Complex terrain

Local topography significantly affects spatial variations of climatic variables and soil water movement in complex terrain. Therefore, the distribution and productivity of ecosystems are closely linked to topography. Using a coupled terrestrial carbon and hydrological model (BEPS-TerrainLab model), the topographic effects on the net primary productivity (NPP) are analyzed through four modelling experiments for a 5700 km 2 area in Baohe River basin, Shaanxi Province, northwest of China. The model was able to capture 81% of the variability in NPP estimated from tree rings, with a mean relative error of 3.1%. The average NPP in 2003 for the study area was 741 g C m À2 yr À1 from a model run including topographic effects on the distributions of climate variables and lateral flow of ground water. Topography has considerable effect on NPP, which peaks near 1350 m above the sea level. An elevation increase of 100 m above this level reduces the average annual NPP by about 25 g C m À2 . The terrain aspect gives rise to a NPP change of 5% for forests located below 1900 m as a result of its influence on incident solar radiation. For the whole study area, a simulation totally excluding topographic effects on the distributions of climatic variables and ground water movement overestimated the average NPP by 5%.

Data assimilation over the complex terrain of the western United States is complicated by the irregular distribution of observations in the horizontal and verti- cal. For example, the method of successive corrections relies on isotropic weights that do not limit the spread horizontally of corrections to the background field through terrain. As a result, observations in one valley can influence the analysis in a neighboring data poor valley so long as they lie within the specified horizontal and vertical radii of influence (ROI). The propagation of corrections may be appropriate during situations when the boundary layer is well mixed; however under certain conditions (e.g., radiational inversions in valleys of dif- fering elevations, cold air confined to one side of a mountain range), it may not be desirable for corrections to propagate through mountain ranges. To mitigate the effects of these problems, an anisotropic weight is pro- posed that limits the propagation of corrections th...

The terrain between grid points is used to modify locally the background error correlation matrix in an objective analysis system. This modification helps to reduce the influence across mountain barriers of corrections to the background field that are derived from surface observations. This change to the background error correlation matrix is tested using an analytic case of surface temperature that encapsulates the significant features of nocturnal radiation inversions in mountain basins, which can be difficult to analyze because of locally sharp gradients in temperature. Bratseth successive corrections, optimal interpolation, and three-dimensional variational approaches are shown to yield exactly the same surface temperature analysis. Adding the intervening terrain term to the Bratseth approach led to solutions that match more closely the specified analytic solution. In addition, the convergence of the Bratseth solutions to the best linear unbiased estimation of the analytic solut...

Several mesoscale data analysis systems are reviewed, of which one is then adapted and applied to the complex terrain of northwest Utah and the western United States. The analysis system relies on the simple, but computationally efficient, successive correction methodology. Near-real-time three-dimensional mesoscale analyses are produced hourly over northwest Utah at 1-km horizontal resolution while analyses are produced every 15 min for surface fields over northwest Utah and the western United States. Surface analyses over the western United States are also generated at 0000 and 1200 UTC to help to initialize 36h mesoscale model forecasts. Comparisons between the 1-km three-dimensional analyses and the background three-dimensional analysis provided by the National Centers for Environmental Prediction Rapid Update Cycle, version 2 (RUC-2), indicate that, where surface and upper-air observations are abundant, the local analysis adds information beyond that of simply interpolating the background (RUC-2) data to the high-resolution analysis grid.

MountainZebra is a data flow configuration that processes and displays radar data over complex terrain. The system combines three elements: the data stream from an operational radar, 3D topographical information, and the NCAR Zebra data visualization and integration software. MountainZebra operates routinely on a 3D data stream from the National Weather Service Weather Surveillance Radar-1988 Doppler (WSR-88D) at Camano Island, Washington (near Seattle). The WSR-88D data are continuously acquired, archived, formatted, and interpolated for multidimensional display. The three-dimensional topographical information in MountainZebra can be automatically underlaid on any horizontal or vertical display of the radar data. This system allows radar data and other geophysical fields to be analyzed in precise relation to the underlying terrain. Terrain-based visualization facilitates radar data analysis by identifying terrain clutter and shadowing and by identifying orographic precipitation mechanisms. The utility of MountainZebra is illustrated in the investigation of stable orographic enhancement over the windward slopes of the Cascade Mountains of the Pacific Northwest and an orographically enhanced squall line to the lee of the European Alps. * Joint Institute for the Study of the Atmosphere and Ocean Contribution Number 672.

