scholarly journals Using the Markov Chain to Analyze Precipitation and Groundwater Drought Characteristics and Linkage with Atmospheric Circulation

2019 ◽  
Vol 11 (6) ◽  
pp. 1817 ◽  
Author(s):  
Hsin-Fu Yeh ◽  
Hsin-Li Hsu
Keyword(s):  
Markov Chain ◽  
Steady State ◽  
Atmospheric Circulation ◽  
River Basin ◽  
Drought Characteristics ◽  
Groundwater Drought ◽  
The Future ◽  
Southern Taiwan ◽  
The Mean

In recent years, Taiwan has been facing water shortages due to the impact of climate change, which has resulted in many serious drought events, especially in southern Taiwan. Long-term records from 25 rainfall stations and 17 groundwater stations in the southern Taiwan basin were used in this study. We used the Standardized Precipitation Index (SPI) and the Standardized Groundwater Level Index (SGI) and employed the first-order Markov chain model and wavelet transform to determine the drought characteristics and propagation, including the steady-state probabilities of drought events and the mean duration for each station. The Drought Index (DI) was also used to investigate the effects of rainfall on groundwater drought. The results show that the steady-state probability of the meteorological drought in the Yanshui River basin in southern Taiwan is higher than that in other basins. The area with the longer mean duration is located in the Yanshui River basin and the Erren River basin, and overall, the mean duration ranges from 3 to 7 months. In addition, the results from the drought proneness analysis indicated that when rainfall causes a longer drought duration, there will be a higher degree of proneness to groundwater drought in the future. Finally, the results show that the mean duration of groundwater droughts are longer than those of meteorological droughts. The results of the wavelet analysis revealed a positive correlation at long-term scales, which may be related to large-scale atmospheric circulation. The information from this research could be used as a reference for water resource management in the future.

scholarly journals Steady-State Analysis of Genetic Regulatory Networks Modelled by Probabilistic Boolean Networks

2003 ◽  
Vol 4 (6) ◽  
pp. 601-608 ◽  
Author(s):  
Ilya Shmulevich ◽  
Ilya Gluhovsky ◽  
Ronaldo F. Hashimoto ◽  
Edward R. Dougherty ◽  
Wei Zhang
Keyword(s):  
Markov Chain ◽  
Steady State ◽  
Markov Chains ◽  
Regulatory Networks ◽  
Boolean Networks ◽  
Genetic Regulatory Networks ◽  
Long Run ◽  
Probabilistic Boolean Networks

Probabilistic Boolean networks (PBNs) have recently been introduced as a promising class of models of genetic regulatory networks. The dynamic behaviour of PBNs can be analysed in the context of Markov chains. A key goal is the determination of the steady-state (long-run) behaviour of a PBN by analysing the corresponding Markov chain. This allows one to compute the long-term influence of a gene on another gene or determine the long-term joint probabilistic behaviour of a few selected genes. Because matrix-based methods quickly become prohibitive for large sizes of networks, we propose the use of Monte Carlo methods. However, the rate of convergence to the stationary distribution becomes a central issue. We discuss several approaches for determining the number of iterations necessary to achieve convergence of the Markov chain corresponding to a PBN. Using a recently introduced method based on the theory of two-state Markov chains, we illustrate the approach on a sub-network designed from human glioma gene expression data and determine the joint steadystate probabilities for several groups of genes.

scholarly journals EVALUATION OF POSSIBLE CHANGES IN THE RIVER LINE OF THE OKA BASIN FOR THE COMING PERIOD OF THE FIRST HALF OF THE XXI CENTURY

2020 ◽  
Vol 1 (5) ◽  
pp. 71-75
Author(s):  
G. Kh. Ismaiylov ◽  
◽  
N.V. Muraschenkova ◽  
Keyword(s):  
River Basin ◽  
21St Century ◽  
River Runoff ◽  
River Flow ◽  
Climatic Conditions ◽  
Global Changes ◽  
The Future ◽  
Seasonal Runoff ◽  
The City

