The volatility information found in high-frequency exchange rate quotations and in implied volatilities is compared by estimating ARCH models for DM/$ returns. Reuters quotations are used to calculate five-minute returns and hence hourly and daily estimates of realised volatility that can be included in equations for the conditional variances of hourly and daily returns. The ARCH results show t...

Evapotranspiration (ET) is the movement and transfer (i.e., flux) of water as a liquid at the Earth’s surface to the atmosphere as a gas. ET is a combination of open water evaporation and plant transpiration ( , which is the Sublimation transition of solid water (i.e., ice, snow) to vapor due to low atmospheric pressure (i.e., high altitude), dry air and high sunlight, is generally considered s...

The Surface Energy Balance Algorithm for Land (SEBAL) is one of the remote sensing (RS) models that are increasingly being used to determine evapotranspiration (ET). SEBAL is a widely used model, mainly due to the fact that it requires minimum weather data, and also no prior knowledge of surface characteristics is needed. However, it has been observed that it underestimates ET under advective c...

Available energy (often expressed in terms of potential evaporation) and precipitation largely determine annual evapotranspiration and runoff rates in a region. The ratio of annual potential evaporation to precipitation, referred to as the aridity index by Budyko, has been shown to describe the evaporation ratio (the ratio of annual evapotranspiration to precipitation) of catchments from a rang...

A very important factor in the assessment of solar energy resources is the availability of direct irradiance data of high quality. Nevertheless, this quantity is seldom measured and thus must be estimated from measures of global solar irradiance, a quantity that is registered in most radiometric stations. In this work we analyze the results provided by different models in the estimation of hour...

Parameterization of physically based and distributed hydrological models for mesoscale catchments remains challenging because the commonly available data base is insufficient for calibration. In this paper, we parameterize a mesoscale catchment for the distributed model HydroGeoSphere by transferring evapotranspiration parameters calibrated at a highly-equipped headwater catchment in addition t...

A study was carried out in central Italy into the evapotranspiration from linseed (Linum usitatissimum L.). In particular, the objectives were to (a) evaluate the accuracy of daily evapotranspiration estimates from partially incomplete Bowen ratio data; (b) measure seasonal evapotranspiration from linseed; (c) test the FAO 56 method for estimating crop coefficients for linseed and (d) calculate...

Usually the energy balance equation is used to estimate evapotranspiration. To calculating the potential evapotranspiration for long periods of time (more than a day), soil heat flux is assumed equal to zero. But in a catchment, the energy balance equation should be in terms of actual evapotranspiration is less than the potential. In this state, the amount of soil heat flux is not equal to zero...

Analysis is made of the accuracy of magneticobservatory hourly means constructed from definitive minute data having missing values (gaps). Bootstrap sampling from different data-gap distributions is used to estimate average errors on hourly means as a function of the number of missing data. Absolute and relative error results are calculated for horizontal-intensity, declination, and vertical-co...

• Future climate and hydrological variables were simulated at a high resolution. The components of two mesoscale Alpine catchments explored. Snowmelt drives future streamflow changes elevations. Liquid rainfall influences lower Changes to means extremes are elevation season dependent. Mountainous cover broad range elevations their response warming is expected vary significantly in space. Nevert...