The quest for the solar g modes

Solar gravity modes (or g modes) -- oscillations of the solar interior for which buoyancy acts as the restoring force -- have the potential to provide unprecedented inference on the structure and dynamics of the solar core, inference that is not possible with the well observed acoustic modes (or p modes). The high amplitude of the g-mode eigenfunctions in the core and the evanesence of the modes in the convection zone make the modes particularly sensitive to the physical and dynamical conditions in the core. Owing to the existence of the convection zone, the g modes have very low amplitudes at photospheric levels, which makes the modes extremely hard to detect. In this paper, we review the current state of play regarding attempts to detect g modes. We review the theory of g modes, including theoretical estimation of the g-mode frequencies, amplitudes and damping rates. Then we go on to discuss the techniques that have been used to try to detect g modes. We review results in the literature, and finish by looking to the future, and the potential advances that can be made -- from both data and data-analysis perspectives -- to give unambiguous detections of individual g modes. The review ends by concluding that, at the time of writing, there is indeed a consensus amongst the authors that there is currently no undisputed detection of solar g modes.Comment: 71 pages, 18 figures, accepted by Astronomy and Astrophysics Revie

Determinação da equação intensidade-duração-frequência para três estações meteorológicas do Estado de Mato Grosso Determination of the intensity-duration-frequency equation for three meteorological stations in Mato Grosso State

Objetivou-se, com este trabalho, determinar a equação intensidade-duração-frequência para três estações meteorológicas pertencentes à rede hidrometeorológica do Instituto Nacional de Meteorologia (INMET), no Estado de Mato Grosso (Cáceres, Cuiabá e Rondonópolis) utilizando-se as metodologias de análise de pluviogramas, desagregação de chuvas de 24 h e de Bell e comparar as estimativas da intensidade de precipitação aplicando-se as equações obtidas através dessas metodologias. Dados pluviográficos e pluviométricos foram utilizados para obtenção da equação de chuvas intensas. As séries históricas de intensidades máximas médias de precipitação, correspondentes às diversas durações, foram submetidas à análise estatística a fim de identificar o modelo probabilístico que apresentasse melhor ajuste aos dados, sendo esta identificação realizada utilizando-se o teste de aderência de Kolmogorov-Smirnov a nível de significância de 5%. O método da Desagregação não só apresentou melhor desempenho global (ERM = 27%) em comparação ao de Bell (ERM = 31%), como possui melhor desempenho em estações com séries mais longas mostrando-se, assim, mais sensível ao tamanho da série em relação ao método de Bell.<br>The main objective of this study was to determine the intensity-duration-frequency equation for three meteorological stations (Cáceres, Cuiabá and Rondonópolis) belonging to the hydrometeorological network of the National Institute of Meteorology (INMET) in Mato Grosso using the methodologies of pluviograms analysis, daily rain disaggregation and Bell, as well as comparing the estimates of intensity of precipitation by applying the equations obtained through these methodologies. Pluviometric and pluviographic data were used to obtain intense precipitation equation. The historical series of average maximum intensity of precipitation, corresponding to the different durations were submitted to statistical analysis to identify the probabilistic model that presented best fit for the data, this identification being performed using the adherence test of Kolmogorov-Smirnov at 5% level of significance. The methodology of the Disaggregation not only presented better overall performance (ERM = 27%) in comparison to the one of Bell (ERM = 31%), as it has better performance in stations with longer series, revealing, thus, more sensitive to the size of the series in relation to the Bell's method

Equações de chuvas intensas para o estado do Pará Intense rainfall equations for the state of Pará, Brazil

As equações de chuvas intensas têm sido usadas como ferramenta importante para o dimensionamento de obras hidráulicas. Devido à grande carência de informações relativas às equações de chuvas intensas, o presente trabalho teve como objetivo a obtenção das relações de intensidade, duração e frequência de precipitação pluvial para o Estado do Pará, utilizando-se a metodologia da desagregação da chuva de 24 h. Foram utilizadas séries históricas de dados pluviométricos de 74 cidades do Estado do Pará, obtidas no Sistema de Informações Hidrológicas da Agência Nacional de Águas-ANA. As equações de intensidade-duração-frequência foram devidamente ajustadas e apresentaram bom ajuste, com coeficientes de determinação acima de 0,99. A maioria das estações (51,4%) apresentou intensidade de precipitação entre 90 e 110 mm h-1, para uma duração de chuva de 30 min e um tempo de retorno de 15 anos. Pode-se perceber uma concentração das maiores precipitações na região próxima ao litoral do nordeste paraense e no sudeste da Ilha do Marajó.<br>The intense rainfall equations have been used as an important tool for design of hydraulic structures. Considering the lack of intense rainfall equations, this study aimed to determine the relations of intensity, duration and frequency of intense rainfall in the Pará State (Brazil), using the one-day rain disaggregation method. In this research rainfall data of 74 cities in the State of Pará were used, obtained from the Hydrological Information System of the National Water Agency-ANA. The equations of intensity-duration-frequency were adjusted and presented good adjustment with coefficients of determination above 0.99. Most stations (51.4%) showed intensity of precipitation between 90 and 110 mm h-1 for duration of 30 min and rainfall return period of 15 years. The highest rainfall intensities were in the region near the northeast coast of Pará State and southeast of the Marajo Island

Realization, calibrations and spatialization of ß-(Al)Ga₂O₃ UVC Photodetectors of Extreme Solar Blindness for Space Observations

International audienceThere is a surge in interest for the ultra wide bandgap (Eg ~ 4.9 eV) semiconductor gallium oxide (Ga 2 O 3). A key driver for this boom is that single crystal wide area bulk β-Ga 2 O 3 substrates have become commercially available and that a variety of methods have been shown to give high quality epitaxial growth. Amongst a whole range of potential applications (power/switching electronics, solar transparent electrodes, etc.) extreme solar blindness photodetectors in β-Ga 2 O 3 , the more stable monoclinic phase of Ga 2 O 3 , offer the most exciting perspectives for deep ultraviolet observations of the Herzberg continuum (200-242 nm) in Space. We present an overview of the complete realization process (epitaxy, photolithography, singulation and packaging), performances evaluation and spatialization of a serie of β-(Al)Ga 2 O 3 photodetecteurs developed (slight Al alloying to enhance ultraviolet response below 253 nm), space qualified and selected for flight on the INSPIRE-SAT 7 nanosatellite (launch planned in early 2023)