Accidental releases of hazardous gases like ammonia present significant safety and environmental threats in industrial-urban interfaces. This study develops a computational fluid dynamics (CFD) framework using ANSYS CFX 13.0 to simulate high-pressure ammonia dispersion through realistic plant geometries. The Reynolds-Averaged Navier-Stokes (RANS) methodology implementing *k*-ε and Shear Stress Transport (SST) turbulence closures quantifies atmospheric dynamics and obstacle interactions governing plume evolution. Validation against experimental datasets confirms model fidelity in replicating spatiotemporal concentration profiles. Parametric analysis of wind velocity (0.1-4.0 m/s), release rates (0.5-2.5 kg/s) and boundary conditions demonstrates obstruction-induced dispersion pattern variations of 25%-40% versus open terrain. The framework achieves 30%-50% improvement in critical exposure zone delineation accuracy over conventional integral models. Integration of site-specific topology and meteorological data enables physics-informed safety buffer zoning (60-150 m), directly enhancing emergency-response protocols and regulatory compliance. This validated approach advances quantitative risk assessment paradigms for industrial chemical hazards, demonstrating the critical role of highfidelity CFD in post-Bhopal safety engineering.

Long narrow lines of precipitating convection that form off the west coast of Africa in the summer are described from satellite, rawinsonde, and quantitative radar data taken during the field phase of the CARP Atlantic Tropical Experiment (GATE). The lines appeared on the satellite images in the eastern Atlantic, west of the coast of Africa near 15*N, along the leading edge of large dust plumes that emerged from the desert regions of Africa in the ridge region of traveling synoptic-scale waves. Analysis of the wave structure showed that the lines were in a region of strong negative relative vorticity and easterly vertical wind shear in the lower and mid-troposphere but with little surface convergence. On the basis of precipitation analyses derived from the radar measurements, the lines were found to contribute about 20-25 percent of the precipitation associated with the waves. Dr. Robert Burpee, whose help speeded up the completion of this thesis. I am grateful to George Huffman and Prof. Peter Stone for many helpful discussions on potential vorticity which were useful in the development of chapter 4. Also, I would like to thank my friends and colleagues in the Weather Radar Project, Spiros (Speed) Geotis, Alan and Ginny Siggia, Bill Silver, Mark Merritt, and Barbara Wysochansky, who helped me greatly through their technical skills and friendship through good times and bad. I would also like to thank the past and present members of the convection club,

Biological neural network (BNN) algorithms have become popular in coverage search in recent years. However, its edge activity values are weak, and it is simple to fall into a local optimum at a late stage of coverage. When applied to complex environments, the 3D BNN network structure has high computational and storage complexity. In order to solve the above problems, we propose an algorithm for multi-robot cooperative coverage of complex terrain based on an improved BNN. The algorithm models the complex terrain using a 2.5-dimensional (2.5D) elevation map. Combining the dual-layer BNN network with the 2.5D elevation map, we propose an elevation value priority mechanism. This mechanism lets the robot make elevation-based decisions and prioritizes higher terrain areas. The dual neural network's first layer plans the robot's path in normal mode. The second network layer helps the robot escape the local optimum. Finally, the algorithm's full coverage effect in complex terrains and the speed of covering high terrain are verified by simulations. The experiments show that our algorithm preferentially covers high points of the region and eventually covers 100% of complex terrain. Compared with other algorithms, our algorithm covers more efficiently and takes fewer steps than others. The speed of covering high terrain areas has increased by 34.51%.

The presented work is a validation of the IASI water vapour integrated columns by means of comparison with GPS measurements and water vapour volume mixing ratio profiles using in situ and remote sensing data, such as GPS tomography, LIDAR ...

A simplified, but quantitatively reliable approximation of atmospheric sound propagation is given by the standard parabolic equation. The waveguide is a cylindrically symmetric, unbounded, domain with an irregular lower boundary. The associated initial-boundary value problem uses a mixed-type boundary condition along the lower boundary and a nonlocal, absorbing boundary condition of the DtN (or NtD) type, applied on an artificial upper boundary. Exterior wave fields of a constant index of refraction and a linear, when squared (as function of height) one, are considered. The physical, complex waveguide reduces to an orthogonal computational domain by the means of a numerical transformation to generalized coordinates, fitting the lower, irregular boundary. The technique presented is of practical interest for its proper handling of complex ground topographies; it is interfaced with a mesh generator and processes the topographic data retrieved from a geographic information system, hence the transformation of coordinates is computed numerically. The transformed initial-boundary value problem (on the orthogonal computational domain) is discretized by the Crank-Nicolson in time and a continuous, piecewise linear finite element method in space. The propagation of cylindrically symmetric sound waves over a complex terrain, emitted to the atmosphere by a harmonic source, has been studied. The effectiveness of the numerical method introduced, is exploited on several test cases.

