Do green roofs cool the air?

AbstractRapid urbanization and an increasing number and duration of heat waves poses a need to mitigate extremely high temperatures. One of the repeatedly suggested measures to moderate the so called urban heat island are green roofs. This study investigates several extensive sedum-covered green roofs in Utrecht (NL) and their effect on air temperature right above the roof surface. The air temperature was measured 15 and 30 cm above the roof surface and also in the substrate. We showed that under well-watered conditions, the air above the green roof, compared to the white gravel roof, was colder at night and warmer during the day. This suggests that extensive sedum-covered green roofs might help decrease air temperatures at night, when the urban heat island is strongest, but possibly contribute to high daytime temperatures. The average 24 h effect of sedum-covered green roof was a 0.2 °C increase of air temperature 15 cm above the ground. During a dry year the examined green roof exhibited behavior similar to conventional white gravel roof even exhibited slight cooling effect in late afternoon. Interestingly, the pattern of soil temperature remained almost the same for both dry and well-prospering green roofs, colder during the day and warmer at night

Practical considerations for enhanced-resolution coil-wrapped Distributed Temperature Sensing

Fibre optic distributed temperature sensing (DTS) is widely applied in Earth sciences. Many applications require a spatial resolution higher than that provided by the DTS instrument. Measurements at these higher resolutions can be achieved with a fibre optic cable helically wrapped on a cylinder. The effect of the probe construction, such as its material, shape, and diameter, on the performance has been poorly understood. In this article, we study data sets obtained from a laboratory experiment using different cable and construction diameters, and three field experiments using different construction characteristics. This study shows that the construction material, shape, diameter, and cable attachment method can have a significant influence on DTS temperature measurements. We present a qualitative and quantitative approximation of errors introduced through the choice of auxiliary construction, influence of solar radiation, coil diameter, and cable attachment method. Our results provide insight into factors that influence DTS measurements, and we present a number of solutions to minimize these errors. These practical considerations allow designers of future DTS measurement set-ups to improve their environmental temperature measurements

Practical considerations for enhanced-resolution coil-wrapped Distributed Temperature Sensing

Fibre optic distributed temperature sensing (DTS) is widely applied in Earth sciences. Many applications require a spatial resolution higher than that provided by the DTS instrument. Measurements at these higher resolutions can be achieved with a fibre optic cable helically wrapped on a cylinder. The effect of the probe construction, such as its material, shape, and diameter, on the performance has been poorly understood. In this article, we study data sets obtained from a laboratory experiment using different cable and construction diameters, and three field experiments using different construction characteristics. This study shows that the construction material, shape, diameter, and cable attachment method can have a significant influence on DTS temperature measurements. We present a qualitative and quantitative approximation of errors introduced through the choice of auxiliary construction, influence of solar radiation, coil diameter, and cable attachment method. Our results provide insight into factors that influence DTS measurements, and we present a number of solutions to minimize these errors. These practical considerations allow designers of future DTS measurement set-ups to improve their environmental temperature measurements

Practical considerations for enhanced-resolution coil-wrapped distributed temperature sensing

Fibre optic distributed temperature sensing (DTS) is widely applied in Earth sciences. Many applications require a spatial resolution higher than that provided by the DTS instrument. Measurements at these higher resolutions can be achieved with a fibre optic cable helically wrapped on a cylinder. The effect of the probe construction, such as its material, shape, and diameter, on the performance has been poorly understood. In this article, we study data sets obtained from a laboratory experiment using different cable and construction diameters, and three field experiments using different construction characteristics. This study shows that the construction material, shape, diameter, and cable attachment method can have a significant influence on DTS temperature measurements. We present a qualitative and quantitative approximation of errors introduced through the choice of auxiliary construction, influence of solar radiation, coil diameter, and cable attachment method. Our results provide insight into factors that influence DTS measurements, and we present a number of solutions to minimize these errors. These practical considerations allow designers of future DTS measurement set-ups to improve their environmental temperature measurements.This is the publisher’s final pdf. The published article is copyrighted by the author(s). The article is copyrighted by European Geosciences Union and published by Copernicus Publications. It can be found at: http://www.geoscientific-instrumentation-methods-and-data-systems.net

HESS Opinions: Science in today's media landscape – challenges and lessons from hydrologists and journalists

