An Analysis of the Urban Heat Island Effect in Munich, Germany

The Urban Heat Island effect is the compared temperature difference from urban areas to rural areas. The density and materials of structures within a central city in addition to the lack of vegetation results in an increased temperature in largely populated areas which can negatively affect city inhabitants. This is attributed to materials such as concrete, cement, and asphalt storing heat more efficiently than organic materials. The urban heat island (UHI) effect is best observed during evening and nighttime. With materials like concrete that maintain heat longer than natural surfaces, strong differences in surface air temperatures are amplified by a lack of infrared radiation escaping from densely built-up areas during the night. Motivated by meteorological and climatic implications, a series of measurements were collected on a study abroad trip in select neighborhoods in Munich, Germany, and are being presented in this study with the intent to better understand the UHI. Munich is a typical European city. The most notable green space in the city is the English Garden, which is where some of the data collection took place. During the days of May 21st - 26th, 2023, temperature data in various areas of the city were collected. Using Kestrel D3 Fire sondes, specific locations were chosen in and around the English Garden based on building density to measure air temperature differences. Temperature measurements were recorded walking to and from these same locations twice within 12 hours, once around sunrise and once around sunset. During the walks, temperature was recorded every 10 seconds with a sensor held approximately 2 meters off the ground, while a GPS app tracked the precise location. In addition to these measurements near the center of Munich, observations were made during two bike rides out of and into the city, starting and ending at the Central Train Station, the former in the morning and the latter during mid-afternoon. UHI magnitudes were determined by comparisons with a temperature station at the Munich International Airport located in a more rural area outside the city. Temperatures varied around six degrees Celsius throughout evening walks through various build-up urban areas, but only around two degrees during the morning walks in the same areas. UHI index calculations show late evening UHI values of four degrees warmer than airport temperature observations, while early morning UHI index values were two degrees cooler than the airport reference temperatures. Further, research will likely investigate the role of weather conditions, sunshine hours, sky view factor, building height, and building materials.