Ultrahigh-resolution bathymetric maps (25 cm grid) are used to quantify the physical dimensions of and spatial relationships between tectonic, volcanic, and hydrothermal features at six hydrothermal vent fields in the Lau back-arc basin. Supplemented with near-bottom photos, and nested within regional DSL-120A side-scan sonar data, these maps provide insight into the nature of hydrothermal systems along the Eastern Lau Spreading Center (ELSC) and Valu Fa Ridge (VFR). Along-axis transitions evident in localized volcanic morphology and tectonic characteristics include a change from broad low-relief volcanic domes (hundreds of meters wide, <10 m tall) that are dominated by pillow and lobate lava morphologies and are cut by faults and fissures to higher aspect ratio volcanic domes (tens of meters wide, tens of meters tall) dominated by aa-type lava morphologies, with finger-like flows, and few tectonic structures. These alongaxis differences in localized seafloor morphology suggest differences in hydrothermal circulation pathways within the shallow crust and correlate with regional transitions in a variety of ridge properties, including the large-scale morphology of the ridge axis (shallow axial valley to axial high), seafloor lava compositions, and seismic properties of the upper crust. Differences in morphologic characteristics of individual flows and lava types were also quantified, providing an important first step toward the remote characterization of complex terrains associated with hydrothermal vent fields.

Land- and sea-breezes are attracting increasing interest for wind energy applications. While these thermally-driven winds are weaker than synoptic winds, their high regularity makes them appealing for the renewable energy sector. In this study, we simulate breezes using a simple model based solely on temperature and terrain roughness data. The simulation focuses on the Llobregat river delta, in the northeast of the Iberian Peninsula, using temperature measurements from a meteorological mast at four different heights. The mast is also equipped with two anemometers. Daily wind profiles were collected during more than a year, and a day characterized by thermal winds was selected for detailed analysis.
Numerical simulations of breezes were conducted using the open-source computational fluid dynamics code OpenFOAM v2312. The influence of roughness on the simulation results was examined. Vertical temperature profiles and velocity magnitudes of breezes were obtained and compared with observations. Results demonstrate that the input of terrain roughness and temperature allow a reliable qualitative study of sea-breezes. They also indicate a significant sensitivity of the thermal boundary layer to roughness height. Although the impact of roughness on wind speed intensity is lower, increase in roughness leads to a reduction in wind speed and earlier sea-breeze onset.

A field study combined with modeling investigation demonstrates that the organization of CO 2 transport by mountain terrain strongly affects the regional CO 2 budget. y conducting model-data assimilation analysis of the long-term eddy covariance dataset from the Niwot Ridge AmeriFlux site operated by the University of Colorado, Schimel et al. (2002, 2007), , 2006a,b), and Moore et al. (2008) showed that 1) an aggrading Rocky Mountain subalpine forest is a net annual CO 2 sink, 2) most of the annual CO 2 uptake occurs in spring when melting snow provides moisture for photosynthesis and low soil temperature inhibits respiration, and 3) the interannual variability of forest CO 2 uptake is largely driven by spring conditions. Studies at the same forest site showed, however, that accurate estimates of ecosystem CO 2 exchange are difficult to obtain because the terrain forces us to consider terms that are otherwise ignored in systems with seemingly simpler terrain

The growing trend of model complexity, data availability and physical representation for watershed simulations has not been matched by adequate developments in computational efficiency. This situation has created a serious bottleneck that limits existing hydrologic models to small domains and short durations. A novel parallel approach has been applied to the TIN-based Real-Time Integrated Basin Simulator (tRIBS), which provides continuous hydrologic simulation using a multiple resolution representation of complex terrain based on a triangulated irregular network (TIN). Our approach utilizes domain decomposition based on sub-basins of a watershed. A stream reach graph based on the channel network structure is used to determine each sub-basin and its connectivity. Individual sub-basins or sub-graphs of sub-basins are assigned to separate processors to carry out internal hydrologic computations (e.g. rainfall-runoff transformation). Routed streamflow from each sub-basin forms the major...

Sea breeze circulations were documented in the framework of the ESCOMPTE program that was performed over the Provence region, South France, during summer 2001. The instrumental set-up was well suited to study the effects of topography on the sea-breeze flow. IOP2b case is very interesting to show the inhomogeneity and the unsteadiness of the breeze flow linked to the interaction with complex terrain (mountains, valleys, coastline shape) and large scale flows. For this period (25 and 26 june 2001), the thermal wind setting-up is disturbed by the development of large-scale winds from different directions and at various heigths. The Rhone and Durance valleys can modify these flows by channeling, flow splitting, but their influence differs since they don't have the same orientation and width. So, the inland penetration, the depth of the sea-breeze and its intensity are not the same everywhere.

We provide a review description of atmospheric inversion methods for the determination of fluxes of long-lived trace gases based on measurements of atmospheric concentration. Emphasis is given to technical aspects of inversion settings, which are crucial to inter-compare and understand inversion results. We briefly sketch the formalism used in such methods, then provide a summary of major currents in research and contemporary problems. Most attention is given to carbon dioxide (CO 2 ) which poses the threat of future climate change. Therefore, there is keen interest in better understanding where and when CO 2 emitted by the combustion of fossil fuels is reabsorbed by land ecosystems and oceans. Using the information contained in concentration fields observed from ground-based networks and from upcoming satellite observations in order to constrain the geographic distribution of surface fluxes is an inverse problem; it consists of finding a set of fluxes that optimally matches the observations available. We review the application of inverse methods to quantify the distribution of the sources and sinks of CO 2 at the surface of the Earth based on global measurements of atmospheric concentration and three-dimensional models of atmospheric transport. We describe the use of topdown atmospheric inversion methods in terms of numerical transport modeling and atmospheric observation networks, and detail some of the currently important issues in assigning uncertainties.