A retrospective analysis and assessment of long-term changes in the annual and seasonal runoff of the Oka River basin over a long 131-year observation period (1881 / 1882–2011/2012) was performed. The changes in the annual distribution of the Oka river runoff over the seasons of the year (spring flood, summer-autumn and winter low water) from its annual value for the selected time periods (before and after 1976/1977) are considered. It has been noted that over the past decades, river runoff has been formed in new climatic conditions associated with global changes and, as a result, regional climate. The assessment of possible changes in the annual and seasonal runoff of the Oka River basin (to the final alignment – the city of Kaluga, with a basin area of 54,900 km2 ) in the first half of the 21st century is carried out. In assessing changes in the river flow of the Oka basin for the future period, the method of trends (trends) is used, based on the identification of cycles in fluctuations in hydrological characteristics and unidirectional trends (trends) inherent in individual phases (ups and downs) of these cycles, as well as to the establishment of functional (correlation) relationships between environmental factors (climatic, anthropogenic) and the nature of the response (river flow). In this case, the trend model serves as an alternative to the homogeneity hypothesis of long-term fluctuations in river flow. The change in the future values of the river flow of the Oka basin was estimated using averaged data of 30-year periods of time characterized by relative stationarity of climatic and hydrological conditions. The dynamics of the average 30-year values of the annual runoff in the upper reaches of the Oka River (the closure target is the city of Kaluga for the period 1881/1882–2011/2012) is considered. Possible forecasted mean annual values of the annual flow of the Oka River for the first half of the 21st century are obtained

scholarly journals Shorter cyclone clusters modulate changes in European wintertime precipitation extremes

2021 ◽  
Author(s):  
Emanuele Bevacqua ◽  
Giuseppe Zappa ◽  
Theodore G Shepherd
Keyword(s):  
Atmospheric Circulation ◽  
Extreme Precipitation ◽  
Climate Models ◽  
Precipitation Extremes ◽  
Southern Europe ◽  
Circulation Change ◽  
The Future ◽  
The Mean ◽  
Future Direction ◽  
Atmospheric Circulation Change

<p>Wintertime extreme precipitation from cyclone clusters, i.e. consecutive cyclones moving across the same region, can lead to flooding and devastating socio-economic impacts in Europe. Previous studies have suggested that the future direction of the changes in these events are uncertain across climate models. By employing an impact-based metric of accumulated precipitation extremes, we show that projections of cyclone clusters are instead broadly robust, i.e. consistent in sign, across models. A novel physical diagnostic shows that accumulated precipitation extremes are projected to grow by only +1.0 %/K on average across Europe, although the mean precipitation per cyclone increases by +4.7 %/K. This results from a decreased number of clustered cyclones, associated with decreased wintertime storminess, the extent of which varies from northern to southern Europe and depends on the future storyline of atmospheric circulation change. Neglecting the changes in the number of clustered cyclones, i.e. assuming that accumulated precipitation extremes would change as the mean precipitation per cyclone, would lead to overestimating the population affected by increased accumulated wintertime precipitation extremes by 130–490 million across Europe.</p>

scholarly journals Spatiotemporal Variation of the Meteorological and Groundwater Droughts in Central Taiwan

2021 ◽  
Vol 3 ◽  
Author(s):  
Hsin-Fu Yeh
Keyword(s):  
River Basin ◽  
Groundwater Level ◽  
Standardized Precipitation Index ◽  
Extreme Drought ◽  
Water Shortages ◽  
Level Data ◽  
Groundwater Drought ◽  
Central Taiwan ◽  
The Standardized Precipitation Index

In recent years, Taiwan has been facing severe water shortages due to extreme drought. In addition, changes in rainfall patterns have resulted in an increasingly notable drought phenomenon, which affects the management and utilization of water resources. Therefore, this work examines basins in Central Taiwan. Long-term records from 13 rainfall and 17 groundwater stations were selected. The Standardized Precipitation Index (SPI) and Standardized Groundwater Level Index (SGI) were used to analyze the drought characteristics of this region. The rainfall and groundwater level data from basins in Central Taiwan were analyzed in this study. The results show that the year 2015 experienced extreme drought conditions due to a correlation with SPI and SGI signals. In addition, with regard to groundwater drought, more drought events occurred in the Da'an River basin; however, the duration and intensity of these events were relatively low, in contrast to those of the Wu River basin. Finally, the correlation between SPI and SGI was observed to vary in different basins, but a certain degree of correlation was observed in all basins. The results show that drought intensity increases with longer drought durations. Moreover, severe droughts caused by rainfall tend to occur at a greater frequency than those caused by groundwater.

scholarly journals Present and potential nitrogen outputs from Norwegian soft water lakes – an assessment made by applying the steady-state First-order Acidity Balance (FAB) model

2002 ◽  
Vol 6 (1) ◽  
pp. 101-112 ◽  
Author(s):  
Ø. Kaste ◽  
A. Henriksen ◽  
M. Posch
Keyword(s):  
Steady State ◽  
Critical Loads ◽  
N Deposition ◽  
Soft Water ◽  
N Leaching ◽  
First Order ◽  
Fab Model ◽  
The Future ◽  
N Immobilisation

