Large Amount Of Precipitation Research Articles

WRF model sensitivity for simulating intense western disturbances over North West India

During winter season, large amount of precipitation is received in the Northwestern part of India due to eastward moving low pressure synoptic weather systems called western disturbances (WDs). These WD’s disturbs the life in Northern India with heavy precipitation, cold wave and fog. The objective of the present study is to examine model sensitivity of different physical parameterization schemes incorporated in the weather research and forecasting model and to identify a combination of the best physics options suited for this region during the passage of a western disturbance. Four cases of intense western disturbances 13–17 January 2002 (case-1), 5–8 February 2002 (case-2), 16–19 January 2013 (case-3) and 4–7 February 2013 (case-4) which affected the northwest India has been simulated with different physics configurations in the model. The model simulation from different physics configurations are validated with the observational datasets and error statistics are presented. It is found that, the performance of the combination of National Severe Storms Laboratory one moment, Kain–Fritsch, Yonsei University, rapid radiative transfer model and Dudhia schemes as a microphysics, cumulus, planetary boundary layer, longwave radiation and shortwave radiation parameterization schemes respectively gives a better simulation of the weather during WD’s over this region. It is found that, in all WD cases intensity and movement of the precipitation, circulation and low pressure area (geopotential height) over the region is well predicted by the model.

Performance of double cropping and relay intercropping for black soybean production in small-scale farms

We investigated the soybean productivity of double cropping and relay intercropping in farmer’s fields for three years using two black soybean cultivars of Kurozukin and Tanbaguro, which are used for the first and second crop, respectively. Kurozukin is the early maturing cultivar for vegetable soybean harvest and Tanbaguro is the late-maturing cultivar for the harvest of vegetable soybean and seeds. The yield of the first crop (Kurozukin) was similar to the mono cropping regardless of cropping patterns. However, the yield of the second crop (Tanbaguro) was affected by cropping patterns. The yield of Tanbaguro in double cropping was prone to decrease by late sowing. The late sowing was induced by the late sowing and late harvesting of Kurozukin because of the low temperature in April and the large amount of precipitation in rainy season, respectively. In relay intercropping that Tanbaguro was sown between the rows of Kurozukin at about one month before the harvest of Kurozukin, the yield of Tanbaguro was similar to the mono cropping and the competition with Kurozukin was not observed. Thus, the land equivalent ratio value of double cropping was lower than that of relay intercropping. These results suggest that relay intercropping is more useful cultivation system than double cropping to increase the annual soybean production.

The influence of deep cryogenic treatment on the properties of high-vanadium alloy steel

Deep cryogenic treatment can improve the mechanical properties of many metallic materials, but there are few reports of the effect of deep cryogenic treatment on high-vanadium alloy steel. The main objective of this work is to investigate the effect of deep cryogenic treatment on the microstructure, hardness, impact toughness and abrasive wear resistance of high-vanadium alloy steel. The results show that large amounts of small secondary carbide precipitation after deep cryogenic treatment and microcracks were detected and occurred preferentially at carbide/matrix interfaces; except for the hardness, the mechanical properties increased compared to those of the conventional treatment sample. By increasing the deep cryogenic processing time and cycle number, impact toughness and abrasive wear resistance can be further improved, the carbide contents continuously increase, and the hardness decreases.

Effect of microalloying with Ca on the microstructure and mechanical properties of Mg-6 mass%Zn alloys

The Mg-6 mass%Zn alloys microalloyed with different amounts of Ca were cast and extruded. The second phase in the as-cast Mg-6Zn alloy is Mg4Zn7, which is replaced by Ca2Mg6Zn3 with an increase of Ca addition. Microalloying by Ca affects the grain size, dynamic recrystallization, and dynamic precipitation of Mg-6Zn alloys during extrusion. The Ca addition inhibits dynamic recrystallization and grain growth due to the pinning effect of fine precipitates, giving rise to fine dynamic recrystallized grains. A large amount of precipitates is observed in the Ca containing alloys after extrusion. Ca effectively improves strength of the as-extruded Mg-6Zn alloy, which is mainly attributed to refined dynamic recrystallized grains, dense precipitates, and deformed regions with high-density dislocations and strong basal texture.

