bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aggregation of Selected Three-Day Periods to Estimate Annual and Seasonal Wet Deposition Totals for Sulfate, Nitrate, and Acidity. Part II: Selection of Events, Deposition Totals, and Source&#x96;Receptor Relationships
Authors: Brook Jeffrey R. , Samson Perry J. , Sillman Sanford 
Published: August 2010

Abstract
A method for deriving estimates of long-term acidic deposition over eastern North America based on a limited number of Regional Acid Deposition Model runs has been developed. The main components of this method are the identification of a representative sample of events for model simulation and the aggregation of the deposition totals associated with the events. Meteorological categories, defined according to 3-day progressions of 850-mb wind flow over eastern North America, were used to guide the selection of events. This paper describes how events were selected from the categories and how they were combined (aggregated) to estimate long-term deposition. The effectiveness of the category-based approach was compared against alternate aggregation approaches and it was found to provide the best sample-based estimates of long-term wet sulfate deposition across eastern North America.
Thirty events from the 1982&#x96;85 time period were selected using a set of predetermined criteria and aggregated to estimate seasonal and annual SO2−4, NO−3, and H+ deposition at 20 Utility Acid Precipitation Study Program sites. The accuracy of the estimates varied geographically and depending upon whether they were for the annual or seasonal time periods. Over the main area of interest (a smaller 13-site region), the mean rms errors for annual deposition were 10%, 15%, and 12% for sulfate, nitrate, and acidity, respectively. Source&#x96;receptor relationships associated with the 30 events were examined for three sites located in Michigan, North Carolina, and upstate New York. It was found that the amount of time that transport was to these areas from the U.S. Midwest (an area of high SO2 emissions) was represented to within 20%.
Estimating the Urban Bias of Surface Shelter Temperatures Using Upper-Air and Satellite Data. Part I: Development of Models Predicting Surface Shelter Temperatures
Authors: Epperson David L. , Davis Jerry M. , Bloomfield Peter , Karl Thomas R. , McNab Alan L. , Gallo Kevin P. 
Published: August 2010

Abstract
Multiple regression techniques were used to predict surface shelter temperatures based on the time period 1986&#x96;89 using upper-air data from the European Centre for Medium-Range Weather Forecasts to represent the background climate and site-specific data to represent the local landscape. Global monthly mean temperature models were developed using data from over 5000 stations available in the Global Historical Climate Network (GHCN). Monthly maximum, mean, and minimum temperature models for the United States were also developed using data from over 1000 stations available in the U.S. Cooperative (COOP) Network and comparative monthly mean temperature models were developed using over 1150 U.S. stations in the GHCN. Initial correlation analyses revealed that data from 700 mb were sufficient to represent the upper-air or background climate. Three-, six-, and full-variable models were developed for comparative purposes. Inferences about the variables selected for the various models were easier for the GHCN models, which displayed month-to-month consistency in which variables were selected, than for the COOP models, which were assigned a different list of variables for nearly every month. These and other results suggest that global calibration is preferred because data from the global spectrum of physical processes that control surface temperatures are incorporated in a global model. All of the models that were developed in this study validated relatively well, especially the global models. Recalibration of the models with validation data resulted in only slightly poorer regression statistics, indicating that the calibration list of variables was valid. Predictions using data from the validation dataset in the calibrated equation were better for the GHCN models, and the globally calibrated GHCN models generally provided better U.S. predictions than the U.S.-calibrated COOP models. Overall, the GHCN and COOP models explained approximately 64%&#x96;95% of the total variance of surface shelter temperatures, depending on the month and the number of model variables. The R2's for the GHCN models ranged between 0,86 and 0.95, whereas the R2's for the COOP models ranged between 0.64 and 0.92. In addition, root-mean-square errors (rmse's) were over 3°C for GHCN models and over 2°C for COOP models for winter months, and near 2°C for GHCN models and near 1.5°C for COOP models for summer months. The results of this study&#x97;a large amount of explained variance and a relatively small rmse&#x97;indicate the usefulness of these models for predicting surface temperatures. Urban landscape data are incorporated into these models in Part II of this study to estimate the urban bias of surface ternperatures.
Estimating the Urban Bias of Surface Shelter Temperatures Using Upper-Air and Satellite Data. Part II: Estimation of the Urban Bias
Authors: Epperson David L. , Davis Jerry M. , Bloomfield Peter , Karl Thomas R. , McNab Alan L. , Gallo Kevin P. 
Published: August 2010

