As climate change intensifies, urban transportation infrastructure faces unprecedented challenges from extreme weather events, such as floods. This study investigates the resilience and vulnerability of such infrastructure under extreme rainfall conditions in Changchun City. Utilizing Multi-Criteria Decision-Making Analysis (MCDM) and Geographic Information System (GIS) techniques, we comprehensively assess the physical, functional, and service vulnerabilities of the transportation network. Our analysis reveals that only 3.57% of the area is classified as highly resilient, demonstrating effective flood management capabilities. In contrast, a significant 61.73% of the area exhibits very low resilience, highlighting substantial vulnerabilities that could impact urban operations. Based on our findings, we propose specific strategies to enhance resilience, including optimizing drainage systems, upgrading infrastructure standards, implementing green infrastructure initiatives, and integrating disaster risk factors into urban planning. These strategies and insights provide valuable references for global cities facing similar climatic challenges.

Based on the precipitation and potential evapotranspiration at 23 stations in the Jilin Province, the standardized precipitation evapotranspiration index (SPEI) was calculated. Based on run theory and combined with previous research in Jilin Province, we redefine the drought threshold, with three characteristics, that is, drought duration, intensity, and severity, were identified and extracted. Two- and three-dimensional copula functions were selected to fit and combine drought variables to calculate the joint recurrence period. In order to make the alternative copula model more complete, 25 representative copula functions are selected for the first time to construct the Joint probability distribution function. The Mann–Kendall test was used to examine abrupt changes in Meihekou County. SPEI trends and the joint cumulative probability of drought variables in the Changbai area were analyzed. The results show that: (1) the SPEI in the Meihekou area was unstable around 2000 and 2010, with abrupt change points; (2) the trend of the SPEI in the Changbai Mountains area indicates that the drought occurrence is similar at various timescales; the drought range and duration increase with increasing timescale; and (3) the correlation between the three drought variables is strong and the fit is good. The results of two- and three-dimensional joint recurrence period calculations are similar, with a high probability of recurrence within three years.

As an important component of the East Asian monsoon system, the northeast cold vortex (NECV) exerts a significant impact on weather and climate, especially in Northeast China. This study investigated the interdecadal spatiotemporal variability of heavy rainfall under the cold vortex of Northeast China (NECVHR) and its relationship with sea surface temperature (SST) during 1961–2019 over Northeast China. To investigate the dominant factors affecting variability in the heavy rainfall between May and September, an empirical orthogonal function (EOF) analysis was performed. To detect the trends and changes, a Mann-Kendall (MK) test was used. The sliding t-test was used to identify the change points and the significance. Pearson correlation analysis was used to analyze the relationship between SST and NECVHR, and the t-test was used to verify the significance. The results showed that the total amount of cold vortex heavy rainfall during May–September ranged from 153 to 12,509 mm for 1961–2019. An abrupt interdecadal change was seen after 2014 in Northeast China. The EOF analyses revealed that the first, second, and third EOFs explain 76%, 12.1%, and 5.5% of the total variance, respectively. The EOF followed the heavy rainfall pattern, with increases in the south (southeast) and decreases in the north (northwest) over Northeast China. Heavy rainfall over Northeast China positively correlated with the Atlantic multidecadal oscillation (AMO) index. The heavier rainfall under cold vortex (MCVHR) years revealed that the equipotential height was obviously located over the Sea of Japan, west of Northeast China and the Qinghai Tibet plateau. The cyclonic circulation over the East China Sea and north (northeasterly) wind prevails over Northeast China during less heavy rainfall under cold vortex (LCVHR) years. A high anticyclonic circulation over the Qinghai Tibet plateau resulted in stronger cold advection over Northeast China. The anticyclonic circulations over the East China Sea and the Sea of Japan (east), and the western (southwesterly) winds prevail over Northeast China, with a relatively shallow cold trough over the Qinghai Tibet plateau. The findings in this paper provided a better understanding of the interdecadal variability of NECVHR over Northeast China. The findings can be helpful for several stakeholders regarding agricultural production, water resource management, and natural habitat conversation in Northeast China.