Effects of tree morphometry on net snow cover radiation on forest floor for varying vegetation densities

Seyednasrollah, Bijan; Kumar, Mukesh

doi:10.1002/2012jd019378

Cited by 12 publications

(20 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Vegetation density is quantified as 138 , where is the average distance between trees in an idealized uniform forest. It is to be 139 emphasized that the model has been previously validated against the observed shortwave and 140 longwave radiation data in a uniform lodgepole pine forest at the Local Scale Observation Site 141 (LSOS, [NSIDC, 2013]) in Fraser, CO, USA [Seyednasrollah et al, 2013]. By using the same 142 configuration of forest at different locations, the role of latitudinal location and associated 143 meteorological characteristics on variation of with changing vegetation density is isolated.…”

Section: Results and Discussion 136mentioning

confidence: 99%

“…The optimum vegetation density at which is minimum, decreases 50 with increasing tree height, crown radius and crown density. On the other hand, larger crown 51 depth leads to an increase in the vegetation density at which radiation is minimum 52 [Seyednasrollah and Kumar, 2013]. 53…”

mentioning

confidence: 99%

“…Additionally, both 57 and are affected by site-specific climatological characteristics (e.g. air temperature 58 for the simulated snow season is obtained by fitting a periodic function to long term 91 air temperature data (Table 2) , is evaluated by quantifying incoming direct ( ), 108 diffuse ( ), and multiple reflected shortwave radiation components between snow and 109 canopy using [Seyednasrollah et al, 2013]: 110…”

mentioning

confidence: 99%

“…Sky view factor, , is estimated using the 122 SkyMap algorithm. More details about the calculation of individual radiation components are 123 available in Seyednasrollah et al [2013] and Seyednasrollah and Kumar [2013].the variability of net radiation for different vegetation densities along a latitudinal transect (see 127 Figure 1). The selection of sites is made based on three criteria: (a) situated in white spruce 128 forests, (b) located in mid to high latitudes, and (c) sites should have long-term temperature 129 records (see Table 1).…”

mentioning

confidence: 99%

See 3 more Smart Citations

Variability of Net Radiation on Snow-Covered Forest Floor for a Range of Vegetation Densities along a Latitudinal Transect

Seyednasrollah¹,

Kumar²

2018

Preprint

Self Cite

View full text Add to dashboard Cite

5Net radiation reaching the forest floor is influenced by vegetation density. Previous studies have 6 confirmed that in mid-latitude conifer forests in Greenville, ME (45.5°N), net radiation decreases 7 and then subsequently increases with increasing vegetation density, for clear sky conditions. This 8 leads to existence of a net radiation minimum at an intermediate vegetation density. With 9 increasing cloud cover, the minimum radiation shifts toward lower densities, sometimes resulting 10 in a monotonically increasing radiation with vegetation density. The net radiation trend, 11 however, is expected to change with location of forests, affecting the magnitude and temporality 12 of individual radiation components. This research explores the variability of net radiation on 13 snow-covered forest floor for different vegetation densities along a latitudinal transect. We 14 especially investigate how the magnitude of minimum/maximum radiation and vegetation 15 density at which they are expressed, changes with site location. To evaluate these, net radiation is 16 calculated using the Forest Radiation Model at six different locations in white spruce (Picea 17 glauca) forests across North America, with latitudes ranging from 45 to 66°N. Results show that 18 the variation of net radiation with vegetation density significantly varies between different 19 latitudes. In higher latitude forests, the magnitude of net radiation is generally smaller, and the 20 minimum radiation is exhibited at relatively sparser vegetation densities, for clear sky conditions. 21For interspersed cloudy sky conditions, net radiation non-monotonically varies with latitude 22 across the sites, depending on the seasonal sky cloudiness and air temperature. Net radiation on 23 north-facing hillslopes is less sensitive to latitudinal location than on south-facing sites. 24 3 1 Introduction 25

show abstract

Section: Results and Discussion 136mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Variability of Net Radiation on Snow-Covered Forest Floor for a Range of Vegetation Densities along a Latitudinal Transect

