Are precipitation anomalies associated with aerosol variations over Eastern China?

Abstract. In Eastern China (EC), strong anthropogenic emissions deteriorate the atmospheric environment harbored by the upstream Tibetan and Loess Plateaus, building a south-north zonal distribution of high anthropogenic aerosols. This research analyzed the interannual variability of precipitations with different intensities in the EC region from 1961 to 2010. We found that the frequency of light rain significantly decreased and the occurrence of rainstorm, especially the extraordinary rainstorm significantly increased over the recent decades. The extreme precipitation events presented the same interannual variability pattern with the frequent haze events. Moreover, the extreme rainfall events of various intensities showed a regular interannual variability trend. During the 1980s, the regional precipitation trends in EC showed an obvious "transform" from more light rain to more extreme rainstorms. The running correlation analysis of interdecadal variation further verified that the correlation between the increasing aerosol emissions and the frequency of abnormal precipitation events tended to be more significant in the EC. The correlation between atmospheric visibility and low cloud amounts, which are both closely related with aerosol concentrations, had a spatial distribution of "northern positive and southern negative" pattern, and the spatial distribution of the frequency variability of regional rainstorms was "southern positive and northern negative". After the 1990s, the visibility in summer season deteriorated more remarkably than other seasons, and the light rain frequency decreased obviously while the rainstorm and extraordinary heavy rainfall occurred more frequently. There were significant differences in the interdecadal variation trends in light rain and rainstorm events between the high aerosol concentration areas in the EC and the relatively "clean area" in western China. The aircraft measurements over the EC confirmed that the diameters of cloud droplets decreased under high aerosol concentration condition, thereby inhibiting weak precipitation process.

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Are precipitation anomalies associated with aerosol variations over eastern China?

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-8011-2017 ◽

2017 ◽

Vol 17 (12) ◽

pp. 8011-8019 ◽

Cited By ~ 14

Author(s):

Xiangde Xu ◽

Xueliang Guo ◽

Tianliang Zhao ◽

Xingqin An ◽

Yang Zhao ◽

...

Keyword(s):

Interannual Variability ◽

Eastern China ◽

Interdecadal Variation ◽

Atmospheric Environment ◽

Precipitation Process ◽

The South ◽

Light Rain ◽

The North ◽

Extreme Precipitation Events ◽

Precipitation Events

Abstract. In eastern China (EC), the strong anthropogenic emissions deteriorate the atmospheric environment, building a south–north zonal distribution of high aerosols harbored by the upstream Tibetan and Loess plateaus in China. This study climatologically analyzed the interannual variability in precipitation with different intensities in association with aerosol variations over the EC region from 1961 to 2010 by using precipitation and visibility data from more than 50 years and aircraft and surface aerosol data from recent years in China, and the impacts of aerosol variations on interannual variability in the intensity of precipitation events and their physical causes are investigated. We found that the frequency of light rain has significantly decreased and the occurrence of rainstorms, especially severe rainstorms, has significantly increased over recent decades. The extreme precipitation events presented an interannual variability pattern similar to that of the frequent haze events over EC. Accompanied by the frequent haze events in EC, light rain frequency significantly decreased and extremely heavy precipitation events have occurred more frequently. During the 1980s, the regional precipitation trends in EC showed an obvious transform from more light rain to more extreme rainstorms. The running correlation analysis of interdecadal variation further verified that the correlation between the increasing aerosols and frequencies of abnormal precipitation events tended to be more significant in EC. The correlation between atmospheric visibility and low cloud amounts, which are both closely related to aerosol concentrations, was positive in the north and negative in the south, and the spatial distribution of the variability in regional rainstorm frequency was positive in the south and negative in the north. After the 1990s, the visibility in summer season deteriorated more remarkably, light rain frequency decreased noticeably, and rainstorms and extraordinarily heavy rainfall occurred more frequently. There were significant differences in the interdecadal variation trends in light rain and rainstorm events between the highly aerosol-polluted area in EC and the relatively clean area on the western plateaus of China. The aircraft measurements over EC confirmed that the diameters of cloud droplets decreased under high aerosol concentration conditions, thereby inhibiting weak precipitation process.

