Analysis of the Spatial and Temporal Characteristics of Extreme Precipitation Events in Liaoning Province

Daily precipitation amounts from 1961 to 2005 in 35 observation stations in Liaoning Province were selected in order to study the temporal and spatial distribution of extreme precipitation events.By dint of EOF,REOF,mean-square-error and other ways,the changes in different regions of extreme precipitation and distribution were reflected.The analysis showed that,extreme precipitation in Liaoning Province could be divided into three areas,which were western Liaoning mountains and parts of northern areas,eastern Liaoning mountainous,near-coastal areas of Liaohe River Plain.In the relatively large precipitation areas,extreme precipitation threshold was also higher,and vice versa.The lower frequency of extreme precipitation events had a greater contribution to total precipitation;extreme precipitation,total precipitation and total rain days had the greatest changes in the summer,and the least changes in the winter;number of days of extreme precipitation changes in each season were not great;the change of extreme precipitation was not obvious in the long term.

Spatial and Temporal Distribution Characteristics of Snowstorm in Ulanqab City in Recent 30 Years

Based on the data of daily snowfall and weather phenomena of 11 national meteorological stations in Ulanqab City from 1991 to 2020,the spatial and temporal distribution characteristics of snowstorm were analyzed.The results show that the snowstorm in Ulanqab had obvious seasonal distribution characteristics,mainly happening in spring(March-May)and autumn(September-November).It also had obvious regional distribution in space,and the snowstorm center appeared in Chahar Right Wing Middle Banner and Jining District,namely the east side of the Yinshan Mountain.In the past 30 years,the amount of snowstorm in the whole year in Ulanqab showed a certain fluctuation trend,and the number of snowstorm days had shown an obvious upward trend since 2011.

Bathymetrical influences on spatial and temporal characteristics of chlorophyll-a concentrations in the Southern Ocean from 2002 to 2012(October to March)using MODIS

Phytoplankton blooms,particularly in the Southern Ocean,can have significant impact on global biogeochemistry cycling.To investigate the accuracy of chlorophyll-a distribution,and to better understand the spatial and temporal dynamics of phytoplankton biomass,we examine chlorophyll-a estimates(October-March from 2002 to 2012)derived from Moderate Resolution Imaging Spectrometer(MODIS)data following the ocean chlorophyll-a 3 model(OC3M)algorithm.Noticeable seasonality occurs in the temporal distribution of chlorophyll-a concentrations,which shows the highest value in December and January and an increasing tendency during the 2002-2012 period.The spatial distribution of chlorophyll-a varies greatly with latitude,as higher latitudes experience more phytoplankton blooms(chlorophyll-a concentration larger than 1 mg/m3)and marginal seas(Ross Sea and Amundsen Sea)show different bloom anomalies caused by two dominant algae species.Areas at higher latitudes and shallow water(<500 m)experience the shorter icefree periods with greater seasonality.A noticeable bathymetry gradient exists at 2500-m isobaths,while water at the 500-2500-m depth experiences quite long ice-free periods with a stable water environment.Blooms generally occur near topographic features where currents have strong interactions when the water depth is more than 2500 m.Based on these findings,we can classify the Southern Ocean into two bloom subregions,0-500 m as an enhanced bloom zone(EBZ),and 500-2500 m as a moderate bloom zone(MBZ).The EBZ has a quite high-bloom probability of about 30%,while the MBZ has only 10%.

Spatial and temporal variation of water mass mixing characteristic in the East China Sea

On the basis of the observation data of Kuroshio since 1984 and relative historical data in the East China Sea, spatial and temporal variation of water mass mixing characteristic in the observation area is analysed. The main results are as follows.

Characteristics of Precipitation and Temperature over the Past 40 Years in Zibo City

Based on monthly precipitation and temperature data of Zibo City over the years from 1966 to 2005,the spatial and temporal characteristics of precipitation and temperature in five districts and three counties of Zibo were analyzed by using climatic diagnosis methods including trend analysis and the method of Mexican-hat wavelet transform analysis. The results showed that the precipitation and temperature in Zibo experienced the interdecadal variations. The precipitation slowly increased at an average annual rate of 1.5 mm,and there existed multi-scale oscillation periods such as 32,25-29,10-23 a and quasi-5 a. Meanwhile,significant mutations were showed in 1977 and 1995. The precipitation was on the high side before 1977 and after 1995 while it was on the low side between 1977 and 1995. The yearly average temperature increased at the rate of 0.48 ℃/10 a,and there existed multi-scale oscillation periods such as 21-32,17-21,9-13 and 2-3 a. In addition,the significant mutation was showed in 1991. The temperature was colder before 1991 while after 1991,it was warmer. The results also indicated that the precipitation and temperature of Zibo City varied greatly in regional distribution,i.e.,the precipitation decreased gradually from south to north,and the temperature in the midst of Zibo City was higher than that in the south and the north,which could be divided into 3 types:south-based type,midst-based type and north-based type.

