Abstract The forcing irradiances (downwelling shortwave and longwave irradiances) are the primary drivers of snowmelt; however, in complex terrain, few observations, use estimated irradiances, influence topography elevation all lead to uncertainties these radiative fluxes. impact on simulations snow is evaluated idealized modeling experiments. Two models contrasting complexity, Utah Energy Balance Model (UEB) Snow Thermal (SNTHERM), forced with prescribed errors structure magnitude...

Ultrasonic pulse propagation through the human abdominal wall has been simulated using a model for two-dimensional anatomically realistic tissue cross sections. The time-domain equations wave in medium of variable sound speed and density were discretized to obtain set coupled finite-difference equations. These difference solved numerically two-step MacCormack scheme that is fourth-order accurate space second-order time. inhomogeneous was represented by matrices values. values determined...

Ultrasonic pulse arrival time and energy level variations introduced by propagation through human abdominal wall specimens have been measured. A hemispheric transducer transmitted an ultrasonic that was detected a linear array after section. The translated in the elevation direction to collect data over two-dimensional aperture. Differences between measured waveforms calculated references account for geometric delay spreading were found. Plots of compensated path, maps differences...

Global “dimming” and “brightening,” the decrease subsequent increase in solar downwelling flux reaching surface observed many locations over past several decades, related issues are examined using satellite data from NASA/Global Energy Water Cycle Experiment (GEWEX) Surface Radiation Budget (SRB) product, version 2.8. A 2.51 W m −2 decade −1 dimming is found between 1983 1991, followed by 3.17 brightening 1991 to 1999, returning 5.26 1999–2004 SRB global mean. This results an insignificant...

Abstract As integration of solar power into the national electric grid rapidly increases, it becomes imperative to improve forecasting this highly variable renewable resource. Thus, a team researchers from public, private, and academic sectors partnered develop assess new system, Sun4Cast. The partnership focused on improving decision-making for utilities independent system operators, ultimately resulting in improved stability cost savings consumers. project followed value chain approach...

Abstract The representation of the long-term radiative energy budgets in NASA’s MERRA and MERRA-2 reanalyses has been evaluated, emphasizing changes associated with reanalysis system update. Data from CERES EBAF Edition 2.8 satellite product over 2001–15 were used as a reference. For both MERRA-2, climatological global means most TOA flux terms agree to within ~3 W m −2 EBAF. However, MERRA-2’s all-sky reflected shortwave is ~7 higher than either or EBAF’s, resulting net imbalance −4 . At...

Ultrasonic wavefront distortion produced by transmission through breast tissue specimens was measured in a two-dimensional aperture. Differences arrival time and energy level between the waveforms references that account for geometric delay spreading were calculated. Also calculated waveform similarity factor is decreased from 1.0 changes shape. For nine different specimens, fluctuations had an average (±s.d.) rms value of 66.8 (±12.6) ns associated correlation length 4.3 (±1.1) mm, while...

The relative importance of the fat and muscle layers human abdominal wall in producing ultrasonic wavefront distortion was assessed by means direct measurements. Specimens employed included six whole specimens twelve partial obtained dividing each specimen into a layer. In measurement technique employed, hemispheric transducer transmitted 3.75-MHz pulse through tissue section. received measured linear array translated elevation direction to synthesize two-dimensional aperture. Insertion loss...

A finite-difference time-domain model for ultrasonic pulse propagation through soft tissue has been extended to incorporate absorption effects as well longitudinal-wave in cartilage and bone. This used simulate anatomically detailed representations of chest wall structure. The inhomogeneous is represented by two-dimensional maps determined staining cross sections distinguish between types, digitally scanning the stained sections, mapping each pixel scanned images fat, muscle, connective...

Wavefront propagation through the abdominal wall was simulated using a finite-difference time-domain implementation of linearized wave equations for lossless, inhomogeneous, two-dimensional fluid as well simplified straight-ray model absorbing medium. Scanned images six human cross sections provided data media in simulations. The were mapped into regions fat, muscle, and connective tissue, each which assigned uniform sound speed, density, absorption values. Propagation whole specimen fat...

The process of retrieving cloud optical thickness and effective radius from radiances measured by satellite instruments is simulated to determine the error in both retrieved properties irradiances computed with them. at 0.64 μm 3.7 are for three fields (stratus, stratocumulus, cumulus) generated large eddy simulation models. When overcast pixels assumed horizontal flux neglected retrieval process, domain‐averaged nadir 1% −32% (1% −27%) 0% 67% (0% 63%) solar zenith angle 30° (50°). Using...

