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28 February 2024, Volume 40 Issue 1 Previous Issue    Next Issue

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Analysis of the causes and climatic background of an extreme freezing rain event at Harbin airport Tianzhu WANG,Chao SUN,Yuhe LI,Jiayu HE,Shaohua YUAN,Yubo NIE 2024, 40 (1):  1-8.  doi: 10.3969/j.issn.1673-503X.2024.01.001 Abstract ( 159 )   HTML ( 34 )   PDF (8121KB) ( 189 )   Save Based on the observational data and ERA5 reanalysis data, the causes of the freezing rain disaster weather were studied by composite analysis methods from the perspective of circulation background at Harbin Taiping International Airport on November 8, 2021. The results show that the temperature over Harbin Airport during the freezing rain has a significant "cold-warm-cold" characteristic, which is a typical "melting mechanism". The key factors of this process are the stable maintenance of 850 hPa low-level warm and humid southeast jet stream and low-level inversion layer, and the lower surface temperature of 2~4 ℃ under the risk control system of northeast surface.According to the Lagrange trajectory model (Hysplit), it is found that there are three main water vapor channels affecting the freezing rain weather of Harbin Airport. The second water vapor channel originating from the Sea of Okhotsk at the height of 850 hPa is the main water vapor channel during the precipitation process, and the Sea of Japan is the important water vapor source. The weather process occurred under the climate background of bimodal La Nina event, and the circulation field, surface pressure field and temperature field showed some abnormal characteristics compared with the same period in previous years. The bimodal La Nina years show the abnormal characteristics of strong warm and humid air flow and low surface temperature, which is similar to this process. Figures and Tables | References | Related Articles | Metrics

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Characteristics and causes of heavy precipitation differences at Wenzhou Airport caused by typhoon "Hagupit" and "Lekima" Gongmei CHEN,Ruixiao LI,Hailing HUANG,Houzhi LUO 2024, 40 (1):  9-16.  doi: 10.3969/j.issn.1673-503X.2024.01.002 Abstract ( 88 )   HTML ( 16 )   PDF (7085KB) ( 201 )   Save Using the conventional observation data, tropical cyclone dataset data from China Meteorological Administration, the 1°×1°reanalysis data of NCEP every six hours and FY-2G temperature of brightness blackbody (TBB) product, the precipitation distribution characteristics caused by "Hagupit" and "Lekima" at Wenzhou airport, the characteristics of environmental field and the physical field causing the difference precipitation are analyzed. The results show that: The influence periods at Wenzhou Airport of "Hagupit" and "Lekima" are different. The "Hagupit" precipitation is concentrated before and after the landing, which is caused by the precipitation of the typhoon itself. The precipitation of "Lekima" is concentrated before the landing, mainly caused by the precipitation carried by the spiral rainband around the typhoon; The low-level jet and the shallow water vapor transport channels provide water vapor and energy for typhoon, and the variation of water vapor flux divergence at 925 hPa has a good corresponding relationship with typhoon rainstorm.Long-term convergence of strong water vapor flux can lead to the continuous enhancement of rainstorm.Compared with "Lekima", the long-term convergence of strong water vapor flux in the shallow layer during the landing of "Hagupit" is the main reason for the long-term heavy rainfall; The dynamic mechanism of high-level divergence and low-level convergence combined with the shallow vertical upward movement is beneficial to the intensification of typhoon precipitation. The dynamic mechanism of "Hagupit" is more powerful and stable than "Lekima", which is the important reason for the difference precipitation between the two typhoons; On the structure of TBB cloud, during the influence period of "Hagupit" the overall cloud cluster structure was symmetrical and compact, and precipitation was mainly affected by its ontological cloud cover, while the precipitation of "Lekima" is mainly influenced by its outer spiral cloud belt. The heavy rain period of airport is related to the coverage of the clouds with TBB ≤-70 ℃, and the long coverage of TBB≤-70 ℃ clouds during the period of "Hagupit" is the direct reason for the stronger precipitation than "Lekima". Figures and Tables | References | Related Articles | Metrics