A series of fieldworks were conducted in the municipality of Goa, Camarines Sur, Philippines from October 2019 to March 2020, focusing on areas that might be affected in a future eruption of Isarog Volcano – one of the 24 active volcanoes in the Philippines. The researcher gathered important data, including the measurement of the outcrops, its coordinates, and the identification of beds. Rock samples were taken from the field to undergo petrographic analysis and paleomagnetic polarity testing. Organic materials, such as charcoal, were also taken from one of the outcrops to undergo radiocarbon dating. The goal of the study is to identify the potential volcanic hazards in the municipality, and create a volcanic hazard map based on the data gathered from the field. Based on Fontijn and Newhall’s research in 2013, the rocks extruded by the volcano are mostly andesite, and an explosive eruption is possible. The downtown area of Goa, Camarines Sur – where the majority of the population lives – sits on block-and-ash flow deposits, a type of pyroclastic flow deposit. It was determined using a portable fluxgate magnetometer. The upper barangays near the foot of the volcano are more susceptible to ballistic projectiles and lava flow. Areas near the rivers are more prone to lahars. The municipality will most likely experience moderate to heavy ash fallout when the volcano erupts while the southwest monsoon (Habagat) is active. The radiocarbon dating of charcoal taken from the municipal transport terminal confirmed that Isarog Volcano erupted 4272-4384 cal yr bp (calibrated years before present). This event is more recent than the volcanic eruption discovered by Fontijn and Newhall in 2013, taking place 5320-5480/5550-5570 cal yr bp.

This paper introduces an autonomous robotic platform designed for condition-based inspection of Ultra High Voltage Centers. The platform uses a mobile robot equipped with thermal and optical sensors to perform frequent, automated inspections, supported by 3D-based mapping, visibility scoring, and traversability analysis of the terrain. A decision support system enables smart scheduling and report generation, while an optimal path planner solves a Generalized Traveling Salesman Problem for efficient routing. Component faults are detected by combining RGB-based object recognition with thermal image analysis. Initial trials show the performance of our system. validating it as a scalable and cost-effective alternative to manual inspection in power infrastructure environments.

Measurements have been made of the deposition of cloud droplets and dissolved chemical species to moorland vegetation. Measurements of liquid water fluxes have been made by the gradient technique using Knollenberg FSS probes and by a weighing lysimeter. Deposition velocities for cloud liquid water in the range 0.1 to 0.24g11-~ at a height of 1.0m were close to those for momentum. The FSS probes enabled the determination of deposition velocities as a function of droplet size. It was found that the deposition velocity increased with droplet radius from 2 . 5 ~m to 6 5 p m radius. Between 6.5 and 12.5pm radius, deposition velocities exceeded those for momentum, but decreased sharply between 12.5 and 15.5 pm. In periods of thin cloud (<0.1 gm-3), evaporation from the surface occurred despite continued deposition.

The success probability of water wells constructed in crystalline rock terrains is largely dependent on the size, location and interconnectivity of the fractures present in them as well as the amount and nature of the material that may clog the fractures. Geological and geoelectrical studies were proposed and conducted at Tatiko to determine the structures in the underlying basement rocks and evaluate their groundwater potential. Geological study was used to delineate the structural control on groundwater availability while the geoelectrical study (Vertical Electrical Sounding) was used to investigate the properties of the subsurface materials and determine their potential to host sufficient quantity of groundwater.Structural data were plotted on a rosset diagram and showed major structural control trending in the NW – SE direction. Quantitative interpretation of the geoelectric data indicates that the major fractures are within the weathered to competent basement indicating good hy...

This paper discusses the observations of the Atmospheric Surface Layer (ASL) parameters during the solar eclipse of August 11th, 1999. Intensive surface layer experiments were conducted at Ahmedabad (23 • 21 N, 72 • 36 E), the western part of India, which was close to the totality path. This rare event provided by nature is utilised to document the surface layer effects during the eclipse period using measurements of high frequency fluctuations of temperature, tri-axial wind components as well as mean parameters such as temperature, humidity, wind speed and subsoil temperature. Analysis showed that during the eclipse period, the turbulence parameters were affected leading to the suppression of the turbulence process, the main dynamic process in the atmospheric boundary layer, while the mean parameters showed variations within the natural variability of the observational period. The spectra of the wind components and temperature indicated decrease in spectral power by one order in magnitude during the eclipse period. The rate of dissipation of turbulent kinetic energy is found to decrease by more than one order during the eclipse period. The stability parameter showed a change from unstable to stable condition during the period of eclipse and back to unstable condition by the end of eclipse.