Effect of Soda Ash on Properties of Mold Flux and Mineralogical Structures of Flux Film

AbstractDuring continuous casting, properties of mold flux and mineralogical structures of flux film play important roles in controlling steel quality. The effect of soda ash on the physical properties and crystallization characteristics of mold flux was investigated using process mineralogy, including polarizing microscopy, X-ray diffraction, and electron microprobe, etc. Mold flux was mainly prepared using cement clinker and industrial mineral materials under laboratory conditions, and the mineralogical structures of the flux film were systematically identified and quantitatively analyzed. The results showed that, by increasing the soda ash content from 10 mass% to 18 mass%, the crystallization temperature, critical cooling rate and crystallization ratio of the flux film decreased, but the crystallization ratio still reached 75% after adding soda ash, and the mineral compositions and microstructures of the flux film changed slightly. When the soda ash content exceeded 14 mass%, the critical cooling rate and the crystallization ratio decreased slightly, whereas the mineral content of the flux film changed evidently, with a large amount of cuspidine precipitation and a significant decrease in the wollastonite content until it reached zero, which resulted in deterioration of the lubrication of the flux film.

Mechanisms producing different precipitation patterns over north‐eastern Italy: insights from HyMeX‐SOP1 and previous events

During the first HyMeX Special Observation Period (SOP1) field campaign, the target site of north‐eastern Italy (NEI) experienced a large amount of precipitation, locally exceeding the climatological values and distributed among several heavy‐rainfall episodes. In particular, two events that occurred during the last period of the campaign drew our attention. These events had common large‐scale patterns and a similar mesoscale setting, characterised by southerly low‐level flow interacting with the Alpine orography, but the precipitation distribution was very different. During Intensive Observing Period IOP18 (31 October–1 November 2012), convective systems were responsible for intense rainfall mainly located over a flat area of the eastern Po Valley, well upstream of the orography. Conversely, during IOP19 (4/5 November 2012), heavy precipitation affected only the Alpine area. In addition to IOP18 and IOP19, the present study analyses other heavy‐precipitation episodes that display similar characteristics and which occurred over NEI during the autumn of recent years. A high‐resolution (2 km grid spacing) non‐hydrostatic NWP model and available observations are used for this purpose.The two different observed precipitation patterns are explained in terms of interaction between the impinging flow and the Alps. Depending on the thermodynamic profile, convection can be triggered when the impinging flow is forced to rise over a pre‐existing cold‐air layer at the base of the orography. In this situation a persistent blocked‐flow condition and upstream convergence are responsible for heavy rain localized over the plain. Conversely, if convection does not develop, flow‐over conditions are established and heavy rain affects the Alps. Numerical parameters proposed in the literature are used to support the analysis.Finally, the role of evaporative cooling beneath the convective systems is evaluated. It turns out that the stationarity of the systems upstream of the Alps is mainly attributable to persistent blocked‐flow conditions, while convective outflow slightly modifies the location of precipitation.

SPATIAL AND TEMPORAL MONITORING OF SNOW COVERAGE LEVEL USING NOAA SATELLITE IMAGES: A CASE STUDY OF BALIGHLOUCHAY BASIN

A large amount of precipitation in the mountainous areas of the North West of Iran, especially in the cold seasons of the year, is in the form of snow; therefore, water from melting snow has an important role in the formation of surface runoff, recharge of the aquifers, and flooding. Balighlouchay basin with an area of 1245.7 km2 is located in Ardabil province. Snow is considered as a prevailing climatic phenomenon of this region in winter. This basin has an important role in supplying water for domestic and agricultural sectors. In the present study, changes in the level of snow coverage were investigated during winter, in a period of 5 years (2009- 2013).To this end, NOAA-AVHRR satellite images and NDSI algorithm were used. The results showed that, the North West and South West of the region due to the existence of Sabalan Mountains and highlands of Bozghoush have a good condition for having snow. The results also showed that, the maximum level of snow coverage in this basin is related to December of 2009 with an area of 1205.7 km2 (96.7%), and the minimum level of snow coverage is related to December of 2010 with an area of 33.8 km2 (2.7%).This represents severe changes of snow coverage in the studied area and it shows vulnerability of water resources dependent on snowmelt.