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Synoptic patterns and characteristics of environmental parameters for early-morning heavy rainfall over Beijing, Tianjin, and most of Hebei Plains Feifan LIU,Yongguang ZHENG,Ran LUO 2024, 40 (1):  17-26.  doi: 10.3969/j.issn.1673-503X.2024.01.003 Abstract ( 106 )   HTML ( 14 )   PDF (6735KB) ( 155 )   Save Beijing, Tianjin and most of the Hebei plains (37°-41°N, 115°-119.5°E) (BTH-P region) are regions with frequent nocturnal precipitation in summer.Based on hourly precipitation dataset from national observation stations during 2010-2021, 42 heavy precipitation cases in the early morning period in this region were classified according to synoptic patterns. The distributions of environmental physical parameters of heavy precipitation cases under different synoptic patterns were then calculated and obtained. The results show that the cases can be classified into four types, i.e.tropical cyclone type, low vortex or shear line type, low trough with cold frontal type and weak synoptic forcing at the edge of West Pacific Subtropical High type.It was found that the tropical cyclone type has much better water vapor conditions, with median PWAT (Precipitable Water) up to 72 mm, but weaker thermal and energy conditions than the other three, with the smallest CAPE (Convective Available Potential Energy) and K index values. The type of weak synoptic forcing in the edge of West Pacific Subtropical High has the most favorable thermal and energy conditions.In terms of dynamic and uplift conditions, the convergence of tropical cyclone type is more obvious and its vertical vorticity is greater than that of others. The 0~6 km vertical wind shear of low-vortex-shear type and frontal type are the more violent, with temperature difference between 850 hPa and 500 hPa being more relatively larger than that of the other two types, which indicates their middle and low troposphere has stronger baroclinity.In summary, the main weather patterns of heavy precipitation in the early morning of BTH-P region are low vortex or shear line, low trough with cold frontal and tropical cyclone, with particularly abundant water vapor conditions, unstable conditions that are not too strong, and moderate weak 0~6 km vertical wind shear environmental conditions. Figures and Tables | References | Related Articles | Metrics

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Application and verification of the spatiotemporal projection model in the extended-range forecast of summer precipitation in Northeast China Xiaoxuan SU,Xiaowei SUN,Chenhe ZHANG,Jia-qi LI,Zengxin LU,Xu YANG 2024, 40 (1):  27-36.  doi: 10.3969/j.issn.1673-503X.2024.01.004 Abstract ( 120 )   HTML ( 8 )   PDF (13448KB) ( 101 )   Save Based on the daily precipitation data and the NCEP/NCAR ((National Center for Environmental Prediction/National Center for Atmospheric Research)) atmospheric reanalysis data in Northeast China from 1979 to 2021, the historical rule of low-frequency precipitation in summer in Northeast China was analyzed using rotating empirical orthogonal function decomposition and ensemble empirical mode decomposition, combined with low-frequency precipitation and its related atmospheric intra-seasonal oscillation.A spatiotemporal projection model (STPM) was used to forecast the extended period of low frequency precipitation. The results show that there are obvious regional differences of low frequency precipitation in Northeast China, and the period of low frequency precipitation in different regions has obvious inter-annual variation, with the period of 10~40 days as the main and 40~80 days as the secondary. The key signals of low-frequency precipitation forecast from 10 to 40 days are tropical atmospheric intra-seasonal oscillation, Eurasian teleconnection, low-frequency wave train of Silk Road teleconnection and zonal wind field near the western Pacific Ocean. The low-frequency precipitation forecast signals from 40 to 80 days mainly come from the factor fields around Northeast China. The experiment on the extension period of the low-frequency precipitation of different frequency bands in Northeast China shows that the forecast ability decreases with the increase of advance forecast time. The predicted validity of low-frequency precipitation for 10~40 days is 10 days. The low frequency precipitation of 40~80 days shows a high forecasting skill, and the forecasting validity can reach about 30 days. Figures and Tables | References | Related Articles | Metrics

