The Simulation of Subsurface Effects on the Diurnal Surface Thermal Regime in Cold Regions

... Layered substrate materials are common in nature; these include naturally stratified soils, ice and snow. ... solar radiation penetrates the surface and produces subsurface heating in snow and ice terrain. The stratification problem has been treated by numerous authors as variation of the periodic heat flow problem using surface temperature as the forcing function. ... In recent years there has been a considerable interest in the possibility of acquiring surface environmental information using the spatial variance in the phase and amplitude of the diurnal surface thermal regime as an indicator. ... It would appear that melting rock glacier ice cores, massive ground ice and active layer depth variations contribute significantly to the surface thermal regime variance when these features are relatively close to the surface. It would however appear that lake and sea ice depth variations with either spatially homogeneous light snow cover or none should be detectable particularly where there are large depth variations. Whereas surface climate simulation presents an explicit method of estimating the influence of a wide range of surface environmental factors, specifically albedo, emissivity, substrate radiation extinction (ice and snow), roughness, wetness, stratified thermal properties, slope and exposure, the method would appear to be extremely valuable in the experimental design and hypothesis formation phases of thermal mapping investigations in cold regions. Furthermore as the strategy can be employed to estimate the sensitivity of the surface thermal response to individual environmental factors the method dictates the ground truth requirements for exploratory investigations. Lastly as process and environmental information becomes available the strategy can be used to construct explicit deterministic physical models of the spatial and temporal variance of surface thermal response which can be employed as an analytical portion of a remote sensing reconnaissance system specific to trafficability and site studies in arctic and alpine environments. In short, the capacity for modelling the surface thermal response as a function of the surface and substrate environment vastly increases the accessible information content of thermal infrared maps particularly where these are acquired at several times during the diurnal cycle

Editor\u27s Message, Winter 1979

This is the last issue under my editorship. As has been planned from the start, Glenn Nyre will be editor for 1980, Volume 2 of this Quarterly. Originally, Lance Buhl was going to be editor for 1981, but his election as Executive Director precluded that since it is improper in volunteer organizations such as POD to ask an individual to take on the two most demanding responsibilities back-to-back. However, the developing strength of POD was demonstrated in the ease by which two highly qualified and enthusiastic members were recruited for future editorships: Sandra Inglis for 1981 and Robert Young for 1982

The simulation of diurnal surface thermal contrast in sea ice and tundra terrain

A simple surface climate simulator has the capacity to model the thermal contrast produced by stratification, variable sea ice or active layer thickness and albedo in the environment of the Alaskan North Slope. These simulations form the background for modeling the probable effects of terrain modifications produced by Arctic construction. This strategy should allow investigators to estimate the most appropriate times for the discrimination of specific targets using thermal imagery as a prospecting medium and facilitate the interpretation of existing imagery. Lastly, the scheme allows investigators of surface modification effects to select probable subsets of processes for field evaluation by examining the sensitivity of the thermal response to variations of the input properties over their anticipated ranges in conjunction with estimates of the local meteorological environment. This sequence can also be used to test the physical validity of process arguments used in the interpretation of thermal contrast in reconnaissance imagery. Ein einfaches Modell des Bodenklimas besitzt die Fähigkeit, den thermischen Kontrast, der durch Stratifikation, variable Eisbedeckung oder aktive Schichtdecke und Albedo in der Umgebung des Nordhanges Alaskas hervorgerufen wird, abzubilden. Die Modellrechnungen bilden die Basis für eine Abschätzung des Effektes von Veränderungen des Geländes im Zusammenhang mit Bauarbeiten in der Arktis. Mit diesem Modell sollte es auch möglich sein, die günstigsten Zeiten für die unterschiedliche Behandlung spezifischer Zielgebiete unter Anwendung von Temperaturabbildungen als Aufschließungsmittel ausfindig zu machen und die Interpretation der bestehenden Temperaturabbildungen zu erleichtern. Letzten Endes erlaubt das Modell, auf Grund einer Untersuchung der Empfindlichkeit der thermischen Reaktion auf Änderungen der Anfangsbedingungen in ihrem möglichen Variationsbereich im Zusammenhang mit den örtlichen meteorologischen Bedingungen die Auswahl von Teilprozessen bei der Untersuchung von Auswirkungen der Veränderungen der Oberflächenschicht des Bodens. Mittels dieses Modells kann auch die physikalische Richtigkeit verschiedener Argumente geprüft werden, die in der Interpretation von Temperaturunterschieden, welche bei Gebietsuntersuchungen auftreten, angewendet werden.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41668/1/704_2005_Article_BF02243724.pd

