Journal article
Variation in the urban vegetation, surface temperature, air temperature nexus
The Science of the total environment, Vol.579, pp.495-505
02/01/2017
DOI: 10.1016/j.scitotenv.2016.11.069
PMID: 27894802
Abstract
Our study examines the urban vegetation – air temperature (Ta) – land surface temperature (LST) nexus at micro- and regional-scales to better understand urban climate dynamics and the uncertainty in using satellite-based LST for characterizing Ta. While vegetated cooling has been repeatedly linked to reductions in urban LST, the effects of vegetation on Ta, the quantity often used to characterize urban heat islands and global warming, and on the interactions between LST and Ta are less well characterized. To address this need we quantified summer temporal and spatial variation in Ta through a network of 300 air temperature sensors in three sub-regions of greater Los Angeles, CA, which spans a coastal to desert climate gradient. Additional sensors were placed within the inland sub-region at two heights (0.1m and 2m) within three groundcover types: bare soil, irrigated grass, and underneath citrus canopy. For the entire study region, we acquired new imagery data, which allowed calculation of the normalized difference vegetation index (NDVI) and LST. At the microscale, daytime Ta measured along a vertical gradient, ranged from 6 to 3°C cooler at 0.1 and 2m, underneath tall canopy compared to bare ground respectively. At the regional scale NDVI and LST were negatively correlated (p<0.001). Relationships between diel variation in Ta and daytime LST at the regional scale were progressively weaker moving away from the coast and were generally limited to evening and nighttime hours. Relationships between NDVI and Ta were stronger during nighttime hours, yet effectiveness of mid-day vegetated cooling increased substantially at the most arid region. The effectiveness of vegetated Ta cooling increased during heat waves throughout the region. Our findings suggest an important but complex role of vegetation on LST and Ta and that vegetation may provide a negative feedback to urban climate warming.
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•We investigated the vegetation – air temperature – land surface temperature nexus in southern California.•We coupled 300 in-situ air temperature sensors with airborne measurements of a vegetation index and surface temperature.•Vegetation was associated with cooler land surface temperature during the day and air temperature at night.•Vegetation provides cooling benefits although the effects on microclimate vary by temperature, vegetation, and time of day.
Details
- Title: Subtitle
- Variation in the urban vegetation, surface temperature, air temperature nexus
- Creators
- Sheri A Shiflett - Department of Botany and Plant Sciences, University of California, Riverside, California, USALiyin L Liang - Department of Botany and Plant Sciences, University of California, Riverside, California, USASteven M Crum - Department of Botany and Plant Sciences, University of California, Riverside, California, USAGudina L Feyisa - Department of Natural Resource Management, Jimma University, EthiopiaJun Wang - Center for Global and Regional Environmental Research, University of Iowa, Iowa City, Iowa, USAG. Darrel Jenerette - Department of Botany and Plant Sciences, University of California, Riverside, California, USA
- Resource Type
- Journal article
- Publication Details
- The Science of the total environment, Vol.579, pp.495-505
- Publisher
- Elsevier B.V
- DOI
- 10.1016/j.scitotenv.2016.11.069
- PMID
- 27894802
- ISSN
- 0048-9697
- eISSN
- 1879-1026
- Grant note
- DOI: 10.13039/100000104, name: National Aeronautics and Space Administration, award: NNX12AQ02G, NNX15AF36G
- Language
- English
- Date published
- 02/01/2017
- Academic Unit
- Electrical and Computer Engineering; Civil and Environmental Engineering; Physics and Astronomy; Chemical and Biochemical Engineering
- Record Identifier
- 9984104805902771
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