Sorin Frasina
Mirela Voiculescu
Gabriel Murariu
INTRODUCTION
The atmospheric environment continuously affects the human body in a significant and noticeable way. Over 75% of Europe’s population lives or mainly works in urban environments. Economic reports identify secondary cities as key drivers of economic growth in the European Union. The combined effect of urban heat islands (UHI) along with recurring heat waves (HW) poses a significant threat to achieving sustainable development goals in these urban areas. Typically, the indicator describing the UHI effect is the temperature difference between densely built urban areas and nearby rural or less dense urban zones. The urban heat island phenomenon also causes modifications to other meteorological variables (such as air relative humidity, soil moisture or precipitation volume), finally impacting the human body.
PURPOSE: Analysis of the UHI effect using other temperature-based composite indices
In this study, an analysis on the effects of the urban heat island effect was conducted on the population, using two additional bioclimatic indices:
• THI – (temperature-humidity index)
• Missenard Index (temperature-humidity-wind speed index).
CALCULATION METHODS/FORMULAS:
• THI=(T•1.8 + 32)–(0.55 – 0.0055•H)•[(T•1.8 + 32) – 58)]
• TEE=37-(37-T)/(0.68 + 0.00014•H+1/(1.76+1.4•v3/4)-0.29T•(1-H/100)
• converting results into scores and warning color code
• converting results into weekly scores (SSIT, SSICT, SSTEE)
CONVERSIONS TEST EXAMPLE
RESULTS COMPARISON EXAMPLE/ AUGUST 2023
The weekly SST temperature score is highest in Galați (SST=59, calculated for ANMGL), closely followed by Tecuci (SST=58, calculated for ANMTC). The maximum disparity observed is 4 points, in comparison to the neighboring rural area of Cuca COWRA (SST=54).
However, when factoring in temperature and relative humidity, a more significant thermal stress is observed for the inhabitants of Galați municipality (SSICT=77, calculated for ANMGL) compared to those in tertiary urban environments and the monitored rural area. The maximum difference in the weekly score of the thermal comfort index is noted when comparing Galați to the tertiary urban environment of Cahul (SSICT=69, calculated for WMOCAH), while the difference with the rural area of Cuca COWRA (SSICT=70) is 7 points. It is also noteworthy that in both the rural area of Cuca and the tertiary urban environment of Cahul, there were no exceedances of the thermal discomfort threshold.
When incorporating wind speed alongside temperature and relative humidity through the application of the updated Missenard formula, the disparities in thermal stress experienced by the populations in the monitored environments become significantly more pronounced. The weekly score of the equivalent effective temperature index recorded in the secondary urban environment of Galați ANMGL (SSTEE=72) is 10 units higher than that of the tertiary urban environment of Tecuci ANMTC (SSTEE=62) and 9 units higher than that of the adjacent rural area of Cuca (SSTEE=63).
RESULTS INTERPRETATION
During the astronomical summer of 2023, the highest level of thermal stress felt by population, calculated for the area of interest, both by the classical method and by the two mentioned methods, was recorded in Galați. The additional thermal stress that population experienced in the secondary urban environment (Galați) compared to the tertiary urban environments (Tecuci and Cahul) can be expressed more clearly by tracking multiparametric bioclimatic indicators. The use of a color-coded warning scheme to inform population about the dangers faced by the human body during heat waves becomes more effective for authorities.
CONCLUSION
Using Temperature-Humidity Index (THI) and/or Missenard Index significantly enhances the precision and accuracy of assessing heat stress caused by the Urban Heat Island effect, compared to relying solely on temperature values.