scholarly journals Suvremene promjene klime i smanjenje protoka Save u Zagrebu

Geoadria ◽  
2017 ◽  
Vol 12 (1) ◽  
pp. 47
Author(s):  
Tomislav Šegota ◽  
Anita Filipčić
Keyword(s):  
Correlation Coefficient ◽  
Atmospheric Pressure ◽  
River Flow ◽  
Pressure Rise ◽  
Summer Precipitation ◽  
Downward Trend ◽  
Precipitation Trend ◽  
Sava River ◽  
Flow Through

Correlation coefficient of 0.81 between Sava River flow through Zagreb and precipitation in Ljubljana points at dominant significance of precipitation. In the warmest months Sava flow is very much dependent on evapotranspiration. Sava River flow has downward trend, and two intervals can be sharply distinguished: 1926-1959 and 1960-1995. That is the result of the identical precipitation trend at the Upper Sava. There is the trend of atmospheric pressure rise in the entire observed period. "Precipitation continentality" is characterized by change of trend. Share of "summer" precipitation has been declining since 1960. 

A quantitative study of moisture transport variation on the interdecadal variation of the summer precipitation in South China from 1979 to 2015

2020 ◽  
Author(s):  
Lijuan Hua
Keyword(s):  
Indian Ocean ◽  
South China ◽  
Moisture Transport ◽  
Summer Precipitation ◽  
Interdecadal Variation ◽  
Downward Trend ◽  
Precipitation Trend ◽  
Long Distance ◽  
Wave Trains ◽  
The Mean

<p>The summer precipitation in South China (SC) has experienced a pronounced interdecadal variation during 1983–2013</p><p>with trend transition in the late 1990s. This study quantitatively investigates the precipitation variation and its connection to</p><p>water vapor transport by combining the Lagrangian trajectory-based Dynamic Recycling Model and the clustering method</p><p>of self-organizing map. The external moisture outside of SC explains most (84%) of the mean and the interdecadal variation</p><p>of the summer rainfall, mainly through the southwest transport pathways. A long-distance southwest pathway related to</p><p>cross-equatorial flow and eastward flow over the Northern Indian Ocean explains 31.5% of mean precipitation and 50.4% of</p><p>the upward precipitation trend before 1997. The other branch of the southwest pathways has relatively shorter length over</p><p>North Indian Ocean, South China Sea, and Southeast Asia, explaining 35.7% of the mean and 51.2% of the downward trend</p><p>after 1997. Also, for the downward trend, the westerly-driven moisture transport over Eurasia acts as the second contributor</p><p>(32.2%) to the precipitation decrease. However, the western-Pacific pathway explains the smallest portion (≤ 3%) of</p><p>the trends, suggesting weak influence from the subtropical high. The large-scale circulation anomaly in the form of zonal</p><p>and meridional wave trains control the interdecadal variability of the SC precipitation. It is found that the circumglobal teleconnection</p><p>and Pacific–Japan teleconnection significantly correlate to the two wave trains, whose match relation strongly</p><p>modulates the trend transition in the 1990s for the SC summer precipitation.</p>

scholarly journals Study on Hydraulic Performances of a 3-Bladed Inducer Based on Different Numerical and Experimental Methods

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Yanxia Fu ◽  
Yujiang Fang ◽  
Jiangping Yuan ◽  
Shouqi Yuan ◽  
Giovanni Pace ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Flow Model ◽  
Static Pressure ◽  
Pressure Rise ◽  
Turbulence Models ◽  
Experimental Methods ◽  
Hydraulic Performance ◽  
Outlet Pressure ◽  
Ansys Cfx ◽  
Flow Through

The hydraulic performances of a 3-bladed inducer, designed at Alta, Pisa, Italy, are investigated both experimentally and numerically. The 3D numerical model developed in ANSYS CFX to simulate the flow through the inducer and different lengths of its inlet/outlet ducts is illustrated. The influence of the inlet/outlet boundary conditions, of the turbulence models, and of the location of inlet/outlet different pressure taps on the evaluation of the hydraulic performance of the inducer is analyzed. As expected, the predicted hydraulic performance of the inducer is significantly affected by the lengths of the inlet/outlet duct portions included in the computations, as well as by the turbulent flow model and the locations of the inlet/outlet pressure taps. It is slightly affected by the computational boundary conditions and better agreement with the test data obtained when adopting the k-ω turbulence model. From the point of the pressure tap locations, the pressure rise coefficient is much higher when the inlet/outlet static pressure taps were chosen in the same locations used in the experiments.

Characterization of particle charging in low-temperature, atmospheric-pressure, flow-through plasmas

2020 ◽  
Vol 53 (24) ◽  
pp. 245204 ◽  
Author(s):  
Girish Sharma ◽  
Nabiel Abuyazid ◽  
Sukrant Dhawan ◽  
Sayali Kshirsagar ◽  
R Mohan Sankaran ◽  
...  
Keyword(s):  
Low Temperature ◽  
Atmospheric Pressure ◽  
Pressure Flow ◽  
Particle Charging ◽  
Flow Through

scholarly journals Impacts of Atmospheric Pressure on the Annual Maximum of Monthly Sea-Levels in the Northeast Asian Marginal Seas

2020 ◽  
Vol 8 (6) ◽  
pp. 425 ◽  
Author(s):  
MyeongHee Han ◽  
Yang-Ki Cho ◽  
Hyoun-Woo Kang ◽  
SungHyun Nam ◽  
Do-Seong Byun ◽  
...  
Keyword(s):  
Sea Level ◽  
Correlation Coefficient ◽  
Atmospheric Pressure ◽  
Northwest Pacific ◽  
Pressure Gradients ◽  
Northwest Pacific Ocean ◽  
Sea Levels ◽  
Marginal Seas ◽  
Pressure Zone ◽  
Northeast Asian

