THE NORTH CENTRAL TEXAS URBAN HEAT ISLAND MAGNITUDE AND ITS RELATION TO SEVERE AND EXTREME DROUGHT
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Date
2021-05-04Author
Standard, Linnea Clarke
0000-0001-8522-5505
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This study focuses on how summer droughts affect the urban heat
island (UHI) in Dallas-Fort Worth (DFW). The nocturnal UHI has been
computed by comparing downtown temperature observations to rural
temperature measurements under the condition that wind speed is less
than 2 m/s, a cloudless sky, and no precipitation. To understand the
combined effects of long-term climate change and UHI, trends of
temperature anomalies from 1902 - 2019 for Waco and 1900 – 2019 DFW
from NOAA COOP were determined relative to a baseline of 1951-1980.
The differing trends of these temperature anomalies have been influenced
by the UHI (which is larger in the DFW metropolitan area than in Waco)
and the higher continentality of the DFW sites. The NOAA Palmer Drought
Severity Index (PDSI) was investigated for Climate Zone 3 in Texas and
used to isolate years of extreme-severe drought during the month of July
and correlated to the UHI magnitude estimates from NOAA COOP and
Texas Commission for Environmental Quality (TCEQ). The findings
suggest a statistically significant correlation between an increase in the
PDSI and the UHI magnitude for the most current decade from 2011 to
2020, in agreement with the study from Winguth and Kelp (2013) for the
previous decade. The reduced latent heat flux under drought conditions
can lead increase of the UHI. Under wet conditions the UHI magnitude is
below 3°C. The most extreme daily UHImag of 5.6°C occurred during the
severe drought in July of 2011. Population change appears to influence
anthropogenic heat flux in the DFW area, however, land surface changes
attribute to latent and sensible heat fluxes that affect the UHI magnitude.