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Intra-urban nocturnal cooling rates: development and evaluation of the NOCRA model

Författare och institution:
Shiho Onomura (Institutionen för geovetenskaper); Björn Holmer (Institutionen för geovetenskaper); Fredrik Lindberg (Institutionen för geovetenskaper); Sofia Thorsson (Institutionen för geovetenskaper)
Publicerad i:
Meteorological Applications, Epub ahead of print
Artikel, refereegranskad vetenskaplig
John Wiley & Sons, Ltd
Sammanfattning (abstract):
A nocturnal cooling rate model (NOCRAM) to simulate nocturnal air temperature at urban sites is presented. The model is designed for urban planners, practitioners and researchers who demand meteorological information for urban planning and research applications. The model is based on the concept of nocturnal cooling, progressing in two distinct phases, i.e. site-dependent cooling around sunset and site-independent cooling from about 1 or 2 h after sunset until sunrise. Cooling rates are usually determined predominantly by prevailing weather conditions (i.e. clearness of the sky and wind speed), followed by maximum daily air temperature and by sky view factors. Second phase cooling is chiefly determined by sky clearness and wind speed. The findings and statistical results from the analysis of observational data during warm months (May–September) from Gothenburg, Sweden, as well as from past studies, were used. The model requires standard meteorological variables (i.e. wind speed, incoming short-wave radiation, air temperature, relative air humidity, air pressure) at a reference station as well as geometrical information (i.e. the sky view factor of the site and the geographical co-ordinates of the reference meteorological station). The model simulates the characteristic development of cooling rates in the two phases at open sites and built-up sites with different sky view factors under a wide range of weather conditions in warm months. Using the modelled cooling rates, nocturnal air temperature is estimated easily with the accuracy of root mean square error (RMSE) ≤1.54 °C and R2 ≥0.78.
Ämne (baseras på Högskoleverkets indelning av forskningsämnen):
Geovetenskap och miljövetenskap ->
Fysisk geografi
Geovetenskap och miljövetenskap ->
Meteorologi och atmosfärforskning
nocturnal cooling rate, two-phase cooling, intra-urban heat island, empirical modelling, urban planning applications
Postens nummer:
Posten skapad:
2016-04-27 10:54
Posten ändrad:
2016-07-05 12:55

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