Characteristics of Drought and Humidification Based on Standardized Precipitation Index in Weifang City during the Past 50 Years

[Objective] This study aimed to analyze the evolution characteristics and occurrence patterns of droughts and floods in Weifang City. [Method] Based on the monthly precipitation data during 1961-2010 obtained from nine meteorological sta- tions of Weifang City, by using standardized precipitation index, monthly SPI index of Weifang City during the past 50 years was calculated to analyze the spatial and temporal distribution characteristics of drought and humidification in Weifang City. [Result] The results showed that the variation of drought and humidification had stage characteristics in Weifang City, which was relatively humid in the 1960s and 1970s and developed from extremely humid in early 1960s to dry in late 1970s, persistent drought was observed throughout the range of Weifang City in the 1980s, and the variation tended to be smooth during the 1990s-2000s. Spatial distribution of drought and humidification in Weifang City showed certain regional characteristics. In the 1960s, the mid-west region of Weifang City was relatively humid, while the southeastern region was relatively dry; in the 1970s, there was little difference among the drought and humidification extent in each region; in the 1980s, each region of Weifang City was generally dry, specifically, drought in the southeastern region was the most severe, while drought in the northern region was the slightest; in the 1990s and 2000s, variation of drought and humidification in each region of Weifang City was basically the same. The uneven spatial and temporal distribution of precipi- tation led to abnormal distribution of drought and humidification in some areas, such as the abnormal phenomenon in 1999; the spatial distribution of drought and humidi- fication duration in each generation had their own characteristics, which brought diffi- culties to the unified deployment of drought and flood control departments. [Conclu- sion] This study provided theoretical basis for the drought resistance, waterlogging prevention and disaster reduction in Weifang City under the background of climate change.

Spatial and Temporal Distribution Characteristics of Flower-viewing Tourism and Its Influencing Factors in China

Despite the rapid development of flower-viewing tourism in China in recent years,there is almost no systematic research on it.Therefore,this study analyzes the spatial and temporal distribution characteristics of flower-viewing tourism and its influencing factors in China using the spatial statistical analysis methods and the geographic detector method.The study uses the Point-of-Interest data of flower-viewing tourist attractions from networks such as Qunar and Ctrip,the flower observation data from China Phenological Observation Network,Chinese network news,and Weibo,and the statistical data from yearbooks.The results are as follows:1)The spatial attribution type of flower-viewing tourism in China is aggregated into areas,including two high-density aggregated areas,three medium-density aggregated areas,and one general-density aggregated area.Furthermore,five major types of flower-viewing tourist attractions have formed several aggregated areas.2)The time of flower viewing in China starts from about February and lasts about eight months till October each year.Florescence and flowering time of different ornamental flowers in different regions are different.3)The spatial and temporal distribution characteristics of flower-viewing tourism in China are mainly affected by ornamental flower phenology,spatial distribution characteristics of flower-viewing resources,regional permanent population size,youth population size,female population size,regional GDP,and added value of the tertiary sector.These conclusions clarify the spatial and temporal distribution characteristics of flower-viewing tourism and its influencing factors in China.They could provide a scientific basis and useful reference for the coordination and sustainable development of regional flower-viewing tourism in China.

SPATIAL AND TEMPORAL VARIATIONS OF THE KINEMATIC CHARACTERISTICS IN THE PROPAGATION OF ATMOSPHERIC STATIONARY WAVES

Time-mean global general circulation data are employed to analyze the temporal and spatial variations of the meridional gradient of zonal mean potential vorticity,the critical wavenumber n_s for horizontal wave- propagation,and the critical wavenumber K_c for vertical wave-propagation.Thereby the kinematic charac- teristics in the propagation of atmospheric stationary waves and their annual variations are studied.Results show that in the troposphere n_s and K_c usually decrease with the increase of either latitude or altitude. Synoptic and near-resonant Rossby waves could be trapped during their upward and meridional propagations. These characteristics possess prominent annual variations,especially in the Northern Hemisphere.It is found that the spatial and temporal variations of these kinematic characteristics are in good agreement with those of the atmospheric wave patterns.

