Research on Extreme Weather Events in Spain - Analysis of high temperature heat wave and extreme precipitation in the Mediterranean Coast of Spain and Barcelona

In the context of global warming, frequent extreme climate events, especially high temperature heat waves and global warming, lead to an increase in the frequency and intensity of heat waves. At the same time, due to changes in climatic and hydrological characteristics, extreme precipitation and drought events closely related to people's lives frequently occur. This research studies the heat waves and extreme precipitation events from 1971 to 2020 in the Mediterranean coast of Spain, mainly in the Barcelona metropolitan area, and analyzes their main causes and influencing factors. It is of great significance to formulate improved policies and protection mechanisms in the future to promote sustainable urban development. We selected 8 different meteorological observatories as primary climate data sources in the provinces of Barcelona and Valencia, Alicante, Murcia and Almeria respectively. Using the OLS model, we estimated the global warming at each temperature by the cosine formula     from the analysis of the daily average temperature, maximum temperature, and minimum temperature for each observation point. As a result, stations with higher average temperatures had lower estimates of their warming. The performance of global warming varies greatly between day and night, and is more pronounced at night than during the day. Raval is the only sample with negative values. We taken 1971-2000 as the observation period, and use the 95% percentile to judge extreme climate. It was found that the frequency of heat waves increased year by year, and the number of heat waves occurred at night was significantly higher than that during the day. The precipitation on a heat wave night is generally higher than that on a heat wave day, but the heat wave is usually accompanied by drought. However high humidity is high during the heatwave in central Barcelona. The occurrence of extreme precipitation decreases, with a higher density of heavy rainfall in the southern region than in Barcelona. In addition, extreme precipitation has made an outstanding contribution to the annual precipitation, up to 88.47%. Finally, various regression models are established to analyze the possible factors affecting extreme climate. High latitudes and long distances from the sea promote heatwaves during the day and can also prolong the number of days that they last. Heatwave nights are more frequent in high latitudes, but staying away from the ocean and high altitude can improve it. In addition, global warming and precipitation are supporting factors for high temperature heat waves. The frequency of extreme precipitation is directly proportional with latitude and mean precipitation, and is inversely correlated with distance and altitude from the sea and daily maximum temperature. There is no obvious relationship between extreme precipitation and daily maximum precipitation.