scholarly journals Spatial and temporal variations of the concentrations of PM<sub>10</sub>, PM<sub>2.5</sub> and PM<sub>1</sub> in China

2015 ◽  
Vol 15 (23) ◽  
pp. 13585-13598 ◽  
Author(s):  
Y. Q. Wang ◽  
X. Y. Zhang ◽  
J. Y. Sun ◽  
X. C. Zhang ◽  
H. Z. Che ◽  
...  
Keyword(s):  
Northeast China ◽  
Southern China ◽  
Northern China ◽  
Temporal Variations ◽  
Substantial Contribution ◽  
Short Term ◽  
Leading Role ◽  
Variation Patterns ◽  
Increasing Trend

Abstract. Concentrations of PM10, PM2.5 and PM1 were monitored at 24 CAWNET (China Atmosphere Watch Network) stations from 2006 to 2014. The highest particulate matter (PM) concentrations were observed at the stations of Xian, Zhengzhou and Gucheng, on the Guanzhong Plain and the Huabei Plain (HBP). The second highest PM concentrations were observed in northeast China, followed by southern China. According to the latest air quality standards of China, 14 stations reached the PM10 standard, and only 7 stations, mainly rural and remote stations, reached the PM2.5 standard. The ratios of PM2.5 to PM10 showed a clear increasing trend from northern to southern China, because of the substantial contribution of coarse mineral aerosol in northern China. The ratios of PM1 to PM2.5 were higher than 80 % at most stations. PM concentrations tended to be highest in winter and lowest in summer at most stations, and mineral dust influenced the results in spring. A decreasing interannual trend was observed on the HBP and in southern China for the period 2006 to 2014, but an increasing trend occurred at some stations in northeast China. Bimodal and unimodal diurnal variation patterns were identified at urban stations. Both emissions and meteorological variations dominate the long-term PM concentration trend, while meteorological factors play a leading role in the short term.

scholarly journals Spatial and temporal variations of the concentrations of PM<sub>10</sub>, PM<sub>2.5</sub> and PM<sub>1</sub> in China

2015 ◽  
Vol 15 (11) ◽  
pp. 15319-15354 ◽  
Author(s):  
Y. Q. Wang ◽  
X. Y. Zhang ◽  
J. Y. Sun ◽  
X. C. Zhang ◽  
H. Z. Che ◽  
...  
Keyword(s):  
Northeast China ◽  
Meteorological Factors ◽  
Southern China ◽  
Northern China ◽  
Temporal Variations ◽  
Diurnal Variations ◽  
Substantial Contribution ◽  
Rural And Remote ◽  
Increasing Trend ◽  
Pm2.5 And Pm10

Abstract. Concentrations of PM10, PM2.5 and PM1 were monitored at 24 stations of CAWNET (China Atmosphere Watch Network) from 2006 to 2014 using GRIMM 180 dust monitors. The highest particulate matter (PM) concentrations were observed at the stations of Xian, Zhengzhou and Gucheng, in Guanzhong and the Hua Bei Plain (HBP). The second highest PM concentrations were observed in northeast China, followed by southern China. According to the latest air quality standards of China, 14 stations reached the PM10 standard and only 7 stations, mainly rural and remote stations, reached the PM2.5 standard. The PM2.5 and PM10 ratios showed a clear increasing trend from northern to southern China, because of the substantial contribution of coarse mineral aerosol in northern China. The PM1 and PM2.5 ratios were higher than 80% at most stations. PM concentrations tended to be highest in winter and lowest in summer at most stations, and mineral dust impacts influenced the results in spring. A decreasing interannual trend was observed in the HBP and southern China from 2006 to 2014, but an increasing trend occurred at some stations in northeast China. Also diurnal variations of PM concentrations and meteorological factors effects were investigated.