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Comparative analysis of the environmental characteristics of short-duration heavy rainfall in the warm season in the Beijing-Tianjin-Hebei region Lili SHEN,Jiangbo LI,Xiuming WANG,Qi ZHONG,Wenqing LI,Zhuo SUN 2024, 40 (1):  37-46.  doi: 10.3969/j.issn.1673-503X.2024.01.005 Abstract ( 123 )   HTML ( 8 )   PDF (5788KB) ( 241 )   Save Based on the hourly precipitation data and the fifth-generation European Center for Medium-Range Weather Forecasts(ECMWF) atmospheric reanalysis(ERA5) data in Beijing-Tianjin-Hebei region in the warm season (June-September) from 2013 to 2021, the temporal and spatial characteristics were statistically analyzed. The evolution characteristics of environmental factors such as dynamic, water vapor, and thermal instability conditions of different synoptic patterns were compared and analyzed. The results show that the Subtropical High (SH) pattern and the Cold Vortex (CV) pattern are the main types of short-duration heavy rainfall, accounting for 55%. The short-duration heavy rainfall mainly occurs from the middle and late July to the early and middle August and concentrates from the afternoon to the midnight.Comparably, the rain distribution differences are obvious.Pattern parting is reasonable.Mostly for low-level convergence and high-level divergence, the Southwest Vortex (SV) pattern are the most prominent, and increase with approaching precipitation, while the Weak Weather (WW) pattern is the smallest in all stages. The water vapor of the SH pattern, the Typhoon Wind (TW) pattern and the SV pattern are the most abundant, median specific humidity on 925 hPa is 19.14 g·kg-1 for SH pattern. The SV pattern has the highest saturation in high and low layers, and the average of median relative humidity reaches 87% in low layers. The WW pattern is relatively low of 74%. The precipitable water vapor of almost all patterns increases with the approaching precipitation. The thermal instability of the WW patter is the strongest, and the median temperature difference on 825 hPa and 500 hPa reaches 25.74℃, while the SV pattern is the weakest. The thermal condition of each type weakens over time except for the WW pattern. Figures and Tables | References | Related Articles | Metrics

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Distribution characteristics of gaseous and liquid water at the foot of Changbai Mountain in summer and autumn Qinhong SUN,Hongbo MA,Yanbin QI,Dongjia YU,Jialu FAN 2024, 40 (1):  47-53.  doi: 10.3969/j.issn.1673-503X.2024.01.006 Abstract ( 100 )   HTML ( 13 )   PDF (1784KB) ( 126 )   Save Utilizing the MWP967KV multi-channel microwave radiometer, ground-based rain gauge, and L-band sounding radar data from the China Meteorological Administration Jilin Cloud Physics Field Experiment Base during June to October from 2019 to 2020, the distribution of gaseous and liquid water in the atmosphere at the foot of Changbai Mountain in summer and autumn and its evolution characteristics before precipitation were analyzed. The results show that there is good correlation between the microwave radiometer retrieved data and sounding radar data, though the retrieved values are generally higher. The atmospheric precipitable water vapor (PWV) and liquid water path (LWP) exhibit the diurnal variation characteristic with the peak at night and the valley in the day. The peak appears between 01:00-03:00 during precipitation, while the valley appears around 11:00. The monthly average maximum values of PWV and LWP appear in August and September respectively, because of the influence of the topography and forest vegetation at Changbai Mountain. The distribution frequency of PWV shows a rising and then a falling trend before and during precipitation, whereas the frequency ratio of LWP in the range of 0.00~0.42 mm is the highest before precipitation. The stronger the precipitation intensity is, the more concentrated the frequency distribution of PWV and LWP is, with a greater likelihood of heavy precipitation for PWV greater than 45 mm and LWP greater than 4.20 mm.A surge in both LWP and PWV occurs within 1 h before precipitation starts, with a more pronounced increase in LWP, indicating that this characteristic can serve as a reference index for the analysis of precipitation approaching forecast and artificial rain enhancement operations. Figures and Tables | References | Related Articles | Metrics

