Ocean Forcing on Titicaca Lake Water Volume

The time series of water level of Titicaca Lake (TL) was compared to the time series of the Pacific Decadal Oscillation (PDO) and El Niño/Southern Oscillation (ENSO) indexes between 1914 and 2014 and 1969 and 2014, monthly and daily, respectively. Results indicate TL water level decreased (increased) during positive (negative) PDO phases. ENSO positive (negative) phase results were similar. Positive (negative) PDO and ENSO phases yielded negative (positive) precipitation anomalies and concomitant decrease (increase) of TL water level. These long-term relationships among TL water levels and both oceanic indexes can be useful and prognostic.

Statistical Analysis of Precipitation Extremes in São Francisco River Basin, Brazil

This study comprises a climatology of the spatial variability of precipitation over the São Francisco River Basin (SFRB), characterized by its geographic heterogeneity. The different rainfall regimes in the region were analyzed through statistical and spectral analyses. Measured precipitation data, Pacific Decennial Climate indexes, ENSO, Atlantic Multidecadal Oscillation, North Atlantic Oscillation, Atlantic dipole, and the sunspot cycle over 65 years were used. The rainfall data were filtered and filled in using the regional weighting method. The spatial and temporal variability of precipitation along the SFRB is remarkable. A pattern was observed along with the time series of precipitation over the SFRB. The cluster analysis identified four homogeneous regions in the SFRB and explained 87.4% of the total variance of the average monthly rainfall of the 199 rain gauges. The Cross-wavelet analysis identified the relationship between the precipitation data series and the climatic indexes that are analyzed in this work.

TOPMODEL Hydrometeorological Modeling with Rain Gauge Data Integrated by High-Resolution Satellite Estimates. A Case Study in MuriaéRiver Basin, Brazil

This study consists of hydrological simulations of the Muriaé river watershed with the topography-based hydrological model (TOPMODEL) and available stream gauge and rain measurements between 2009 and 2013 for two subbasins, namely Carangola and Patrocínio do Muriaé. The simulations were carried out with the Climate Prediction Center morphing method (CMORPH) precipitation estimates and rain gauge measurements integrated into CM- ORPH by the Statistical Objective Analysis Scheme (SOAS). TOPMODEL calibration was performed with the shuffled complex evolution (SCE-UA) method with Nash-Sutcliffe efficiency (NSE). The best overall results were obtained with CMORPH (NSE ~ 0.6) for both subbasins. The simulations with SOAS resulted in an NSE ~ 0.2. However, in an analysis of days with high- level stages, SOAS simulations resulted in a better hit rate (23%) compared to CMORPH (10%). CMORPH simulations underestimated the flows at the flood periods, which indicates the importance to use multi-sensor precipitation data. The results with TOPMODEL allow an estimate of future discharges, which allows for better planning of a flood warning system and discharge measurement schedule.

Diurnal Cycle of Heating and Water Vapor in the Metropolitan Area of Porto in Portugal

In this work, it is investigated the Urban Heat Island (UHI) using conservative thermodynamic variables observed by surface weather stations on the Metropolitan Area of Porto (Oporto) in Portugal, under adiabatic conditions at the surface. These conditions are usually present and associated with the development of a mixture layer into the diurnal Convective Boundary Layer (CBL), which residual layer in the late afternoon defines the initial state for the development of the nocturnal UHI. Both the spatial structure and temporal variation of potential temperature and specific humidity were considered, along the hours and days of the year, from a statistical point of view, resulting in hourly climatology. Details of the hourly evolution of the meteorological variables on the Oporto surface are presented and discussed. Results show a seasonal variation of the potential temperature up to 17°C throughout the year, which is associated with horizontal thermal gradients that can control and trigger mesoscale circulations such as sea-land, urban and valley-mountain breezes.

The Effect of the Atmospheric and Cloud Properties on the Retrieval of Fog Microphysics at Night for MSG/SEVIRI: A Sensitivity Test Using LibRadtran

The simplest way of building a look-up table (LUT) for the retrieval of cloud microphysical properties is to use a standard atmospheric profile and vertically uniform cloud microphysics. Such an assumption has been demonstrated to be incoherent with in-cloud observations. This paper aims to show the effect of some atmospheric conditions associated with fog as well as its macro-and microstructure on brightness temperature (BT) for the MSG/ SEVIRI satellite using libRadtran. The sensitivity tests were performed by gradually changing some features from the initial data, such as cloud cover, total water vapor column, thermal inversion intensity, fog depth, fog microstructure, and others. The results revealed that some variables can cause significant variations on BT and, consequently, discrepancies in the retrieval of fog microphysical properties. Also, a variation as high as 0.5°C was found on BT just by switching uniform to the non-uniform profile of fog microphysics depending on the channel, the droplet size, and optical thickness.