scholarly journals Data driven clustering of rain events: microphysics information derived from macro scale observations

2016 ◽  
Author(s):  
Mohamed Djallel Dilmi ◽  
Cécile Mallet ◽  
Laurent Barthes ◽  
Aymeric Chazottes
Keyword(s):  
Rain Rate ◽  
Dimensional Space ◽  
Hierarchical Cluster ◽  
Rate Variation ◽  
Rain Event ◽  
Minimal Set ◽  
Initial Space ◽  
Macro Scale ◽  
Minimal Subset ◽  
Rain Events

Abstract. The study of rain time series records is mainly carried out using rainfall rate or rain accumulation parameters estimated on a fixed duration (typically 1 min, 1 hour or 1 day). In this paper we used the concept of rain event. Among the numerous existing variables dedicated to the characterisation of rain events, the first part of this paper aims to obtain a parsimonious characterisation of these events using a minimal set of variables. In this context an algorithm based on Genetic Algorithm (GA) and Self Organising Maps (SOM) is proposed. The use of SOM is justify by the fact that it allows to maps a high dimensional data space to a two dimensional space while preserving as much as possible the initial space topology in an unsupervised way. The obtained 2D maps allow to provide the dependencies between variables and consequently to remove redundant variables leading to a minimal subset of variables. The ability of the obtained 2D map to deduce all events characteristics from only five features (the event duration, the rain rate peak, the rain event depth, the event rain rate standard deviation and the absolute rain rate variation of order 0.5) is verified. From this minimal subset of variables hierarchical cluster analysis were conducted. We show that a clustering in two classes allows finding the classic convective and stratiform classes while a classification in five classes allows refining this convective/stratiform classification. Finally, the last objective of this paper is to study the possible relationship between these five classes and their associated rain event microphysics. Some relationship between these classes and microphysics parameters are highlighted.

scholarly journals Data-driven clustering of rain events: microphysics information derived from macro-scale observations

2017 ◽  
Vol 10 (4) ◽  
pp. 1557-1574 ◽  
Author(s):  
Mohamed Djallel Dilmi ◽  
Cécile Mallet ◽  
Laurent Barthes ◽  
Aymeric Chazottes
Keyword(s):  
Rain Rate ◽  
Dimensional Space ◽  
Hierarchical Cluster ◽  
Rate Variation ◽  
Rain Event ◽  
Self Organizing Maps ◽  
Macro Scale ◽  
Minimal Subset ◽  
Rain Events

Abstract. Rain time series records are generally studied using rainfall rate or accumulation parameters, which are estimated for a fixed duration (typically 1 min, 1 h or 1 day). In this study we use the concept of rain events. The aim of the first part of this paper is to establish a parsimonious characterization of rain events, using a minimal set of variables selected among those normally used for the characterization of these events. A methodology is proposed, based on the combined use of a genetic algorithm (GA) and self-organizing maps (SOMs). It can be advantageous to use an SOM, since it allows a high-dimensional data space to be mapped onto a two-dimensional space while preserving, in an unsupervised manner, most of the information contained in the initial space topology. The 2-D maps obtained in this way allow the relationships between variables to be determined and redundant variables to be removed, thus leading to a minimal subset of variables. We verify that such 2-D maps make it possible to determine the characteristics of all events, on the basis of only five features (the event duration, the peak rain rate, the rain event depth, the standard deviation of the rain rate event and the absolute rain rate variation of the order of 0.5). From this minimal subset of variables, hierarchical cluster analyses were carried out. We show that clustering into two classes allows the conventional convective and stratiform classes to be determined, whereas classification into five classes allows this convective–stratiform classification to be further refined. Finally, our study made it possible to reveal the presence of some specific relationships between these five classes and the microphysics of their associated rain events.