URBAN TERRAIN CLIMATOLOGY AND REMOTE SENSING *

. Urban areas have been conceived of as monolithic heat islands because traditional ground observation techniques do not lend themselves to more specific analyses. Observations of urban energy-exchange obtained from calibrated electro-optical scanners combined with energy budget simulation techniques provide tools to relate the urban land use mosaic to the heat island phenomenon. Maps of surface energy-related phenomena were made from airborne scanner outputs for selected flightpaths across the city of Baltimore, Maryland. Conditions for the flight time were simulated according to the various types of land use using an energy budget simulation model which lends itself to extrapolation of simulated grid-point conditions into a map form. Maps made by simulation compare sufficiently well with those made by aerial observation to encourage further refinement of the simulation approach.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72392/1/j.1467-8306.1976.tb01110.x.pd

Influence of reproduction cutting methods on structure, growth and regeneration of longleaf pine forests in flatwoods and uplands

Though longleaf pine (Pinus palustris Mill.) forests have been primarily managed with even-aged methods, interest is increasing in uneven-aged systems, as a means of achieving a wider range of stewardship goals. Selection silviculture has been practiced on a limited scale in longleaf pine, but difficulty with using traditional approaches and absence of an evaluation across a range of site types has left managers in doubt concerning its suitability. This study was conducted to quantify the effects on stand dynamics of applying single-tree selection, group selection, irregular shelterwood and uniform shelterwood in longleaf pine forests on flatwoods and uplands of the southeastern United States. Selection treatments reduced stand basal area to approximately 11.5 m2 ha-1 and shelterwood treatments left a basal area of approximately 5.8 m2 ha-1. In spite of initial decreases in tree density and standing volume, growth rates were normal in all stands (1–5% per year), as were subsequent increases in basal area and tree density. Despite the continuing abundance of saw-palmetto (Serenoa repens W. Bartram) cover and absence of prescribed fire during the eight post-treatment years, significant increases in pine regeneration were observed in all treated stands in the flatwoods. Because of a multi-year drought in the uplands, pine seedling numbers dramatically declined, no matter which reproduction approach was employed. Although seedling numbers eventually began to recover, they were again precipitously depressed by a wildfire in 2013. Even with such losses, sufficient pine seedlings remained in each treatment to foster successful stand regeneration. Single-tree selection produced less overall change in the forest ecosystem than group selection, which caused less alteration than shelterwood treatment. Single-tree selection appears to be an effective way for achieving stand regeneration, while maintaining a continuous canopy cover that aids in the control of woody competitors and supports an array of resource values. Selection silviculture seems to be a lower risk approach for guiding forests along a trajectory of gradual improvement, with adjustments provided by frequent surface fires and periodic tree harvest. Long-term observation will be required to verify that selection can sustain forest ecosystems on sites characterized by differing environments

Influence of reproduction cutting methods on structure, growth and regeneration of longleaf pine forests in flatwoods and uplands