Seyednasrollah¹,

Kumar²

2018

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…In addition to calibrating the coarse resolution climate models, there has been an increasing need for high-resolution land surface shortwave radiation data in surface energy balance modeling and in agricultural, ecological, and urban environmental studies (e.g., Kuusinen, Tomppo, Shuai, & Berninger, 2014;Roberts, Quattrochi, Hulley, Hook, & Green, 2012;Seyednasrollah & Kumar, 2013;Tasumi, Allen, & Trezza, 2008). To satisfy the needs for such research applications, NSR estimation at finer resolutions (b1 km) is required.…”

Section: Introductionmentioning

confidence: 99%

Estimation of high-resolution land surface net shortwave radiation from AVIRIS data: Algorithm development and preliminary results

Liang

Wang

et al. 2015

Remote Sensing of Environment

View full text Add to dashboard Cite

Hyperspectral remote sensing provides unique and abundant spectral information for quantification of the land surface shortwave radiation budget, which can be used to calibrate climate models and to estimate surface energy budget for monitoring agriculture and urban environment. However, only single broadband or multispectral data have been used in previous studies. In the present study, two methods are proposed to estimate the instantaneous land surface net shortwave radiation (NSR) with high spatial resolutions using hyperspectral remote sensing observations from the Airborne Visible Infrared Imaging Spectrometer (AVIRIS) data. Method A calculates the NSR based on separate estimation of downward radiation and surface broadband albedo, which requires ancillary information for aerosol optical depth; and Method B directly estimates the NSR from the observed radiance. Results based on radiative transfer simulations showed that the use of hyperspectral data can significantly improve NSR estimation compared with the multispectral data method. Atmospheric water vapor correction was applied to adjust the surface radiation estimation. Validation of AVIRIS NSR estimates against ground measurements from two flux networks for the period of 2006-2014 showed that the two methods were similar and had consistent accuracy in the all-sky instantaneous NSR estimation with root-mean-square-errors (RMSEs) of approximately 28-56 W/m 2 . The pixel-based water vapor content estimation from AVIRIS data provided slightly different results than those obtained using coarse resolution remote sensing data. A simplified topographic correction algorithm was found to be able to improve the results generated from Method A; however, the degree of improvement provided by Method B was unclear, possibly because of the lack of consideration of horizontal atmospheric scattering effects from adjacent pixels. In general, hyperspectral remote sensing data have been shown to improve the NSR estimation accuracies compared with results obtained in previous studies. Additional efforts are needed to refine the NSR estimation for application to future satellite hyperspectral data.

show abstract

Net radiation in a snow‐covered discontinuous forest gap for a range of gap sizes and topographic configurations

Seyednasrollah

Kumar

2014

JGR Atmospheres

Self Cite

View full text Add to dashboard Cite

Estimating net radiation on the forest floor is crucial for predicting snowmelt recharge and for quantifying water yield from snow-dominated forested watersheds. However, complex characteristics of radiation transfer in discontinuous forest gaps make this estimation challenging. This study quantifies net radiation within a forest gap for a range of gap sizes, slopes and aspects, and meteorological conditions. The spatial distribution of net radiation in the gap is found to be heterogeneous with southern and northern areas of the gap receiving minimum and maximum energy amounts, respectively. At a midlatitude site and for completely clear sky conditions in the snow season, results suggest that net radiation in the forest gap is minimum for gaps of size equal to half of the surrounding tree height. In contrast, when sky cloudiness in the snow season is considered, net radiation shows a monotonically increasing trend with gap size. Slope and aspect of forest gap floor also impact the net radiation and its variation with gap size. Net radiation is largest and smallest on steep south-facing and north-facing slopes, respectively. Variation of net radiation with slope and aspect is largest for larger gaps. Results also suggest that net radiation in north-facing forest gaps is larger than in open areas for a longer duration in the snow season than in forest gaps on flat and south-facing slopes. Since net radiation directly affects melt recharge and evaporation, these findings have implications on forest and water management, wildfire hazard, and forest health.

show abstract

Effects of tree morphometry on net snow cover radiation on forest floor for varying vegetation densities

Cited by 12 publications

References 35 publications

Variability of Net Radiation on Snow-Covered Forest Floor for a Range of Vegetation Densities along a Latitudinal Transect

Variability of Net Radiation on Snow-Covered Forest Floor for a Range of Vegetation Densities along a Latitudinal Transect

Estimation of high-resolution land surface net shortwave radiation from AVIRIS data: Algorithm development and preliminary results

Net radiation in a snow‐covered discontinuous forest gap for a range of gap sizes and topographic configurations

Contact Info

Product

Resources

About