Dew observed on cars as a proxy for quantitative measurements

Beysens, Daniel; Pruvost, V.; Pruvost, B.

doi:10.1016/j.jaridenv.2016.08.014

Cited by 14 publications

(14 citation statements)

References 33 publications

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“…In comparison to horizontal substrate and the 30°s ide (which yielded similar values to that of the horizontal substrate), substrates at 45°, 60°, 75°, and 90°exhibited decreasing amounts, being only 75%, 39%, 31%, and 22% that of the horizontal (and 30°) substrate, respectively (Figure 6a; Kidron, 2005). Similar results were recently reported by Beysens, Pruvost, and Pruvost (2016) using the different sections of cars as proxy for the assessment of the angle effect on NRW. All these results were explained by SVF.…”

Section: Figuresupporting

confidence: 86%

Measurements and ecological implications of non‐rainfall water in desert ecosystems—A review

Kidron

Starinsky

2019

Ecohydrology

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The current review focuses on the contribution of non-rainfall water (NRW) to arid and semiarid regions (with a focus on the Negev), where NRW may provide a constant source of water that may facilitate the survival of different organisms, especially microorganisms. Factors that determine the amounts of NRW and the contribution of NRW to plants and organisms are discussed. Nevertheless, although important, significant variation exists regarding the amounts of NRW, which may stem from improper use or inherent drawbacks of some of the measurement devices. This may lead to erroneous conclusions regarding the possible role played by NRW. For instance, with prokaryotes (bacteria and cyanobacteria) requiring liquid water (≥0.1 mm) for growth, small inaccuracies in NRW around this threshold may either lead to the conclusion that NRW is sufficiently high to facilitate their growth, or rather, is too low to facilitate their growth. Arguing that some of the devices used to measure NRW may greatly overestimate the amounts, the possible contribution of NRW to soil bacteria and cyanobacterial biocrusts is analysed. We suggest that although NRW may assist the growth and survival of mosses and some types of lichens (mostly non-crustose), no conclusive findings were thus far reported regarding the use of dew for cyanobacteria growth. The use of dew by cyanobacterial crust for growth should be critically examined, and the possibility that NRW may even result in a negative carbon balance for cyanobacterial crusts should be considered.

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Section: Figuresupporting

confidence: 86%

Measurements and ecological implications of non‐rainfall water in desert ecosystems—A review

Kidron

Starinsky

2019

Ecohydrology

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“…Dew yield was positively correlated to relative humidity (RH) with its threshold greater than 70% (Figure 9b) and negatively correlated to the difference between air temperature and dewpoint temperature (T ad ) with its threshold less than 6 • C (Figure 9h). This is similar to the results of Clus et al [57], Maestre-Valero et al [58] and Beysens [2,34]. In particular, dew yield increases significantly when RH is greater than 80% and T ad is less than 3 • C. This indicates that dew forms before the relative humidity reaches saturation and before the air temperature drops to the dewpoint.…”

Section: Discussionsupporting

confidence: 90%

“…The difficulty of dew measurement is both in the definition of dew and in its actual measurement. However, scholars have developed various dew measurement instruments or methods in the past 70 years, including dew gauge [23], electrical resistance sensor [24], hiltner-type dew balance method [25], soil moisture sensor [1], leaf wetness sensor [26][27][28][29][30], artificial condensation surface method [31][32][33][34], and weighing method [6,12,35,36]. The last three items of the methods mentioned above are widely used.…”

mentioning

confidence: 99%

Dew Yield and Its Influencing Factors at the Western Edge of Gurbantunggut Desert, China