scholarly journals Rain event properties at the source of the Blue Nile River

2011 ◽  
Vol 15 (3) ◽  
pp. 1023-1034 ◽  
Author(s):  
A. T. Haile ◽  
T. H. M. Rientjes ◽  
E. Habib ◽  
V. Jetten ◽  
M. Gebremichael
Keyword(s):  
Rain Rate ◽  
Rainfall Data ◽  
Nile River ◽  
Rain Event ◽  
Spatial And Temporal Patterns ◽  
Mountain Area ◽  
Event Duration ◽  
Blue Nile ◽  
Event Time ◽  
Rain Events

Abstract. In the present study, spatial and temporal patterns of rain event properties are analysed. These event properties are rain event depth, event duration, mean event rain rate, peak rain rate and the time span between two consecutive rain events which is referred to as inter-event time (IET). In addition, we assessed how rain event properties change when the period over which rainfall data is aggregated changes from 1 to 6 min and when the minimum inter-event time (MIT) changes from 30 min to 8 h. Rainfall data is obtained from a field campaign in two wet seasons of June–August (JJA) of 2007 and 2008 in Gilgel Abbay watershed that is situated at the source basin of the Upper Blue Nile River in Ethiopia. The rainfall data was automatically recorded at eight stations. The results revealed that rain event depth is more related to peak rain rate than to event duration. At the start and towards the end of the wet season, the rain events have larger depth with longer duration and longer IET than those in mid-season. Event rain rate and IET are strongly related to terrain elevation. Sekela which is on a mountain area has the shortest IET while Bahir Dar which is at the south shore of Lake Tana has the longest IET. The period over which rainfall data is aggregated significantly affected the values of rain event properties that are estimated using relatively small value (30 min) of MIT but its effect diminished when the MIT is increased to 8 h. It is shown that increasing the value of MIT has the largest effect on rain event properties of mountain stations that are characterised by high rainfall intermittency.

scholarly journals Continuous Monitoring of Turbidity and Conductivity in Wastewater Networks

2015 ◽  
Vol 28 (1) ◽  
pp. 9-17 ◽  
Author(s):  
Thomas Bersinger ◽  
Isabelle Le Hécho ◽  
Gilles Bareille ◽  
Thierry Pigot ◽  
Alexandre Lecomte
Keyword(s):  
Total Nitrogen ◽  
Continuous Monitoring ◽  
Oxygen Demand ◽  
Rain Event ◽  
Aquatic Life ◽  
Pollutant Concentrations ◽  
Rain Events ◽  
The One ◽  
Continuous Estimation ◽  
The Impact

Continuous monitoring of the sanitation network of the urban catchment of Pau (southwest France) has been performed since March 2012 using rain gauges, flowmeters, as well as turbidity and conductivity probes. Good correlations were obtained between turbidity, total suspended solids (TSS) and chemical oxygen demand (COD) on the one hand, and conductivity and total nitrogen on the other hand. This allowed an instantaneous and continuous estimation of pollutant concentrations and fluxes since that date. In the present paper we focused on the results of October 2012, which was characterized by alternating periods of dry and rainy events. Turbidity and conductivity raw data show different trends during the study period depending on the parameter and the rain events. A turbidity peak is observed at the beginning of each rain event but its amplitude varies with the intensity of the rain and the length of the preceding dry weather period. Conversely, conductivity decrease during each rain event implying, that rain water acts as a dilution factor. The behaviour of COD and total nitrogen differ markedly due to their partitioning between the dissolved (total nitrogen) and particulate phases (COD). Daily pollutant fluxes allow a global comprehension and monitoring of the sewer system. Important COD fluxes during a rain event preceded by a long dry weather period highlight the importance of erosion of sedimentary deposits in the sewerage network. During these events, important fluxes are discharged into receiving water leading to the question of the impact on aquatic life. Generally, these results highlight the potential of online monitoring to better understand the behaviour of the sewer network on long or short time scales. This could be a useful tool to manage wastewater treatment.

scholarly journals Scale invariant events and dry spells for medium-resolution local rain data