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Recognizing the Aggregation Characteristics of Extreme Precipitation Events Using Spatio-Temporal Scanning and the Local Spatial Autocorrelation Model

Atmosphere ◽

10.3390/atmos12020218 ◽

2021 ◽

Vol 12 (2) ◽

pp. 218

Author(s):

Changjun Wan ◽

Changxiu Cheng ◽

Sijing Ye ◽

Shi Shen ◽

Ting Zhang

Keyword(s):

Spatial Autocorrelation ◽

Extreme Precipitation ◽

Eastern China ◽

Temporal Aggregation ◽

Global Changes ◽

Percentile Method ◽

Extreme Precipitation Events ◽

Spatio Temporal ◽

Precipitation Events ◽

Local Spatial Autocorrelation

Precipitation is an essential climate variable in the hydrologic cycle. Its abnormal change would have a serious impact on the social economy, ecological development and life safety. In recent decades, many studies about extreme precipitation have been performed on spatio-temporal variation patterns under global changes; little research has been conducted on the regionality and persistence, which tend to be more destructive. This study defines extreme precipitation events by percentile method, then applies the spatio-temporal scanning model (STSM) and the local spatial autocorrelation model (LSAM) to explore the spatio-temporal aggregation characteristics of extreme precipitation, taking China in July as a case. The study result showed that the STSM with the LSAM can effectively detect the spatio-temporal accumulation areas. The extreme precipitation events of China in July 2016 have a significant spatio-temporal aggregation characteristic. From the spatial perspective, China’s summer extreme precipitation spatio-temporal clusters are mainly distributed in eastern China and northern China, such as Dongting Lake plain, the Circum-Bohai Sea region, Gansu, and Xinjiang. From the temporal perspective, the spatio-temporal clusters of extreme precipitation are mainly distributed in July, and its occurrence was delayed with an increase in latitude, except for in Xinjiang, where extreme precipitation events often take place earlier and persist longer.

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Interannual variability of Tropical Atlantic and its influence on extreme precipitation events: Focus on the Amazon Basin

10.11606/d.14.2020.tde-27072020-135440 ◽

2020 ◽

Author(s):

Katherine Lisbeth Ccoica López

Keyword(s):

Interannual Variability ◽

Extreme Precipitation ◽

Amazon Basin ◽

Tropical Atlantic ◽

Extreme Precipitation Events ◽

Precipitation Events

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Internal Coordinated Development of China's Urbanization and its Spatiotemporal Evolution

Sustainability ◽

10.3390/su11030626 ◽

2019 ◽

Vol 11 (3) ◽

pp. 626 ◽

Cited By ~ 5

Author(s):

Liangzhen Zang ◽

Yiqing Su

Keyword(s):

Growth Rate ◽

Spatial Distribution ◽

Eastern China ◽

River Delta ◽

Spatial Data Analysis ◽

Western China ◽

Spatiotemporal Evolution ◽

Coordinated Development ◽

Urbanization Development ◽

Coordination Degree

High urbanization quality, predominantly determined by the degree of internal coordinated development, is the most important factor in promoting urbanization development. Based on the panel data of 283 Chinese cities from 2007 to 2016, this paper analysed the internal coordination degree, spatial distribution and spatiotemporal evolution of urbanization using the methods of range standardization, entropy, and coupling and coordination models, as well as exploratory spatial data analysis. We found the following results: (1) The internal coordination degree of China’s urbanization was at a low level for a long time, but it presented a gradually increasing trend; (2) The internal coordinated development of urbanization exhibited an obvious spatial agglomeration. Specifically, it displayed a stepped pattern with a higher internal coordination degree in eastern China, a lower degree in western China, and a spatial distribution with multi-centre agglomeration and diffusion. (3) The spatial distribution of the internal coordinated development of urbanization was stable in most regions of China, only changing in a few. (4) The growth rate of the internal coordination degree of China’s urbanization presented the pattern of a dotted distribution, while the growth rate in western China was higher than in central and eastern China. The spatiotemporal evolution relates to the policies changes of China’s urbanization. In particular, the urbanization in China transfers its focus from population transfer to the development of quality from 2007 to 2016. To promote the sustainable and healthy development of China's new urbanization, Beijing-Tianjin-Hebei Region, Yangtze River Delta and Pearl River Delta shall focus on accelerating the transformation of economic development mode; The provinces located around the above three regions shall strengthen the upgrading and promotion of basic public services. The northeast and central provinces shall speed up the innovation of systems and mechanisms and gradually release the potential of urbanization development by promoting the mobility of urban population, and the vast majority of provinces in Western China shall further improve the spatial development potential for urbanization.

