Water balance backward: estimation of annual watershed precipitation and its long-term trend with the help of the calibration-free generalized complementary relationship of evaporation

Watershed-scale annual evapotranspiration (ET) is routinely estimated by a simplified water balance as the difference in catchment precipitation (P) and stream discharge (Q). With recent developments in ET estimation by the calibration-free generalized complementary relationship, the water balance equation is employed to estimate watershed/basin P at an annual scale as ET + Q on the United States (US) Geological Survey’s Hydrologic Unit Code (HUC) 2- and 6-level watersheds over the 1979–2015 period. On the HUC2 level, mean annual PRISM P was estimated with a correlation coefficient (R) of 0.99, relative bias (RB) of zero, root-mean-squared-error (RMSE) of 54 mm yr−1, ratio of standard deviations (RS) of 1.08, and Nash–Sutcliffe efficiency (NSE) of 0.98. On the HUC6 level, R, RS, and NSE hardly changed, RB remained zero, while RMSE increased to 90 mm yr−1. Even the long-term linear trend values were found to be fairly consistent between observed and estimated values with R = 0.97 (0.81), RMSE = 0.63 (1.63) mm yr−1, RS = 0.99 (1.05), NSE = 0.92 (0.59) on the HUC2 and HUC6 (in parentheses) levels. This calibration-free water-balance method demonstrates that annual watershed precipitation can be estimated with an acceptable accuracy from standard atmospheric/radiation and stream discharge data

An explicit harmonic code for black-hole evolution using excision

We describe an explicit in time, finite-difference code designed to simulate black holes by using the excision method. The code is based upon the harmonic formulation of the Einstein equations and incorporates several features regarding the well-posedness and numerical stability of the initial-boundary problem for the quasilinear wave equation. After a discussion of the equations solved and of the techniques employed, we present a series of testbeds carried out to validate the code. Such tests range from the evolution of isolated black holes to the head-on collision of two black holes and then to a binary black hole inspiral and merger. Besides assessing the accuracy of the code, the inspiral and merger test has revealed that individual apparent horizons can touch and even intersect. This novel feature in the dynamics of the marginally trapped surfaces is unexpected but consistent with theorems on the properties of apparent horizons

Estimating spatially distributed monthly evapotranspiration rates by linear transformations of MODIS daytime land surface temperature data

Under simplifying conditions catchment-scale vapor pressure at the drying land surface can be calculated as a function of its watershed-representative temperature (<<i>T<sub>s</sub></i>>) by the wet-surface equation (WSE, similar to the wet-bulb equation in meteorology for calculating the dry-bulb thermometer vapor pressure) of the Complementary Relationship of evaporation. The corresponding watershed ET rate, <ET>, is obtained from the Bowen ratio with the help of air temperature, humidity and percent possible sunshine data. The resulting (<<i>T<sub>s</sub></i>>,<ET>) pair together with the wet-environment surface temperature (<<i>T<sub>ws</sub></i>>) and ET rate (ET<i><sub>w</sub></i>), obtained by the Priestley-Taylor equation, define a linear transformation on a monthly basis by which spatially distributed ET rates can be estimated as a sole function of MODIS daytime land surface temperature, <i>T<sub>s</sub></i>, values within the watershed. The linear transformation preserves the mean which is highly desirable. <<i>T<sub>ws</sub></i>>, in the lack of significant open water surfaces within the study watershed (Elkhorn, Nebraska), was obtained as the mean of the smallest MODIS <i>T<sub>s</sub></i> values each month. The resulting period-averaged (2000–2007) catchment-scale ET rate of 624 mm/yr is very close to the water-balance derived ET rate of about 617 mm/yr. The latter is a somewhat uncertain value due to the effects of (a) observed groundwater depletion of about 1m over the study period caused by extensive irrigation, and; (b) the uncertain rate of net regional groundwater supply toward the watershed. The spatially distributed ET rates correspond well with soil/aquifer properties and the resulting land use type (i.e. rangeland versus center-pivot irrigated crops)

FT-IR Spectroscopic Studies of Catalysts

The role of FTIR speetroscopy in catalytic studies is briefly discussed and some typical examples are shown. IR spectra of weakly bound hydrogen on PtjSi02 reveal surface heterogeneity; The hydrogen concentration on the surface is described by a Temkin isotherm. Adsorption of unsaturated C6 ring compounds on hydrogen poor Pt/Si02 is essentially a self\u27-hydrogenation process resulting in the formation of cyclohexane and carbon deposit on the metal surface. Chemisorption of n-hexane and benzene on hydrogen-rlch Ni/Si02 surface gives identical spectra under similar conditions. The same phenomenon is established for n-butane and benzene after chemisorption on the hydrogen-poor surface. The infrared and Raman spectra of C.H6 on NijSi02 suggested a symmetry lowering somewhere between C6v and C3v because of the nonplanarity of C6H6and the site symmetry of the surface

Kangaroo Bond Issuance in Australia

The issue of kangaroo bonds (foreign A$-denominated bonds) has become a significant part of the Australian bond market. The Australian experience offers some lessons to other countries interested in developing their domestic bond markets