Abstract An important question in regional climate downscaling is whether to constrain (nudge) the interior of limited-area domain toward larger-scale driving fields. Prior research has demonstrated that nudging can increase skill predictions originating from historical data. However, there concern may also inhibit model’s ability properly develop and simulate mesoscale features, which reduce value added by altering representation local extremes. Extreme events result large economic losses...

Abstract This study evaluates interior nudging techniques using the Weather Research and Forecasting (WRF) model for regional climate modeling over conterminous United States (CONUS) a two-way nested configuration. NCEP–Department of Energy Atmospheric Model Intercomparison Project (AMIP-II) Reanalysis (R-2) data are downscaled to 36 km × by only at lateral boundaries, gridpoint (i.e., analysis) spectral nudging. Seven annual simulations conducted evaluated 1988 comparing 2-m temperature,...

ABSTRACT Understanding and predicting complex biological systems are best accomplished through the synthesis integration of information across relevant spatial, temporal thematic scales. We propose that mechanistic transport models, which integrate atmospheric turbulence with on attributes, can effectively incorporate key elements aerial processes at scales ranging from a few centimetres fractions seconds, to hundreds kilometres decades. This capability models is critically important for...

Abstract Numerical models have long predicted that the deforestation of Amazon would lead to large regional changes in precipitation and temperature, but extratropical effects been a matter controversy. This paper investigates simulated impacts on northwest United States December–February climate. Integrations are carried out using Ocean–Land–Atmosphere Model (OLAM), here run as variable-resolution atmospheric GCM, configured with three alternative horizontal grid meshes: 1) 25-km...

Spectral nudging—a scale-selective interior constraint technique—is commonly used in regional climate models to maintain consistency with large-scale forcing while permitting mesoscale features develop the downscaled simulations. Several studies have demonstrated that spectral nudging improves representation of reanalysis-forced simulations compared not using domain. However, Weather Research and Forecasting (WRF) model, tends produce degraded precipitation when analysis nudging—an technique...

The structure of the interfacial layer capping atmospheric boundary is not well understood. dominant influence on turbulence within stable stratification induced by inversion. A series 26 high-resolution large eddy simulation runs ranging from neutral, inversion-capped to free-convection cases are used study turbulence. found be similar in many aspects a classic layer. For example, shapes spectra and cospectra, including locations spectral peaks, agree with previous observations nocturnal...

Advances in computers and computational techniques now allow the calculation of electromagnetic (EM) wave propagation through simulated refractive index turbulence lower atmosphere. Such applications call for instantaneous fields, not statistics, traditional focus community. We clarify their important differences review what is known about key statistics turbulence. discuss EM with a parabolic equation model that uses composite larger scales being calculated dynamical mesoscale smaller...

Abstract This work continues the presentation and evaluation of Ocean–Land–Atmosphere Model (OLAM), focusing on model’s ability to represent radiation precipitation. OLAM is a new, state-of-the-art earth system model, capable user-specified grid resolution local mesh refinement. An objective optimization microphysics parameterization carried out. Data products from Clouds Earth’s Radiant Energy System (CERES) Global Precipitation Climatology Project (GPCP) are used construct maximum...

Large‐eddy simulation (LES) provides three‐dimensional, time‐dependent fields of turbulent refractivity in the atmospheric boundary layer on spatial scales down to a few tens meters. These are directly applicable computation electromagnetic (EM) wave propagation megahertz range but not gigahertz range. We present an approximate technique for extending LES smaller needed calculating EM at frequencies. demonstrate by computing through 128 3 LES, them two dimensions, and using parabolic...

Traditional a posteriori tests of subgrid-scale (SGS) models often compare large eddy simulation (LES) profiles various statistics with measurements. In this study we propose and employ new test to SGS model performance. We the conditional means LES-generated stress production rate on resolvable-scale velocity These must be reproduced by for LES correctly predict one-point joint probability density function. Our using data obtained in convective atmospheric boundary layers show that results...

The pressure–strain-rate correlation and pressure fluctuations in convective near neutral atmospheric surface layers are investigated. Their scaling properties, spectral characteristics, the contributions from different source terms Poisson equation effects of wall investigated using high-resolution (up to $2048^{3}$ ) large-eddy simulation fields through predictions. was found have mixed-layer surface-layer strongly layers, respectively. Its apparent moderately layer is due slow variations...

Turbulent fluctuations of a conservative scalar in the atmospheric boundary layer (ABL) can be generated by flux at surface, entrainment ABL top, and “chewing up” variations on mesoscale. The first two have been previously studied, while third is examined this paper through large-eddy simulation (LES). LES results show that due to breakdown mesoscale advected fields, which authors call “log-chipper” component fluctuations, are uniformly distributed depth convective ABL, unlike top–down...

Abstract Meteorological observations and model simulations are used to show that the catastrophic ice storm of 4–5 December 2002 in southeastern United States resulted from combination a classic winter warm sea surface temperature (SST) anomaly western Atlantic Ocean. At time storm, SST near U.S. coast was 1.0°–1.5°C warmer than its multiyear mean. The impact this anomalous on accumulation evaluated with Regional Atmospheric Modeling System. shows ocean leads conversion more snow into...

Mixed-layer models are computationally efficient, but they do not realistically represent the structure of boundary layer under many conditions. Many deficiencies mixed-layer model can be attributed to assumed flat profiles. A new method is proposed that, by relaxing assumption well-mixed profiles, makes possible an integral PBL parameterization that yet accurately describes mean layer. The vertical variables in represented a truncated series Legendre polynomials. first mode, average,...

A surface monitoring system that can detect turbulence aloft would benefit wind turbine damage prevention, aircraft safety, and be a new probe to study the atmospheric boundary layer. Previous research indicated elevated velocity events may trigger pressure fluctuations on ground. If is true, it should possible monitor gusts by measuring these fluctuations. The goal of this project was develop ground based detection method monitors for indicators gust event taking place at higher altitudes....