Contribution of impervious surfaces to urban evaporation

Ramamurthy, Prathap; Bou‐Zeid, Elie

doi:10.1002/2013wr013909

Cited by 105 publications

(70 citation statements)

References 67 publications

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“…Since our study area is in the urban setting, evaporation over impervious surfaces did not follow the evaporation characteristics that have been found in soil and vegetated areas. Ramamurthy and Bou-Zeid [17] suggested that substantial contribution from impervious surfaces to urban evaporation usually occurs in the first 48 hours after precipitation. Since the amount of precipitation was below 1mm within 48 hours prior to both image acquisition dates, the urban evaporation conditions of the two dates were assumed to be similar.…”

Section: Methodsmentioning

confidence: 99%

Assessing the Impacts of Urbanization-Associated Land Use/Cover Change on Land Surface Temperature and Surface Moisture: A Case Study in the Midwestern United States

2015

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Urbanization-associated land use and land cover (LULC) changes lead to modifications of surface microclimatic and hydrological conditions, including the formation of urban heat islands and changes in surface runoff pattern. The goal of the paper is to investigate the changes of biophysical variables due to urbanization induced LULC changes in Indianapolis, USA, from 2001 to 2006. The biophysical parameters analyzed included Land Surface Temperature (LST), fractional vegetation cover, Normalized Difference Water Index (NDWI), impervious fractions evaporative fraction, and soil moisture. Land cover classification and changes and impervious fractions were obtained from the National Land Cover Database of 2001 and 2006. The Temperature-Vegetation Index (TVX) space was created to analyze how these satellite-derived biophysical parameters change during urbanization. The results showed that the general trend of pixel migration in response to the LULC changes was from the areas of low temperature, dense vegetation cover, and high surface moisture conditions to the areas of high temperature, sparse vegetation cover, and low surface moisture condition in the TVX space. Analyses of the T-soil moisture and T-NDWI spaces revealed similar changed patterns. The rate of change in LST, vegetation cover, and moisture varied with LULC type and percent imperviousness. Compared to conversion from cultivated to residential land, the change from forest to commercial land altered LST and moisture more intensively. Compared to the area changed from cultivated to residential, the area changed from forest to commercial altered 48% more in fractional OPEN ACCESS Remote Sens. 2015, 7 4881 vegetation cover, 71% more in LST, and 15% more in soil moisture Soil moisture and NDWI were both tested as measures of surface moisture in the urban areas. NDWI was proven to be a useful measure of vegetation liquid water and was more sensitive to the land cover changes comparing to soil moisture. From a change forest to commercial land, the mean soil moisture changed 17%, while the mean NDWI changed 90%.

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Section: Methodsmentioning

confidence: 99%

Assessing the Impacts of Urbanization-Associated Land Use/Cover Change on Land Surface Temperature and Surface Moisture: A Case Study in the Midwestern United States

2015

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“…of PFD will presumably be greater for regions with a larger proportion of impervious surfaces, as these surfaces have very low evaporation under dry conditions but can support very high evaporation rates when wet (Ramamurthy and Bou-Zeid, 2014;Ward et al, 2015). This is supported by Figure 7, which shows the annual difference in modelled evaporation and runoff for different resolutions of PFD for a range of surface cover fractions.…”

Section: Surface Covermentioning

confidence: 70%

“…E-mail: h.c.ward@reading.ac.uk et al, 2015). For example, Ramamurthy and Bou-Zeid (2014) showed that following precipitation events over a wet 10-day period, nearly 17% of the total latent heat flux was from impervious surfaces. Evidence of increased evaporation rates 12-18 h after rain has been observed in central London (Kotthaus and Grimmond, 2014) and in Toulouse (Wouters et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Impact of temporal resolution of precipitation forcing data on modelled urban‐atmosphere exchanges and surface conditions

