Comprehensive identification of drought events is of great significance for monitoring and evaluating drought processes. Based on the date of daily precipitation, temperature and drought-affected area of 403 meteorological stations in North China from 1960 to 2019, the Comprehensive Drought Process Intensity Index (CDPII) has been developed by using the Meteorological-drought Composite Index (MCI) and regional drought process identification method, as well as the EIDR theory method. The regional drought processes in the past 60 years in North China, including Beijing, Tianjin, Hebei, Shanxi and Middle Inner Mongolia, were analyzed and identified. The result shows that the distribution characteristic of droughts with different intensities is as follows: The number of days of all annual-average mild droughts, moderate droughts and severe droughts was highest in Tianjin and that of extreme droughts was highest in Shanxi. The number of days of mild droughts was highest in May and lowest in January. The number of days of moderate droughts was highest in June. The number of days with mild and moderate drought showed an overall increasing trend, while the number of days with severe drought and above showed an overall decreasing trend (through a 95% significance test). The number of drought days was the highest in the 1990s. The annual frequency of drought is between 66.7% and 86.7%; the drought frequency in Hebei is the highest at 86.7%, followed by Beijing at 80%. There were 75 regional drought processes in North China from 1960 to 2019, and the correlation coefficient between process intensity and the drought-affected area was 0.55, which passed the 99% significance test. The comprehensive intensity of drought process from 27 April to 1 September 1972 was the strongest. From 18 May to 31 October 1965, the drought lasted 167 days. The overall drought intensity had a slight weakening trend in the past 60 years. A total of 75 regional drought processes occurred in North China, and the process intensity showed a trend of wavy decline with a determination coefficient (R²) of 0.079 (95% significance test). Overall, the regional drought process identification method and strength assessment result tally with the drought disaster, which can better identify the regional drought process. Furthermore, including the last days, the average intensity, average scope comprehensive strength, there are many angles to monitor and evaluate the drought and drought process. These provide a reference for drought control and decision-making.

The planning techniques and strategies for optimizing the urban wind and heat environment are important means for cities to adapt to climate change at the source. This study used Shenzhen, a sub-tropical megacity in southern China, as an example for evaluating the climate environment, heat island intensity, and urban form, and then for analyzing the relationships between them. The results revealed a high-quality climate area located southeast of Shenzhen that can provide a high wind speed and low temperature. Low-quality climate areas were located in the central and western regions and were less comfortable. The relationship between surface ventilation potential and urban form was analyzed using linear regression and the Pearson correlation coefficient, showing that there was a significant correlation between a surface urban heat island (SUHI) and building density (BD) as well as the sky view factor (SVF), and that there was also a correlation between the ventilation potential coefficient (VPC) and other factors, such as the surface’s roughness length (RL) and building height (BH). The results showed that ventilation capacity deteriorated as BH and RL increased. An environmentally sensitive thermal area was identified from the surface urban heat island intensity, which was always in a strong heat island (SHI) or sub-strong heat island (SSHI) year-round. It was recommended that seven level one corridors and nine level two corridors be formed. Additionally, thermal and wind environment optimization strategies and protective suggestions were proposed for the city’s overall development.

The rapid development of urbanization has caused obstructed urban natural ventilation and the contribution rate of urbanization is relatively high. Therefore, there is an urgent need for urban development planning that should respect natural ventilation and local climate to reduce negative impacts. By optimizing the urban construction layout to reduce obstruction and leave a passageway for wind to blow in, the natural ventilation environment could be improved. This paper presents a promising approach for natural ventilation planning at both the city and community scales. Based on the assessment of wind environment, heat island intensity, and ventilation potential, the results revealed that winds blowing from the western and northern mountainous area of Shijiazhuang play a natural ventilation inlet role which can provide clean air. The SSHI and SHI were mainly distributed within the Second Ring Road, which has a large proportion of the low ventilation potential level. Thus, six first-class ventilation corridors and thirteen secondary corridors were recommended, which were set to be adapted to the dominant wind direction. Subsequently, an urban climate analysis map (UCAnMap) was developed considering climate sensitivity, and planning recommendations were provided for different climate zones. The relationship between architectural spatial structure and ventilation efficiency was analyzed; the results revealed that increasing the height of the buildings will decrease the proportion of comfortable wind zones, and the overall ventilation efficiency will weaken, so the average building height of a typical block should be controlled within 45 m, which matches ventilation performance requirements. The ventilation efficiency of the block has a certain negative correlation with the building density, and as the building density decreased by more than 10%, the proportion of the comfortable wind zones could increase by 4–5%.