Monthly mean sea-levels have annual maxima in August in the northeast Asian marginal seas (NEAMS). Based on satellite altimetry data, the rising rate of the August NEAMS sea-level (ANS, 4.2 mm∙yr−1) is greater than those of the NEAMS (3.6 mm∙yr−1) and global (3.4 mm∙yr−1) annual mean sea-levels. Thus, the interannual variations of ANS are classified as relatively high (period H) and low (period L) years and have been analysed because of the high risk of sea-level fluctuation to the coastal regions in August. In period H, there are large atmospheric pressure gradients between the high pressure zone in the Kuroshio Extension (KE) and the low pressure zone in the west of Taiwan (WT). In period L, the atmospheric pressure gradients are small between the above-mentioned zones. Large atmospheric pressure gradients induce strong west-northwestward wind stresses and more Ekman transport from the northwest Pacific Ocean into the NEAMS. The correlation coefficient between August NEAMS sea-level index (ANSI), which is the difference of atmospheric pressure anomalies between the KE and the WT, and the August NEAMS sea-level anomaly (ANSA) is 0.73. Although there is a significant correlation (coefficient: 0.64) between ANSA and the East Asian summer monsoon index (EASMI), ANSI might be more useful in estimating the variability of ANSA.

scholarly journals Evaluation of spatial-temporal variation performance of ERA5 precipitation data in China

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Donglai Jiao ◽  
Nannan Xu ◽  
Fan Yang ◽  
Ke Xu
Keyword(s):  
Observational Data ◽  
Correlation Coefficient ◽  
Global Scale ◽  
Precipitation Trend ◽  
Strongly Correlated ◽  
Precipitation Data ◽  
Weather Forecasts ◽  
Fifth Generation ◽  
Data Assessment ◽  
Long Time

AbstractERA5 is the latest fifth-generation reanalysis global atmosphere dataset from the European Centre for Medium-Range Weather Forecasts, replacing ERA-Interim as the next generation of representative satellite-observational data on the global scale. ERA5 data have been evaluated and applied in different regions, but the performances are inconsistent. Meanwhile, there are few precise evaluations of ERA5 precipitation data over long time series have been performed in Chinese mainland. This study evaluates the temporal-spatial performance of ERA5 precipitation data from 1979 to 2018 based on gridded-ground meteorological station observational data across China. The results showed that ERA5 data could capture the annual and seasonal patterns of observed precipitation in China well, with correlation coefficient values ranging from 0.796 to 0.945, but ERA5 slightly overestimated precipitation in the summer. Nonetheless, the results also showed that the accuracy of the precipitation products was strongly correlated with topographic distribution and climatic divisions. The performance of ERA5 shows spatial inherently across China that the highest correlation coefficient values locate in eastern, Northwestern and North China and the lowest biases locate in Southeast China. This study provides a reliable data assessment of the ERA5 data and precipitation trend analyses in China. The results provide accuracy references for the further use of precipitation satellite data for hydrological calculations and climate numerical simulations.

scholarly journals Seasonal streamflow forecasts for Europe – Part I: Hindcast verification with pseudo- and real observations

2018 ◽  
Vol 22 (6) ◽  
pp. 3453-3472 ◽  
Author(s):  
Wouter Greuell ◽  
Wietse H. P. Franssen ◽  
Hester Biemans ◽  
Ronald W. A. Hutjes
Keyword(s):  
Correlation Coefficient ◽  
Lead Time ◽  
River Flow ◽  
Irrigation Management ◽  
Skill Score ◽  
Operating Characteristics ◽  
Infiltration Capacity ◽  
Run Off ◽  
Spatio Temporal ◽  
Roc Area

Abstract. Seasonal predictions of river flow can be exploited among others to optimise hydropower energy generation, navigability of rivers and irrigation management to decrease crop yield losses. This paper is the first of two papers dealing with a physical model-based system built to produce probabilistic seasonal hydrological forecasts, applied here to Europe. This paper presents the development of the system and the evaluation of its skill. The variable infiltration capacity (VIC) hydrological model is forced with bias-corrected output of ECMWF's seasonal forecast system 4. For the assessment of skill, we analysed hindcasts (1981–2010) against a reference run, in which VIC was forced by gridded meteorological observations. The reference run was also used to generate initial hydrological conditions for the hindcasts. The skill in run-off and discharge hindcasts is analysed with monthly temporal resolution, up to 7 months of lead time, for the entire annual cycle. Using the reference run output as pseudo-observations and taking the correlation coefficient as metric, hot spots of significant theoretical skill in discharge and run-off were identified in Fennoscandia (from January to October), the southern part of the Mediterranean (from June to August), Poland, northern Germany, Romania and Bulgaria (mainly from November to January), western France (from December to May) and the eastern side of Great Britain (January to April). Generally, the skill decreases with increasing lead time, except in spring in regions with snow-rich winters. In some areas some skill persists even at the longest lead times (7 months). Theoretical skill was compared to actual skill as determined with real discharge observations from 747 stations. Actual skill is generally substantially less than theoretical skill. This effect is stronger for small basins than for large basins. Qualitatively, the use of different skill metrics (correlation coefficient; relative operating characteristics, ROC, area; and ranked probability skill score, RPSS) leads to broadly similar spatio-temporal patterns of skill, but the level of skill decreases, and the area of skill shrinks, in the following order: correlation coefficient; ROC area below-normal (BN) tercile; ROC area above-normal (AN) tercile; ranked probability skill score; and, finally, ROC near-normal (NN) tercile.

Sign in / Sign up

Export Citation Format

Share Document