Ge6potential on the 300 mb isobaric surface at (a) 0 Z, and (b) 12 Z on 14 April 1985 (Stage 1). Contour intervals are 10.0 m 2 S-2. . . .. . . . . . .. 36 14 Geopotential on the 100 mb isobaric surface at (a) 0 Z, and (b) 12 Z on 14 April 1985 (Stage 1). Contour intervals are 10.0 m S-I. . . . . . . . . . . . 37 15 Pressure fields on the 360 K isentropic surface at (a) 0 Z, and (b) 12 Zan 14 April 1985 (Stage 2). Contour intervals are 0.2 kPo.. The maximum wind vector is 43.8 m s-l.

Accurate simulation of planetary boundary layer height (PBLH) is key to greenhouse gas emission estimation, air quality prediction, and weather forecasting. This paper describes an extensive performance assessment of several Weather Research and Forecasting (WRF) Model configurations in which novel observations from ceilometers, surface stations, and a flux tower were used to study their ability to reproduce the PBLH and the impact that the urban heat island (UHI) has on the modeled PBLHs in the greater Washington, D.C., area. In addition, CO2 measurements at two urban towers were compared with tracer transport simulations. The ensemble of models used four PBL parameterizations, two sources of initial and boundary conditions, and one configuration including the building energy parameterization urban canopy model. Results have shown low biases over the whole domain and period for wind speed, wind direction, and temperature, with no drastic differences between meteorological drivers. ...

Recently developed system for assessment of radiation budget for the Baltic Sea has been presented and verified. The system utilizes data from various sources: satellite, model and in situ measurements. It has been developed within the SatBałtyk project (Satellite Monitoring of the Baltic Sea Environment - www.satbaltyk.eu) where the energy radiation budget is one of the key element. The SatBałtyk system generates daily maps of the all components of radiation budget on every day basis. We show the scheme of making daily maps, applied algorithms and empirical data collection within the system. An empirical verification of the system has been carried out based on empirical data collected on the oil rig placed on the Baltic Sea. This verification concerned all the components of the surface radiation budget. The average daily NET products are estimated with statistical error ca. 13 Wm-2. The biggest absolute statistical error is for LWd component and equals 14 Wm-2. The relative error i...

Urban flash flooding is a serious problem in large highly populated areas such as the Dallas-Fort Worth metroplex (DFW). Being able to monitor and predict flash flooding at a high spatiotemporal resolution is critical to mitigating its threats and for cost effective emergency management. In this work, the prototype high resolution flash flood warning system under de velopment for DFW is described and a case study of the flash flooding event of 2014-06-24 in Fort Worth presented. The high resolution (500 m, 1 min) precipitation input comes from the DFW Demonstration Network of the Collaborative Adaptive Sensing of the Atmosphere (CASA) X-band radars. The hydrologic model used is the National Weather Service Hydrology Laboratory's Distributed Hydrologic Model (HL-RDHM) operating at a 500 m resolution. The model simulation results are assessed using the flooding reports received from residents throughout the event by the City of Fort Worth.

Progress made in recent years in fire science, particularly as applied to forest fire protection, coupled with the increased power offered by mathematical processors integrated into computers, has led to important developments in the field of dynamic and static simulation of forest fires. Furthermore, and similarly, econometric models applied to economic evaluation of natural resources have generated algorithms of great scientific consistency that have allowed determining the monetary value of resources that have not traditionally had a commercial or market interaction treatment. VISUAL-SEVEIF (Spanish acronym for System for the Economic Evaluation of Wildfires) is a software tool that allows working both in real time, simulating the spatial development of ground and canopy fires, and addressing the implementation of territorial studies by which possible fire evolutions are determined and characterized, subject to final spatial or temporal contour conditions. The spatial resolution of work will be conditioned by the quality and accuracy of fuel model mapping, as well as the characteristics of the digital terrain model, so that in high-precision models the results of the fire behavior dynamic can be up to a square meter.

In this paper we present an atmospheric dispersion scenario for a proposed nuclear power plant in Pakistan involving the hypothetical accidental release of radionuclides. For this, a concept involving a Lagrangian stochastic particle model (LSPM) coupled with an Eulerian regional atmospheric modelling system (RAMS) is used. The atmospheric turbulent dispersion of radionuclides (represented by non-buoyant particles/neutral traces) in the LSPM is modelled by applying non-homogeneous turbulence conditions. The mean wind velocities governed by the topography of the region and the surface fluxes of momentum and heat are calculated by the RAMS code. A moving least squares (MLS) technique is introduced to calculate the concentration of radionuclides at ground level. The numerically calculated vertical profiles of wind velocity and temperature are compared with observed data. The results obtained demonstrate that in regions of complex terrain it is not sufficient to model the atmospheric dispersion of particles using a straight-line Gaussian plume model, and that by utilising a Lagrangian stochastic particle model and regional atmospheric modelling system a much more realistic estimation of the dispersion in such a hypothetical scenario was ascertained. The particle dispersion results for a 12 h ground release show that a triangular area of about 400 km 2 situated in the north-west quadrant of release is under radiological threat. The particle distribution shows that the use of a Gaussian plume model (GPM) in such situations will yield quite misleading results.

