@MastersThesis{Martins:2007:CaMiPr,
author = "Martins, Rafael Castelo Guedes",
title = "Caracteriza{\c{c}}{\~a}o da microf{\'{\i}}sica da
precipita{\c{c}}{\~a}o na regi{\~a}o da Amaz{\^o}nia
utilizando dados de radar e disdr{\^o}metro",
school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
year = "2007",
address = "S{\~a}o Jos{\'e} dos Campos",
month = "2007-03-28",
keywords = "METEOROLOGIA.",
abstract = "A modula{\c{c}}{\~a}o diurna da convec{\c{c}}{\~a}o tem uma
importante influ{\^e}ncia na for{\c{c}}ante radiativa da
cobertura de nuvens, sendo assim um fator de extrema
relev{\^a}ncia no balan{\c{c}}o de radia{\c{c}}{\~a}o da Terra
e na caracteriza{\c{c}}{\~a}o do ciclo diurno da
precipita{\c{c}}{\~a}o descrita pelos modelos de
circula{\c{c}}{\~a}o geral da atmosfera. A
combina{\c{c}}{\~a}o entre diferentes medidas permite descrever
o ciclo diurno da cobertura de nuvens, da precipita{\c{c}}{\~a}o
e das vari{\'a}veis microf{\'{\i}}sicas envolvidas. Este
trabalho {\'e} composto de tr{\^e}s estudos. Inicialmente,
combinando dados de perfis de refletividade de radar e dados de
distribui{\c{c}}{\~a}o de tamanho de gotas, observou-se que
87,22 % das distribui{\c{c}}{\~o}es de gotas apresentaram picos
em 0,5 ou 1,0 ou 2,0 mm. Com isso torna-se vi{\'a}vel a
possibilidade de modelar o ciclo diurno precipita{\c{c}}{\~a}o e
partir da distribui{\c{c}}{\~a}o de gotas associada. Dessa forma
foi ajustada uma fun{\c{c}}{\~a}o gama separadamente para
distribui{\c{c}}{\~o}es m{\'e}dias com pico em 0,5, 1,0 e 2,0
mm. Para essa an{\'a}lise utilizou-se dados de um Radar de
Apontamento Vertical (RAV) e um disdr{\^o}metro do experimento
WET-AMC de 1999. Em um segundo momento analisou-se a
rela{\c{c}}{\~a}o entre a derivada temporal da
varia{\c{c}}{\~a}o da altura do topo das nuvens
{{(\δH/\δt)}} e a componente vertical da velocidade
Doppler. O {{\δH/\δt}} foi calculado a partir da
evolu{\c{c}}{\~a}o de um limiar de 20 dBZ utilizando dados do
RAV. A an{\'a}lise n{\~a}o mostrou uma rela{\c{c}}{\~a}o
linear entre a taxa de varia{\c{c}}{\~a}o da altura do topo e as
velocidades verticais no interior da nuvem. Todavia, essa
an{\'a}lise ainda {\'e} preliminar, sendo necess{\'a}rios
estudos mais detalhados para verificar a rela{\c{c}}{\~a}o entre
esses par{\^a}metros. Em uma {\'u}ltima an{\'a}lise
verificou-se o potencial do {{\δH/\δt}} para uso em
previs{\~a}o imediata. Nessa an{\'a}lise o
{{\δH/\δt}} foi calculado a partir de dados de um
radar Doppler do experimento RACCI de 2002. O
{{\δh/\δt,}} calculado para 20 dBz, mostrou que para
classes com alto valor de {{\δh/\δt,}} acima de 15
m/s, {\'e} poss{\'{\i}}vel prever at{\'e} 30 min um aumento da
precipita{\c{c}}{\~a}o na superf{\'{\i}}cie. Classes
positivas, mas com valores mais baixos de {{\δh/\δt,}}
em torno de 3 m/s, apresentam uma previsibilidade menor. Classes
com {{\δh/\δt}} negativo mostram que a nuvem nos
pr{\'o}ximos 10 minutos tende a diminuir consideravelmente a
precipita{\c{c}}{\~a}o na superf{\'{\i}}cie. ABSTRACT: The
diurnal modulation of the convection has an important role in the
cloud radiative forcing. It is a factor of extreme relevance in
the earth radiation budget and in the characterization of the
diurnal cycle of precipitation simulated by the atmospheric
general circulation models. The combination among different
measurements allows a better description of the diurnal cycle of
many variables such as cloud coverage, precipitation and cloud
microphysics. This work is composed by three studies. Initially,
it was combined reflective radar profiles and drops size
distribution data. The results showed that 87.22 % of drops
distributions had presented peaks in 0.5 or 1.0 or 2.0 mm, making
possible to model the diurnal cycle of precipitation from the DSD.
A Gamma Function was fitted for mean distributions whose peak was
0.5, 1.0 and 2.0 mm. This assignment used data from Microwave
Vertical Profiler and one disdrometer used in the 1999 WET-AMC
experiment. The second step consisted in analyzing the
relationship between the variation of the heights of the cloud top
{{(\δH/\δt)}} and the vertical component of the
Doppler velocity. {{\δH/\δt}} was calculated from the
evolution of a threshold of 20 dBZ using the microwave vertical
profiler. The analysis did not show a linear relation between
{{\δH/\δt}} and velocity in the interior of the cloud.
This work is only a preliminary research, and it is necessary more
studies to verify the relation between those parameters. In a last
analysis the potential of the {{\δH/\δt}} for use in
immediate forecast was verified. In this analysis the
{{\δH/\δt}} was calculated from data from a Doppler
radar used by the 2002 RACCI experiment. The
{{\δH/\δt,}} calculated for 20 dBZ, showed that for
classes with high value of the {{\δH/\δt}} (above of
15 m/s) it is possible to make prediction an increase of the
precipitation in the surface up to 30 min in advance. Positive
classes, but with lower values of the {{\δH/\δt,}}
around 3 m/s, presented poor prediction. Classes with negative
{{\δH/\δt}} show that the cloud tends to considerably
diminish the precipitation in the surface in next the 10
minutes.",
committee = "Satyamurty, Prakki (presidente) and Machado, Luiz Augusto Toledo
(orientador) and Oyama, Marcos Daisuke and Costa, Alexandre
Ara{\'u}jo",
englishtitle = "Characterization of microphisics of the precipitation in Amazon
region using radar and disdrometer data",
language = "pt",
pages = "116",
ibi = "6qtX3pFwXQZGivnK2Y/QCDc6",
url = "http://urlib.net/ibi/6qtX3pFwXQZGivnK2Y/QCDc6",
targetfile = "Rafael Castelo Guedes Martins.pdf",
urlaccessdate = "10 maio 2024"
}