Comparative risk assessment of exploitation of old and new thermal power plant's ash disposal sites in Kostolac, according to hydrological scenario

In this paper a comparative risk assessment of the exploitation of old and new ash disposal sites in Kostolac is given. Risk assessment is carried out according to the FMEA (Failure Modes and Effects Analysis) method in combination with a risk matrix, which includes a detailed elaboration of potential accident scenario at disposal sites and analysis of consequences that accident can cause. As a potential accident scenario only hydrological scenario is taken into consideration, which is based on the influx of large amounts of precipitation, the cause of the largest number of accidents at industrial disposal sites. Analyses of environmental consequences, potential human losses and economic consequences are given. According to the risk matrix it is found that both of disposal sites are in the 'blue' zone of risk, which is interpreted as a tolerable level of risk, although the new disposal site is still in a better position than the old one because the expected level of risk is lower by one degree.

Atmospheric deposition of mercury in central Poland: Sources and seasonal trends

Atmospheric deposition of total mercury was studied at two sites in central Poland, between April 2013 and October 2014. Hg in rainwater (bulk deposition) was analyzed in relation to meteorological parameters and major ions (H+, NO3−, Cl−, SO42−) in order to investigate seasonal variation, identify sources and determine factors affecting atmospheric Hg chemistry and deposition. Total mercury concentrations varied between 1.24 and 22.1ngL−1 at the urban sampling site (Poznań) and between 0.57 and 18.3ngL−1 in the woodland protected area (Jeziory), with quite similar mean values of 6.96 and 6.37ngL−1, respectively. Mercury in precipitation exhibited lower spatial variability within the study domain (urban/forest transect) than the concentrations determined during other similar observations, reflecting the predominant influence of the same local sources. In our study, a significant seasonal pattern of Hg deposition was observed at both sampling sites, with higher and more variable concentrations of Hg reported for the urban area. In particular, deposition values of Hg were higher in the samples attributed to relatively large precipitation amounts in the summer and in those collected during the winter season (the result of higher contributions from combustion sources, i.e. intensive combustion of fossil fuels in residential and commercial boilers, individual power/heat-generating plants). In addition, a significant relationship between Hg concentration and precipitation amount was found while considering different types of wintertime samples (i.e. rain, snow and mixed precipitation). The analysis of backward trajectories showed that air masses arriving from polluted regions of western Europe and southern Poland largely affected the amount of Hg in rainwater. A seasonal variation in Hg deposition fluxes was also observed, with the maximum value of Hg in spring and minimum in winter. Our results indicated that rainwater Hg and, consequently, the wet deposition flux of Hg are related to seasonal differences in precipitation (type, intensity, amount) and the emission source.

Initiation of the last ice age in Canada by extreme precipitation resulting from a cascade of oceanic salinity increases

Numerical modeling has failed to confirm the classical Milankovitch hypothesis of initiation of the last ice age by Northern Hemisphere high latitude cooling due to decreasing summer insolation caused by orbital effects. The modeling failed to confirm ice sheet growth even with a widespread layer of glacial ice as an initial condition to embody positive feedback. The failure probably occurred because the initial conditions of the calculation did not include the actual effects of an altered climate in northeastern Canada that brought a sharp cooling to Europe and extreme amounts of precipitation to cloud-covered lands west of Greenland. In the conceptual model proposed here, diminishing orbital summer insolation in northern Africa is causally linked to this regional climate change by a cascade of oceanic salinity changes. The summer cooling in northern Africa weakened the monsoons, reduced the Nile River flow, and increased Mediterranean salinity and outflow at Gibraltar. The salt in the outflow contributes substantially to the salinities of the North Atlantic Drift and the Greenland Sea, to the formation rate of North Atlantic Deep Water (NADW) there, and to the northward flow of the Spitsbergen-Atlantic Current (SAC) that replaces the sinking NADW. When the increasing salt in the Mediterranean outflow made the SAC replacement flow sufficiently strong, the flow penetrated into the polar ocean along the north coast of Greenland. Denser and more saline Atlantic water then replaced the polar water flowing southward into Baffin Bay through the Nares Strait and Lancaster Sound, thus eliminating the stratification in the bay that enables freezing of winter sea ice. Without the southward flow of sea ice out of Baffin Bay, the Labrador Sea became much warmer. The warmer seas west of Greenland then triggered a persistent cyclonic circulation that caused large amounts of precipitation in eastern Canada and a much colder northern Europe. The resulting Canadian erosion yielded a 500yr-long deep-sea sediment record of the ice-free condition. Heavy snowfall started new ice sheet growth on Baffin Island, northern Quebec, Labrador, western Greenland, and the Barents Sea, causing world sea level to fall at a rate of 0.5cmyr-1. The modern increasing salinity of the Mediterranean Sea and extension of SAC flow into the polar ocean are now following the cascade steps toward an ice-free Baffin Bay and possible near term regional climate deterioration.

