Dramatic decline of observed atmospheric CO_(2) and CH_(4) during the COVID-19 lockdown over the Yangtze River Delta of China

The temporal variation of greenhouse gas concentrations in China during the COVID-19 lockdown in China is analyzed in this work using high resolution measurements of near surface ΔCO_(2),ΔCH_(4) andΔCO concentrations above the background conditions at Lin’an station(LAN),a regional background station in the Yangtze River Delta region.During the pre-lockdown observational period(IOP-1),bothΔCO_(2) andΔCH_(4) exhibited a significant increasing trend relative to the 2011-2019 climatological mean.The reduction ofΔCO_(2),ΔCH_(4) andΔCO during the lockdown observational period(IOP-2)(which also coincided with the Chinese New Year Holiday)reached up to 15.0 ppm,14.2 ppb and 146.8 ppb,respectively,and a reduction ofΔCO_(2)/ΔCO probably due to a dramatic reduction from industrial emissions.ΔCO_(2),ΔCH_(4) and ΔCO were observed to keep declining during the post-lockdown easing phase(IOP-3),which is the synthetic result of lower than normal CO_(2) emissions from rural regions around LAN coupled with strong uptake of the terrestrial ecosystem.Interestingly,the trend reversed to gradual increase for all species during the later easing phase(IOP-4),with ΔCO_(2)/ΔCO constantly increasing from IOP-2 to IOP-3 and finally IOP-4,consistent with recovery in industrial emissions associated with the staged resumption of economic activity.On average,ΔCO_(2) declined sharply throughout the days during IOP-2 but increased gradually throughout the days during IOP-4.The findings showcase the significant role of emission reduction in accounting for the dramatic changes in measured atmosphericΔCO_(2) and ΔCH_(4) associated with the COVID-19 lockdown and recovery.

Reconstruction of typhoons in the Yangtze River Delta during 1644-1949AD based on historical chorographies

The proxy records on typhoons in the Yangtze River Delta from 1644 to 1949AD were extracted from historical chorographies in the Qing Dynasty and the Republic of China Period. In reference to the basic principles for identifying historical typhoons, time series on the Yangtze River Delta over a period of 306 years were developed. The conclusions are as follows. （1） There were a total of 241 typhoons from 1644 to 1949AD. Using the historical chorographies from 1884 to 1949AD, the number of typhoons was 65, equal to 87.8% re- corded by meteorological observation. The number of years with differences in typhoon ac- tivities reconstructed using two ways no more than once is 55, reaching 83.3% in the period from 1884 to 1949AD. This result means the series of historical typhoons reconstructed using historical chorographies can represent the change of typhoon activities over years. （2） The average number of typhoon activities is 0.79 times per year from 1644 to 1949AD, and they show an increasing trend. These 306 years can be divided into three periods by the average number of typhoon activities： it is low from 1644 to 1784AD, and more typhoon activities are found from 1785 to 1904AD. It is worth noting that the number of typhoon activities reaches the summit in the last period, which is 1.2 times per year from 1905 to 1949AD. （3） Before the 20th century, the number of typhoon activities in warm periods is less than the number of cold periods. However, the number of typhoon activities increased dramatically in the early 20th century. Comparing the typhoon activities with El Nifio events, the data show that the number of typhoon activities did not increase when El Nifio occurred.

Changes of spring phenodates for the past 150 years over the Yangtze River Delta

Based on phenological records extracted from Chinese historical dairies, spring phenological series in the Yangtze River Delta （YRD） of China since 1834 is reconstructed. Together with temperature and phenological observation data, the indicating significance of spring phenological series to temperature changes is also analyzed. The results are shown as follows. （1） From 1834 to 1893, spring phenodate in the YRD was fluctuated and gradually delayed, but, advanced greatly at the end of the 19th century. From 1900 to 1990, although the decadal variations were found, no clear multi-decadal trend was detected. From 1990 to 2010, spring phenodate showed significantly advance again. Compared with the mean value for 1977-1996, the latest phenodate occurred in 1893 with 27 days delayed while the earliest phenodate occurred in 2007 with 17 days advanced. （2） The correlation coefficients between spring phenodates and temperatures from December to March and from January to March exceeded -0.75 and -0.80, respectively, indicating that our phenodate series well presents the long-term changes of winter and early spring （especially from January to March） tem- peratures. These results provide important basic data for the long-term integrated tempera- ture reconstruction over China in the future work.

Possible effect of climate changes on the coastal zone of the Yangtze River Delta

A coastal historical evolution of the Yangtze River Delta was discussed in this paper on the basis of the historical data of the coastal zone and an estimation was made for the future change of the coast The emphasis was put on the future climate change that will have influence on the sea wall, coastal navigation and freshwater resources in the Delta It was also pointed out that the global warming and precipitation increase in the Yangtze River Valley may exert more impact on the zone In addition, some measures describing how to adapt to the climate change and reduce its impact were put forward

Study on the City Form of the Yangtze River Delta Region

The Yangtze River Delta is a rapiddeveloping region in China. With fast economicgrowth, it is facing many environmental problems.This paper discusses the major problems and proposessome strategies for its future development.