2014 ◽  
Vol 21 (2) ◽  
pp. 555-567 ◽  
Author(s):  
A. Deluca ◽  
Á. Corral
Keyword(s):  
Finite Size ◽  
Mediterranean Coast ◽  
Rain Event ◽  
Scale Invariant ◽  
Scaling Properties ◽  
Medium Resolution ◽  
Dry Spells ◽  
Dry Spell ◽  
Rain Events ◽  
Rain Data

Abstract. We analyze distributions of rain-event sizes, rain-event durations, and dry-spell durations for data obtained from a network of 20 rain gauges scattered in a region of the northwestern Mediterranean coast. While power-law distributions model the dry-spell durations with a common exponent 1.50 ± 0.05, density analysis is inconclusive for event sizes and event durations, due to finite size effects. However, we present alternative evidence of the existence of scale invariance in these distributions by means of different data collapses of the distributions. These results demonstrate that scaling properties of rain events and dry spells can also be observed for medium-resolution rain data.

scholarly journals Export of <sup>134</sup>Cs and <sup>137</sup>Cs in the Fukushima river systems at heavy rains by Typhoon Roke in September 2011

2013 ◽  
Vol 10 (2) ◽  
pp. 2767-2790 ◽  
Author(s):  
S. Nagao ◽  
M. Kanamori ◽  
S. Ochiai ◽  
S. Tomihara ◽  
K. Fukushi ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Heavy Rain ◽  
Rain Event ◽  
Normal Flow ◽  
Flow Conditions ◽  
Pulse Input ◽  
Heavy Rain Event ◽  
Coastal Marine ◽  
Rain Events ◽  
Heavy Rains

Abstract. Effects of a heavy rain event on radiocesium export were studied at stations on the Natsui River and the Same River in Fukushima Prefecture, Japan after Typhoon Roke during 21–22 September 2011, six months after the Fukushima Daiichi Nuclear Power Plant accident. Radioactivity of 134Cs and 137Cs in river waters was 0.011–0.098 Bq L−1 at normal flow conditions during July–September in 2011, but it increased to 0.85 Bq L−1 in high flow conditions by heavy rains occurring with the typhoon. The particulate fractions of 134Cs and 137Cs were 21–56% in the normal flow condition, but were close to 100% after the typhoon. These results indicate that the pulse input of radiocesium associated with suspended particles from land to coastal ocean occurred by the heavy rain event. Export flux of 134Cs and 137Cs by the heavy rain accounts for 30–50% of annual radiocesium flux in 2011. Results show that rain events are one factor controlling the transport and dispersion of radiocesium in river watersheds and coastal marine environments.

Impact of a severe rain event on C- and N-DBP precursor removal using IEX

2018 ◽  
Vol 18 (6) ◽  
pp. 2092-2099
Author(s):  
K. Doederer ◽  
Z. Ilieva ◽  
J. Keller
Keyword(s):  
Ion Exchange ◽  
Heavy Rain ◽  
Health Concern ◽  
Rain Event ◽  
Heavy Rain Event ◽  
Removal Capacity ◽  
C And N ◽  
Pre Treatment ◽  
Rain Events ◽  
Magnetic Ion

Abstract During disinfection, dissolved organic matter (DOM) is the major precursor to form disinfection by-products (DBPs), which may be of potential human health concern. Previous research focused on waters of continental climates and less on subtropical environments. However, water sources in subtropical climates are regularly impacted by major rain events during the summer months. This study evaluated the C- and N-DBP precursor removal capacity of two conventional ion exchange (IEX) resins and one magnetic ion exchange (MIEX) resin with a raw water at normal conditions and impacted by a heavy rain event. The rain event introduced 3 mg C/L total organic carbon (TOC) comprised mainly of low to medium molecular weight organics. All three resins were able to remove TOC and DBP precursors (&gt;66%) but being less efficient in reducing turbidity (3–48%) and colour (9–24%). The resin with the smallest bead size was affected the most by the increased medium MW DOM loading resulting in DOM and C-DBP precursor removal performance losses of 10% and 22%. When applied as a pre-treatment for coagulation, MIEX was more efficient in DBP precursor control than coagulation in addressing the additional organic and DBP precursor loading after a heavy rain event.