An approach to determine the convective available potential energy (CAPE) and the convective inhibition (CIN) based on the use of data from a Raman lidar system is illustrated in this work. The use of Raman lidar data allows to provide high temporal resolution measurements (5 min) of CAPE and CIN and follow their evolution over extended time periods covering the full cycle of convective activity. Lidar-based measurements of CAPE and CIN are obtained from Raman lidar measurements of the temperature and water vapour mixing ratio profiles and the surface measurements of temperature, pressure and dew point temperature provided by a surface weather station. The approach is applied to the data collected by the Raman lidar system BASIL in the frame of COPS. Attention was focused on 15 July and 25-26 July 2007. Lidar-based measurements are in good agreement with simultaneous measurements from radiosondes and with estimates from different mesoscale models.

The performance of sodar technology for wind resource measurement is well documented in simple terrain with good relationships and high levels of accuracy expected for lidar and sodar due to the homogenous flow fields found in such terrain. When remote sensing is used in complex terrain, for comparison with conventional anemometry, the potential for error increases due to the variation in the flow field through the measurement volume. Methodologies are available to correct the volumetric measurements obtained through the use of lidars to their equivalent point source with the aim to compensate for the bias in the error from the variation in flow through the measurement volume. This paper describes a technique incorporating computational fluid dynamics (CFD) to investigate the correction of this measurement bias made using remote sensing equipment. An example of a typical lidar comparison with anemometer measurements is shown as well as a comparison with a sodar measurement. The resu...

We collected ground-based and aircraft vertical profile measurements of meteorological parameters during a 2-week intensive campaign over the Valencia basin, in order to understand how mesoscale circulations develop over complex terrain and affect the atmospheric transport of tracers. A high-resolution version of the RAMS model was run to simulate the campaign and characterize the diurnal patterns of the flow regime: night-time katabatic drainage, morning seabreeze development and its subsequent coupling with mountain up-slopes, and evening flow-veering under larger-scale interactions. An application of this mesoscale model to the transport of CO 2 is given in a companion paper. A careful evaluation of the model performances against diverse meteorological observations is carried out. Despite the complexity of the processes interacting with each other, and the uncertainties on modeled soil moisture boundary conditions and turbulence parameterizations, we show that it is possible to simulate faithfully the contrasted flow regimes during the course of one day, especially the inland progression and organization of the sea breeze. This gives confidence with respect to future applicability of mesoscale models to establish a reliable link between surface sources of tracers and their atmospheric concentration signals over complex terrain.

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Quantitative precipitation forecasting (QPF) in low-mountain regions is a great challenge for the atmospheric sciences community. On the one hand, orographic enhancement of precipitation in these regions can result in severe flash-flood events. On the other hand, the relative importance of forcing mechanisms leading to convection initiation (CI) is neither well understood nor adequately reproduced by weather forecast models. This results in poor QPF skill, both in terms of the spatial distribution of precipitation and its temporal evolution. Two prominent systematic errors of state-of-theart mesoscale models are identified. Figure shows the difference between a 1-month average of 24-h integrated precipitation forecasted with the Consortium for Small-Scale Modeling (COSMO)-EU Model (formerly known as Lokalmodell) of the German Meteorological Service (DWD) and the corresponding observational data. Shown on this figure is the Black Forest low-mountain region in southwestern Germany. Strong systematic errors are found on both the windward and the lee sides. On the windward side, the model strongly overestimates precipitation, whereas on the lee side it is underestimated, which we call the "windward/lee effect." To our knowledge, this error is found in all mesoscale models for both weather prediction and climate simulations, which require convection parameterization, such as in COSMOCH7 of Meteo Swiss, ARPEGE and ALADIN of Meteo France, as well as in the mesoscale models MM5 and ETA. Although we show a summertime example here, Baldauf and Schulz previously demonstrated that this error structure exists during all seasons.

In this paper, a gait transition method has proposed that allows a group of multi-agent hexapod robot to switch from one gait to another gait with stable condition, during different terrain navigation. Typical gaits of locomotion are analyzed for hexapod robot. Hexapod robots frequently operate various gaits to locomote over a variety of surfaces. To enable locomotion in a changing surface, hexapod must be able to stably change between gaits while continuing to locomote. A comparative study, based on different gaits for different ...

Weather radar is an active remote sensing instrument for various hydrological and meteorological applications. One advantage of weather radar is its ability to detect rainfall in space and time with high spatial resolution. However, one of the issues that contaminate radar observations is ground clutter. Ground clutter is a signal or echo from non-meteorological objects on the earth's surface that are stationary in the time domain. Detecting and mitigating clutter effects is crucial to achieve precise weather measurements. This research aims to implement the Gabella and random forest methods to detect ground clutter in Padang weather radar data and determine the optimal method between the two. The implementation of the Gabella method for detecting ground clutter in Padang weather radar data was suboptimal. This was due to the most duplicated data at the same point being only 15.97% of the total data. Meanwhile the random forest method obtained a kappa value of 92.03%. This indicates that the random forest model created using 2000 trees as the parameter performs well. Based on these results, the random forest method identified as the most optimal approach for detecting ground clutter in Padang weather radar data.

