scholarly journals Spatiotemporal Variability of Precipitation in Beijing, China during the Wet Seasons

Water ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 716 ◽  
Author(s):  
Meifang Ren ◽  
Zongxue Xu ◽  
Bo Pang ◽  
Jiangtao Liu ◽  
Longgang Du
Keyword(s):  
Urban Area ◽  
Global Climate ◽  
Spatiotemporal Variability ◽  
Annual Precipitation ◽  
Circulation Index ◽  
Intensity Index ◽  
Suburban Areas ◽  
The Past ◽  
Beijing China ◽  
Average Annual Precipitation

To comprehensively evaluate the changes in precipitation patterns in the context of global climate change and urbanization, the spatiotemporal variability of precipitation during the wet seasons of 1981–2017 in Beijing was analyzed in this study using up-to-date daily and hourly precipitation data from observation stations. It was concluded that the average annual precipitation in wet seasons showed a downward trend, while the simple daily intensity index (SDII) showed an upward trend. Precipitation in the central urban area of Beijing showed obvious changes from 1981 to 2017; the average annual precipitation in the central urban area was almost as great as that in Miyun country after 2010, which was the storm center for the past three decades. The average annual maximum 3-h and 6-h precipitation in the 2010s was higher than the past three decades, especially in urban and suburban areas. In addition, the atmospheric circulation index, urbanization impact, and topography were all found to be important factors that affect the pattern of precipitation in Beijing.

scholarly journals Climatological features and trends of extreme precipitation during 1979–2012 in Beijing, China

2015 ◽  
Vol 369 ◽  
pp. 97-102 ◽  
Author(s):  
Z. X. Xu ◽  
Q. Chu
Keyword(s):  
Spatial Distribution ◽  
Urban Area ◽  
Extreme Precipitation ◽  
Precipitation Amount ◽  
Annual Precipitation ◽  
Mountain Area ◽  
Beijing Area ◽  
North Eastern ◽  
Precipitation Threshold ◽  
Beijing China

Abstract. In this study, three kinds of hourly precipitation series with the spatial resolution of 0.1° are used to analyze the climatological features and trends of extreme precipitation during the period of 1979–2012 in Beijing, China. The results show that: (1) the spatial distribution of median annual precipitation, with a range from 500 to 825 mm, is similar to that of local topography, which increases from the northwest to the southeast. Taking the urban area as a centre, the inter-annual precipitation in the Beijing area displays an outward decreasing tendency at the maximum rate of 125 mm per decade (125 mm × 10 a−1); (2) extreme precipitation amount, which accounts for 40–48% of total precipitation amount, has a similar spatial distribution to average annual precipitation; (3) the spatial distribution of extreme precipitation days and threshold estimated as the upper 95 percentile are significantly different from that of extreme precipitation, with maximum values concentrated on the urban area and the eastern mountain area, and minimum values in northwest; (4) extreme precipitation days (Ex_pd95) show an opposite distribution to extreme precipitation threshold (Ex_pv95), indicating that areas with greater precipitation threshold may has less precipitation days, and vice versa; (5) an apparent spatiotemporal decreasing tendency is detected in extreme precipitation amount. The downward tendencies are also found in extreme precipitation threshold. Unlike Ex_pv95, in most of the study area, Ex_pd95 is virtually unchanged; (6) downward trends of extreme precipitation is slightly smaller than that of annual precipitation, and the reducing amplitude of north-eastern areas are much higher than the areas in the southwest.

scholarly journals Specific changes in main climatic characteristics of the Debed river basin (Armenia)

2021 ◽  
Keyword(s):  
Climate Change ◽  
River Basin ◽  
Air Temperature ◽  
Global Climate ◽  
Atmospheric Precipitation ◽  
Annual Precipitation ◽  
Local Circulation ◽  
The Past ◽  
Annual Amount ◽  
Climatic Characteristics