Ultrasonic wavefront distortion produced by transmission through human chest wall specimens was measured over a two-dimensional aperture. Measured pulse wavefronts were sometimes disrupted secondary interaction between the transmitted pulses and bone cartilage structures of rib cage. The large distortions in received waveforms interfered with determination caused soft-tissue inhomogeneities. effects minimized reducing region analysis. Differences arrival time energy level these restricted...

Abstract Observations have revealed strong variability of shortwave (SW) irradiance at Earth’s surface on decadal time scales, referred to as global dimming and brightening. Previous studies attributed the brightening changes in clouds atmospheric aerosols. This study assesses influence circulation SW separate “natural” from direct and, some extent, indirect aerosol effects. The focus is northern Europe summer spring because there little high-latitude during winter. As a measure large-scale...

Abstract This paper describes the development and testing of a cloud-regime-dependent short-range solar irradiance forecasting system for predictions 15-min-average clearness index (global horizontal irradiance). regime-dependent artificial neural network (RD-ANN) classifies cloud regimes with k -means algorithm on basis combination surface weather observations, GOES-East satellite data. The ANNs are then trained each regime to predict index. RD-ANN improves over mean absolute error baseline...

Abstract Studies of land surface processes in complex terrain often require estimates meteorological variables, i.e., the incoming solar irradiance ( Q si ), to force models. However, are rarely evaluated within mountainous environments. We four methods estimating : CERES Synoptic Radiative Fluxes and Clouds (SYN) product, MTCLIM, a regional reanalysis product derived from long‐term Weather Research Forecast simulation, Mountain Microclimate Simulation Model (MTCLIM). These products over...

Abstract Many studies involving surface radiative fluxes rely on retrieved by the Clouds and Earth's Radiant Energy System (CERES) project or derived from spaceborne cloud radar lidar observations (CloudSat‐CALIPSO). In particular, most climate models that participated in Coupled Model Intercomparison Project Phase 5 (CMIP5) were found to have too little shortwave (SW) radiation being reflected back space excessive SW reaching over Southern Ocean—an error with significant consequences for...

Global atmospheric energy balance is one of the fundamental processes for earth's climate system. This study uses currently available satellite data sets radiative at top atmosphere (TOA) and surface as well latent sensible heat over oceans year 2000 to assess global annual budget. Over land, radiation are used constrain assimilated results force radiation, turbulent heat, storage into due a lack observation‐based flux estimates. means TOA net obtained from both direct measurements...

Abstract The benefit of using solar and longwave surface irradiance data from NASA’s Clouds the Earth’s Radiant Energy System (CERES) synoptic (SYN) satellite product in simulations snowmelt has been examined. accuracy SYN downwelling irradiances was first assessed by comparison to measurements at NOAA’s Surface Radiation Network (SURFRAD) reference stations remote mountain observations. Typical shortwave (longwave) biases had magnitudes less than 30 (10) W m−2, with most standard deviations...

Abstract. A method for retrieving cloud optical depth (τc) using a UCSD developed ground-based sky imager (USI) is presented. The radiance red–blue ratio (RRBR) motivated from the analysis of simulated images various τc produced by radiative transfer model (RTM). From these basic parameters affecting and (RBR) pixel are identified as solar zenith angle (θ0), τc, angle/scattering (ϑs), angle/view (ϑz). effects described functions radiance, Iλτc, θ0, ϑs, ϑz, RBRτc, ϑz retrieved RTM results....

Time‐series output from the Eta forecast model of National Weather Service's Centers for Environmental Prediction was evaluated by comparison with measured values a location in Oklahoma. The data were drawn archives Department Energy's Atmospheric Radiation Measurement program southern Great Plains site. Surface energy budget components and cloud indicators examined first half 1997. Overall, surface found to be nearly balanced, as intended physics, except one instance when light snowfall...

Abstract Cumulus clouds can become tilted or elongated in the presence of wind shear. Nevertheless, most studies interaction cumulus and radiation have assumed these to be isotropic. This paper describes an investigation effect fair-weather cloud field anisotropy on domain-averaged solar fluxes atmospheric heating rate profiles. A stochastic generation algorithm was used produce 20 three-dimensional liquid water content fields based statistical properties scenes from a large eddy simulation....

Abstract Atmospheric reanalyses are valuable tools for studying the atmosphere, as they provide temporally and spatially complete coverage of atmospheric variables. However, some regions susceptible to large biases in reanalysis products due scarce data available assimilate into reanalyses. Consequently, evaluation using measurements is essential quantifying regional errors. Here we use NASA's CERES satellite estimates evaluate surface radiative fluxes total cloud fraction Northeast Pacific...