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apps:biomet_utci [A holistic microclimate model]

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 apps:biomet_utci [2015/12/22 22:27]enviadmin apps:biomet_utci [2017/11/10 09:25] Line 1: Line 1: - ====== UTCI ====== - The calculation of UTCI is based on a 6th order polynomial regression function estimating UTCI from wind speed, air temperature,​ mean radiant temperature and air vapour pressure (see [[http://​www.utci.org/​utci_doku.php|COST 730 Webpage]]). Due to that approach, there is almost nothing that can be changed in the personal settings such as clothing, activity etc. - - - **Limits:** - * Wind Speed: UTCI as used in the software is limited to a wind speed range of 0.5 to 17 m/s related to 10 m Height - * Height reference: UTCI always related to wind speed at 10 m height while the biometeorological parameters are normally define between 1.5 and 2 m... - - - As the UTCI calculation expects the wind given at the 10 m level, ENVI-met BioMet uses the calculated local wind speed in the model domain related to the pedestrian level (zlevel) and scales it up to the  10 m level equivalent using the logarithmic wind power profile ​ - $$Wind_{10m} := \frac{ln(10 / z0)}{ln(zlevel / z0)} \cdot Wind_{zlevel}$$ - - In other word, if you calculate UTCI at some point for zlevel= 1.6 m, all ENVI-met data such as air temperature or radiative temperature will be used from this level, except of the wind speed which will be extrapolated to the 10 m level value. - - Obviously, that doesn'​t make much sense as the $z0$ roughness value is unknown for most sites, but ENVI-met provides detailed and calculated wind flow data for all levels. ​ - - ==== Final Remarks ==== - We do not recommend to use UTCI in the regression-based version based on using 2m (1.6m) level wind speeds extrapolated to 10m. In a complex urban environment,​ wind speeds at pedestrian level are unique and cannot be related to some above-roof general quantity. ​ Instead, we propose the application of a pure physically-based approach such as PET. PET is a much more open platform and the final outcomes are more or less the same for all static indicators. ​ - - - **Please Note**: ​ Due to these restrictions,​ areas outside the official bounds of UTCI will not be calculated by BioMet. These areas are marked with "No Data". Especially in urban areas, the lower limit of 0.5 m/s can create a number of white "No Data" areas in the maps. In future versions of BioMet, will add an option to ignore these UTCI bounds. BUT: Remember that UTCI is not a part of ENVI-met. Using this option, ​ your maps might look better and  more complete. But scientifically,​ you are leaving the "​official"​ and pre-calcuated UTCI range. - - **References** - - Link to the original source code and to the EU COST Action 730 Homepage: [[http://​www.utci.org/​utci_doku.php]]