Modeling the Surface Energy Budget during the Thawing Period of the 2006 Montreal Urban Snow Experiment

Abstract The Montreal Urban Snow Experiment was dedicated to furthering the understanding of micrometeorological processes involved in the late winter–early spring transition period in a Canadian city. A surface energy budget (SEB) measurement site was installed in a dense residential area of Montreal for several weeks in 2005 and 2006. This paper focuses on the last 6 days of the 2006 experiment (23–28 March 2006), after snowmelt and before vegetation became active, with the objectives of providing a better understanding of physical processes involved during this transition period and examining their impact on the SEB. The Town Energy Balance urban canopy model and the Interactions between Soil, Biosphere, and Atmosphere force–restore land surface model are used in stand-alone mode and are forced with meteorological data measured at the top of a 20-m AGL instrumented tower. Preliminary results reveal deficiencies in the models’ ability to simulate the surface energy budget partitioning, and in particular show overestimation of the sensible heat flux. Sensitivity studies indicate that a large portion of these problems is related to the latent heat transfer involved in natural soil freeze/thaw processes, which has a significant effect on the surface energy budget in this urban area. It is also found that the SEB in this particular situation is very sensitive to the thermal roughness length used for local energy exchange over the roof and road surfaces.

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Case analyses and numerical simulation of soil thermal impacts on land surface energy budget based on an off-line land surface model

Advances in Atmospheric Sciences ◽

10.1007/s00376-002-0082-0 ◽

2002 ◽

Vol 19 (3) ◽

pp. 500-512 ◽

Cited By ~ 5

Author(s):

Guo Weidong ◽

Sun Shufen ◽

Qian Yongfu

Keyword(s):

Numerical Simulation ◽

Surface Energy ◽

Energy Budget ◽

Land Surface ◽

Land Surface Model ◽

Surface Energy Budget ◽

Surface Model

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Auto-calibration System Developed to Assimilate AMSR-E Data into a Land Surface Model for Estimating Soil Moisture and the Surface Energy Budget

Journal of the Meteorological Society of Japan Ser II ◽

10.2151/jmsj.85a.229 ◽

2007 ◽

Vol 85A ◽

pp. 229-242 ◽

Cited By ~ 118

Author(s):

Kun YANG ◽

Takahiro WATANABE ◽

Toshio KOIKE ◽

Xin LI ◽

Hideyuki FUJII ◽

...

Keyword(s):

Soil Moisture ◽

Surface Energy ◽

Energy Budget ◽

Land Surface ◽

Land Surface Model ◽

Surface Energy Budget ◽

Surface Model ◽

Calibration System

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An Observational Analysis and Evaluation of Land Surface Model Accuracy in the Nebraska Sand Hills

Journal of Hydrometeorology ◽

10.1175/2007jhm913.1 ◽

2008 ◽

Vol 9 (4) ◽

pp. 601-621 ◽

Cited By ~ 11

Author(s):

David B. Radell ◽

Clinton M. Rowe

Keyword(s):

Surface Energy ◽

Energy Budget ◽

Land Surface ◽

Land Surface Model ◽

Surface Energy Budget ◽

Subsurface Water ◽

Surface Model ◽

Latent Heating ◽

Dry Valley ◽

The Mean

Abstract In this study, the influence of subsurface water on the energy budget components of three locations with heterogeneous land surfaces in the Nebraska Sand Hills are examined through observations and use of the Noah land surface model (LSM). Observations of the four primary components of the surface energy budget are compared for a wet interdunal meadow valley, a dry interdunal valley, and a dunal upland location. With similar atmospheric forcing at each site, it was determined that differences in the partitioning of the mean diurnal net radiation (Rnet) existed among the three locations due to the influence of varied soil moisture and vegetation through the year. At the wet valley, observations indicated that almost 65% of the mean daily peak Rnet was used for latent heating, due to the relatively higher soil moisture content resulting from an annual upward gradient of subsurface water and denser vegetation. In sharp contrast, the dunal upland site yielded only 21% of the mean daily peak Rnet going to latent heating, and a greater mean diurnal soil heat flux with typically drier soils and sparser vegetation than at the wet valley. The dry valley partition of the peak Rnet fell between the wet valley and dunal upland site, with approximately 50% going to sensible heating and 50% toward latent heating. In addition to the observational analysis, an uncoupled land surface model was forced with the observations from each site to simulate the energy budgets, with no tuning of the model’s fundamental equations and with little adjustment of the model parameters to improve results. While the model was able to reasonably simulate the mean diurnal and annual energy budget components at all locations, in most instances with root-mean-square errors within 20%–25% of the observed values, the lack of explicit treatment of subsurface water within the model limited predictability, particularly at the wet valley site. For instance, only 25% of the peak mean diurnal Rnet went toward latent heating in the model simulation of the wet valley, compared to 65% as estimated by observations. Model evaluation statistics are presented to document the land surface model’s ability to capture the annual and mean diurnal variations in the surface energy budget terms at the dry valley and dunal upland sites, but the absence of subsurface water results in large errors in the wet valley simulation. From these results, a case is made for the future inclusion of the explicit treatment of subsurface water within the Noah LSM to better approximate the prediction of the surface energy budget in such environments.

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Influence of Subfacet Heterogeneity and Material Properties on the Urban Surface Energy Budget

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-13-0286.1 ◽

2014 ◽

Vol 53 (9) ◽

pp. 2114-2129 ◽

Cited By ~ 23

Author(s):

Prathap Ramamurthy ◽

Elie Bou-Zeid ◽

James A. Smith ◽

Zhihua Wang ◽

Mary L. Baeck ◽

...

Keyword(s):

Surface Energy ◽

Energy Budget ◽

Material Properties ◽

Sensible Heat Flux ◽

Role Reversal ◽

Surface Energy Budget ◽

Urban Surface ◽

Urban Site ◽

Peak Time ◽

Sensible Heat

AbstractUrban facets—the walls, roofs, and ground in built-up terrain—are often conceptualized as homogeneous surfaces, despite the obvious variability in the composition and material properties of the urban fabric at the subfacet scale. This study focuses on understanding the influence of this subfacet heterogeneity, and the associated influence of different material properties, on the urban surface energy budget. The Princeton Urban Canopy Model, which was developed with the ability to capture subfacet variability, is evaluated at sites of various building densities and then applied to simulate the energy exchanges of each subfacet with the atmosphere over a densely built site. The analyses show that, although all impervious built surfaces convert most of the incoming energy into sensible heat rather than latent heat, sensible heat fluxes from asphalt pavements and dark rooftops are 2 times as high as those from concrete surfaces and light-colored roofs. Another important characteristic of urban areas—the shift in the peak time of sensible heat flux in comparison with rural areas—is here shown to be mainly linked to concrete’s high heat storage capacity as well as to radiative trapping in the urban canyon. The results also illustrate that the vegetated pervious soil surfaces that dot the urban landscape play a dual role: during wet periods they redistribute much of the available energy into evaporative fluxes but when moisture stressed they behave more like an impervious surface. This role reversal, along with the direct evaporation of water stored over impervious surfaces, significantly reduces the overall Bowen ratio of the urban site after rain events.

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