Energy budget above a high-elevation subalpine forest in complex topography

Turnipseed, Andrew A.; Blanken, Peter D.; Anderson, Dean E.; Monson, Russell K.

doi:10.1016/s0168-1923(01)00290-8

Cited by 167 publications

(184 citation statements)

References 44 publications

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“…For latent heat flux, a krypton hygrometer (Campbell Scientific, model KH2O) was the primary instrument used to measure the humidity fluctuations. However, a closed-path infrared gas analyzer (IRGA; LI-COR, model LI-6262) with an inlet at 21.5 m was used when the krypton hygrometer was not available (Monson et al 2002;Turnipseed et al 2002;Molotch et al 2009). In the subcanopy, water vapor fluctuations were measured at 2.5 m with an open-path IRGA (LI-COR, model LI-7500) and collocated CSAT3 on the accompanying 6-m subcanopy flux tower (Molotch et al 2007).…”

Section: A Turbulent and Radiative Fluxesmentioning

confidence: 99%

“…, and canopy gap fraction is 18% (Turnipseed et al 2002). Turnipseed et al (2002) supplies additional information about long-term measurements of radiation, soil heat flux, soil temperature, and soil moisture content.…”

mentioning

confidence: 99%

“…Turnipseed et al (2002) supplies additional information about long-term measurements of radiation, soil heat flux, soil temperature, and soil moisture content. A summary of recent changes to the soil temperature and moisture measurements at NWT are described below.…”

mentioning

confidence: 99%

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Snow Temperature Changes within a Seasonal Snowpack and Their Relationship to Turbulent Fluxes of Sensible and Latent Heat

Burns

Molotch

Williams

et al. 2014

Journal of Hydrometeorology

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Snowpack temperatures from a subalpine forest below Niwot Ridge, Colorado, are examined with respect to atmospheric conditions and the 30-min above-canopy and subcanopy eddy covariance fluxes of sensible Q h and latent Q e heat. In the lower snowpack, daily snow temperature changes greater than 18C day 21 occurred about 1-2 times in late winter and early spring, which resulted in transitions to and from an isothermal snowpack. Though air temperature was a primary control on snowpack temperature, rapid snowpack warm-up events were sometimes preceded by strong downslope winds that kept the nighttime air (and canopy) temperature above freezing, thus increasing sensible heat and longwave radiative transfer from the canopy to the snowpack. There was an indication that water vapor condensation on the snow surface intensified the snowpack warm-up. In late winter, subcanopy Q h was typically between 210 and 10 W m 22 and rarely had a magnitude larger than 20 W m 22 . The direction of subcanopy Q h was closely related to the canopy temperature and only weakly dependent on the time of day. The daytime subcanopy Q h monthly frequency distribution was near normal, whereas the nighttime distribution was more peaked near zero with a large positive skewness. In contrast, above-canopy Q h was larger in magnitude (100-400 W m 22 ) and primarily warmed the forest-surface at night and cooled it during the day. Around midday, decoupling of subcanopy and above-canopy air led to an apparent cooling of the snow surface by sensible heat. Sources of uncertainty in the subcanopy eddy covariance flux measurements are suggested. Implications of the observed snowpack temperature changes for future climates are discussed.

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Section: A Turbulent and Radiative Fluxesmentioning

confidence: 99%

mentioning

confidence: 99%

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Snow Temperature Changes within a Seasonal Snowpack and Their Relationship to Turbulent Fluxes of Sensible and Latent Heat

Burns

Molotch

Williams

et al. 2014

Journal of Hydrometeorology

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“…The degree of closure of the energy balance is a common approach for validating data. Complete closure (H + E = À(NR + G)) is rarely, if ever, attained [Turnipseed et al, 2002]. A scatterplot of (H + E ) versus (NR + G) together with the corresponding regression analysis is presented in Figure 4.…”

Section: Data Analysis and Evaluationmentioning

confidence: 99%

Soil water evaporation during the dry season in an arid zone

Agam¹

2004

J. Geophys. Res.

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[1] The objective of this study was to assess the relative magnitude of latent heat flux density over a bare loess soil in the Negev desert throughout the dry season, during which the atmospheric models usually assume the lack of latent heat flux. The measurements were carried out in the northern Negev, Israel, over a bare loess soil, during nine 24-hour field campaigns throughout the dry season of 2002. In addition to a micrometeorological station that was set up in the research site, an improved microlysimeter was installed. The representativity of the microlysimeter was assessed by comparing its surface temperature to that of the surrounding surface using thermal images acquired on an hourly basis during several campaigns. It was found that although the water content of the uppermost soil is significantly lower than the wilting point, for which most of the commonly used meteorological models would assume no latent heat flux, the latter was $20% of the net-radiation during the night and 10-15% during the day. It is therefore concluded that latent heat flux plays a major role in the dissipation of the net radiation during the dry season in the Negev desert.

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“…Initial measurements of NEE, GPF? and ecosystem respiration dynamics have been established in an aggrading sub-alpine forest in the Rocky Mountains of Colorado [Turnipseed et al, 2002] .The Niwot Ridge Ameriflux site is locally level, with a 5-6° slope, to accommodate traditional micrometeorological techniques (Figure 3).The site is located at 3050 m elevation and consists of three towers; two are used to make continu ous eddy correlation measurements of C0 2 and H 2 0 fluxes, and wind and scalar concen trations are measured on all three. Prevailing winds are from the west, with fetch consisting of spruce-fir forest for 1.5 km.…”

Section: Preliminary Flux Measurements In the Mountainsmentioning

confidence: 99%

Carbon sequestration studied in western U.S. mountains

Schimel¹,

Kittel²,

Running³

et al. 2002

EoS Transactions

110

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The U.S. carbon budget has been the focus of recent scientific debate [Fan et al., 1998; Pacala et al., 2001; Gurney et al., 2002] Even conservative estimates suggest that U.S. ecosystems take up a significant amount of carbon, largely as a result of historical land use practices [Houghton et al., 1999; Schimel et al.,2000; Pacala et al., 2001]. In the western United States, a key cause of carbon sequestration is fire suppression. Fire suppression, of course, also sets the stage for the catastrophic losses that are occurring during fire season 2002. Increases in fire due to the effects of fire suppression, increased prescribed burning and thinning, and climate change could significantly affect the national carbon budget. At the continental scale, a comprehensive research approach—the North American Carbon Program (NACP)—is planned to quantify carbon exchange and improve our understanding of the contributing processes [Wofsy and Harriss, 2002].

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Energy budget above a high-elevation subalpine forest in complex topography

Cited by 167 publications

References 44 publications

Snow Temperature Changes within a Seasonal Snowpack and Their Relationship to Turbulent Fluxes of Sensible and Latent Heat

Snow Temperature Changes within a Seasonal Snowpack and Their Relationship to Turbulent Fluxes of Sensible and Latent Heat

Soil water evaporation during the dry season in an arid zone

Carbon sequestration studied in western U.S. mountains

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