Spatial variation of East Asian winter monsoon evolution between northern and southern China since the last glacial maximum

2021 ◽  
pp. 1-14
Author(s):  
Qin Li ◽  
Haibin Wu ◽  
Jun Cheng ◽  
Shuya Zhu ◽  
Chunxia Zhang ◽  
...  
Keyword(s):  
East Asian Winter Monsoon ◽  
Southern China ◽  
Ice Sheets ◽  
Northern China ◽  
Winter Monsoon ◽  
Asian Winter Monsoon ◽  
Spatial Differences ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract The East Asian winter monsoon (EAWM) is one of the most dynamic components of the global climate system. Although poorly understood, knowledge of long-term spatial differences in EAWM variability during the glacial–interglacial cycles is important for understanding the dynamic processes of the EAWM. We reconstructed the spatiotemporal characteristics of the EAWM since the last glacial maximum (LGM) using a comparison of proxy records and long-term transient simulations. A loess grain-size record from northern China (a sensitive EAWM proxy) and the sea surface temperature gradient of an EAWM index in sediments of the southern South China Sea were compared. The data–model comparison indicates pronounced spatial differences in EAWM evolution, with a weakened EAWM since the LGM in northern China but a strengthened EAWM from the LGM to the early Holocene, followed by a weakening trend, in southern China. The model results suggest that variations in the EAWM in northern China were driven mainly by changes in atmospheric carbon dioxide (CO2) concentration and Northern Hemisphere ice sheets, whereas orbital insolation and ice sheets were important drivers in southern China. We propose that the relative importance of insolation, ice sheets, and atmospheric CO2 for EAWM evolution varied spatially within East Asia.

Structural Characteristics and Stability of the Aggregates in the Orchard Soils with Different Cultivation Years in Northern China

2013 ◽  
Vol 864-867 ◽  
pp. 2569-2576
Author(s):  
Wen Li Liu ◽  
Jing Gui Wu ◽  
Xin Yu Zhao
Keyword(s):  
Fractal Dimension ◽  
Structural Characteristics ◽  
Northern China ◽  
Soil Bulk Density ◽  
Annual Growth ◽  
Annual Average ◽  
Average Decrease ◽  
Increasing Trend ◽  
Orchard Soils

With dry sieving and wet sieving methods, we studied the distribution characteristics and stability of the aggregates in the typical orchard soils with different cultivation years in northern China under long-term freezing-thawing conditions. The results show that: the contents of the aggregates with particle size above 10 mm or between 0.25 and 10 mm are significantly increased with cultivation years and annual growth rates were respectively 1.28% and 0.078%. Fractal dimension in the orchard soils was gradually decreased and lower than that in uncultivated area near the orchard in corresponding cultivation year. MWD of orchard soils shows annual increasing trend of 0.76%. The content of the water stable macro aggregates in orchard soils was increased with the cultivation years and was about 11.65%-20.18% higher than that of uncultivated soils near the orchard. Average annual growth of orchard soils was 0.37%. Fractal dimension was decreased year by year on the water stable macro aggregates. MWD of the water stable macro aggregates was significantly greater than that of uncultivated soils near the orchard and increased with cultivation years. Aggregate destruction rate was gradually decreased to 31.61% of that in the 60th year and annual average decrease rate was 0.91%. Soil bulk density was gradually decreased.

Dynamic Modeling of Stock Market Interdependencies: An Empirical Investigation of Australia and the Asian NICs

2001 ◽  
Vol 04 (02) ◽  
pp. 235-264 ◽  
Author(s):  
Abul M. M. Masih ◽  
Rumi Masih
Keyword(s):  
Hong Kong ◽  
Stock Prices ◽  
Stock Markets ◽  
The Other ◽  
Substantial Contribution ◽  
Exogenous Shocks ◽  
Leading Role ◽  
Equilibrium Relationship ◽  
Short Run

This article examines the patterns of dynamic linkages among national stock prices of Australia and four Asian NIC stock markets namely, Taiwan, South Korea, Singapore and Hong Kong. By employing recently developed time-series techniques results seem to consistently suggest the relatively leading role of the Hong Kong market in driving fluctuations in the Australian and other NIC stock markets. In other words, given the generality of the techniques employed, Hong Kong showed up consistently as the initial receptor of exogenous shocks to the (long-term) equilibrium relationship whereas the Australian and the other NIC markets, particularly the Singaporean and Taiwanese markets had to bear most of the brunt of the burden of short-run adjustment to re-establish the long term equilibrium. Furthermore, given the dominance of the Hong Kong market in the region, the study also brings to light the substantial contribution of the Australian market in explaining the fluctuations to the other three markets, particularly Singapore and Taiwan. Finally, in comparison to all other NIC markets, Taiwan and Singapore appear as the most endogenous, with the former providing significant evidence of its short-term vulnerability to shocks from the more established market such as Australia.