Formulation of the problem. The article discusses changes in the main climatic characteristics in the Debed river basin (Armenia) at six meteorological stations. The aim of the work is to analyze and assess peculiar territorial distribution of the main climatic indicators in the Debed river basin, their changes over the past 80-90 years in different conditions of Armenia. Methods. To solve the set tasks, the authors used corresponding research and published works as a theoretical basis in the work. As a starting material, the work used the daily factual data of the "Center for Hydrometeorology and Monitoring" of the SNCO, Ministry of Environment of the Republic of Armenia for the period from 1930 to 2018 at six meteorological stations. The authors applied the following research methods in the article: mathematical and statistical, extrapolation, analysis, analogy, correlation, cartographic. Results. Climate of the earth has been changing rapidly over the past decades, leading to global warming. As a result, we are facing the problem of assessing the macroeconomic consequences of climate change in this territory. Armenia did not remain aloof from the problems of global climate change. On the territory of the river Debed's basin air temperature distribution and precipitation is uneven, due to the geographical latitude of the area, general and local circulation of the atmosphere, radiation energy and orographic features. We notice a decrease in air temperature and an increase in precipitation with the height of the terrain and the vertical gradient, respectively, is 0.54 ºC / 100 m and -20 mm / 100 m. The average annual air temperature ranges from 3.74 ºC to 12.3 ºC, and the annual precipitation is from 462 mm to 770 mm. Studies have also shown that long-term fluctuations in average air temperature over the year are generally characterized by positive trends. Air temperature in the basin of the river Debed increased by 1.65 °С on average over the year from 1964 to 2018. A particularly significant increase in annual temperatures has been observed after the 1990s, when the rate of annual warming reached +0.389 ºС / 10 years (for the period 1993-2018). The warmest years were 1966, 2010 and 2018. The tendency towards a decrease in the annual amount of precipitation prevails in the area. The most significant amount of precipitation decreased in the basin of the river Debed after 2002. The rate of changes in the annual amount of atmospheric precipitation for the period 2002–2018 reached -61.7 mm / 10 years, and for the entire period 1964-2018 - 1.02 mm / 10 years. On average a decrease in annual precipitation was 126 mm from 1964 to 2001, 105 mm - from 2002 to 2018 in the basin of the river Debed. There is a tendency for a slight increase in the amount of precipitation at the Stepanavan weather station.

scholarly journals Contrasting Evolution Patterns of Endorheic and Exorheic Lakes on the Central Tibetan Plateau and Climate Cause Analysis during 1988–2017

Water ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 1962
Author(s):  
Zhilong Zhao ◽  
Yue Zhang ◽  
Zengzeng Hu ◽  
Xuanhua Nie
Keyword(s):  
Climate Change ◽  
Tibetan Plateau ◽  
Climatic Factors ◽  
Global Climate ◽  
Rapid Expansion ◽  
Annual Precipitation ◽  
The Tibetan Plateau ◽  
Lake Area ◽  
Climate Change Research ◽  
Mean Temperature

The alpine lakes on the Tibetan Plateau (TP) are indicators of climate change. The assessment of lake dynamics on the TP is an important component of global climate change research. With a focus on lakes in the 33° N zone of the central TP, this study investigates the temporal evolution patterns of the lake areas of different types of lakes, i.e., non-glacier-fed endorheic lakes and non-glacier-fed exorheic lakes, during 1988–2017, and examines their relationship with changes in climatic factors. From 1988 to 2017, two endorheic lakes (Lake Yagenco and Lake Zhamcomaqiong) in the study area expanded significantly, i.e., by more than 50%. Over the same period, two exorheic lakes within the study area also exhibited spatio-temporal variability: Lake Gaeencuonama increased by 5.48%, and the change in Lake Zhamuco was not significant. The 2000s was a period of rapid expansion of both the closed lakes (endorheic lakes) and open lakes (exorheic lakes) in the study area. However, the endorheic lakes maintained the increase in lake area after the period of rapid expansion, while the exorheic lakes decreased after significant expansion. During 1988–2017, the annual mean temperature significantly increased at a rate of 0.04 °C/a, while the annual precipitation slightly increased at a rate of 2.23 mm/a. Furthermore, the annual precipitation significantly increased at a rate of 14.28 mm/a during 1995–2008. The results of this study demonstrate that the change in precipitation was responsible for the observed changes in the lake areas of the two exorheic lakes within the study area, while the changes in the lake areas of the two endorheic lakes were more sensitive to the annual mean temperature between 1988 and 2017. Given the importance of lakes to the TP, these are not trivial issues, and we now need accelerated research based on long-term and continuous remote sensing data.

