Banca de DEFESA: FELIPE JEFERSON DE MEDEIROS

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : FELIPE JEFERSON DE MEDEIROS
DATE: 28/08/2024
TIME: 08:00
LOCAL: Auditorio do CCET
TITLE:

ASSESSMENT AND PROJECTION OF CLIMATE EXTREMES OF PRECIPITATION IN BRAZIL WITH CMIP MODEL GENERATIONS

KEY WORDS:

Climate indices, extreme events, climate change, IPCC.

PAGES: 145
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUBÁREA: Meteorologia
SPECIALTY: Climatologia
SUMMARY:

The occurrence of extreme climate events usually causes numerous economic and social losses, especially in vulnerable and low adaptive capacity areas, such as Brazil. Despite these aspects and verifying that extreme events are becoming increasingly frequent, intense and long-lasting few studies have investigated this subject in Brazil, and most of them rarely ever evaluate the climate projections. In this context, the main goal of this study is to evaluate the performance of the Coupled Model Intercomparison Project (CMIP) models in simulate the extreme climate events of precipitation and assess their projected changes for Brazil. Within this scope, several General Circulation Models (GCMs) from different generations of CMIP have been used. With the daily data from some of these models, the number of dry (DD - absolute threshold of less than 1 mm) and heavy rainfall days (HRD – rainfall above the 99th percentile) over NEB in the historical period (1981–2005) and their climate projections for the near (2016–2040) and far future (2076– 2100) under three Shared Socioeconomic Pathways (SSP2-4.5, SSP3-7.0 and SSP5-8.5) scenarios were investigated. The results indicate that four (three) models show an overall superior performance in reproducing the dry (heavy rainfall) days, being common in both aspects only the EC-EARTH3. Thus, the skill of the CMIP6 models for NEB varies according to the extreme rainfall conditions analyzed. For the future climate (near and far), results show that dry days are project to increase over the entire NEB territory, especially during DJF and MAM and more pronounce in the east coast, with projections that these conditions will be more severe under the SSP5-8.5 scenario. The number of dry days may increase up to 15%. For HRD, although the results indicate that the number of days with heavy precipitation will be more frequent in the future (the increase can exceed 140%), the analysis show that under the low (SSP2-4.5) or intermediate (SSP3-7.0) forcing scenarios the HRD tends to be higher than in the most pessimistic scenario (SSP5-8.5). In short, this initial part of the study has shown that it might either rain too much within a short range of time or the water scarcity will be longer-lasting in the future in NEB. It was also found that the evolution of the CMIP models has apparently not improved the representation of climate extremes over the NEB. In order to investigate this aspect in more detail, this subject was investigated deeply in the second part of the study, expanding the analysis to the whole of Brazil territory, analyzing a greater number of extreme precipitation climate indices - this time those suggested by the Expert Team on Climate Change Detection and Indices (ETCCDI) - and using models from all generations of CMIP. In this case, eight extreme climate indices were calculated for the period 1981-2005 and the projections for the middle (2046-2065) and far future (2081-2100) were evaluated, considering the worst-case scenario for each CMIP generation (SRES A2, RCP8-5 and SSP5-8.5). For that, four statistical metrics were used: Percent Bias (PBIAS), RMSE-observations standard deviation ratio (RSR), refined index of agreement (dr) and Pearson correlation coefficient (CORR). Furthermore, the comprehensive model rank (Mr rank) was applied to analyze whether the evolution of the CMIP models provided an improvement in the simulation of extreme climate events. Results reveal that CDD are the most challenging precipitation index to be simulated, while the best ones were PRCPTOT and R20mm. The model performance shows that CMIP3 has the best skill for Northeast Brazil, CMIP5 for Center-West, and CMIP6 for North, Southeast and South regions. Thus, at least for Brazil, the evolution of the ESMs from CMIP did not reflect a substantial improvement in the representation of precipitation climate extremes over all Brazilian regions. In addition, all the models across CMIP generations have difficulty in simulating the observed trends. This indicate that improvements are still needed in CMIP models. Despite the relative low performance in the historical climate, the climate projections indicate a consensus signal among most of precipitation climate extremes and CMIP generations, which increase its reliability. Overall, the extreme precipitation events are projected to be more severe, frequent, and long-lasting in all Brazilian regions, with the more pronounce changes expected in heavy rainfall and severe droughts in the central northern portion of Brazil and in the southern sector.

COMMITTEE MEMBERS:
Presidente - 1280761 - CRISTIANO PRESTRELO DE OLIVEIRA
Interno - 1752417 - CLAUDIO MOISES SANTOS E SILVA
Externo à Instituição - ALVARO JAVIER AVILA DIAZ - URosario
Externa à Instituição - MARIA LEIDINICE DA SILVA - ICTP
Externo à Instituição - WANDERSON LUIZ SILVA - UFRJ