Relative influence of vegetation on urban energy budgets and surface temperatures

1981 ◽  
Vol 21 (2) ◽  
pp. 255-263 ◽  
Author(s):  
Werner H. Terjung ◽  
Patricia A. O'Rourke
Keyword(s):  
Relative Influence ◽  
Energy Budgets ◽  
Surface Temperatures ◽  
Urban Energy

A Climatic Model of Urban Energy Budgets

2010 ◽  
Vol 6 (4) ◽  
pp. 341-367 ◽  
Author(s):  
Werner H. Terjung ◽  
Stella S-F. Louie
Keyword(s):  
Energy Budgets ◽  
Urban Energy

scholarly journals Dew frequency across the US from a network of in situ radiometers

2019 ◽  
Vol 23 (2) ◽  
pp. 1179-1197 ◽  
Author(s):  
François Ritter ◽  
Max Berkelhammer ◽  
Daniel Beysens
Keyword(s):  
Similarity Theory ◽  
Bowen Ratio ◽  
Surface Characteristics ◽  
Dew Point ◽  
Energy Budgets ◽  
High Temporal Resolution ◽  
Surface Temperatures ◽  
Dew Formation ◽  
The Mean

Abstract. Dew formation is a ubiquitous process, but its importance to energy budgets or ecosystem health is difficult to constrain. This uncertainty arises largely because of a lack of continuous quantitative measurements on dew across ecosystems with varying climate states and surface characteristics. This study analyzes dew frequency from the National Ecological Observatory Network (NEON), which includes 11 grasslands and 19 forest sites from 2015 to 2017. Dew formation is determined at 30 min intervals using in situ radiometric surface temperatures from multiple heights within the canopy along with meteorological measurements. Dew frequency in the grasslands ranges from 15 % to 95 % of the nights with a strong linear dependency on the nighttime relative humidity (RH), while dew frequency in the forests is less frequent and more homogeneous (25±14 %, 1 standard deviation – SD). Dew mostly forms at the top of the canopy for the grasslands due to more effective radiative cooling and within the canopy for the forests because of higher within the canopy RH. The high temporal resolution of our data showed that dew duration reaches maximum values (∼6–15 h) for RH∼96 % and for a wind speed of ∼0.5ms-1, independent of the ecosystem type. While dew duration can be inferred from the observations, dew yield needs to be estimated based on the Monin–Obukhov similarity theory. We find yields of 0.14±0.12mmnight-1 (1 SD from nine grasslands) similar to previous studies, and dew yield and duration are related by a quadratic relationship. The latent heat flux released by dew formation is estimated to be non-negligible (∼10Wm-2), associated with a Bowen ratio of ∼3. The radiometers used here provide canopy-averaged surface temperatures, which may underestimate dew frequency because of localized cold points in the canopy that fall below the dew point. A statistical model is used to test this effect and shows that dew frequency can increase by an additional ∼5 % for both ecosystems by considering a reasonable distribution around the mean canopy temperature. The mean dew duration is almost unaffected by this sensitivity analysis. In situ radiometric surface temperatures provide a continuous, non-invasive and robust tool for studying dew frequency and duration on a fine temporal scale.

Influences of physical structures on urban energy budgets

1980 ◽  
Vol 19 (4) ◽  
pp. 421-439 ◽  
Author(s):  
Werner H. Terjung ◽  
Patricia A. O'Rourke
Keyword(s):  
Energy Budgets ◽  
Urban Energy

scholarly journals Characterization of the Thermal Structure inside an Urban Canyon: Field Measurements and Validation of a Simple Model

2013 ◽  
Vol 52 (1) ◽  
pp. 64-81 ◽  
Author(s):  
Lorenzo Giovannini ◽  
Dino Zardi ◽  
Massimiliano de Franceschi
Keyword(s):  
Solar Radiation ◽  
Energy Use ◽  
Thermal Structure ◽  
Climatic Conditions ◽  
Surface Fluxes ◽  
Urban Canyon ◽  
Energy Budgets ◽  
Traffic Light ◽  
Surface Temperatures ◽  
Air Temperatures

AbstractThe results of measurement campaigns are analyzed to investigate the thermal structure in an urban canyon and to validate a simplified model simulating the air and surface temperatures from surface energy budgets. Starting from measurements at roof-top level, the model provides time series of air and surface temperatures, as well as surface fluxes. Two campaigns were carried out in summer 2007 and in winter 2008/09 in a street of the city of Trento (Italy). Temperature sensors were placed at various levels near the walls flanking the canyon and on a traffic light in the street center. Furthermore, the atmosphere above the mean roof-top level was monitored by a weather station on top of a tower located nearby. Air temperatures near the walls, being strongly influenced by direct solar radiation, display considerable contrasts between the opposite sides of the canyon. On the other hand, when solar radiation is weak or absent, the temperature field remains mostly homogeneous. Moreover, air temperature inside the canyon is generally higher than above roof level, with larger differences during summertime. Air temperatures from the above street measurements are well simulated by the model in both seasons. Furthermore, the modeled surface temperatures are tested against a dataset of wall surface temperatures from the Advanced Tools for Rational Energy Use Towards Sustainability–Photocatalytic Innovative Coverings Applications for Depollution (ATREUS–PICADA) experiment, and a very good agreement is found. Results suggest that the model is a reliable and convenient tool for simplified assessment of climatic conditions occurring in urban canyons under various weather situations.

scholarly journals Estimating Evapotranspiration from Commonly Occurring Urban Plant Species Using Porometry and Canopy Stomatal Conductance

Water ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2262
Author(s):  
Syed Hamza Askari ◽  
Simon De-Ville ◽  
Elizabeth Abigail Hathway ◽  
Virginia Stovin
Keyword(s):  
Stomatal Conductance ◽  
Plant Species ◽  
Green Infrastructure ◽  
Soil Moisture Content ◽  
Moisture Flux ◽  
Energy Budgets ◽  
Primula Vulgaris ◽  
Urban Energy ◽  
Preliminary Study ◽  
Loss Method

Evapotranspiration (ET) is a key moisture flux in both the urban stormwater management and the urban energy budgets. While there are established methods for estimating ET for agricultural crops, relatively little is known about ET rates associated with plants in urban Green Infrastructure settings. The aim of this study was to evaluate the feasibility of using porometry to estimate ET rates. Porometry provides an instantaneous measurement of leaf stomatal conductance. There are two challenges when estimating ET from porometry: converting from leaf stomatal conductance to leaf ET and scaling from leaf ET to canopy ET. Novel approaches to both challenges are proposed here. ET was measured from three commonly occurring urban plant species (Sedum spectabile, Bergenia cordifolia and Primula vulgaris) using a direct mass loss method. This data was used to evaluate the estimates made from porometry in a preliminary study (Sheffield, UK). The Porometry data captured expected trends in ET, with clear differences between the plant species and the reproducible decreasing rates of ET in response to reductions in soil moisture content.

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