Based on the daily temperature and precipitation data from 1961 to 2021 obtained from 2019 national meteorological stations of China, and by means of Meteorological Drought Comprehensive Index (MCI) and some improved identification methods, we identified all drought event processes in all the seven regions of China in this paper. We also carefully analyzed these regional droughts and made following conclusions: drought was spreading towards southern China with an increasing frequency; consecutive drought year group occurred in all the seven regions of China with an increasing frequency under the background of global warming; both drought duration and comprehensive intensity consistently changed with the area affected by drought, with a correlation coefficient of 0.52–0.67 and 0.88–0.99 respectively, and passed the significance test of 0.05. The method used in this paper could be employed to effectively monitor and evaluate drought processes from multiple dimensions including duration, comprehensive intensity and area affected by drought. Thus, it actually provided a helpful decision-making basis for governments to prevent the risk of drought.

Optimizing the urban spatial layout is an important guarantee for improving natural ventilation in cities. Based on meteorological observation statistical analysis, numerical model simulation, and remote sensing inversion calculation, a natural ventilation planning technology covering both the city and community scales is proposed and applied in the Shijiazhuang metropolitan area in Hebei Province, China. Meteorological data obtained from observation stations were utilized to analyze local wind speed, direction, and frequency. The results revealed diverse wind characteristics in different regions. Winds blowing from the western mountainous area, characterized by high vegetation coverage, are predominantly west and northwest. This wind is a significant source of clean air and serves as a natural ventilation inlet for Shijiazhuang. In the northern area, winds are primarily northwest and north, while in the southern area, winds are mainly southeast and south. Additionally, there is a notable heat island effect within the second ring road, which has an elliptical shape with the long axis oriented from east to west and the short axis oriented from south to north. This effect shows a clear trend of eastward expansion. Based on this research, six primary ventilation corridors and thirteen secondary ventilation corridors have been established. The direction of these corridors aligns with the local wind patterns, and the width of the corridor is calculated based on the city’s capacity and required ventilation efficiency. Subsequently, an urban climate analysis map (UCAnMap) was developed considering climate sensitivity. Planning recommendations were provided to enhance the urban climate environment and optimize spatial layout in different climate zones. It’s worth nothing that there exists a negative correlation between ventilation efficiency and building height within the blocks. Increasing the height of the buildings will decrease the proportion of comfortable wind zones, and the overall ventilation efficiency of the block will weaken. Based on the principle that the average wind speed ratio is greater than or equal to 0.5, it is concluded that the average building height of a typical block should be controlled within 45 m, which matches the ventilation performance requirements, and these results can also serve as a guide for building parameters that are conducive to ventilation. The ventilation efficiency of the block has a certain negative correlation with the building density. By reducing the building density, the mean wind velocity ratio and the comfortable wind zone ratio of the block can be appropriately increased. If the building density decreases by more than 10%, the proportion of calm wind areas will decrease by about 2–5% compared to the original situation.

This article focuses on how to further explore the impact of building layout and form on the local wind environment in micro scale ventilation corridors connected to the urban scale. Taking Shijiazhuang as the research area, three typical blocks of complex building forms, including old and new ones, were selected near the built ventilation corridors. CFD numerical simulation and on-site observation experiments were conducted to analyze the impact of different building heights and layouts on the wind environment in each typical block qualitatively and quantitatively. The above can provide a reference and guidance for the construction of secondary and tertiary ventilation corridors and the spatial form design of functional buildings during urban renewal in the stock era. The results show the following: (1) average wind speed, Mean Wind Velocity ratio, and the proportion of the outdoor pedestrian comfort zone are negatively correlated with the building height, but there is a threshold for them to decrease with the increase in the building height. Observation experiments also indicate that in the background of the south wind, the internal and leeward wind environment of new high-rise residential areas is better than that of old low residential areas. (2) Regression analysis was conducted between the simulated average wind speed and the building height, indicating that regulating the average building height to be below 45 m can improve the wind environment as the building height decreases. (3) The enclosed building complex has the smallest impact distance on downstream wind speed compared to point, row, and staggered layouts, but its internal ventilation environment is relatively poor. To ensure the ventilation performance, the upper limit of the building height should be stricter, and it should be controlled within at least 40 m, especially below 30 m. (4) In the process of urban renewal in the future, it is recommended to conduct an overall ventilation efficiency evaluation for different blocks. Compared to others, increasing the height of buildings and leaving more space to increase the inter site ratio/building spacing is more beneficial for the overall ventilation environment.