The typically sparse distribution of weather stations in mountainous terrain inadequately resolves temperature variability. Accordingly, high‐resolution gridding of climate data (for applications such as hydrological modeling) often relies on assumptions such as a constant surface temperature lapse rate (i.e., decrease of surface temperature with altitude) of 6.5°C km−1. Using an example of the Cascade Mountains, we describe the temporal and spatial variability of the surface temperature lapse rate, combining data from: (1) COOP stations, (2) nearby radiosonde launches, (3) a temporary dense network of sensors, (4) forecasts from the MM5 regional model, and (5) PRISM geo‐statistical analyses. On the windward side of the range, the various data sources reveal annual mean lapse rates of 3.9–5.2°C km−1, substantially smaller than the often‐assumed 6.5°C km−1. The data sets show similar seasonal and diurnal variability, with lapse rates smallest (2.5–3.5°C km−1) in late‐summer minimum t...

In this paper two mesoscale meteorological models are applied to the Lisbon region. A special concern is directed to the initial conditions and input parameterization in order to assure that equal simulation constraints were imposed to both models. Results obtained for 4 August 1992 (a typical summer day) are compared to meteorological data acquired in three monitoring stations. Both simulations show similar reactions to the mesoscale forcings that occur in the modelling region. The minor differences found between simulation and reality for the meteorological situation can cause major errors in predicting air quality.

Although regional climate models (RCMs) are powerful tools for describing regional and even smaller scale climate conditions, they still feature severe systematic errors. In order to provide optimized climate scenarios for climate change impact research, this study merges linear and nonlinear empirical-statistical downscaling techniques with bias correction methods and investigates their ability for reducing RCM error characteristics. An ensemble of seven empiricalstatistical downscaling and error correction methods (DECMs) is applied to post-process daily precipitation sums of a high-resolution regional climate hindcast simulation over the Alpine region, their error characteristics are analysed and compared to the raw RCM results. Drastic reductions in error characteristics due to application of DECMs are demonstrated. Direct point-wise methods like quantile mapping and local intensity scaling as well as indirect spatial methods as nonlinear analogue methods yield systematic improvements in median, variance, frequency, intensity and extremes of daily precipitation. Multiple linear regression methods, even if optimized by predictor selection, transformation and randomization, exhibit significant shortcomings for modelling daily precipitation due to their linear framework. Comparing the well-performing methods to each other, quantile mapping shows the best performance, particularly at high quantiles, which is advantageous for applications related to extreme precipitation events. The improvements are obtained regardless of season and region, which indicates the potential transferability of these methods to other regions.

complex terrain net ecosystem exchange spruce forest sapflow transpiration grasslands alpine meadows up-scaling land use change A process-based spatial simulation model was used to estimate gross primary production, ecosystem respiration, net ecosystem CO 2 exchange and water use by the vegetation in Stubai Valley, Austria at landscape scale. The simulations were run for individual years from early spring to late fall, providing estimates in grasslands for carbon gain, biomass and leaf area development, allocation of photoproducts to the below ground ecosystem compartment, and water use. In the case of evergreen coniferous forests, gas exchange is estimated, but spatial simulation of growth over the single annual cycles is not included. Spatial parameterization of the model is derived for forest LAI based on remote sensing, for soil characteristics by generalization from spatial surveys and for climate drivers from observations at monitoring stations along the elevation gradient and from modelling of incident radiation in complex terrain. Validation of the model was carried out at point scale, and was based on comparison of model output at selected locations with observations along elevation gradients in Stubai Valley and Berchtesgaden National Park, Germany as well as with known trends in ecosystem response documented in the literature. The utility of the model for describing long-term changes in carbon and water balances at landscape scale is demonstrated in the context of land use change that occurred between 1861 and 2002 in Stubai Valley. During this period, coniferous forest increased in extent by ca. 11% of the vegetated area of 1861, primarily in the subalpine zone. Managed grassland decreased by 46%, while abandoned grassland and natural alpine mats increased by 14 and 11%, respectively. At point scale, the formulated model predicts higher canopy conductance in 1861 due to lower atmospheric CO 2 concentration which opens stomata. As a result, water use at point scale decreased by ca. 8% in 2002 in the valley bottoms versus 10% at tree line. At landscape level, the decrease in water use by vegetation in 2002 was predicted to be twice as high (ca. 17%) due to increase in subalpine forest, reduction of managed grassland in the valley and on slopes, as well as abandonment of grassland which results in natural succession. Net ecosystem CO 2 exchange (NEE) was predicted to increase (become more negative) at point scale depending on vegetation type by 10 to 20% in 2002 due to increasing atmospheric CO 2 concentration. However, due to the shift from grassland to forest and natural vegetation, landscape level CO 2 exchange did not change. As a result of land use change, the export of carbon in harvested biomass in 2002 was estimated at only 30% of that in 1861. While the need for further validation of model assumptions is recognized, especially changes in ecosystem behavior with changing atmospheric CO 2 concentration, the model analysis indicates a long-term reduction in water use by vegetation and a shift in ecosystem services. The results provide a case study, where land use change may compensate or override the influences of increasing atmospheric CO 2 concentration, maintaining a relatively constant NEE in present time period simulations as compared to 1861, as well as reducing export of carbon from the alpine landscape of Stubai Valley. Use of the model in evaluation of scenarios of future land use change and in relation to vulnerability of ecosystem services are discussed.