Though longleaf pine (Pinus palustris Mill.) forests have been primarily managed with even-aged methods, interest is increasing in uneven-aged systems, as a means of achieving a wider range of stewardship goals. Selection silviculture has been practiced on a limited scale in longleaf pine, but difficulty with using traditional approaches and absence of an evaluation across a range of site types has left managers in doubt concerning its suitability. This study was conducted to quantify the effects on stand dynamics of applying single-tree selection, group selection, irregular shelterwood and uniform shelterwood in longleaf pine forests on flatwoods and uplands of the southeastern United States. Selection treatments reduced stand basal area to approximately 11.5 m2 ha-1 and shelterwood treatments left a basal area of approximately 5.8 m2 ha-1. In spite of initial decreases in tree density and standing volume, growth rates were normal in all stands (1–5% per year), as were subsequent increases in basal area and tree density. Despite the continuing abundance of saw-palmetto (Serenoa repens W. Bartram) cover and absence of prescribed fire during the eight post-treatment years, significant increases in pine regeneration were observed in all treated stands in the flatwoods. Because of a multi-year drought in the uplands, pine seedling numbers dramatically declined, no matter which reproduction approach was employed. Although seedling numbers eventually began to recover, they were again precipitously depressed by a wildfire in 2013. Even with such losses, sufficient pine seedlings remained in each treatment to foster successful stand regeneration. Single-tree selection produced less overall change in the forest ecosystem than group selection, which caused less alteration than shelterwood treatment. Single-tree selection appears to be an effective way for achieving stand regeneration, while maintaining a continuous canopy cover that aids in the control of woody competitors and supports an array of resource values. Selection silviculture seems to be a lower risk approach for guiding forests along a trajectory of gradual improvement, with adjustments provided by frequent surface fires and periodic tree harvest. Long-term observation will be required to verify that selection can sustain forest ecosystems on sites characterized by differing environments

The climatonomy of a needle ice event: An experiment in simulation climatology

Soil surface temperature, net radiation and surface heave are used to evaluate a computer simulation of a needle ice event at Vancouver, Canada. The simulation which includes fusion and soil water flow effects, provides a working example of a simulation-sensitivity experiment in climatology and therefore has implications which transcend the rather restricted subject of diurnal soil frost effects. Die Temperatur der Bodenoberfläche, die Strahlungsbilanz und die Bodenbewegung werden in einem Rechenmodell benützt, das die Eisnadelbildung in Vancouver, Kanada, simuliert. Das Modell, welches den Gefriervorgang und den Effekt der Wasserströmung im Boden einbezieht, stellt ein Beispiel eines Simulations- und Sensitivitätsexperiments in der Klimatologie dar, welches über die Belange des beschränkten Sachgebietes der Bodenfrosteffekte hinausgeht.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41665/1/704_2005_Article_BF02253559.pd

Diurnal Thermal Regime in a Peat-Covered Palsa, Toolik Lake, Alaska

Strong spatial and temporal variations in temperature and effective thermal diffusivity are apparent from short-term thermal records measured in the peat atop an ice-cored palsa in northern Alaska. Intersite differences in near-surface temperature regimes apparently result from topographic influences, vegetative cover, and site wetness. Values of effective thermal diffusivity indicate that ablation of the ice core is inhibited by advection of cold water near the ice-peat contact and by internal evaporation near the surface. These findings support the conclusions of earlier investigators, who emphasized the importance of peat for maintaining palsas near their equatorward limit.Key words: active layer, frost mound, palsa, peat, permafrost, soil temperature, thermal properties, AlaskaMots clés: couche active, tertre de gel, palsa, tourbe, pergélisol, température du sol, propriétés thermiques, Alask

Lightning, fire and longleaf pine: Using natural disturbance to guide management.

Abstract The importance of lightning as an ignition source for the fire adapted longleaf pine (Pinus palustris) ecosystem is widely recognized. Lightning also impacts this system on a smaller scale by causing individual tree mortality. The objective of this study was to determine mortality due to lightning and other agents in longleaf stands on the Ocala National Forest in central Florida and to quantify lightning ignited fire. Mortality from lightning was also tracked in longleaf stands on the Savannah River Site in South Carolina. Lightning killed more trees than any other agent with a mean mortality of nearly 1 tree/3 ha/yr in Florida and 1 tree/8 ha/yr in South Carolina. The probability of a tree being struck by lightning increased as a function of tree height at both sites, i.e. lightning preferentially removed the largest trees from the stand. In addition lightning strikes were clumped within stands, sometimes killed multiple trees with a single strike, and often hit trees on the edge of existing gaps. The combination of these processes means gaps suitable for regeneration within longleaf stands are created quite rapidly. This information provides guidelines for the development of selection harvest systems based on this natural disturbance. Although lightning activity was greatest during the summer months in Florida and most fires occurred in June, the probability of a strike causing a fire was highest in February to May. Published by Elsevier B.V