Abstract
A methodology is presented for estimating the urban bias of surface shelter temperatures due to the effect of the urban heat island. Multiple regression techniques were used to predict surface shelter temperatures based on the time period 1986&#x96;89 using upper-air data from the European Centre for Medium-Range Weather Forecasts to represent the background climate, site-specific data to represent the local landscape, and satellite-derived data&#x97;the normalized difference vegetation index (NDVI) and the Defense Meteorological Satellite Program (DMSP) nighttime brightness data&#x97;to represent the urban and rural landscape. Local NDVI and DMSP values were calculated for each station using the mean NDVI and DMSP values from a 3 km × 3 km area centered over the given station. Regional NDVI and DMSP values were calculated to represent a typical rural value for each station using the mean NDVI and DMSP values from a 1° × 1° latitude&#x96;longitude area in which the given station was located. Models for the United States were then developed for monthly maximum, mean, and minimum temperatures using data from over 1000 stations in the U.S. Cooperative Network and for monthly mean temperatures with data from over 1150 stations in the Global Historical Climate Network. Local biases, or the differences between the model predictions using the observed NDVI and DMSP values, and the predictions using the background regional values were calculated and compared with the results of other research. The local or urban bias of U.S. temperatures, as derived from all U.S. stations (urban and rural) used in the models, averaged near 0.40°C for monthly minimum temperatures, near 0.25°C for monthly mean temperatures, and near 0.10°C for monthly maximum temperatures. The biases of monthly minimum temperatures for individual stations ranged from near −1.1°C for rural stations to 2.4°C for stations from the largest urban areas. There are some regions of the United States where a regional NDVI value based on a 1° × 1° latitude&#x96;longitude area will not represent a typical “rural” NDVI value for the given region, Thus, for some regions of the United States, the urban bias of this study may underestimate the actual current urban bias. The results of this study indicate minimal problems for global application once global NDVI and DMSP data become available. It is anticipated that results from global application will provide insights into the urban bias of the global temperature record.
Mobile Microwave Radiometer Observations: Spatial Characteristics of Supercooled Cloud Water and Cloud Seeding Implications
Authors: Huggins Arlen W. 
Published: August 2010

Abstract
Previous studies of the spatial distribution of supercooled liquid water in winter storms over mountainous terrain were performed primarily with instrumented aircraft and to a lesser extent with scans from a stationary microwave radiometer. The present work describes a new technique of mobile radiometer operation that was successfully used during numerous winter storms that occurred over the Wasatch Plateau of central Utah to determine the integrated depth of cloud liquid water relative to horizontal position on the mountain barrier. The technique had the advantage of being able to measure total liquid from the terrain upward, without the usual terrain avoidance problems that research aircraft face in cloudy conditions. The radiometer also collected data during several storms in which a research aircraft could not be operated because of severe turbulence and icing conditions.
Repeated radiometer transects of specific regions of the plateau showed significant variability in liquid water depth over 30&#x96;60-min time periods, but also revealed that the profile of orographically generated cloud liquid was consistent, regardless of the absolute quantities. Radiometer liquid depth generally increased across the windward slope of the plateau to a peak near the western edge of the plateau top and then decreased across the relatively flat top of the plateau. These observations were consistent with regions where maximum and minimum vertical velocities were expected, and with depiction of cloud liquid by accretional ice particle growth across the mountain barrier. A comparison of data from the mobile radiometer and a stationary radiometer verified the general decrease in liquid depth from the windward slope to the top of the plateau and also showed that many liquid water regions were transient mesoscale features that moved across the plateau.
Implications of the results, relative to the seeding of orographic clouds, were that seeding aerosols released from valley-based generators could at times be inhibited by stable conditions from reaching appropriate super-cooled liquid water regions and, as found by others, the region of cloud most likely to be encountered by an AgI seeding agent released from the ground was also relatively warm compared to the ice-forming capability of the particular agent used in these experiments. Also, one convective case study that exhibited relatively warm temperatures in the cloud layer indicated that, even in conditions that permit vertical transport to supercooled liquid zones, sufficient time for ice particle growth and fallout from seeded plumes on this plateau may be lacking.
Considerations for Modeling Thin Cirrus Effects via Brightness Temperature Differences
Authors: Schmidt E. O. , Arduini R. F. , Wielicki B. A. , Stone R. S. , Tsay S-C. 
Published: August 2010

