Banca de DEFESA: JOELMA MAYARA DA SILVA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : JOELMA MAYARA DA SILVA
DATE: 28/02/2025
TIME: 09:30
LOCAL: https://meet.google.com/yvr-esyh-bwr
TITLE:

Analysis of nonlinear dynamics from precipitation and drought indices in Pernambuco using the horizontal visibility graph

KEY WORDS:

Precipitation, Horizontal Visibility Graph, Standardized Precipitation Index.

PAGES: 46
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUMMARY:

Recent climate changes driven by global warming have altered precipitation patterns across multiple regions of the planet. Droughts and floods have become more frequent, particularly in tropical countries how to Brazil. In this context, this study aims to analyze the dynamics of precipitation and the Standardized Precipitation Index (SPI) in the Pernambuco state. For this, the Horizontal Visibility Graph (HVG) method was applied. Particularly, the study utilized the Clustering Coefficient (C), the Average Shortest Path Length (L), and the slope of the semi-logarithmic degree distribution (λ). The HVG was applied to time series of precipitation (originals and anomaly) and the Standardized Precipitation Index at 1, 3, 6, and 12 month scales, using data from five representative stations across Pernambuco’s mesoregions: Metropolitan Region (Recife), Zona da Mata (Vitória de Santo Antão), Agreste (Jucati), Sertão Pernambucano (Serrita), and Sertão São Francisco (Petrolina), in the period from 1962 to 2012. The calculated indices enabled the identification of similarities and differences in the rainfall generating processes across the state's mesoregions, allowing for the distinction between chaotic and stochastic regions based on the λ coefficient. Additionally, the results revealed variations in the connectivity (C) and integration (L) properties of the networks derived from precipitation and anomaly series. A similar pattern was observed for the Standardized Precipitation Index, indicating distinct behaviors across different temporal scales (1, 3, 6, and 12 months). Furthermore, 133 rainfall stations distributed throughout Pernambuco were analyzed over the same period and grouped into three climatic regions: Zona da Mata (humid climate), Agreste (transition zone), and Sertão (semi-arid climate). The Mann-Kendall test was employed to assess significant differences among these regions based on the calculated indices. The test confirmed significant differences in the C and L indices but failed to distinguish the climatic regions significantly based on the λ coefficient, for both precipitation and anomaly series. Thus, the analysis of topological indices derived from the constructed networks provides valuable insights into the processes governing precipitation and the Standardized Precipitation Index.

COMMITTEE MEMBERS:
Interno - ANTONIO SAMUEL ALVES DA SILVA
Presidente - BORKO STOSIC
Externo à Instituição - JOSÉ DOMINGOS ALBUQUERQUE AGUIAR - IFPE
Interno - LUCIAN BOGDAN BEJAN
Externo à Instituição - SILVIO FERNANDO ALVES XAVIER JUNIOR - UEPB