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Analysis of the atmospheric circulation causes of drought during the water demand key period of soybean in Liaoning province based on the standardized precipitation index Fei LI,Shujie ZHANG,Chunyu ZHAO,Chunli HU,Rong LIN,Yihe FANG 2024, 40 (1):  54-62.  doi: 10.3969/j.issn.1673-503X.2024.01.007 Abstract ( 81 )   HTML ( 6 )   PDF (6091KB) ( 191 )   Save Using daily precipitation data from 54 meteorological stations and daily reanalysis data from the NCEP/NCAR (National Center for Atmospheric Research and National Centers for Environmental Prediction in the United States) in Liaoning province from 1971 to 2020, the Standardized Precipitation Index (SPI) for the water demand key period of soybeans (from flowering to pod-setting phase) was calculated for each station in Liaoning province. The typical drought years and the atmospheric circulation causes during the water demand key period of soybeans were analyzed. The results show that the different configuration of tropospheric circulation in high and low levels caused by the anomaly of subtropical westerly jet is the main cause of the atmospheric circulation in the dry years with different climatic characteristics during the key period of soybean in Liaoning province.When the position of westerly jet in the water demand key period of soybean is more northerly than usual, it is prone to high temperature and drought, and the main soybean producing areas in Liaoning province are affected greatly. The westerly jet is located to the north, and Liaoning province is located to the south of the upper jet axis and the center of the upper divergent wind field. The West Pacific subtropical high is anomalously northward in phase, which controls the whole Liaoning province. The main cause of high temperature and drought is the poor water vapor condition of the downdraft through the tropospheric wind field.Low temperature and drought are easy to occur when the westerly jet is located in the south during the water demand key period of soybean, and the central and northern parts of the main soybean producing areas in Liaoning province are more affected. The position of the westerly jet is southward, and the seasonal process is slow. The position of the Western Pacific subtropical high continues to be southward and west compared with the usual year. The vertical upward movement of the upper troposphere is obvious, and the cold air activity is frequent.However, the consistent subsidence movement in the middle and lower troposphere combined with poor water vapor conditions is not conducive to precipitation, resulting in the simultaneous occurrence of low temperature and drought. Figures and Tables | References | Related Articles | Metrics

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Evaluation of regional ecotourism suitability in He'nan province based on multi-source data Shan FENG,Xinwei WANG,Xiaochen ZHU 2024, 40 (1):  63-70.  doi: 10.3969/j.issn.1673-503X.2024.01.008 Abstract ( 119 )   HTML ( 3 )   PDF (3553KB) ( 251 )   Save Using MODIS remote sensing data products from 2001 to 2020 and climate data from He'nan province over the last 30 years (from 1991 to 2020), an ecological tourism suitability Index (ESI) considering vegetation coverage, ecological oxygen release, aerosol optical thickness, and holiday climate index was established based on the principal component analysis method. The ESI was then used to evaluate the ecological tourism suitability in He'nan province over the past 20 years. The results show that over the past 20 years, the vegetation coverage and ecological oxygen release in He'nan province have generally shown an increasing trend with change rates of 12.5% and 191 g·m-2 as well as relative change rates of 30.2% and 32.3%, respectively. The aerosol optical thickness and holiday climate index show an overall decreasing trend with change rates of -0.07 and -1.65, and relative change rates of -13.6% and -2.25%, respectively, indicating an overall improvement in the ecological environment of He'nan province. The ESI constructed using principal component analysis avoids the bias in results caused by different weight settings due to subjective methods, and is more objective and reliable. The evaluation results are generally consistent with the current distribution of ecological tourism areas in He'nan province and can objectively reflect the spatial differences in ecological tourism suitability within the region. The high-value areas of the ESI are concentrated in the Funiu Mountain area of the west and the Dabie Mountain area of the south, while the low-value areas are concentrated in the North China Plain area. The change rate of the ESI in 2020 relative to that in 2001 was 3%, indicating an improving trend in the ESI. Figures and Tables | References | Related Articles | Metrics