The decadal abrupt change in the global land vapor pressure deficit

The vapor pressure deficit(VPD) is an important variable used to characterize atmospheric aridity.This paper analyses the spatial and temporal characteristics of the decadal abrupt change(DAC) in the global land VPD after 1980 using monthly scale data from the Climatic Research Unit.The results show that 60.5% of the global land area underwent a significantly increased decadal abrupt change(IDAC) in the VPD,and the persistent IDAC of the VPD was obvious in the middle and low latitudes of Eurasia,Africa and parts of South America but not in central North America or Western Siberia.From 1980 to 2020,most regions experienced no more than two persistent IDACs,while more than two significant increases occurred mainly around the Mediterranean and in eastern South America.The persistent IDAC occurred relatively early in the middle and low latitudes of Eurasia,Africa,and eastern South America and after 2000 in the high latitude regions,Eastern Europe,and near the Qinghai-Tibet Plateau.The regions where the persistent IDAC lasted longer than 10 years mainly included North Africa,West Asia,eastern South America,and parts of East Asia,indicating that the persistent increases in atmospheric aridity in these regions were obvious.In general,the persistent IDAC that began in 1993–2000 was significantly more than that occurred in other periods and lasted longer than that before 1990,suggesting that the land area experiencing an abrupt increase has an expansion after the 1990s and that the role of water limitation in this persistent IDAC in Central Asia and most of China strengthened.In addition,the VPD showed another large-scale persistent IDAC over the global land region in 2009,indicating that global atmospheric aridity intensified over the last decade.At the same time,in a few global regions,the VPD has exhibited decreased decadal abrupt changes(DDACs) with durations shorter than 2 years.

Investigating spatio-temporal characteristics and influencing factors for green energy consumption in China

The green transformation of energy consumption is beneficial for promoting green development in China.This study constructed a green energy consumption evaluation index system and measured the green energy consumption levels in 30 provinces of China from 2000 to 2019 using the fuzzy comprehensive evaluation method.This study further employed the spatial Durbin model to examine influencing factors and spillover effects of green energy consumption.The results showed that,temporally,China’s green energy consumption levels had a fluctuating upward trend.While,spatially,the overall levels of green energy consumption in China showed apparent characteristics of“high in the west and low in the east”.In terms of influencing factors,environmental regulations played an important role in promoting green energy consumption in the region,while economic development,opening up,and industrial structure had considerably inhibiting effects.Additionally,economic development,opening up,and industrial structure of neighboring regions showed marked positive spillover effects,while urbanization level and technological innovation showed substantial negative spillover effects.The regional heterogeneity test results showed that environmental regulation and industrial structure rationalization were the important factors for promoting green energy consumption in the eastern region,environmental regulation played an important driving role in the central region,and opening to the outside world and technological innovation helped improve the level of green energy consumption in the western region.

Recognition Algorithm and Risk Assessment of Airport Hotspots

The hotspot recognition algorithm is proposed based on a potential collision in order to study the aircraft taxi conflicts in large airports.The spatial and temporal distribution characteristics of hotspots are analyzed based on the risk assessment model of hotspot constructed in this paper.Firstly,approaches for monitoring of the aerodrome movement were compared.The hotspot recognition algorithm taken into account of whether aircrafts'taxi track has spatial and temporal overlap based on the aerodrome surveillance radar(ASR)data was presented,by identifying the hotspots through analyzing whether the aircrafts'time of entering and exiting the same taxiway is overlap or not,and the heading difference and distance of the two aircrafts satisfy the specified threshold constraint condition.Then,the ASR data were divided into several parts,and then airport hotspots were recognized and the spatial and temporal distribution characteristics were analyzed.The risk assessment model of airport safety hotspots was constructed which is taken into account of the conflict probability and its severity consequence.Finally,based on the risk grade assessment criteria and hotspots'risk value,the risk grade ranking of hotspot in one airport of China was evaluated and designated.According to the result,the spatial and temporal distribution characteristics of airport hotspots were varied with the variation of airport traffic flow and operational mode of runway,which shows that the hotspots have the characteristics of dynamic periodicity and diurnal variation.And the risk assessment results were consistent with experts'opinions and actual operation condition,which verified the rationality of the hotspot recognition algorithm,risk assessment model as well as the risk grade ranking criteria.