Jia

Zhao

2019

Water

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Dew is a significant water resource in arid desert areas. However, information regarding dew is scarce because it is difficult to measure due to the harsh environment of locations such as Gurbantunggut Desert, China. In this study, a non-destructive field experiment was conducted from 2015 to 2018 at a desert test station located in the western edge of the Gurbantunggut Desert, using a calibrated leaf wetness sensor (LWS) to measure dew yield. The results are as follows: (1) Dew formed after sunset with the atmospheric temperature gradually dropping and evaporated after sunrise with the temperature increasing in the second morning. (2) Dew was featured as ‘high frequency and low yield’. The average daily dew yield during dew days was 0.10 mm with a daily maximum of 0.62 mm, while dew days accounted for 44% of the total monitoring days, with a monthly maximum of 25 days. Compared with rainfall, dew days were two times as frequent as rainy days, while the average annual dewfall (12.21 mm) was about 1/11th of the average annual rainfall (134.6 mm), which indicates the dew contribution to regional water balance is about 9%. (3) March–April and October–November are the main periods of dew occurrence in this region because accumulated snow begins to melt slowly in March–April, providing sufficient vapor for dew formation, and the air temperature difference between day and night in October–November is the highest in the year, meaning that the temperature drops rapidly at night, making it easier to reach the dewpoint for vapor condensation. (4) Daily dew yield (D) was positively correlated to relative humidity (RH) and the difference between soil temperature at 10 cm below the ground and surface soil temperature (Tss), and negatively correlated to wind speed (V), air temperature (Ta), surface soil temperature (Ts), cloud cover (N), dewpoint temperature (Td) and the difference between air temperature and dewpoint temperature (Tad). It should be noted that the measured values of all factors above were the average value of the overnight period. The multivariate regression equation, D = −0.705 + 0.011 ×RH− 0.006 ×N− 0.01 × V, can estimate the daily dew yield with the thresholds of the parameters, i.e., RH > 70%, N < 7 (oktas) and V < 6 m/s.

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“…Most fog events during these observation periods (four field campaigns) occurred in the morning between 4 a.m. and 8 a.m., and only one fog event occurred at night (9 p.m.–11 p.m. in June 2017). Dew was collected using clean paper towels from a car, similar to the method described in Beysens, Pruvost, and Pruvost (). Based on previous field experiences, a dew event with around 15 ml of water collected was considered as a regular dew event, and larger than 30 ml of water collected was considered as a heavy dew event in this study.…”

Section: Methodsmentioning

confidence: 99%

Convergent vegetation fog and dew water use in the Namib Desert

et al. 2019

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Nonrainfall water inputs (e.g., fog and dew) are the least studied hydrological components in ecohydrology. The importance of nonrainfall waters on vegetation water status in arid ecosystems is receiving increasing attention. However, a clear understanding on how common plant water status benefits from nonrainfall waters, the impacts of different types of fog and dew events on vegetation water status, and the vegetation uptake mechanisms of nonrainfall waters is still lacking. In this study, we used concurrent leaf and soil water potential measurements from 3 years to investigate the species‐specific capacity to utilize moisture from fog and dew within the Namib Desert. Eight common plant species in the Namib Desert were selected. Our results showed that both fog and dew significantly increased soil water potential. Seven of the eight plant species studied responded to fog and dew events, although the magnitude of the response differed. Plants generally showed stronger responses to fog than to dew. Fog timing seemed to be an important factor determining vegetation response; for example, night fog did not affect plant water potential. We also found that Euclea pseudebenus and Faidherbia albida likely exploit fog moisture through foliar uptake. This study provides a first comprehensive assessment of the effects of nonrainfall waters on plant water status within the Namib Desert. Furthermore, this study highlights the importance of concurrent leaf and soil water potential measurements to identify the pathways of nonrainfall water use by desert vegetation. Our results fill a knowledge gap in dryland ecohydrology and have important implications for other drylands.

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Dew observed on cars as a proxy for quantitative measurements

Cited by 14 publications

References 33 publications

Measurements and ecological implications of non‐rainfall water in desert ecosystems—A review

Measurements and ecological implications of non‐rainfall water in desert ecosystems—A review

Dew Yield and Its Influencing Factors at the Western Edge of Gurbantunggut Desert, China

Convergent vegetation fog and dew water use in the Namib Desert

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