Mesospheric water vapor and D/H ratio at the Venus terminator from SOIR/VEx

2020 ◽  
Author(s):  
Arnaud Mahieux ◽  
Ann Carine Vandaele ◽  
Sarah Chamberlain ◽  
Valérie Wilquet ◽  
Séverine Robert ◽  
...  
Keyword(s):  
Water Vapor ◽  
Full Range ◽  
Lower Thermosphere ◽  
Temporal Variations ◽  
Mixing Ratio ◽  
Short Term ◽  
Data Set ◽  
Solar Occultation ◽  
Venus Express

&lt;p&gt;The Solar Occultation in the InfraRed (SOIR) instrument onboard Venus Express sounded the Venus mesosphere and lower thermosphere at the terminator using solar occultation technique between April 2006 and December 2014.&lt;/p&gt;&lt;p&gt;We report on the water vapor vertical distribution above the clouds and geo-temporal variations, observed during the full Venus Express mission. Water vapor profiles are sampled between 80 and 120 km, and calculations of the water vapor volume mixing ratio agrees with those from previous studies. Short term variations over several Earth days dominate the data set, with densities varying by up to a factor 19 over a 24 hr period. Similarly to what was found for other trace gases detected with the SOIR instrument, such as HCl, HF and SO&lt;sub&gt;2&lt;/sub&gt;, no significant spatial or long term trends are observed.&lt;/p&gt;&lt;p&gt;287 water vapor vertical profiles obtained at the Venus terminator between 80 km and 120 km from August 2006 and September 2014 were analyzed for temporal and spatial abundance variations. Standard deviations are significantly smaller than the full range of volume mixing ratio values at all altitudes indicating that the variations are real.&lt;/p&gt;&lt;p&gt;The decrease in volume mixing ratio abundance below 100&amp;#160;km appears to be a common feature of most water vapor volume mixing ratio profiles and agrees with the decrease in water vapor reported in previous studies. Based on a very limited number of spectra, the variability of the water vapor VMR was found to be higher in the lower than in the upper mesosphere of Venus; this is in agreement with our observations as the standard deviation of the SOIR mean profile is the smallest at 100 km and increases with decreasing altitude.&lt;/p&gt;&lt;p&gt;No significant spatial variations or long term temporal variations are observed in the present data set in which short term variability masks all other possible trends. Our observations agree that short term (between 1 and 10 Earth days) variability is dominant.&lt;/p&gt;&lt;p&gt;We also report on simultaneous observations of the water first isotopologue HDO made by SOIR, which occurred 194 times during the whole VEx mission. Similarly to water vapor, we observe a large variation of HDO with time and space, without any clear time of spatial dependency.&lt;/p&gt;&lt;p&gt;We report on the ratio of the simultaneously measured HDO and H&lt;sub&gt;2&lt;/sub&gt;O profiles, that show a constant ratio of 0.1 &amp;#177; 0.1 below 100&amp;#160;km, and increase exponentially at higher altitude to reach a value of 1 &amp;#177; 0.4 at 120&amp;#160;km of altitude. The results are in agreement with previous works below 100&amp;#160;km.&lt;/p&gt;

scholarly journals Meteorological Detrending of Ozone at Three Sites in the Dallas-Fort Worth Area: Application of KZ Filter Method