Media such as television, newspapers and social media play a key role in the communication between scientists and the general public. Communicating your science via the media can be positive and rewarding by providing the inherent joy of sharing your knowledge with a broader audience, promoting science as a fundamental part of culture and society, impacting decision and policy makers, and giving you a greater recognition by institutions, colleagues and funders. However, the interaction between scientists and journalists is not always straightforward. For instance, scientists may not always be able to translate their work into a compelling story, and journalists may sometimes misinterpret scientific output. In this paper, we present insights from hydrologists and journalists discussing the advantages and benefits as well as the potential pitfalls and aftermath of science-media interaction. As we perceive interacting with the media as a rewarding and essential part of our work, we aim to encourage scientists to participate in the diverse and evolving media landscape. With this paper, we call on the scientific community to support scientists who actively contribute to a fruitful science-media relationship

Uchimizu: A Cool(ing) Tradition to Locally Decrease Air Temperature

The urban heat island effect was first described 200 years ago, but the development of ways to mitigate heat in urban areas reaches much further into the past. Uchimizu is a 17th century Japanese tradition, in which water is sprinkled around houses to cool the ground surface and air by evaporation. Unfortunately, the number of published studies that have quantified the cooling effects of uchimizu are limited and only use surface temperature or air temperature at a single height as a measure of the cooling effect. In this research, a dense three-dimensional Distributed Temperature Sensing (DTS) setup was used to measure air temperature with high spatial and temporal resolution within one cubic meter of air above an urban surface. Six experiments were performed to systematically study the effects of (1) the amount of applied water; (2) the initial surface temperature; and (3) shading on the cooling effect of uchimizu. The measurements showed a decrease in air temperature of up to 1.5 °C at a height of 2 m, and up to 6 °C for near-ground temperature. The strongest cooling was measured in the shade experiment. For water applied in quantities of 1 mm and 2 mm, there was no clear difference in cooling effect, but after application of a large amount of water (>5 mm), the strong near-ground cooling effect was approximately twice as high as when only 1 mm of water was applied. The dense measurement grid used in this research also enabled us to detect the rising turbulent eddies created by the heated surface

Water and air temperature at Amalia van Solmslaan pond, Delft, 2014

This data set contains: (1) two DTS datasets for two 2m tall setups reaching from the muddy under-layer of the pond through the water to the air above the pond, and (2) meteorological data measured above the middle of the pond during the same period (wind speed and direction, temperature, relative humidity, rain, radiation (longwave, shortwave, in, and out)). The meteo data are in local time (LC), DTS data in LC-1, and the radiation data in LC-1. The meteo data and radiation data are in the form of excel file, the DTS data are in a matlab file

Koelen blauw-groene daken de stad?

Stel, we maken alle mogelijke daken in de stad goed verdampend en groen. Kunnen we daarmee een stad koel houden tijdens een snikhete dag? Dat valt tegen: in een stad als Amsterdam is het verschil kleiner dan 0,3 °C. Dat zal niet merkbaar zijn als je puffend over straat loopt

What is the thermal effect of 'blue' in blue-green roofs?: A quantitative case study on the insulative effects of blue-green roofs in Amsterdam for the RESILIO Project

Green roofs received increased scientific attention with respect to climate adaptation in urban environments for their hydrological, biodiversity and insulative capacities. Yet, the thermal properties of roofs with an additional water layer underneath the vegetation substrate (blue-green roofs) are not well represented in scientific research. In this field study, we examined the impact of surface temperatures, indoor temperature and insulative properties of blue-green, green, and conventional gravel/bitumen roofs in the city of Amsterdam for early 20th century buildings. Temperature sensor (IButtons) results indicate that outside surface temperatures of blue-green roofs were more stable than for conventional roofs. For instance, for three warm periods during summer (2021) surface substrate temperatures peaked much higher for gravel roofs (+8 oC) or bitumen roofs (+18 oC) than for blue-green roofs. On top of that, during a cold period in winter average water crate layer temperatures remained 3.0 oC higher and much more stable than substrate temperatures of blue-green roofs and conventional roofs, implicating that the blue layer functions as an extra temperature buffer. The effect of lower daily variation of surface temperatures in winter and summer is also reflected by inside air temperatures. Inside temperatures showed that locations with blue-green roofs are less sensitive to outside air temperatures, as daily temperature fluctuations (standard deviations) were 0.19 and 0.23 oC lower for warm and cold periods, respectively, compared to conventional roofs. This effect seems rather small but comprises a relatively large proportion of the total daily variation of 24% and 64% of warm and cold periods respectively