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- Unveiling the Thermo‐Hygrometric Influence of Summer Sea and Estuarine Breezes (SEBs) in Lisbon (Portugal)Publication . Reis, Cláudia; Lopes, António; Nouri, A. Santos; Vasconcelos, JoãoLocal wind, such as sea breezes, play a crucial role in cooling coastal cities. This study presents new insights about the thermo-hygrometric influence of the Tagus and Atlantic Ocean breezes(sea and estuarine breezes [SEBs]) in Lisbon’s urban climate (Portugal). SEB events were identified in the summer of 2022 according to a wind rotation criterion: the interruption of prevailing North and Northwest (Nortada) winds during the morning, the wind shift to Northeast/East/Southeast and, sometimes, to further South/Southwest/West (rotation between 22.6° and 292.5°) and the return of the regional flow at late afternoon. Additionally, air temperature and absolute humidity anomalies (ΔT/Haurb) were calculated according to the distance to the riverfront area. Results show that SEB occurred on 37 (31%) out of 120 days, mainly in July (43%) and August (32%), between, on average, 10:00 AM and 4:00 PM, and average wind speeds of 3.4 m/s. According to the daily thermo-hygrometric cycle, the areas up to 4 km of the Tagus estuary were, on average, cooler than northern Lisbon during SEB events, especially the areas up to 500 m (average ΔTurb reached −1.7°C). Additionally, there was a significant increase in the moisture content during SEB hours across the city but especially close to the riverfront area: the areas up to 500 m registered, on average, ΔHaurb of 4.2 g/m3 on SEB events (12:00 PM) against 2.1 g/m3 during typical Nortada days. This research is a starting point for a future delimitation and preservation of SEB penetration zones in Lisbon to address outdoor thermal discomfort during summer.
- Assessing urban heat island effects through local weather types in Lisbon's Metropolitan Area using big data from the Copernicus servicePublication . Reis, Cláudia; Lopes, António; Nouri, A. SantosIn this study UHI in Lisbon's Metropolitan Area (LMA) is analyzed through Local Weather Types (LWT) using an air temperature dataset produced by Copernicus. Over 61,000 hourly air temperature maps between 2008 and 2014 are extracted, divided into thermal seasons and LWT, and UHI is calculated by the anomaly between each raster cell and a pixel from “Low Plants” Local Climate Zone (LCZ) class. UHI daily cycle is analyzed by LWT. Statistical analysis shows that rainy days produce lower median UHI intensities (close to 0 ◦C), while sunny days, especially very cold winter days, produce higher UHI intensities (median values close to 1,5 ◦C). Analysis of the UHI pattern displays a S/SE-N/NW dichotomy in the right bank of the Tagus river and an N-S dichotomy in the Peninsula of Setúbal. The UHI effect is more pronounced in Lisbon, particularly in the riverfront area, and on the opposite bank of Tagus due to the shelter effect of frequent N winds. As previous studies have proven, UHI in LMA is mainly a nighttime phenomenon. This methodology may help decision makers to identify critical heating districts as well as weather conditions most conducive to a significant overheating of the urban atmosphere.