@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 = "26 abr. 2024"
}