Abstract
Brightness temperature difference (BTD) values are calculated for selected Geostationary Operational Environmental Satellite (GOES-6) channels (3.9, 12.7 µm) and Advanced Very High Resolution Radiometer channels (3.7, 12.0 µm). Daytime and nighttime discrimination of particle size information is possible given the infrared cloud extinction optical depth and the BTD value. BTD values are presented and compared for cirrus clouds composed of equivalent ice spheres (volume, surface area) versus randomly oriented hexagonal ice crystals. The effect of the hexagonal ice crystals is to increase the magnitude of the BTD values calculated relative to equivalent ice sphere (volume, surface area) BTDs. Equivalent spheres (volume or surface area) do not do a very good job of modeling hexagonal ice crystal effects on BTDs; however, the use of composite spheres improves the simulation and offers interesting prospects. Careful consideration of the number of Legendre polynomial coefficients used to fit the scattering phase functions is crucial to realistic modeling of cirrus BTDs. Surface and view-angle effects are incorporated to provide more realistic simulation.
Geometrical Thickness, Liquid Water Content, and Radiative Properties of Stratocumulus Clouds over the Western North Pacific
Authors: Hayasaka Tadahiro , Nakajima Teruyuki , Fujiyoshi Yasushi , Ishizaka Yutaka , Takeda Takao , Tanaka Masayuki 
Published: August 2010

Abstract
An algorithm was developed for retrieving cloud geometrical thickness from a measured liquid water path and equivalent width of 0.94-µm water vapor absorption band. The algorithm was applied to aircraft observations obtained by a microwave radiometer and a spectrometer in the winter of 1991 over the western North Pacific Ocean. Retrieved values of the cloud geometrical thickness are apt to be smaller than those observed by eye, especially for horizontally inhomogeneous clouds. Measured cloud albedos in the visible and near-infrared spectral region were also compared with calculated values. For homogeneous clouds there exists a single droplet size distribution that satisfies both spectral regions. However, for inhomogeneous clouds no single size distribution exists that satisfies the albedo observed in both spectral regions.
Measurement of Vertical Liquid Water Path by Means of an Airborne Radiometer and the Shortwave Albedo of Marine Low-Level Clouds during WENPEX in Japan
Authors: Fujiyoshi Y. , Ishizaka Y. , Takeda T. , Hayasaka T. , Tanaka M. 
Published: August 2010

Abstract
Special observations were made over the southwest island area of the East China Sea from 12 to 27 January 1991 as part of the World Climate Research Program in Japan (WENPEX&#x97;Western North Pacific Cloud&#x96;Radiation Experiment). Two aircraft were used to determine the air truth of the total vertical liquid water path (LWP) using a microwave radiometer. One airplane was fitted with a 37-GHz radiometer and flew above planetary boundary layer clouds. The other flew inside the clouds with a cloud droplet spectrometer. These aircraft flew simultaneously along the same flight path when planetary boundary layer clouds were formed over the warm sea during an outbreak of cold air.
The result of the air truth of the LWPradiometer indicates that the 37-GHZ microwave radiometer gives an estimation of the LWP accurate to 100 mg cm−2. The shortwave cloud albedo was related to the LWPradiometer. The albedo increases with the LWP, independent of cloud type, when measured just above the cloud tops. The measured albedo is nearly the same as the calculated albedo when the LWPradiometer is larger than 60 mg cm−2 but much smaller than the calculated albedo when the LWPradiometer is less than 40 mg cm−2. Cloud-top irregularity is suggested to be the primary cause of this discrepancy. The degree of inhomogeneity of the horizontal distribution of liquid water appears to be correlated with the amount of precipitable water in the planetary boundary layer.
Numerical Simulation on the TIBL Structure in Shoreline Areas with a 2D Higher-Order Turbulence Closure Model
Authors: Weimei Jiang , Xiaoming Wu , Jingnan Zhou 
Published: August 2010

Abstract
A 2D higher-order turbulence closure model for research on the structure of the thermal internal boundary layer (TIBL) has been developed in this paper. The mean quantities (temperature and wind), as well as their turbulent moments and their distribution under the TIBL, were computed. Results of numerical simulation show that under the initial condition of onshore flow and surface temperature on land being higher, than on water. 1) the profile of the TIBL on shore can be identified by the distributions of the mean wind and temperature, and during the integration hours there is an unstable stratified region over land that extends upward and inland gradually; 2) the shape of the profiles of the TIBL is roughly in concordance with observed profiles, but there are some differences, obviously, between the results computed by the formula of h ∼ x1/2 and the results of the numerical experiment; and 3) u′2, v′2, w′2, and u′w′, θ′w′ and their general features are well reproduced by the model. It is shown that the numerical model is feasible and effective.
Characteristics of Convective Turbulence in the Surface Layer Investigated by Principal Component Analysis
Authors: Weijers E. P. , Van Delden A. , Vugts H. F. , Meesters A. G. C. A. 
Published: August 2010