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Spatial controls of microbial pesticide degradation in soils – A model-based scenario analysis

10.5194/egusphere-egu21-15697 ◽

2021 ◽

Author(s):

Erik Schwarz ◽

Swamini Khurana ◽

Luciana Chavez Rodriguez ◽

Johannes Wirsching ◽

Christian Poll ◽

...

Keyword(s):

Spatial Distribution ◽

Scenario Analysis ◽

Soil Column ◽

Heavy Rain ◽

Spatial Aggregation ◽

Pesticide Degradation ◽

Natural Soils ◽

Light Rain ◽

Rain Events ◽

Precipitation Events

Despite all legislative efforts, pesticides persist in soils at low concentrations and are leached to groundwater. This environmental issue has previously been associated with control factors relevant in natural soils but elusive in lab experiments and standard modeling approaches. One such factor is the small-scale spatial distribution of pesticide-degrading microorganisms in soil. Microbes are distributed heterogeneously in natural soils. They are aggregated in biogeochemical &#8220;hotspots&#8221; at the centimeter scale. The aim of our study is to investigate the relevance of such aggregation for pesticide degradation. For this, we upscaled the effect of the heterogeneity-induced accessibility limitations to degradation to the soil-column scale and analyzed kinetic constraints and amplifying factors under contrasting unsaturated flow regimes.We performed a 2D spatially explicit, site-specific model-based scenario analysis for bioreactive transport of the model pesticide 4-chloro-2-methylphenoxyacetic acid (MCPA) in an arable soil (Luvisol). Stochastic centimeter-scale spatial distributions of microbial degraders were simulated with a spatial statistical model (log Gaussian Cox process), parametrized to meet experimentally observed spatial distribution metrics. Three heterogeneity levels were considered, representing homogenized soil conditions, and the lower and upper limit of expected microbial spatial aggregation in natural soils. Additionally, two contrasting precipitation scenarios (continuous light rain vs. heavy rain events directly following MCPA application) were assessed. A reactive transport model was set up to simulate a 0.3 m x 0.9 m soil column based on hydraulic and bioreactive measurements from a soil monitoring station (Germany, SM#3/ DFG CRC 1253 CAMPOS).Our simulations revealed that heavy precipitation events were the main driver of pesticide leaching. Leached amounts from the topsoil increased by two to five orders of magnitude compared to the light rain scenario and at max. ca. 20 ng was leached from 90 cm after one year. With the increasing spatial aggregation of microbial degraders, upscaled pesticide degradation rates decreased, and considerable differences emerged between homogeneous and highly aggregated scenarios. In the latter, leaching from the plow layer into the subsoil was more pronounced and MCPA was detectable (LOD = 4 &#181;g/kg) 5-6 times longer. In heterogeneous scenarios, degradation in microbial hotspots was mainly diffusion-limited during &#8220;hot moments&#8221; (times of high substrate availability), with a fraction of MCPA simultaneously &#8220;locked in&#8221; in coldspots with low microbial abundance. During intense precipitation events MCPA was remobilised from these coldspots by advective-dispersive transport, thereby increasing pesticide accessibility.Our results indicate that predicted environmental concentrations and detectability of pesticides might be underestimated if spatial heterogeneity of microbial degraders is neglected, and they highlight the importance of heavy rain events as drivers of leaching and substrate accessibility.