Concept of neuron types in gustation in the rat

1979 ◽  
Vol 42 (5) ◽  
pp. 1390-1409 ◽  
Author(s):  
D. C. Woolston ◽  
R. P. Erickson
Keyword(s):  
Dimensional Space ◽  
Correlation Coefficients ◽  
Hierarchical Cluster ◽  
Scaling Analysis ◽  
Peripheral Neurons ◽  
Neuron Response ◽  
The Matrix ◽  
Formal Taxonomy ◽  
Response Profiles ◽  
Mathematical Techniques

1. In taste neurophysiology, from Pfaffmann's (49, 50) pioneering work until the present, the possibility of types of neurons corresponding in some sense with the "primary" taste qualities of Henning (33) has been entertained: recently types of gustatory neurons in peripheral nerves have been established according to which of the four classical stimuli is the "best stimulus." However, considerable variation occurs in the response profiles within neurons classified as belonging to the same type. The purpose of this research is to determine, using mathematical techniques where appropriate, if the within-type variation is spurious or, instead, indicates the absence of a typology of taste neurons. The data used were counts of the spike discharges of 50 individual taste neurons in the nucleus of the solitary tract of the rat, evoked by 32 diverse chemical stimuli. 2. Using as input the matrix of Pearson r correlation coefficients calculated for the responses of all pairings of neurons to all stimuli, multidimensional scaling analysis revealed a two-dimensional space in which no clear groupings of neurons occurred. 3. In a hierarchical cluster analysis of the neuron response profile similarities, no evidence of grouping was found, suggesting a more-or-less continuous variation among neurons. 4. When the organization of the 32 stimuli utilized was studied by the same techniques, no clear evidence for stimulus types was found, although the possibility of two stimulus types--"sweet" and "nonsweet"--was raised. 5. Construction of a joint neuron-stimulus space supported a spatial model of taste neuron-stimulus interaction, while analysis of the number and pattern of high correlations among neurons--even after allowance for attenuation due to measurement error--failed to support the notion of types of taste neurons with identical response profiles. 6. Aspects of the logical role of types of neurons in gustatory coding were discussed, and the results and methods of the present investigation were related to classification schemes for neurons in general. Suggestions for a formal taxonomy of neurons were given. 7. It should be emphasized that the present study and conclusions are of second-order, CNS neurons, whereas the studies advocating the presence of neurons types were of peripheral neurons. Taken together, the implication to be drawn from these studies is that if neural types do exist in peripheral taste nerves, the typology is lost at the first synapse and is thus unavailable to the CNS for coding purposes, at least in the rat.

scholarly journals Changing character of rainfall in eastern China, 1951–2007

2018 ◽  
Vol 115 (9) ◽  
pp. 2016-2021 ◽  
Author(s):  
Jesse A. Day ◽  
Inez Fung ◽  
Weihan Liu
Keyword(s):  
Summer Monsoon ◽  
East Asian Summer Monsoon ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Eastern China ◽  
East China ◽  
Northwestern Pacific ◽  
Rain Event ◽  
Asian Summer ◽  
Rain Events