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Spatio-temporal variation characteristics of NDVI in the three northeast provinces and their responses to climatic factors Yong XIE,Shuang WANG,Hengyang WANG,Xu YANG,Fulong ZHANG,Ning WANG,Feng TAO 2024, 40 (1):  71-78.  doi: 10.3969/j.issn.1673-503X.2024.01.009 Abstract ( 117 )   HTML ( 4 )   PDF (4891KB) ( 187 )   Save The northeast region of China is one of the most sensitive areas responsing to global climate change. Understanding the spatio-temporal variation of vegetation and its response to climatic factors is of great significance for the construction and evaluation of the ecological environment in the three northeast provinces, and also plays an important indicative role in the response to global climate change. Based on the MODIS Normalized Difference Vegetation Index (NDVI), the spatio-temporal evolution characteristics and the future change trends of NDVI in the three northeast provinces from 2000 to 2021 were investigated using the methods of Theil-Sen slope estimation, Mann-Kendall test, and Hurst index, and the response of NDVI to climatic factors was estimated with correlation analysis. The results show that from 2000 to 2021, the annual growth rate of NDVI is 0.003 per year, whereas from 2010 to 2021, NDVI is a highly significant increasing trend, with an annual growth rate of 0.006 per year. NDVIs in 86.93% of the area in the three northeast provinces is projected to increase in the future, indicating a positive trend in vegetation growth. In addition, correlation analysis shows that NDVI depends on climatic factors at a spatial scale. Specifically, temperature shows a better correlation with NDVI. In the most areas of the three northeast provinces, both temperature and precipitation contribute positively to NDVI change, and their contributions are comparable though spatial differences exist. Figures and Tables | References | Related Articles | Metrics

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The impact of winter sea surface temperature change in the central eastern tropical Pacific on the number of heavy fog days in Guangxi Hao QIN,Fengqin ZHENG,Chongzhi SUN 2024, 40 (1):  79-87.  doi: 10.3969/j.issn.1673-503X.2024.01.010 Abstract ( 85 )   HTML ( 10 )   PDF (5817KB) ( 205 )   Save Using daily heavy fog data from 80 stations in Guangxi from 1979 to 2020, sea surface temperature data from the Hadley Centre, and NCEP/NCAR reanalysis data, and employing correlation analysis, composite analysis, and information flow causality theory, this study analyzed the impact of winter sea surface temperature change in the central eastern tropical Pacific on the number of heavy fog days in Guangxi. The results show that the winter sea surface temperature in the central eastern tropical Pacific is a significant source of influence on the number of fog days in Guangxi, with higher (lower) temperatures contributing to more (fewer) heavy fog events in winter. Higher sea surface temperature in the central eastern tropical Pacific causes abnormal rising motions aloft, weakening the Walker Circulation and leading to abnormal descending motions over the tropical western Pacific, resulting in locally negative heating anomalies, and in turn triggering anomalous anticyclones in the lower troposphere around the Philippines to the north of the tropical western Pacific. Under the influence of the southwest winds on the northwest side of the anomalous anticyclone over the Philippines, Guangxi experiences a dynamic reduction in near-surface northerly winter monsoon wind speed, favoring the formation and maintenance of heavy fog. Furthermore, this situation makes a significant anomalous anticyclonic moisture circulation from the South China Sea to the northwest Pacific maintained, facilitating the transportation of moisture from the South China Sea to southern China, which enhances the entire atmospheric column's moisture flux convergence over Guangxi, increases the absolute humidity in the lower troposphere, and generates gradually saturated the water vapor near the surface, and then enhances the stability of the near-surface layer, and provides favorable conditions for heavy fog formation, ultimately leads to an increase in foggy days. Conversely, lower winter sea surface temperatures in the central eastern tropical Pacific generally leads to the opposite situation i.e. fewer heavy fog events in Guangxi. Figures and Tables | References | Related Articles | Metrics

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Analysis of the catalytic operation conditions for ground silver iodide smoke generator in the Liupan mountain area Lei TIAN,Jianhua MU,Zhuolin CHANG,Hejiang ZUO,Ning CAO,Tong LIN 2024, 40 (1):  88-96.  doi: 10.3969/j.issn.1673-503X.2024.01.0011 Abstract ( 63 )   HTML ( 1 )   PDF (3886KB) ( 121 )   Save Based on 1 km×1 km vertical velocity data simulated by the numerical model from June 2009 to May 2010 in the Liupan Mountain area, meteorological data from 173 intensive weather stations in Ningxia and cloud height observation data, the conditions for catalytic operations of silver iodide smoke generator were studied. The results show that there are significant updrafts at heights of 2 km, 2.5 km, 3 km, and 3.5 km during precipitation processes in the Liupan mountain area. The effective diffusion height of the silver iodide catalyst released from ground-based smoke generator can reach 3000 m. From 6 h before the snowfall to 12 h after the snowfall, there are significant updrafts at the smoke generator locations, with the average updraft velocity exceeding 0.3 m·s-1 for more than 80% of the time. The suitability of conducting silver iodide smoke generator catalytic operations at different times of the year on the east and west sides and the summit of Liupan Mountain is presented by integrating the heights of cloud base and characteristics of the 0 ℃ layer and other layers. Figures and Tables | References | Related Articles | Metrics