区域卫生健康标准一体化建设现状与长三角的实践

以开展长三角区域卫生健康领域标准化研究为基础,调查和分析我国京津冀地区、粤港澳地区和长三角地区区域协同标准发展现状,标准化工作运行机制和管理模式。结合区域统一地方标准立项和研制实践,提出长三角区域卫生健康标准一体化机制建立的初步思考,为建立长三角区域卫生健康标准化合作模式、组织框架、工作任务等提供研究基础。

Evaluation of nine major satellite soil moisture products in a typical subtropical monsoon region with complex land surface characteristics

Assessing accuracies of satellite soil moisture(SM)products in areas with strong anthropogenic activities,abundant precipitation,and dense vegetation is important but limited.In this study,performances of nine satellite SM products,including the European Space Agency Climate Change Initiative(ESA CCI),and the ascending and descending products of the Advanced Microwave Scanning Radiometer 2(AMSR2),Chinese Fengyun-3B(FY3B),Chinese Fengyun-3C(FY3C),and Soil Moisture Active Passive(SMAP),were evaluated against in-situ SM in the Yangtze River Delta(YRD)from 2015 to 2018.Results showed that the ESA CCI outperformed other products,with averaged correlation coefficient(R)of 0.522,correlation coefficient for SM anomalies(Rano)of 0.419,and unbiased root mean square error(ubRMSE)of 0.040 m^(3)m^(-3),followed by the SMAP_A and SMAP_D.Overestimation was observed in the AMSR2 products(Bias>0.081 m^(3)m^(-3)),while underestimation was found in the FY3B and FY3C products(Bias<-0.104 m^(3)m^(-3)).Moreover,R values decreased with the increase in water area percentage(WAP),land cover heterogeneity(GSI),fractional vegetation cover(FVC),and precipitation(PRE).Threshold values were observed at 3%for the WAP,0.05 for the FVC,and 900 mm yr^(-1)for the PRE,below which sharp declines of accuracy were observed.The WAP,GSI,and FVC were divided into five sub-classes with their values increasing with the sub-class level(I to V).Correlations coefficients between these perturbing factors and R(correlation between satellite and in-situ SM)increased as sub-class levels increased.Under sub-classes I,II,and III,these three factors had limited influences on accuracies of satellite SM products.However,under sub-classes IV and V,significant impacts of these three perturbing factors were observed.Moreover,when sub-classes of the PRE increased from I to V,correlations between Bias and PRE decreased first and then increased.These findings can help to determine suitable satellite SM products in the YRD and similar areas.

基于B2B电商企业关联网络的长三角功能空间格局研究

With the increasing impact of globalization and informatization,the functional spatial pattern of the Yangtze River Delta,being reshaped by the new economy led by"Internet Plus,"is becoming more complicated.Hence,the study on the spatial pattern of e-commerce has much practical significance.Considering that B2 B e-commerce is a typical representative of the e-commerce economy currently in China,this paper analyzes the B2 B e-commerce enterprise network and explores whether the globalization and informatization processes have brought about a new spatial pattern in the Yangtze River Delta,to improve its spatial structure recognition.It is found that:(1)the status of Shanghai and Yiwu as two cores of the network has become prominent,while the status of Nanjing and Ningbo as traditional network centers has been weakened;(2)the regional axis has changed,with the Shanghai-Hangzhou-Yiwu axis rising and the traditional economic corridors such as the Shanghai-Nanjing axis and the Hangzhou-Ningbo axis being weakened;(3)the core area of the network connection has expanded,with the Jinhua-Yiwu region and the WenzhouTaizhou region becoming areas with close connections.

企业间关联:专利咨询业务在长三角城市的分布网络

Corporate-based networks have provided an important lens for the understanding of regional configuration,but the sole focus on intrafirm linkages limited the revealing of the whole picture of a region.In this regard,this study centers at the inter-firm linkages in the Yangtze River Delta,and employs the data concerning business interactions between patent consulting companies and their clients to supplement the analysis on the urban network in the region.The results show that the local administrative power represented by provincial government is still decisive in determining the economic relations among enterprises.Provincial capital cities including Nanjing,Hangzhou,and Hefei occupy the center positions of the regional network,while Shanghai,due to its lack of administrative hinterland,fails to show significant centralized functions.A comparative analysis on urban network from multiple perspectives shows that although the Yangtze River Delta region presents the characteristics of a flat spatial structure in certain fields,significant administrative constraints are still observed in the advanced producer service functions,demonstrating a distinctive feature of market division in the region.By employing new data,this study introduces a new lens for the research on urban network,and,to a certain extent,achieves a breakthrough in the existing theoretical framework of related research.