Abstract. The steady-state First-order Acidity Balance (FAB) model for calculating critical loads of sulphur (S) and nitrogen (N) is applied to 609 Norwegian soft-water lakes to assess the future nitrate (NO3‾) leaching potential under present (1992-96) S and N deposition. The lakes were separated into five groups receiving increasing levels of N deposition (<25, 25-49, 50-74, 75-99 and 100-125 meq m-2yr-1). Using long-term sustainable N sink rates presently recommended for FAB model applications, N immobilisation, net N uptake in forests, denitrification and in-lake N retention were estimated for each group of lakes. Altogether, the long-term N sinks constituted 9.9 ± 3.2 to 40.5 ± 11.4 meq m-2yr-1 in the lowest and highest N deposition categories, respectively. At most sites, the current N deposition exceeds the amount of N retained by long-term sustainable N sinks plus the NO3‾ loss via the lake outlets. This excess N, which is currently retained within the catchments may, according to the FAB model, leach as acidifying NO3‾ in the future. If these predictions are fulfilled, NO3‾ leaching at sites in the various N deposition categories will increase dramatically from present (1995) mean levels of 1-20 meq m-2yr-1, to mean levels of 7-70 meq m-2yr-1 at future steady state. To illustrate the significance of such an increase in NO3‾ leaching, the mean Acid Neutralising Capacity (ANC) at sites in the highest N deposition category may decrease from -18 ± 15 μeq L-1 at present, to -40 ± 20 μeq L-1. Under present S and N deposition levels, the FAB model predicts that 46% of the Norwegian lakes may experience exceedances of critical loads for acidifying deposition. In comparison, the Steady-State Water Chemistry model (SSWC), which considers only the present N leaching level, estimates critical load exceedances in 37% of the lakes under the same deposition level. Thus far, there are great uncertainties regarding both the time scales and the extent of future N leaching, and it is largely unknown whether the FAB model predictions will ever be fulfilled. Hence, long-term monitoring and further studies on N immobilisation processes under varying N deposition levels and ecosystem types seem necessary to make better predictions of future NO3‾ leaching. Keywords: Lakes, hydrochemistry, nitrogen, nitrate, sinks, leaching, acidification, critical loads, FAB model

Probabilistic Analysis of Long-Term Climate Drought Using Steady-State Markov Chain Approach

2020 ◽  
Vol 34 (15) ◽  
pp. 4703-4724
Author(s):  
Saeed Azimi ◽  
Erfan Hassannayebi ◽  
Morteza Boroun ◽  
Mohammad Tahmoures
Keyword(s):  
Markov Chain ◽  
Steady State ◽  
Probabilistic Analysis ◽  
Markov Chain Approach

Eye Movements While Driving Cars around Curves

1977 ◽  
Vol 44 (3) ◽  
pp. 683-689 ◽  
Author(s):  
Amos S. Cohen ◽  
Herbert Studach
Keyword(s):  
Eye Movements ◽  
Eye Movement ◽  
Vehicle Control ◽  
Eye Fixation ◽  
Eye Fixations ◽  
The Future ◽  
The Mean ◽  
The Right

The eye fixations of 5 experienced and 4 inexperienced car drivers were analyzed while driving curves to the left and to the right. For experienced drivers in a curve to the left the mean duration of eye fixations was longer and the amplitude of the eye movements greater than in a curve to the right. No such difference was observed in inexperienced drivers who manifested neither uniformity within the same curves nor differentiation between the two types of curves. Mean duration of eye fixations of experienced subjects was shorter while driving in a curve to right, but their amplitude of eye movement was greater in a curve to left than those of inexperienced drivers. In Exp. 2, it was pointed out that there is already a change in the pattern of eye movements prior to entering a curve. Upon approaching the curve the mean duration of eye fixation decreased, and the fixations were mainly shifted toward the future driving path. Results are interpreted in terms of the adequacy of the eye fixations (supposedly influenced by prior long-term learning) for information at near distance for vehicle control and at longer distances for setting up proprioceptive forward programs for possible future sensomotoric activity.

scholarly journals Regionalisation of groundwater droughts using hydrograph classification