scholarly journals Global climatology and trends in convective environments from ERA5 and rawinsonde data

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Mateusz Taszarek ◽  
John T. Allen ◽  
Mattia Marchio ◽  
Harold E. Brooks
Keyword(s):  
Large Scale ◽  
Climate Models ◽  
Global Climate ◽  
Convective Available Potential Energy ◽  
Global Climate Models ◽  
Convective Precipitation ◽  
The Past ◽  
The Tropics ◽  
Rawinsonde Data

AbstractGlobally, thunderstorms are responsible for a significant fraction of rainfall, and in the mid-latitudes often produce extreme weather, including large hail, tornadoes and damaging winds. Despite this importance, how the global frequency of thunderstorms and their accompanying hazards has changed over the past 4 decades remains unclear. Large-scale diagnostics applied to global climate models have suggested that the frequency of thunderstorms and their intensity is likely to increase in the future. Here, we show that according to ERA5 convective available potential energy (CAPE) and convective precipitation (CP) have decreased over the tropics and subtropics with simultaneous increases in 0–6 km wind shear (BS06). Conversely, rawinsonde observations paint a different picture across the mid-latitudes with increasing CAPE and significant decreases to BS06. Differing trends and disagreement between ERA5 and rawinsondes observed over some regions suggest that results should be interpreted with caution, especially for CAPE and CP across tropics where uncertainty is the highest and reliable long-term rawinsonde observations are missing.

scholarly journals InSAR Multitemporal Data over Persistent Scatterers to Detect Floodwater in Urban Areas: A Case Study in Beletweyne, Somalia

2020 ◽  
Vol 13 (1) ◽  
pp. 37
Author(s):  
Luca Pulvirenti ◽  
Marco Chini ◽  
Nazzareno Pierdicca
Keyword(s):  
Urban Area ◽  
Urban Areas ◽  
The Other ◽  
Spatial Average ◽  
Calibration Data ◽  
Suburban Areas ◽  
Persistent Scatterers ◽  
Optical Images ◽  
Interferometric Phase ◽  
Multitemporal Data

A stack of Sentinel-1 InSAR data in an urban area where flood events recurrently occur, namely Beletweyne town in Somalia, has been analyzed. From this analysis, a novel method to deal with the problem of flood mapping in urban areas has been derived. The approach assumes the availability of a map of persistent scatterers (PSs) inside the urban settlement and is based on the analysis of the temporal trend of the InSAR coherence and the spatial average of the exponential of the InSAR phase in each PS. Both interferometric products are expected to have high and stable values in the PSs; therefore, anomalous decreases may indicate that floodwater is present in an urban area. The stack of Sentinel-1 data has been divided into two subsets. The first one has been used as a calibration set to identify the PSs and determine, for each PS, reference values of the coherence and the spatial average of the exponential of the interferometric phase under standard non-flooded conditions. The other subset has been used for validation purposes. Flood maps produced by UNOSAT, analyzing very-high-resolution optical images of the floods that occurred in Beletweyne in April–May 2018, October–November 2019, and April–May 2020, have been used as reference data. In particular, the map of the April–May 2018 flood has been used for training purposes together with the subset of Sentinel-1 calibration data, whilst the other two maps have been used to validate the products generated by applying the proposed method. The main product is a binary map of flooded PSs that complements the floodwater map of rural/suburban areas produced by applying a well-consolidated algorithm based on intensity data. In addition, a flood severity map that labels the different districts of Beletweyne, as not, partially, or totally flooded has been generated to consolidate the validation. The results have confirmed the effectiveness of the proposed method.