Abstract
Principal component analysis (PCA) was applied to 182 half-hour runs containing time series of turbulent wind velocity and temperature measured in the convective atmospheric surface layer. A field experiment with four sonic anemometers on the vertices and one in the centroid of a square (with sides of 80 m) was performed to obtain the necessary dataset. Physical explanations of the most important eigenvectors are presented. Two of the major principal components (PCs) identify the variance in wind speed along and across the background wind direction. Always, one major PC accounts for the presence of large-scale thermal activity: periods with higher (lower) temperatures coincide with lower (higher) wind speeds, convergence (divergence) in the wind fields, and upward (downward) movements. As an application, variance in the velocity fields was expressed in terms of horizontal divergence and vertical vorticity. These can be derived directly from the eigenvectors when PCA is combined with a planimetric method. Using the PC that identifies thermal activity, it is found that the magnitude of divergence increases and the magnitude of vorticity decreases when atmospheric conditions become more unstable. It is found that the (absolute) ratio between vorticity and divergence scales with a function of the friction velocity divided by the convective vertical scaling velocity. Both kinematic parameters are larger for updrafts than for downdrafts. It is concluded that PCA can be a useful tool to distinguish variance of thermal and nonthermal origin and in the estimation of the kinematics of dominant flow fields.
Numerical Simulation of Boundary Layer Variables Using ē&#x96;ε Closure Scheme
Authors: Ramanathan N. , Srinivasan K. , Seshasayee B. V. 
Published: August 2010

Abstract
In this study, a one-and-a-half-order ē&#x96;ε closure scheme is used to study the planetary boundary layer development over a full diurnal cycle using Wangara 33d-day observations as initial conditions. The simulated results are compared with a first-order closure model and higher-order closure model results. A scheme of this kind has the advantage of taking into account the history of turbulence state in terms of a prognostic equation for turbulence kinetic energy and provides a better basis for the representation of clouds. The results of the model simulations compare favorably with other investigators’ results.
Horizontal Heat Fluxes over Complex Terrain Computed Using a Simple Mixed-Layer Model and a Numerical Model
Authors: Kimura Fujio , Kuwagata Tuneo 
Published: August 2010

Abstract
The thermally induced local circulation over a periodic valley is simulated by a two-dimensional numerical model that does not include condensational processes. During the daytime of a clear, calm day, heat is transported from the mountainous region to the valley area by anabatic wind and its return flow. The specific humidity is, however, transported in an inverse manner. The horizontal exchange rate of sensible heat has a horizontal scale similarity, as long as the horizontal scale is less than a critical width of about 100 km.
The sensible heat accumulated in an atmospheric column over an arbitrary point can be estimated by a simple model termed the uniform mixed-layer model (UML). The model assumes that the potential temperature is both vertically and horizontally uniform in the mixed layer, even over the complex terrain. The UML model is valid only when the horizontal scale of the topography is less than the critical width and the maximum difference in the elevation of the topography is less than about 1500 m.
Latent heat is accumulated over the mountainous region while the atmosphere becomes dry over the valley area. When the horizontal scale is close to the critical width, the largest amount of humidity is accumulated during the late afternoon over the mountainous region.
Boundary Layer Characteristics over Areas of Inhomogeneous Surface Fluxes
Authors: Doran J. C. , Shaw W. J. , Hubbe J. M. 
Published: August 2010

Abstract
This paper describes results from a June 1992 field program to study the response of the boundary layer over a site with well-defined extreme differences in sensible and latent heat fluxes over clearly separated areas, each with characteristic length scales of 10 km or more. The experiment region consisted of semiarid grassland steppe and irrigated farmland. Sensible heat flux maxima over the steppe regularly reached values in excess of 300 W m−2 and were typically a factor of 4 or more greater than those over the farmland. Two days were selected for analysis: one with moderate winds of 7&#x96;10 m s−1 and one with lighter winds of 4&#x96;7 m s−1 over the steppe. In both cases the wind directions were nearly perpendicular to the boundary between the steppe and farm. An analysis of potential temperature soundings showed that mixed-layer characteristics over both the farm and the steppe were largely determined by heating over the steppe, with advection from the steppe to the farm playing a significant role. On the day with the lighter winds, a secondary circulation related to the thermal contrasts between the two areas was observed. A simple conceptual model is described that predicts the extent of the cooler area required to generate such circulations. The observations illustrate how predictions of boundary layer structure in terms of local surface sensible heat fluxes may be compromised by advective effects. Such difficulties complicate efforts to obtain accurate representations of surface fluxes over inhomogeneous surfaces even if parameterizations of mesoscale contributions to the heat flux are included.
The Roughness Length for Heat of Sparse Vegetation
Authors: Blyth E. M. , Dolman A. J. 
Published: August 2010

Abstract
A dual-source model that solves the energy balance over vegetation and soil separately can be inverted to obtain the roughness length for heat z0h of a single-source model. Model parameters for the dual-source model were taken from previous analysis of data from a sparse canopy in semiarid terrain. In these circumstances, the value of z0h, is shown to be dependent on the humidity deficit, the available energy, the vegetation fraction, and the surface resistance of the soil and the vegetation.