Observational Evidence of Neighborhood Scale Reductions in Air Temperature Associated with Increases in Roof Albedo
The effects of neighborhood-scale land use and land cover (LULC) properties on observed air temperatures are investigated in two regions within Los Angeles County: Central Los Angeles and the San Fernando Valley (SFV). LULC properties of particular interest in this study are albedo and tree fraction...
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MDPI AG
2018-12-01
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| Series: | Climate |
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| Online Access: | https://www.mdpi.com/2225-1154/6/4/98 |
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doaj-f60889d15b3d4c97ad628cbed8c46bd82020-11-25T01:28:27ZengMDPI AGClimate2225-11542018-12-01649810.3390/cli6040098cli6040098Observational Evidence of Neighborhood Scale Reductions in Air Temperature Associated with Increases in Roof AlbedoArash Mohegh0Ronnen Levinson1Haider Taha2Haley Gilbert3Jiachen Zhang4Yun Li5Tianbo Tang6George A. Ban-Weiss7Civil and Environmental Engineering, University of Southern California, Los Angeles, CA 90089, USAHeat Island Group, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USAAltostratus, Inc., 940 Toulouse Way, Martinez, CA 94553, USAHeat Island Group, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USACivil and Environmental Engineering, University of Southern California, Los Angeles, CA 90089, USACivil and Environmental Engineering, University of Southern California, Los Angeles, CA 90089, USACivil and Environmental Engineering, University of Southern California, Los Angeles, CA 90089, USACivil and Environmental Engineering, University of Southern California, Los Angeles, CA 90089, USAThe effects of neighborhood-scale land use and land cover (LULC) properties on observed air temperatures are investigated in two regions within Los Angeles County: Central Los Angeles and the San Fernando Valley (SFV). LULC properties of particular interest in this study are albedo and tree fraction. High spatial density meteorological observations are obtained from 76 personal weather-stations. Observed air temperatures were then related to the spatial mean of each LULC parameter within a 500 m radius “neighborhood„ of each weather station, using robust regression for each hour of July 2015. For the neighborhoods under investigation, increases in roof albedo are associated with decreases in air temperature, with the strongest sensitivities occurring in the afternoon. Air temperatures at 14:00⁻15:00 local daylight time are reduced by 0.31 °C and 0.49 °C per 1 MW increase in daily average solar power reflected from roofs per neighborhood in SFV and Central Los Angeles, respectively. Per 0.10 increase in neighborhood average albedo, daily average air temperatures were reduced by 0.25 °C and 1.84 °C. While roof albedo effects on air temperature seem to exceed tree fraction effects during the day in these two regions, increases in tree fraction are associated with reduced air temperatures at night.https://www.mdpi.com/2225-1154/6/4/98urban heat islandurban climateLos Angelesland use land covercool roofsheat mitigationvegetationtree |
| collection |
DOAJ |
| language |
English |
| format |
Article |
| sources |
DOAJ |
| author |
Arash Mohegh Ronnen Levinson Haider Taha Haley Gilbert Jiachen Zhang Yun Li Tianbo Tang George A. Ban-Weiss |
| spellingShingle |
Arash Mohegh Ronnen Levinson Haider Taha Haley Gilbert Jiachen Zhang Yun Li Tianbo Tang George A. Ban-Weiss Observational Evidence of Neighborhood Scale Reductions in Air Temperature Associated with Increases in Roof Albedo Climate urban heat island urban climate Los Angeles land use land cover cool roofs heat mitigation vegetation tree |
| author_facet |
Arash Mohegh Ronnen Levinson Haider Taha Haley Gilbert Jiachen Zhang Yun Li Tianbo Tang George A. Ban-Weiss |
| author_sort |
Arash Mohegh |
| title |
Observational Evidence of Neighborhood Scale Reductions in Air Temperature Associated with Increases in Roof Albedo |
| title_short |
Observational Evidence of Neighborhood Scale Reductions in Air Temperature Associated with Increases in Roof Albedo |
| title_full |
Observational Evidence of Neighborhood Scale Reductions in Air Temperature Associated with Increases in Roof Albedo |
| title_fullStr |
Observational Evidence of Neighborhood Scale Reductions in Air Temperature Associated with Increases in Roof Albedo |
| title_full_unstemmed |
Observational Evidence of Neighborhood Scale Reductions in Air Temperature Associated with Increases in Roof Albedo |
| title_sort |
observational evidence of neighborhood scale reductions in air temperature associated with increases in roof albedo |
| publisher |
MDPI AG |
| series |
Climate |
| issn |
2225-1154 |
| publishDate |
2018-12-01 |
| description |
The effects of neighborhood-scale land use and land cover (LULC) properties on observed air temperatures are investigated in two regions within Los Angeles County: Central Los Angeles and the San Fernando Valley (SFV). LULC properties of particular interest in this study are albedo and tree fraction. High spatial density meteorological observations are obtained from 76 personal weather-stations. Observed air temperatures were then related to the spatial mean of each LULC parameter within a 500 m radius “neighborhood„ of each weather station, using robust regression for each hour of July 2015. For the neighborhoods under investigation, increases in roof albedo are associated with decreases in air temperature, with the strongest sensitivities occurring in the afternoon. Air temperatures at 14:00⁻15:00 local daylight time are reduced by 0.31 °C and 0.49 °C per 1 MW increase in daily average solar power reflected from roofs per neighborhood in SFV and Central Los Angeles, respectively. Per 0.10 increase in neighborhood average albedo, daily average air temperatures were reduced by 0.25 °C and 1.84 °C. While roof albedo effects on air temperature seem to exceed tree fraction effects during the day in these two regions, increases in tree fraction are associated with reduced air temperatures at night. |
| topic |
urban heat island urban climate Los Angeles land use land cover cool roofs heat mitigation vegetation tree |
| url |
https://www.mdpi.com/2225-1154/6/4/98 |
| work_keys_str_mv |
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