud properties (rain rate, cloud top, Liquid 
                         Water path (LWP), Ice Water Path (IWP), polarization and 
                         Polarization Corrected Temperature at 85 GHZ (PCT85)) while the 
                         overestimation error is only function of the IWP. The use of 
                         combinations of low and high frequency channels was able to 
                         identify some characteristics associated with under- and 
                         over-estimated cases. A high positive difference between the 
                         10\ GHz and 85\ GHz as well as 19\ GHz 
                         85\ GHz is characteristic of very high scattering at 
                         85\ GHz (high amount of ice) and small liquid water amounts 
                         corresponding to cases that are often overestimated by the 
                         radiometer. On the other hand, underestimated cases have smaller 
                         ice particles that are not sensitive to the high frequency 
                         microwaves channels measured by TMI. These results open potential 
                         new avenues to improve the quality of passive microwave rainfall 
                         estimates.",
                  doi = "10.1016/j.atmosres.2018.06.011",
                  url = "http://dx.doi.org/10.1016/j.atmosres.2018.06.011",
                 issn = "0169-8095",
             language = "en",
           targetfile = "costa_examination.pdf",
        urlaccessdate = "29 nov. 2020"
}


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