Climate variables on the hydrographic basin of Uruçuí Preto River – Piauí, Brazil subsidies for the management of water and agricultural resources

The knowledge of the climatic characteristics of the hydrographic basins, especially regarding the temporal and spatial distribution of rainfall, the relative humidity of the air and the maximum, minimum and average temperatures of the air, which offer important subsidies to the management of water resources and agriculture. The irregular distribution of rainfall indicates instability in the entry of water into the hydrological system, exercising control over water availability in time and space, the relative humidity of the air influences animal and plant behaviors and the amount of water available in the atmosphere. The temperature, on the other hand, influences the evapotranspiration rates, indicating the energy availability of the environment and, consequently, the environmental water demand. The work presents characteristics of the hydrographic basin of the Uruçuí Preto River (BHRUP), in terms of rainfall, relative humidity, temperature, climatological water balance and climatic regimes. The graphs of annual behavior and seasonal regimes elaborated for 25 pluviometric stations distributed in the interior and around the basin, most of them in operation since the 1960s, followed by the elaboration of average isoietas charts and the one of the rainiest semester, relative humidity of the air, isotherms of the maximum, minimum and average temperatures, and of the letters of potential evapotranspiration, real evaporation and water deficit. The climatic types were appreciated due to the influence of the habitual behavior of the atmosphere on the potential and real environmental demand for water and also on the anthropic demand. The Thornthwaite (1948, 1953) climate system was used, based on the comparison between potential evapotranspiration and rainfall.

Estimate of the Wave Climate on the Most Energetic Locations of the South-Southeastern Brazilian Shelf

The wave energy availability has become a field of intensive research around the world. In this sense, this study aims to estimate the wave climate at the most energetic spots on the South-Southeastern Brazilian Shelf (SSBS). To achieve this goal, the sea state model TOMAWAC was used to simulate 18 years of wave conditions on the SSBS. The results showed that the sites at Santa Marta cape and Ilhabela are quite similar, with mean wave height of 1.4 m and period of 8.5 s along the climatological year. Farol island, on the other hand, showed higher averages, of 1.7 m and 8.9 s for wave height and period, respectively. The annual behavior of the wave parameters showed greater stability at Santa Marta cape and Ilhabela, and less at Farol island. The mean wave power yield at the Santa Marta cape and Ilhabela is nearly 10 kW/m and at Farol island, 15 kW/m. A wavelet analysis pointed that the most energetic events are those with periods of occurrence from 6 to 12 days, with the apex at 7 days. The wavelet analysis also showed that the most energetic spectrum is the one at Farol island, with 2.5 times the energy of the other locations at the period band of 7 days.

ANÁLISE DOS EFEITOS DO DÉFICIT HÍDRICO NA RESPOSTA TEMPORAL DO ÍNDICE DE VEGETAÇÃO POR DIFERENÇA NORMALIZADA (NDVI) NO ESTADO DO AMAZONAS

Vegetation indices derived by remote sensing can help identify occurrence of drought on a regional scale. The Normalized Difference Vegetation Index (NDVI) has been widely used in vegetation monitoring, with promising results. This study aims to identify the patterns of temporal response of NDVI in relation to occurrence of deficit/surplus water to different regions of the Amazon biome, as well as understand its seasonal and inter-annual cycles. Therefore, data from five weather stations of the National Institute of Meteorology (INMET) and a set of orbital data of EFAI-NDVI were used. The study period covers the years 1982 to 1990. The results indicate that the response of NDVI to the occurrence of drought is one month in all regions. In the case of water surplus, that response varies from one to four months. Seasonally, the highest NDVI values occur after the rainy season in the region and the lowest values occurring after the dry season. On inter-annual behavior, the NDVI decreases in El Niño years and rises in La Niña years.

Planetary wave seasonality from meteor wind measurements at 7.4° S and 22.7° S

In this study we have used wind observation data from the mesosphere and lower thermosphere (MLT) region, obtained from meteor radar measurements in São João do Cariri (7.4° S, 36.5° W) from July 2004 to December 2008 and in Cachoeira Paulista (22.7° S, 45.0° W) from January 2002 to July 2006 and from September 2007 to November 2008. From the spectral analysis it was possible to identify the presence of planetary-scale oscillations in the hourly winds for the two latitudes and to study their transient character, which allowed elaboration of a climatology of planetary oscillation signatures. Planetary waves with periods near 2-days, 6–7 days, and 16 days were focussed on in this study. The quasi-2-day waves in the meteoric winds showed a seasonal cycle, with intense amplitudes occurring after the austral summer solstice and extending until the end of the season. The vertical wavelengths of the 2-day wave over Cachoeira Paulista were larger than those at São João do Cariri. A possible modulation of the quasi-2-day wave amplitudes by the quasi-biennial oscillation (QBO) has been observed only at São João do Cariri. The 6–7 day oscillations presented more intense amplitudes during August–November but were present with lower amplitudes during March–April at both sites. The 6–7 day vertical wavelengths over São João do Cariri were larger than at Cachoeira Paulista. The 6–7 day amplitudes exhibited intra-seasonal and annual behavior, however, there was no clear evidence of QBO modulation. The 16-day oscillations showed a seasonal cycle at São João do Cariri, with amplifications from austral spring to mid-summer and weaker amplitudes from autumn until early winter, however, there was no clear seasonality over Cachoeira Paulista. The 16-day vertical wavelengths have assumed values of λz ~ 45–85 km over both sites. 16-day wave amplitudes at the two sites showed different long-term behaviors.