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Spatial Distribution and Temporal Change of Extreme Precipitation Events on the Koshi Basin of Nepal

Journal on Geoinformatics, Nepal ◽

10.3126/njg.v17i1.23007 ◽

2018 ◽

Vol 17 (1) ◽

pp. 38-46

Author(s):

Sanjeevan Shrestha ◽

Tina Baidar

Keyword(s):

Adverse Effect ◽

Spatial Distribution ◽

Extreme Events ◽

Extreme Precipitation ◽

Temporal Change ◽

Extreme Weather Events ◽

Extreme Precipitation Events ◽

Increasing Trend ◽

Koshi Basin ◽

Precipitation Events

Climate change, particularly at South Asia region is having a huge impact on precipitation patterns, its intensity and extremeness. Mountainous area is much sensitive to these extreme events, hence having adverse effect on environment as well as people in term of fluctuation in water supply as well as frequent extreme weather events such as flood, landslide etc. So, prediction of extreme precipitation is imperative for proper management. The objective of this study was to assess the spatial distribution and temporal change of extreme precipitation events on Koshi basin of Nepal during 1980-2010. Five indicators (R1day, R5 day, R > 25.4 mm, SDII and CDD) were chosen for 41 meteorological stations to test the extreme events. Inverse distance weighting and kriging interpolation technique was used to interpolate the spatial patterns. Result showed that most extreme precipitation events increased up to mountain regions from low river valley; and then it decreased subsequently up to Himalayan regions (south to north direction). However, there is high value of indices for lowland Terai valley also. Most of the indices have hotspot with higher value at north western and southern part of the study area. For temporal change, most of the extreme precipitation indices showed increasing trend within 30 years’ period. The spatial distribution of temporal change in indices suggests that there is increasing trend in lowland area and decreasing trend in mountainous and Himalayan area. So, adaptive measure should be adopted through proper land use planning, especially at those hotspot areas and their tributaries; to reduce adverse effect of extreme precipitation events.

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Performance evaluation of ensemble precipitation forecasts and satellite products for the spring 2019 severe floods in Iran

10.5194/egusphere-egu21-9089 ◽

2021 ◽

Author(s):

Saleh Aminyavari ◽

Bahram Saghafian ◽

Ehsan Sharifi

Keyword(s):

Spatial Distribution ◽

Weather Prediction ◽

Precipitation Amount ◽

Warning System ◽

Extreme Precipitation Events ◽

Spatial Coverage ◽

Precipitation Estimates ◽

Precipitation Threshold ◽

Precipitation Thresholds ◽

Precipitation Events

In this study, the performance of ensemble precipitation forecasts of three numerical weather prediction (NWP) models within the TIGGE database as well as the integrated multi-satellite retrievals for global precipitation measurement (GPM), namely IMERG-RT V05B, for precipitation estimates were evaluated in recent severe floods in Iran over the March&#8211;April 2019 period. The evaluations were conducted in two modes: spatial distribution of precipitation and the dichotomous evaluation in four precipitation thresholds (25, 50, 75, and 100 mm per day). The results showed that the United Kingdom Met Office (UKMO) model, in terms of spatial coverage and satellite estimates as well as the precipitation amount, were closer to the observations. Although, generally, the models captured the spatial distribution of heavy precipitation events, the hot spots were not located in the correct area. The National Centers for Environmental Forecast (NCEP) model performed well at low precipitation thresholds, while at high thresholds, its performance decreased significantly. On the contrary, the accuracy of IMERG improved when the precipitation threshold increased. The UKMO had better forecasts than the other models at the 100 mm/day precipitation threshold, whereas the Medium-Range Weather Forecasts (ECMWF) had acceptable forecasts in all thresholds and was able to forecast precipitation events with a lower false alarm ratio and better detection when compared to other models. Although, the models and IMERG product underestimated or overestimated the amount of precipitation, but they were able to detect most extreme precipitation events. Overall, the results of this study show the IMERG precipitation estimates and NWP ensemble forecasts performed well in the three major flood events in spring 2019 in Iran. Given wide spread damages caused by the floods, the necessity of establishing an efficient flood warning system using the best precipitation products is advised.&#160;

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