2015 ◽  
Vol 12 (6) ◽  
pp. 5293-5341
Author(s):  
J. P. Bloomfield ◽  
B. P. Marchant ◽  
S. H. Bricker ◽  
R. B. Morgan
Keyword(s):  
Time Series ◽  
Study Region ◽  
Drought Characteristics ◽  
Maximum Duration ◽  
Groundwater Drought ◽  
Short Period ◽  
Standardised Precipitation Index ◽  
Aquifer Characteristics ◽  
The Mean

Abstract. Groundwater drought is a spatially and temporally variable phenomenon. Here we describe the development and application of a method to regionalize and quantify groundwater drought based on categorisation of Standardised Groundwater level Index (SGI) time series. The categorisation scheme uses non-hierarchical k-means cluster analysis. This has been applied to 74 SGI time series for the period January 1983 to August 2012 for a case study from Lincolnshire, UK. Six SGI time series clusters have been identified. For each cluster a correlation can be established between the mean SGI and a mean Standardised Precipitation Index (SPI) associated with an optimal SPI accumulation period, qmax. Based on a comparison of SPI time series for each cluster and SPI estimated for the whole study area, it is inferred that the clusters are largely independent of heterogeneity in the diving meteorology across the study region and are primarily a function of catchment and hydrogeological factors. This inference is supported by the observation that the majority of sites in each cluster are associated with one of three principal aquifers in the study region. The groundwater drought characteristics of the three largest clusters (CL1, CL2 and CL4 that constitute ~80% of the sites) have been analyzed. There is a common linear relationship between drought magnitude and duration for each of three clusters. However, there are differences in the character of the groundwater drought events between the three clusters as a function of autocorrelation of the mean SGI time series for each cluster. For example, CL1 has a relatively short period of significant SGI autocorrelation compared with CL2 (15 and 23 months respectively); CL1 has more than twice the number of drought episodes (39 episodes) than CL2 (15 episodes), and the average and maximum duration of droughts in CL1 (4.6 and 27 months) are less than half those of CL2 (11.3 and 61 months). The drought characteristics of CL4 are intermediate between those of CL1 and CL2. Differences in characteristics between the three clusters are also seen in their response to three major multi-annual droughts that occurred during the analysis period. For example, sites in CL2 with the longest SGI autocorrelation experience the greatest magnitude droughts and are the slowest to recover from drought, with groundwater drought conditions typically persisting at least six months longer than at sites in the other two clusters. Membership of the clusters reflects differences in the autocorrelation of the SGI time series that in turn is shown to be related to unsaturated zone thickness at individual boreholes. This last observation emphasises the importance of catchment and aquifer characteristics as (non-trivial) controls on groundwater drought hydrographs.

Long-Term Wind Speed Trends over Australia

2012 ◽  
Vol 25 (1) ◽  
pp. 170-183 ◽  
Author(s):  
Alberto Troccoli ◽  
Karl Muller ◽  
Peter Coppin ◽  
Robert Davy ◽  
Chris Russell ◽  
...  
Keyword(s):  
Wind Speed ◽  
Atmospheric Circulation ◽  
Sea Level Pressure ◽  
Mean Sea Level ◽  
Long Period ◽  
The Mean ◽  
Strong Winds ◽  
Circulation Changes ◽  
Linear Trends

Abstract Accurate estimates of long-term linear trends of wind speed provide a useful indicator for circulation changes in the atmosphere and are invaluable for the planning and financing of sectors such as wind energy. Here a large number of wind observations over Australia and reanalysis products are analyzed to compute such trends. After a thorough quality control of the observations, it is found that the wind speed trends for 1975–2006 and 1989–2006 over Australia are sensitive to the height of the station: they are largely negative for the 2-m data but are predominantly positive for the 10-m data. The mean relative trend at 2 m is −0.10 ± 0.03% yr−1 (−0.36 ± 0.04% yr−1) for the 1975–2006 (1989–2006) period, whereas at 10 m it is 0.90 ± 0.03% yr−1 (0.69 ± 0.04% yr−1) for the 1975–2006 (1989–2006) period. Also, at 10 m light winds tend to increase more rapidly than the mean winds, whereas strong winds increase less rapidly than the mean winds; at 2 m the trends in both light and strong winds vary in line with the mean winds. It was found that a qualitative link could be established between the observed features in the linear trends and some atmospheric circulation indicators (mean sea level pressure, wind speed at 850 hPa, and geopotential at 850 hPa), particularly for the 10-m observations. Further, the magnitude of the trend is also sensitive to the period selected, being closer to zero when a very long period, 1948–2006, is considered. As a consequence, changes in the atmospheric circulation on climatic time scales appear unlikely.

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