Modulation of the relationship between summer temperatures in the Qinghai–Tibetan Plateau and Arctic over the past millennium by external forcings

2021 ◽  
pp. 1-9
Author(s):  
Feng Shi ◽  
Anmin Duan ◽  
Qiuzhen Yin ◽  
John T Bruun ◽  
Cunde Xiao ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Global Climate ◽  
Volcanic Eruptions ◽  
Warm Period ◽  
Temperature Correlation ◽  
The Past ◽  
External Forcings ◽  
Centennial Variation ◽  
Summer Temperatures ◽  
Past Millennium

Abstract The Qinghai–Tibetan Plateau and Arctic both have an important influence on global climate, but the correlation between climate variations in these two regions remains unclear. Here we reconstructed and compared the summer temperature anomalies over the past 1,120 yr (900–2019 CE) in the Qinghai–Tibetan Plateau and Arctic. The temperature correlation during the past millennium in these two regions has a distinct centennial variation caused by volcanic eruptions. Furthermore, the abrupt weak-to-strong transition in the temperature correlation during the sixteenth century could be analogous to this type of transition during the Modern Warm Period. The former was forced by volcanic eruptions, while the latter was controlled by changes in greenhouse gases. This implies that anthropogenic, as opposed to natural, forcing has acted to amplify the teleconnection between the Qinghai–Tibetan Plateau and Arctic during the Modern Warm Period.

scholarly journals A Multimethod Analysis for Average Annual Precipitation Mapping in the Khorasan Razavi Province (Northeastern Iran)

Atmosphere ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 592
Author(s):  
Mehdi Aalijahan ◽  
Azra Khosravichenar
Keyword(s):  
Regional Planning ◽  
Interpolation Method ◽  
Absolute Error ◽  
Rain Gauge ◽  
Annual Precipitation ◽  
Coefficient Of Determination ◽  
Distance Weighting ◽  
Average Annual Precipitation ◽  
Inverse Distance

The spatial distribution of precipitation is one of the most important climatic variables used in geographic and environmental studies. However, when there is a lack of full coverage of meteorological stations, precipitation estimations are necessary to interpolate precipitation for larger areas. The purpose of this research was to find the best interpolation method for precipitation mapping in the partly densely populated Khorasan Razavi province of northeastern Iran. To achieve this, we compared five methods by applying average precipitation data from 97 rain gauge stations in that province for a period of 20 years (1994–2014): Inverse Distance Weighting, Radial Basis Functions (Completely Regularized Spline, Spline with Tension, Multiquadric, Inverse Multiquadric, Thin Plate Spline), Kriging (Simple, Ordinary, Universal), Co-Kriging (Simple, Ordinary, Universal) with an auxiliary elevation parameter, and non-linear Regression. Root Mean Square Error (RMSE), Mean Absolute Error (MAE), and the Coefficient of Determination (R2) were used to determine the best-performing method of precipitation interpolation. Our study shows that Ordinary Co-Kriging with an auxiliary elevation parameter was the best method for determining the distribution of annual precipitation for this region, showing the highest coefficient of determination of 0.46% between estimated and observed values. Therefore, the application of this method of precipitation mapping would form a mandatory base for regional planning and policy making in the arid to semi-arid Khorasan Razavi province during the future.

scholarly journals Ensemble models on palaeoclimate to predict India's groundwater challenge

2013 ◽  
Vol 2 (3) ◽  
Author(s):  
Partha Sarathi Datta
Keyword(s):  
Climate Change ◽  
Climate Models ◽  
Global Climate ◽  
Global Climate Models ◽  
Humid Climate ◽  
Ensemble Models ◽  
North West ◽  
The Past ◽  
The North ◽  
14C Age

In many parts of the world, freshwater crisis is largely due to increasing water consumption and pollution by rapidly growing population and aspirations for economic development, but, ascribed usually to the climate. However, limited understanding and knowledge gaps in the factors controlling climate and uncertainties in the climate models are unable to assess the probable impacts on water availability in tropical regions. In this context, review of ensemble models on δ18O and δD in rainfall and groundwater, 3H- and 14C- ages of groundwater and 14C- age of lakes sediments helped to reconstruct palaeoclimate and long-term recharge in the North-west India; and predict future groundwater challenge. The annual mean temperature trend indicates both warming/cooling in different parts of India in the past and during 1901–2010. Neither the GCMs (Global Climate Models) nor the observational record indicates any significant change/increase in temperature and rainfall over the last century, and climate change during the last 1200 yrs BP. In much of the North-West region, deep groundwater renewal occurred from past humid climate, and shallow groundwater renewal from limited modern recharge over the past decades. To make water management to be more responsive to climate change, the gaps in the science of climate change need to be bridged.

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