The N-Factor in Natural Landscapes: Variability of Air and Soil-Surface Temperatures, Kuparuk River Basin, Alaska, U.S.A.

Abstract

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. INSTAAR, University of Colorado andThe Regents of the University of Colorado, a body corporate, contracting on behalf of the University of Colorado at Boulder for the benefit of INSTAAR are collaborating with JSTOR to digitize, preserve and extend access to Arctic, Antarctic, and Alpine Research. IntroductionAccurate, high-resolution soil-surface temperature fields are vital for modeling many ecosystem interactions, over a wide range of spatial and temporal scales. Despite the importance of soil-surface temperature to many ecological, hydrological, geomorphological, and climatological investigations, instrumental networks report air temperature at screen height almost exclusively. Relatively few soil temperatures data sets have been obtained from a wide variety of land-cover types. This lack of information presents difficulties for ecologists, soil scientists, physical geographers, and geocryologists. Microenvironmental studies of plant physiology (Arft et al., 1999; Mueller et al., 1999), animal populations (Peach et al., 1994; Reid and Krebs, 1996), soil climate (Halliwell et al., 1990; Goulden et al., 1998), freeze/thaw depths (Nelson et al., 1997), trace-gas fluxes (Vourlitis et al., 1993), and geomorphic studies (Sellmann et al., 1975), for example, could benefit from detailed information about soil-surface temperatures.However intuitive a relationship between air and soil temperatures may appear, these thermal regimes can be very different, depending on the properties of the ground surface. One method for addressing this problem is to estimate soil-surface temperature from air temperature, a standard meteorological measurement. The n-factor (Carlson, 1952) is the ratio of seasonal degree-day sums at the soil-surface to those in the air at standard screen height. This index has been used for construction and engineering purposes in the Arctic since World War II (Hildebrand, 1983), but applications in natural landscapes have remained largely conceptual until recently, owing to difficulties involved with obtaining the large numbers of measurements needed for any but a few homogenous, engineered surfaces. Recent advances in data-logger technology provide the means by which to record and store thousands of temperature observations Abstract The n-factor, or ratio of the seasonal degree-day sum at the soil surface to that in the air at standard screen height, has been used for more than 40 yr in engineering studies to parameterize the temperature regime at the ground surface. Conceptually, this index represents the complex energy balance at the surface as a single dimensionless number and has applications in ecology, climatology, and geocryology. Although the n-factor has been use...

Scaling-up permafrost thermal measurements in western Alaska using an ecotype approach

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Comparison of MODIS-derived land surface temperatures with ground surface and air temperature measurements in continuous permafrost terrain

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A new map of permafrost distribution on the Tibetan Plateau

“…Although air temperature produces inaccurate and low-resolution estimates of ground surface temperature (GST, defined as the surface or near-surface temperature of the ground (bedrock or surficial deposit) and measured in the uppermost centimetres of the ground), it was still widely used in practical applications because of limited GST observations. In these studies, the N factor has been the most effective way to transform the air temperature to the GST (Lunardini, 1978;Klene et al, 2001). With the recent development of infrared remote sensing technology, an increasing number of land surface temperature (LST, defined as the average temperature of an element of the exact surface of the Earth (e.g.…”