The topography and continental configuration of East Asia favor the year-round existence of storm tracks that extend thousands of kilometers from China into the northwestern Pacific Ocean, producing zonally elongated patterns of rainfall that we call “frontal rain events.” In spring and early summer (known as “Meiyu Season”), frontal rainfall intensifies and shifts northward during a series of stages collectively known as the East Asian summer monsoon. Using a technique called the Frontal Rain Event Detection Algorithm, we create a daily catalog of all frontal rain events in east China during 1951–2007, quantify their attributes, and classify all rainfall on each day as either frontal, resulting from large-scale convergence, or nonfrontal, produced by local buoyancy, topography, or typhoons. Our climatology shows that the East Asian summer monsoon consists of a series of coupled changes in frontal rain event frequency, latitude, and daily accumulation. Furthermore, decadal changes in the amount and distribution of rainfall in east China are overwhelmingly due to changes in frontal rainfall. We attribute the “South Flood–North Drought” pattern observed beginning in the 1980s to changes in the frequency of frontal rain events, while the years 1994–2007 witnessed an uptick in event daily accumulation relative to the rest of the study years. This particular signature may reflect the relative impacts of global warming, aerosol loading, and natural variability on regional rainfall, potentially via shifting the East Asian jet stream.

scholarly journals Characterization of S-Band Dual-Polarized Radar Data for the Convective Rain Melting Layer Detection in A Tropical Region

2018 ◽  
Vol 10 (11) ◽  
pp. 1740 ◽  
Author(s):  
Feng Yuan ◽  
Yee Lee ◽  
Yu Meng ◽  
Jin Ong
Keyword(s):  
Radar Data ◽  
Tropical Region ◽  
Rain Event ◽  
Melting Layer ◽  
Convective Rain ◽  
Radar Measurements ◽  
Dual Polarized ◽  
Rain Events ◽  
Differential Reflectivity

In the tropical region, convective rain is a dominant rain event. However, very little information is known about the convective rain melting layer. In this paper, S-band dual-polarized radar data is studied in order to identify both the stratiform and convective rain melting layers in the tropical region, with a focus on the convective events. By studying and analyzing the above-mentioned two types of rain events, amongst three radar measurements of reflectivity ( Z ), differential reflectivity ( Z DR ), and cross correlation coefficient ( ρ HV ), the latter one is the best indicator for convective rain melting layer detection. From two years (2014 and 2015) of radar and radiosonde observations, 13 convective rain melting layers are identified with available 0 °C isothermal heights which are derived from radiosonde vertical profiles. By comparing the melting layer top heights with the corresponding 0 °C isothermal heights, it is found that for convective rain events, the threshold to detect melting layer should be modified to ρ HV = 0.95 for the tropical region. The melting layer top and bottom heights are then estimated using the proposed threshold, and it is observed from this study that the thickness of convective rain melting layer is around 2 times that of stratiform rain melting layer which is detected by using the conventional ρ HV = 0.97 .

Modelling the total ammonia impact of CSO and WWTP effluent on the receiving water

1998 ◽  
Vol 38 (10) ◽  
pp. 31-39 ◽  
Author(s):  
Peter Holzer ◽  
Peter Krebs
Keyword(s):  
Treatment Plant ◽  
Rain Event ◽  
Combined System ◽  
Sewer System ◽  
Wwtp Effluent ◽  
Fish Poison ◽  
Combined Sewer ◽  
Total Ammonia ◽  
High Concentrations ◽  
Rain Events

For 25 rain events test runs were performed on a catchment of a small town, where 40% of the person equivalents are connected to a separate sewer system and 60% to a combined one. We investigate the effects of rain events with regard to NH4-loads discharged by the wastewater treatment plant and by a combined sewer overflow. NH4-concentrations in the river caused by these loads are also discussed. NH4 is important as (i) it closely interrelates with NH3 – a fish poison – and (ii) it stands for dissolved compounds that mainly origin from the wastewater. The sewer system is simulated with three different options: with a combined water retention tank connected to the CSO structure, with a sewage retention tank at the interface between the separate and the combined system, and without any retention structure. While the sewage retention tank performs better concerning the integrated load discharged into the river, the combined sewer retention tank is more efficient in decreasing peak values and duration of high concentrations in the river. We also show that NH4 peak concentrations in the river are largely due to a wash-out effect in the main sewer at the beginning of a rain event.

Sign in / Sign up

Export Citation Format

Share Document