Atmosphere ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 1226
Author(s):  
Poojan Upadhaya ◽  
Hongbo Du ◽  
Raghava R. Kommalapati
Keyword(s):  
Regression Analysis ◽  
Solar Radiation ◽  
Total Variation ◽  
Fort Worth ◽  
Short Term ◽  
Temporal Separation ◽  
Daily Average ◽  
Kz Filter ◽  
Increasing Trend

The Dallas-Fort Worth (DFW) area that experiences high temperature and intense solar radiation falls into the moderate nonattainment classification. The variation in meteorological parameters plays an important role in ambient ozone levels variation. Meteorological influences need to be decoupled from ozone data for long-term trend analysis. Temporal separation of maximum daily average 8-h ozone (MDA8 ozone), maximum daily temperature (TMAX), daily average solar radiation (DASR), and daily average wind speed (DAWS) were conducted using Kolmogorov-Zurbenko (KZ) filter for ozone records at Keller (C17), Arlington (C61), Red Bird (C402) monitoring stations in the DFW area from 2003 to 2017. Temporal separation, regression analysis, and meteorological detrending were performed. The long-term component had a clear and stable trend. The contribution of the long-term component to total variation was negligible, which is less than 2%. This is due to the removal of the data noise from the original time series data. The seasonal component had a major contribution (55% to 72%) in the total variation of the maximum temperature and solar radiation. However, the short-term component was dominant in the total variation of the MDA8 ozone (41–54%) and wind speed (68–79%). Regression analysis showed the baseline component bears the highest correlation than the short-term and raw. Solar radiation had the highest correlation to the MDA8 ozone, followed by temperature data in all three stations. Meteorological detrending showed the detrended long-term ozone had an increasing trend. The increasing trend was significant at C402 with a trend of 0.19 ± 0.006 ppb/y (0.398 R2), whereas slight increasing trends were found at C17 (0.072 ± 0.006 (0.107 R2)) and at C61 (0.019 ± 0.007 (0.005 R2)). The increasing trend of long-term components of MDA8 ozone was justified by the increasing level of NOx and VOCs from the mobile sources in the DFW area.

scholarly journals Temporal variations in COVID-19: an epidemiological discussion with a practical application

2021 ◽  
Vol 49 (8) ◽  
pp. 030006052110332
Author(s):  
Mahnaz Derakhshan ◽  
Hamid Reza Ansarian ◽  
Mory Ghomshei
Keyword(s):  
Time Series ◽  
Community Dynamics ◽  
Control Strategies ◽  
Case Fatality ◽  
Temporal Variations ◽  
Host Community ◽  
Short Term ◽  
Weekly Cycles ◽  
And Control

Objective We aimed to characterize the temporal variation in coronavirus disease 2019 (COVID-19) infection and mortality as a possible tool to monitor and control the spread of this disease. Methods We analyzed cyclicity and synchronicity in cases of COVID-19 infection and time series of deaths using Fourier transform, its inverse method, and statistical treatments. Epidemiological indices (e.g., case fatality rate) were used to quantify the observations in the time series. The possible causes of short-term variations are reviewed. Results We observed that were both short-term and long-term variations in the COVID-19 time series. The short cycles were 7 days and synchronized among all countries. This periodicity is believed to be caused by weekly cycles in community social factors, combined with diagnostic and reporting cycles. This could also be related to virus–host–community dynamics. Conclusion The observed synchronized weekly cycles could serve as herd defense by providing a form of social distancing in time. The effect of such temporal distancing could be enhanced if combined with spatial distancing. Integrated spatiotemporal distancing is therefore recommended to optimize infection control strategies, taking into account the quiescent and active intervals of COVID-19.

scholarly journals Cooperation as a Foreign Policy Instrument

2019 ◽  
Vol 1 (2) ◽  
pp. 67
Author(s):  
Rodrigo Contreras
Keyword(s):  
Foreign Policy ◽  
International Cooperation ◽  
Policy Instrument ◽  
Evaluation Methodology ◽  
Small Scale ◽  
The South ◽  
Short Term ◽  
Leading Role ◽  
Bilateral Relations

