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Vegetated roofs or green roofs, may supply a number of different urban ecosystem services such as thermal regulation of local air temperature by evaporative cooling or climate change mitigation by sequestration of CO2. However, knowledge about the annual and seasonal variations of green roof carbon uptake due to changes in meteorological conditions and water availability remains scarce. We studied the annual variation of net ecosystem exchange (NEE) by eddy‐covariance flux measurements during a five‐year period from 2014 to 2019 on a large and unirrigated green roof at the Berlin‐Brandenburg airport (BER) in Berlin, Germany. The roof vegetation was dominated by Sedum species and herbs. The BER green roof showed net uptake of carbon in each of the five study years with an average uptake of ‐141.1 g C m‐2 y‐1 and an average measurement uncertainty of ±15.5 g C m‐2 y‐1. The NEE, however, was characterized by significant interannual variation in which the maximum annual uptake of ‐189 g C m‐2 y‐1 in a year with above average precipitation roughly doubles the minimum uptake of ‐95 g C m‐2 y‐1 in a dry year. The variation of NEE was a function of the annual amount of precipitation and the frequency of rainfall, i.e. the number of dry days per year (DDY). The roof might lose its carbon uptake function in a warmer future climate with an increasing number of DDY. Sustainable irrigation of the roof (e.g. rainwater harvesting) could help maintain the carbon uptake function of the green roof vegetation.
J. Konopka; J. Heusinger; S. Weber. Extensive Urban Green Roof Shows Consistent Annual Net Uptake of Carbon as Documented by 5 Years of Eddy‐Covariance Flux Measurements. Journal of Geophysical Research: Biogeosciences 2021, 126, 1 .
AMA StyleJ. Konopka, J. Heusinger, S. Weber. Extensive Urban Green Roof Shows Consistent Annual Net Uptake of Carbon as Documented by 5 Years of Eddy‐Covariance Flux Measurements. Journal of Geophysical Research: Biogeosciences. 2021; 126 (2):1.
Chicago/Turabian StyleJ. Konopka; J. Heusinger; S. Weber. 2021. "Extensive Urban Green Roof Shows Consistent Annual Net Uptake of Carbon as Documented by 5 Years of Eddy‐Covariance Flux Measurements." Journal of Geophysical Research: Biogeosciences 126, no. 2: 1.
Knowledge about the annual and seasonal variation of green roof carbon uptake due to variation in ambient meteorological conditions and water availability remains scarce. That is why we studied the annual variation of net ecosystem exchange (NEE, i.e. the difference between ecosystem respiration (Reco) and gross primary production (GPP), i.e. CO2 assimilation) for the observation period from September 2014 until August 2019 by eddy-covariance measurements on a green roof at the Berlin Brandenburg airport (BER). A year was defined from September until August of the following year. We found a mean annual uptake of -141.1 and an average uncertainty of ±15.5 g C m-2 y-1. In each annual balance of the NEE the roof had higher carbon uptake than emissions despite dry conditions. Main drivers for the NEE variation are the difference in the number of dry days per year and soil moisture. C uptake might be constrained due to higher number of dry periods in future climate. This dataset provides the presented data in the research article "Extensive Urban Green Roof Shows Consistent Annual Net Uptake of Carbon as Documented by 5 Years of Eddy‐Covariance Flux Measurements". Halfhour and daily data are available. Please contact the author Jan Konopka ([email protected]) to make a request for the research data.
Jan Konopka; Jannik Heusinger; Stephan Weber. BER green roof Eddy-Covariance data. 2020, 1 .
AMA StyleJan Konopka, Jannik Heusinger, Stephan Weber. BER green roof Eddy-Covariance data. . 2020; ():1.
Chicago/Turabian StyleJan Konopka; Jannik Heusinger; Stephan Weber. 2020. "BER green roof Eddy-Covariance data." , no. : 1.
Wind energy is relevant to self-sufficiency in urban areas, but the accuracy of wind assessment is a barrier to allowing wind energy development. The aim of this work is to test the performance of the Griggs-Putnam Index of Deformity of trees (G-PID) over urban areas as an alternative method for assessing wind conditions. G-PID has been widely used in open terrains, but this work is the first attempt to apply it in urban areas. The results were compared with CFD simulations (ENVI-met), and finally, with the linear model WAsP to inspect if deformed trees can offer acceptable wind power assessments. WAsP (meso-) and ENVI-met (micrometeorological model) showed similar results in a test area inside the University of Lisbon Campus. All trees showed a deformation with the wind direction (S and SE). The mean G-PID wind speed for all trees was 5.9 m/s. Comparing this to the ENVI-met simulations results (mean speed for all trees was 4.25 m/s) made it necessary to adapt the index to urban terrains by reducing each Index Deformation class by about ~2 m/s. Nevertheless, more investigation is needed, since this study is just a first approach to this integrated methodology. Also, tree species and characteristics were not taken into account. These questions should be addressed in future studies, because the deformation of trees depends also on the tree species and phytosanitary conditions.
Jan Konopka; António Lopes; Andreas Matzarakis. An Original Approach Combining CFD, Linearized Models, and Deformation of Trees for Urban Wind Power Assessment. Sustainability 2018, 10, 1915 .
AMA StyleJan Konopka, António Lopes, Andreas Matzarakis. An Original Approach Combining CFD, Linearized Models, and Deformation of Trees for Urban Wind Power Assessment. Sustainability. 2018; 10 (6):1915.
Chicago/Turabian StyleJan Konopka; António Lopes; Andreas Matzarakis. 2018. "An Original Approach Combining CFD, Linearized Models, and Deformation of Trees for Urban Wind Power Assessment." Sustainability 10, no. 6: 1915.