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The construction of an evaluation index system for provincial-level summer resort tourism destinations Shanshan ZHAO,Dianxiu YE,Chan XIAO,Ying LI 2024, 40 (1):  97-104.  doi: 10.3969/j.issn.1673-503X.2024.01.0012 Abstract ( 156 )   HTML ( 8 )   PDF (1140KB) ( 217 )   Save Based on the connotation and characteristics of summer resort tourism destinations, this study constructs an index system for provincial-level summer resort tourism destinations from four dimensions, i.e. summer climate endowment, adverse climatic conditions, ecological environment, tourism foundation and development potential. Utilizing meteorological observation station data from southern regions of the Yellow River in China during the summer months (June to August) from 1991 to 2020, this index system was used to evaluate potential advantageous areas for developing summer resort tourism destinations in 14 provinces (regions, cities). Excellent summer climate endowment is the primary condition for summer resort destinations, incorporating elements such as temperature, wind, humidity, precipitation, human comfort, and vacation climate index. Low impact of adverse climatic conditions is a guarantee for the development of summer resort tourism, reflected by high-impact weather conditions impacting summer resorts such as high temperatures, heavy precipitation, strong winds, and severe convection. The ecological environment of summer resort destinations is represented by air quality, water quality, and vegetation status, while the foundation capacity and development potential of summer resort destinations are indicated by the richness of tourism resources, accessibility of transportation, local honors, and future planning. The results show that the threshold indicators of summer climate endowment and adverse climatic conditions of the 14 provinces (regions, cities) have spatial differences due to climatic systems and topography. The proportion of potential summer resort tourism sites to the total number of sites is 10.5%, which mainly distributed in areas of relatively high elevation within the provinces (regions, cities). In Jiangsu and Shandong, provinces where the elevations are generally low, the potential summer tourist destination is mainly in the coastal region of northeastern Jiangsu and eastern part of the Shandong Peninsula. The findings of this study can provide a scientific reference for objective evaluation and development strategies of summer resort tourism destinations at the provincial (regional, municipal) level. Figures and Tables | References | Related Articles | Metrics

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Analysis and prediction of driving factors for carbon emissions in typical cities of China based on remote sensing data and machine learning method Yuheng WU,Jingchang BAI 2024, 40 (1):  105-112.  doi: 10.3969/j.issn.1673-503X.2024.01.0013 Abstract ( 81 )   HTML ( 4 )   PDF (908KB) ( 220 )   Save Utilizing national statistical data and remote sensing nighttime light data, this study performs a contribution rate analysis of the influencing factors on carbon emissions in 15 typical cities through the Logarithmic Mean Divisia Index (LMDI), and constructs three sets of variables for predictive analysis using machine learning Ridge and Lasso regression models. The results indicate that seven factors including urban Gross Domestic Product (GDP), Energy Consumption (ES), Population (P), Real Estate Construction Area (RECA), Nighttime Light Intensity (NL), Cargo Transportation Volume (CT), and Passenger Transportation Volume (PT) play a promoting role in CO2 emissions, whereas Energy Consumption Structure (EI) and the Proportion of Tertiary Industry (TIR) have an inhibiting effect on CO2 emissions. The more mature a city, the richer the industry, the more diverse the impacting factors of carbon emissions. The correlation coefficient exceeds 0.8 between simulated results from predictive models of ridge and Lasso regression across variables set 1 to set 3 and the results from the test datasets. Among them, the result from set 1 is the best, followed by set 2, and finally, set 3. Figures and Tables | References | Related Articles | Metrics