Cooperation is undoubtedly a great tool to deploy Chilean foreign policy, since it creates long-term ties with the beneficiary countries. This generates small-scale retributions in bilateral relations and in specific technical areas, as well at the multilateral level. Chile's cooperation flows have undergone important changes since the creation of the International Cooperation Agency in the 90s, to the present, since Chile has gone from being a net recipient, to being a participant in international cooperation through the South-South modality or horizontal. In spite of this, it is not possible to clearly establish the benefits that cooperation generates for the country because there is no clear evaluation methodology. Finally, Chilean cooperation does not have a priority budget, and its programs are affected by short-term issues in the absence of a more leading role in the formulation of Chilean foreign policy.

scholarly journals Long-term measurements of ground-level ozone in Windsor, Canada – Part I. temporal variations and trends

2018 ◽  
Author(s):  
Xiaohong Xu ◽  
Tianchu Zhang ◽  
Yushan Su
Keyword(s):  
Ground Level ◽  
Temporal Variations ◽  
Control Measures ◽  
Ground Level Ozone ◽  
Ozone Formation Potential ◽  
Volatile Organic ◽  
Increasing Trend ◽  
Annual Means ◽  
Collaborative Efforts

Abstract. This study investigates temporal variations and long-term (1996–2015) trends of ground-level O3 (ozone) and its precursors, NOx (nitrogen oxides) and volatile organic compounds in Windsor, Ontario, Canada. During the 20-year study period, NOx, non-methane hydrocarbon concentrations and ozone formation potential decreased significantly by 58 %, 61 %, and 73 %, respectively, while O3 concentrations increased by 33 % (20.3 ppb in 1996 vs. 27 ppb in 2015). Our analysis revealed that the increased annual O3 concentrations in Windsor were due to (1) decreased O3 titration (by 50 % between 1996 and 2015) owing to declining nitric oxide concentrations, which is suggested by a slightly decreasing trend of annual mean total O3 concentrations after the titration effect is removed, (2) reduced local photochemical production of O3, because of dwindling precursor emissions, and (3) increased background O3 level that has more impact on the low-to-median concentrations. The net effect of those factors is decreasing peak O3 levels during the smog season from May to September, but an overall increasing trend of annual means. These results indicate that the emission control measures are effective in reducing peak ozone concentrations. However, challenges in lowering annual O3 levels call for long-term collaborative efforts in the region and around the globe.

scholarly journals Analysis of Spatiotemporal Groundwater-Storage Variations in China from GRACE

Water ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2378
Author(s):  
Fangfang Liu ◽  
Ping Kang ◽  
Haitao Zhu ◽  
Jiafu Han ◽  
Yaohuan Huang
Keyword(s):  
Southern China ◽  
Northern China ◽  
Northwest China ◽  
Tibet Plateau ◽  
Groundwater Depletion ◽  
Positive Trend ◽  
Groundwater Storage ◽  
Increasing Trend ◽  
Groundwater Consumption ◽  
National Perspective

In China, where some regions are over-reliant on groundwater, groundwater consumption is faster than replenishment, which results in a continuous decrease in the groundwater level. Here, we applied spatial and temporal methods to analyze the spatiotemporal variations in groundwater in China from GRACE, GRACE-FO, and GLDAS data. From a national perspective, groundwater storage showed a decreasing trend in northern China and an increasing trend in southern China. The results showed that the rates of groundwater depletion in North China, the Loess Plateau, and Northwest China were −10.09 ± 0.94, −10.05 ± 1.05, and –4.91 ± 0.28 mm y−1 equivalent height of water from 2003 to 2019, respectively. Furthermore, the groundwater in South China, the middle-lower Yangtze River, and the Ch-Yu region had a positive trend, with rates of 7.26 ± 1.51, 7.73 ± 1.35, and 3.61 ± 0.53 mm y−1 equivalent height of water, respectively. We also found that groundwater storage fluctuated slightly before 2016 on the Qinhai-Tibet Plateau and in Northeast China and decreased significantly after 2016. The Yun-Gui Plateau had a fluctuating trend. Investigating the spatiotemporal variation in groundwater storage in China can provide data for initiating regional ecological and environmental protection.

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