Ward

Tan

Gabey

et al. 2017

Intl Journal of Climatology

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Representative precipitation data sets are very difficult to obtain due to the inherent spatial and temporal variability of rainfall. Gridded rainfall products exist at various scales, but temporal resolution is coarse (daily or, at best, a few hours). This study demonstrates the impact of low temporal resolution precipitation forcing data (PFD) on modelled energy fluxes, runoff and surface conditions, which could have implications for a range of applications including flood forecasting, irrigation scheduling and epidemiology. An evaporation-interception model originally developed for forests is applied here within the framework of the Surface Urban Energy and Water balance Scheme (SUEWS). The model is forced with rainfall data representative of a range of temporal resolutions (from 5 min to 3 h). Taking the highest resolution case as a reference, differences in model output are found as the temporal resolution of PFD decreases, depending on the timing of rainfall occurrence, intensity and duration. Modelled evaporation, runoff and surface wetness deviate from the reference case, which affect other variables such as the turbulent sensible heat flux. The largest impacts are seen on days with greatest daily total rainfall and, even on days with no rain, differences in antecedent conditions (soil moisture or surface wetness) can cause deviations from the reference case. Errors can be reduced by applying a disaggregation scheme that provides a more realistic distribution of rainfall, importantly, one that allows for intermittent rainfall.

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“…The contrast between patches of hot, dry impervious areas and cool, wet vegetation may be reduced by altogether wetter surfaces in 2012, which is thought to increase correlation between temperature and humidity (Lamaud and Irvine, 2006;Moene and Schüttemeyer, 2008;Ramamurthy and Bou-Zeid, 2014). On the other hand, Lüdi et al (2005) found lower r T q coincides with lower β.…”

Section: Temperature-humidity Correlationmentioning

confidence: 98%

“…EC data from open-path gas analysers cannot be used if the instrument windows are wet, such as during and after rainfall (Heusinkveld et al, 2008). Consequently, water vapour measurements from open-path systems significantly under-represent these times and may result in an appreciable underestimation of mean Q E (Ramamurthy and Bou-Zeid, 2014) and C 2 q . Mean values for C 2 T calculated using daytime data only when all quantities are available concurrently (i.e.…”

Section: Comparison Of Eddy Covariance and Scintillometry Techniquesmentioning

confidence: 99%

Infrared and millimetre-wave scintillometry in the suburban environment – Part 1: Structure parameters

et al. 2015

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Abstract. Scintillometry, a form of ground-based remote sensing, provides the capability to estimate surface heat fluxes over scales of a few hundred metres to kilometres. Measurements are spatial averages, making this technique particularly valuable over areas with moderate heterogeneity such as mixed agricultural or urban environments. In this study, we present the structure parameters of temperature and humidity, which can be related to the sensible and latent heat fluxes through similarity theory, for a suburban area in the UK. The fluxes are provided in the second paper of this two-part series. A millimetre-wave scintillometer was combined with an infrared scintillometer along a 5.5 km path over northern Swindon. The pairing of these two wavelengths offers sensitivity to both temperature and humidity fluctuations, and the correlation between wavelengths is also used to retrieve the path-averaged temperature-humidity correlation. Comparison is made with structure parameters calculated from an eddy covariance station located close to the centre of the scintillometer path. The performance of the measurement techniques under different conditions is discussed. Similar behaviour is seen between the two data sets at sub-daily timescales. For the two summer-to-winter periods presented here, similar evolution is displayed across the seasons. A higher vegetation fraction within the scintillometer source area is consistent with the lower Bowen ratio observed (midday Bowen ratio < 1) compared with more built-up areas around the eddy covariance station. The energy partitioning is further explored in the companion paper.

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Contribution of impervious surfaces to urban evaporation

Cited by 105 publications

References 67 publications

Assessing the Impacts of Urbanization-Associated Land Use/Cover Change on Land Surface Temperature and Surface Moisture: A Case Study in the Midwestern United States

Assessing the Impacts of Urbanization-Associated Land Use/Cover Change on Land Surface Temperature and Surface Moisture: A Case Study in the Midwestern United States

Impact of temporal resolution of precipitation forcing data on modelled urban‐atmosphere exchanges and surface conditions

Infrared and millimetre-wave scintillometry in the suburban environment – Part 1: Structure parameters

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