This letter aims to help scholars and practitioners alike prepare for the 15th Conference of the Parties (COP15) to the United Nations Framework Convention on Climate Change (UNFCCC), to be held in Copenhagen in December 2009, by providing a bird's eye view of the increasingly complex terrain of the global climate negotiations. It identifies and explains the most important and contentious 'tripping points' for reaching any agreement on a post-2012 framework, by explaining the primary barriers among countries to reaching consensus and the bargaining chips that countries may draw upon to get there. Namely, the letter details the contours of the ongoing debates on: developed and developing country mitigation; reducing emissions from deforestation and forest degradation (REDD); technology transfer; adaptation; and finance.

The former Apollo facility in western Pennsylvania converted enriched uranium hexafluoride into uranium oxide for shipment to nuclear fuel fabrication plants from 1957 to 1983. Atmospheric releases of uranium from plant operations were estimated from stack sampling and production records. Releases occurred through stacks, rooftop vents, and an incinerator that operated from 1964 to 1969. Roof vents that exhausted workplace air was the major emission source from the plant. Total estimated release of uranium activity (including 234 U, 235 U, and 238 U) to the air was 27.9 GBq. Atmospheric transport modeling was performed using a complex terrain model because the plant was located in an incised river valley. Almost two years of meteorological data were collected from a nearby 10-m tower, along with sounding from a collocated sodar. Light mean wind speed (1.56 m s -1 ) and predominately stable atmospheric conditions frequently resulted in poor dispersion conditions in the facility environs. Environmental sampling included continuous air monitoring data and depth profiles of uranium in soil that was deposited from airborne releases. Soil measurements exhibited a sharp drop-off in uranium concentrations with distance from the facility, indicating that large non-inhalable particles were emitted to the atmosphere. Large particles (~15-25 μm aerodynamic equivalent diameter) accounted for 17.5% of the total emissions. Soil measurements were used for model calibration and validation, while air measurements were used to evaluate model performance. Air concentrations were generally over-predicted for locations near the facility but showed only a slight positive bias for locations north of the facility. Predicted uranium activity air concentrations from Apollo sources averaged over 34 years were about three times greater than the background gross alpha activity value of 81 μBq m -3 in a ~0.5 km 2 region surrounding the Apollo facility. The contribution of Apollo uranium to the gross alpha air concentration would have been negligible several kilometers from the facility.

Avtà ) Difference of wind speed measurement (vector mean) between wind tunnel and sonics at 4 m s -1 dependent from azimuth and tilt in %. The plots illustrate the effects of different sensor types with an azimuth resolution of 4° and 11 tilt positions. Gill R2 (omnidirectional) and Gill HS were operated in "uncalibrated mode". The high underestimations at 180° of the asymmetric instruments CSAT3 and HS correspond to the spar/fixing.

The nowcasting and prediction of strong winds are still far from adequate, using either statistical or numerical modelling approaches. During the last decade, Switzerland has been struck by two extratropical storms, namely the February 1990 storm "Vivian", and the December 1999 storm "Lothar", that caused severe damage to infrastructure and to forests. Although numerical weather prediction models captured in both cases the cyclone tracks on the synoptic scale, the severity of local gusts was not properly predicted over the Swiss territory. To help predicting such phenomena, a combined approach to diagnose the wind gust speeds over Switzerland is described. The diagnostics aim at computing the probability of exceeding a gust speed based on the mean wind in relation to the prevailing synoptic weather type for a limited number of groups of climatological stations distributed throughout Switzerland. Based on ten years of Swiss station observations, the computation of this probability uses an empirical gust factor which is a function of the daily gust speed, itself a function of the daily mean wind speed. For this period, each day has been categorised into three weather types according to the Schüepp classification. Principal Component Analysis and Cluster Analysis are performed in order to group climatological stations having similar characteristics in daily wind gust velocities. The results show that the gust factor provides an accurate method to compute the daily wind gust speeds at each Swiss climatological station for the given period. When combined to the three weather types and group of stations, the proposed diagnostics are an efficient method to predict the distribution of wind gust speeds. The gusts associated with the "Vivian" and "Lothar" storms are then diagnosed for each specific group where more than 85 % of the stations responded similarly to their specific group members, which is highly satisfactory in this case.