RECORD
Estimating the Longwave Radiation Underneath the Forest Canopy in Snow-dominated Setting
- Title:
- Estimating the Longwave Radiation Underneath the Forest Canopy in Snow-dominated Setting
- Creator:
- Zhou, Y.; Kumar, M.; Link, T.E.
- Date Created:
- 2017
- Description:
- Forest canopies alter incoming longwave radiation at the land surface, thus influencing snow cover energetics. The snow surface receives longwave radiation from the sky as well as from surrounding vegetation. The longwave radiation from trees is determined by its skin temperature, which shows significant heterogeneity depending on its position and morphometric attributes. Here our goal is to derive an effective tree temperature that can be used to estimate the longwave radiation received by the land surface pixel. To this end, we implement these three steps: 1) derive a relation between tree trunk surface temperature and the incident longwave radiation, shortwave radiation, and air temperature; 2) develop an inverse model to calculate the effective temperature by establishing a relationship between the effective temperature and the actual tree temperature; and 3) estimate the effective temperature using widely measured variables, such as solar radiation and forest density. Data used to derive aforementioned relations were obtained at the University of Idaho Experimental Forest, in northern Idaho. Tree skin temperature, incoming longwave radiation, solar radiation received by the tree surface, and air temperature were measured at an isolated tree and a tree within a homogeneous forest stand. Longwave radiation received by the land surface and the sky view factors were also measured at the same two locations. The calculated effective temperature was then compared with the measured tree trunk surface temperature. Additional longwave radiation measurements with pyrgeometer arrays were conducted under forests with different densities to evaluate the relationship between effective temperature and forest density. Our preliminary results show that when exposed to direct shortwave radiation, the tree surface temperature shows a significant difference from the air temperature. Under cloudy or shaded conditions, the tree surface temperature closely follows the air temperature. The effective tree temperature follows the air temperature in a dense forest stand, although it is significantly larger than the air temperature near the isolated tree. This discrepancy motivates us to explore ways to represent the effective tree temperature for stands with different densities.
- Document Type:
- Presentation
- Subjects:
- UIEF cyosphere snow snowmelt remote sensing snow and ice hydrology forest canopy longwave radiation snow surface solar radiation tree skin temperature
- Latitude:
- 46.869607
- Longitude:
- -116.733856
- Publisher:
- American Geophysical Union, Fall Meeting 2017, abstract #C53B-1029
- Department:
- Nicholas School of the Environment, Duke University; University of Idaho
- Source:
- Zhou,Y; Kumar, M. Estimating the Longwave Radiation Underneath the Forest Canpoy in Snow-dominated Setting. Dec. 2017. https://ui.adsabs.harvard.edu/abs/2017AGUFM.C53B1029Z
- Type:
- Text
- Format:
- record
Source
- Preferred Citation:
- "Estimating the Longwave Radiation Underneath the Forest Canopy in Snow-dominated Setting", UIEF Research Exchange, University of Idaho Library Digital Collections, https://www.lib.uidaho.edu/digital/uief/items/uief_0322.html
Rights
- Rights:
- In copyright, educational use permitted.
- Standardized Rights:
- http://rightsstatements.org/vocab/InC-EDU/1.0/