Convecção profunda na Amazônia Central
The Amazon region has the main ingredients for deep convection development: water vapor, instability and convective available potential energy (CAPE). But the march of daytime moist convection in this region is influenced by a complex interation of convective scales ranging from small to large sc...
| Autor principal: | Tanaka, Ludmila Monteiro da Silva |
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| Grau: | Tese |
| Idioma: | por |
| Publicado em: |
Instituto Nacional de Pesquisas da Amazônia - INPA
2020
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| Assuntos: | |
| Acesso em linha: |
https://repositorio.inpa.gov.br/handle/1/12946 http://lattes.cnpq.br/1565865589398547 |
| Resumo: |
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The Amazon region has the main ingredients for deep convection development: water
vapor, instability and convective available potential energy (CAPE). But the march of
daytime moist convection in this region is influenced by a complex interation of convective
scales ranging from small to large scale. The main objective of this research is to understand
the relationship between the moist convective activity and vertical distribution of
water vapor in the Central Amazon. For this, precipitation data of four stations, cloud
top temperature (CTT) and radiosondes were used. This database includes information
from 2006 to 2011. The study area is approximately 4800 km2, centered on the city of
Manaus-AM. Analysis is conducted at four sites, two representative of forest area and two
representative of urban area. The metodology consisted primarily of evaluating seasonal
and diurnal variability of rainfall in terms of intensity and frequency. Subsequently a
classification of deep convection events based on the 95 % percentile of rainfall threshold
values and CTT was realized. From selected events intensity and time of occurrence of
rainfall from deep convection are obtained. Also humidity, temperature and wind profiles
as well as the stability of the atmospheric column are analyzed. The results show that
precipitation in forest areas is 20 % higher than in urban areas, especially in the early
afternoon hours. The frequency of rain events varies with the time of the day, while the
average rainfall intensity does not. For all stations, in the rainy season (NOV-MAY) the
frequency of rainfall is approximately three times higher than in the dry season (JUNOCT)
and the peak of daytime frequency in the afternoon is more pronounced in forest
areas. Higher frequencies in the early morning hours near the river are possibly due to the
effect of river breeze. Approximately 76.3 % of the intense rain events ( 20 mm/hora)
are caused by deep convective events (DCE), which are more frequent in the rainy season
and in forest areas. Among the vertical profiles of the atmosphere, humidity showed
higher differences between DCE and other types of rain and no-rain events, principally in
the 900 to 500 hPa layer. The humidity in this layer is decisive for the occurrence of the
transition from shallow to deep convection. Finally, the CAPE analysis showed that the
thermodynamic instability is not a limiting factor for the occurrence of deep convection,
but for most less deep convective events (LDCE) and DCE it must be greater than 1000
J.kg��1, while for the shallow convective events (SCE) it always showed values less than
2500 J.kg��1. |