TY - JOUR A1 - Gadêlha, André N. A1 - Coelho, Victor Hugo R. A1 - Xavier, Alexandre C. A1 - Barbosa, Luís Romero A1 - Melo, Davi C. D. A1 - Xuan, Yunqing A1 - Huffman, George J. A1 - Petersen, Walt A. A1 - Almeida, Cristiano das Neves T1 - Grid box-level evaluation of IMERG over Brazil at various space and time scales JF - Atmospheric Research N2 - Rainfall data from the Global Precipitation Measurement (GPM) mission provide a new source of information with high spatiotemporal resolution that overcomes the limitations of ground-based rainfall information worldwide. This study evaluates the performance of the Integrated multi-satellitE Retrievals for GPM (IMERG) Final Run product over Brazil by means of multi-temporal and -spatial analyses. The assessment of the IMERG Final Run product is based on six statistics obtained for the period between January-December 2016 (daily, monthly, and annual basis). The analysis consisted of comparing the satellite-based estimates against a ground-based gridded rainfall product created using daily records from 4911 rain gauges distributed throughout Brazil. Overall, the results show that the IMERG product can effectively capture the spatial patterns of rainfall across Brazil. However, the IMERG product presents a slight tendency in overestimating the ground-based rainfall at all timescales. Furthermore, the performance of the satellite product varies throughout the region. The higher errors and biases are found in the North and Central-West regions, but the low density of rain gauges in those regions can be a source of large deviations between IMERG estimates and observations. A large underestimation of the IMERG data is evident along the coastal zone of the North-east region, probably due to the inability of the passive microwave and infrared sensors to detect warm-rain processes over land. This study shows that the IMERG product can be a good source of rainfall data to complement the ground precipitation measurements in most of Brazil, although some uncertainties are found and need to be further studied KW - Gridded rainfall KW - Global precipitation measurement KW - Final run KW - Performance Y1 - 2018 U6 - https://doi.org/10.1016/j.atmosres.2018.12.001 SN - 0169-8095 SN - 1873-2895 VL - 218 SP - 231 EP - 244 PB - Elsevier CY - New York ER - TY - JOUR A1 - Barbosa, Luis Romero A1 - de Lira, Nicholas Borges A1 - Rabelo Coelho, Victor Hugo A1 - Bernard Passerat de Silans, Alain Marie A1 - Gadelha, Andre Nobrega A1 - Almeida, Cristiano das Neves T1 - Stability of Soil Moisture Patterns Retrieved at Different Temporal Resolutions in a Tropical Watershed JF - Revista brasileira de ciencias do solo N2 - Above and underground hydrological processes depend on soil moisture (SM) variability, driven by different environmental factors that seldom are well-monitored, leading to a misunderstanding of soil water temporal patterns. This study investigated the stability of the SM temporal dynamics to different monitoring temporal resolutions around the border between two soil types in a tropical watershed. Four locations were instrumented in a small-scale watershed (5.84 km(2)) within the tropical coast of Northeast Brazil, encompassing different soil types (Espodossolo Humiluvico or Carbic Podzol, and Argissolo Vermelho-Amarelo or Haplic Acrisol), land covers (Atlantic Forest, bush vegetation, and grassland) and topographies (flat and moderate slope). The SM was monitored at a temporal resolution of one hour along the 2013-2014 hydrological year and then resampled a resolutions of 6 h, 12 h, 1 day, 2 days, 4 days, 7 days, and 15 days. Descriptive statistics, temporal variability, time-stability ranking, and hierarchical clustering revealed uneven associations among SM time components. The results show that the time-invariant component ruled SM temporal variability over the time-varying parcel, either at high or low temporal resolutions. Time-steps longer than 2 days affected the mean statistical metrics of the SM time-variant parcel. Additionally, SM at downstream and upstream sites behaved differently, suggesting that the temporal mean was regulated by steady soil properties (slope, restrictive layer, and soil texture), whereas their temporal anomalies were driven by climate (rainfall) and hydrogeological (groundwater level) factors. Therefore, it is concluded that around the border between tropical soil types, the distinct behaviour of time-variant and time-invariant components of SM time series reflects different combinations of their soil properties. KW - soil moisture variability KW - time-domain reflectometry KW - temporal resolution KW - Carbic Podzol KW - Haplic Acrisol Y1 - 2019 U6 - https://doi.org/10.1590/18069657rbcs20180236 SN - 0100-0683 VL - 43 PB - Sociedade Brasileira de Ciencia do Solo CY - Vicosa ER - TY - JOUR A1 - Barbosa, Luis Romero A1 - Almeida, Cristiano das Neves A1 - Rabelo Coelho, Victor Hugo A1 - Freitas, Emerson da Silva A1 - Galvao, Carlos de Oliveira A1 - de Araujo, Jose Carlos T1 - Sub-hourly rainfall patterns by hyetograph type under distinct climate conditions in Northeast of Brazil BT - a comparative inference of their key properties BT - uma inferência comparativa das suas principais propriedades JF - RBRH Revista Brasileira de Recursos Hídricos Brazilian Journal of Water Resources N2 - The lack of process-based classification procedures may lead to unrealistic hyetograph design due to complex oscillation of rainfall depths when assimilated at high temporal resolutions. Four consecutive years of sub-hourly rainfall data were assimilated in three study areas (Guaraira, GEB, Sao Joao do Cariri, CEB, and Aiuaba, AEB) under distinct climates (very hot semi-arid and tropical wet). This study aimed to define rainfall events (for Minimum Inter-event Time, MIT, and Minimum Rainfall Depth, MRD, equal to 30 min and 1.016 mm, respectively), classify their hyetograph types (rectangular, R, unimodal with left-skewed, UL, right-skewed, UR, and centred peaks, UC, bimodal, B, and shapeless, SL), and compare their key rainfall properties (frequency, duration, depth, rate and peak). A rain pulse aggregation process allowed for reshaping SL-events for six different time spans varying from 2 to 30 min. The results revealed that the coastal area held predominantly R-events (64% events and 49% rainfall depth), in western semi-arid prevailed UL-events (57% events and 63% rainfall depth), whereas in eastern semi-arid mostly were R-events (61% events and 30% rainfall depth) similar to coastal area. It is concluded that each cloud formation type had important effects on hyetograph properties, differentiating them even within the same climate. N2 - A falta de procedimentos de classificação baseados em processos pode levar a uma projeção irreal de hietogramas devido à complexa oscilação das lâminas precipitadas quando assimiladas em altas resoluções temporais. Quatro anos consecutivos de dados pluviográficos sub-horários foram assimilados em três áreas de estudo (Guaraíra, GEB, São João do Cariri, CEB, e Aiuaba, AEB) sob climas distintos (semiárido muito quente e tropical úmido). O objetivo deste estudo foi definir os eventos chuvosos (para Tempo Mínimo entre Eventos, MIT, e Altura Mínima de Precipitação, MRD, iguais a 30 min e 1.016 mm, respectivamente), classificar seus tipos de hietograma (retangular, R, unimodal com pico oblíquo à esquerda, UL, oblíquo à direita, UR, e centrado, UC, bimodal, B, e disforme, SL), e comparar suas principais propriedades de precipitação (frequência, duração, altura, taxa e pico). Um processo de agregação de pulsos de precipitação permitiu remodelar os eventos SL para seis períodos de tempo variando de 2 a 30 min. Os resultados revelaram que a área costeira possuía predominantemente eventos R (64% de eventos e 49% de lâmina precipitada), no semiárido ocidental prevaleceram os eventos UL (57% de eventos e 63% de lâmina precipitada), enquanto no semiárido oriental a maioria foram os eventos R (61% de eventos e 30% de lâmina precipitada) semelhante à área costeira. Conclui-se que cada tipo de formação de nuvens teve efeitos importantes sobre as propriedades dos hietogramas, diferenciando-os até dentro do mesmo clima. T2 - Padrões sub-horários da precipitação por tipo de hietograma em condições climáticas distintas no Nordeste do Brasil KW - Rainfall event KW - MIT KW - MRD KW - Hyetograph classification KW - Northeast of Brazil Y1 - 2018 U6 - https://doi.org/10.1590/2318-0331.231820180076 SN - 1414-381X SN - 2318-0331 VL - 23 PB - Associação Brasileira de Recursos Hídricos CY - Porto Alegre ER -