Effect of high Mn content on development of ultra-fine grain extruded magnesium alloy

High Mn content added to Mg–6Zn–0.3Ca extruded alloy remarkably refined dynamically recrystallized (DRXed) grains, and enhanced tensile and compressive strengths without sacrificing ductility. The large amount of fine Mn precipitates of homogenized alloy that formed effectively restricted new grain growth during the subsequent extrusion and generated ultra-fine DRXed grains. The ultra-fine DRXed grains and large amount of precipitates essentially enhanced the strength and improved the anisotropy of alloy. The Mg–Mn–x ternary systems that potentially formed ultra-fine grains were also discussed.

On the sluggish recrystallization of a cold-rolled Al–Mn–Fe–Si alloy

Annealing of supersaturated AA3xxx alloys at low temperatures usually results in sluggish recrystallization kinetics. This is due to the joint effect of the following factors: low nucleation rate, reduced grain boundary mobility, and large amount of fine precipitates (dispersoids). In this paper, samples of Al–Mn–Fe–Si alloy were appropriately homogenized in different conditions to produce different microchemistries before deformation, i.e. solutes and second-phase particles. The sluggish recrystallization behaviour of these cold-rolled Al–Mn–Fe–Si samples annealed in three different conditions was then investigated, the first condition being recrystallization without precipitation, followed by recrystallization and precipitation occurring concurrently, and finally precipitation occurring before recrystallization. The results clearly show that in all these conditions, an incubation time is involved, which decreases with increasing annealing temperature and cold deformation, as well as with decreasing solute amount. Qualitative analysis of the microstructure evolution after a sudden increase of annealing temperature suggests that the effective retarding force from solute and/or particles decreases at higher temperatures. When recrystallization occurs concurrently with precipitation, the growth of successful nuclei can still be suppressed by concurrent precipitation.

Martensitic transformation, shape memory effect and mechanical properties of dual-phase Ni50−xTbxMn30Ga20 (x=0–1) alloys

The addition of rare earth elements (RE) is an effective way to improve the mechanical properties of Ni–Mn–Ga alloys. Unlike previous investigations which were completely focused on the N–Mn–(Ga,RE) alloys, in this work Ni50−xTbxMn30Ga20 (x=0–1) alloys in the form of (Ni,RE)–Mn–Ga were systematically studied with the microstructure, martensitic transformation, shape memory effect and mechanical properties. Dual-phase microstructure containing body-centered tetragonal martensite and Tb-rich hexagonal precipitates were formed. With the increasing Tb content, the volume fraction of the precipitates was also increased. Yet stable martensitic transformation occurring at about 80°C was observed over the whole composition range. Both the transformation temperatures and hysteresis (∼11°C) were quite insensitive to the composition variation. Sizable shape memory effect is obtained in all the polycrytalline alloys. Shape memory effect of 2.68% was detected for the alloy x=1 with large amount of precipitate. With the increasing volume fraction of precipitates both the compressive strength and strain were well increased for x≤0.2 and gradually decreased for 0.2≤x≤1. The transition of fracture mode from intergranular fracture to transgranular fracture and then to interphase fracture was revealed to contribute to the evolution of the mechanical properties.

Large-scale circulation classification and its links to observed precipitation in the eastern and central Tibetan Plateau

The relationship between the large-scale circulation dynamics and regional precipitation regime in the Tibetan Plateau (TP) has so far not been well understood. In this study, we classify the circulation types using the self-organizing maps based on the daily field of 500 hPa geopotential height and link them to the precipitation climatology in the eastern and central TP. By virtue of an objective determining method, 18 circulation types are quantified. The results show that the large amount of precipitation in summer is closely related to the circulation types in which the enhanced and northward shifted subtropical high (SH) over the northwest Pacific and the obvious cyclconic circulation anomaly over the Bay of Bengal are helpful for the Indian summer monsoon and East Asian summer monsoon to take abundant low-latitude moisture to the eastern and southern TP. On the contrary, the dry winter in the central and eastern Tibet corresponds to the circulation types with divergence over the central and eastern TP and the water vapor transportations of East Asian winter monsoon and mid-latitude westerly are very weak. Some circulation types are associated with some well-known circulation patterns/monsoons influencing the TP (e.g. East Atlantic Pattern, El Nino Southern Oscillation, Indian Summer Monsoon and the mid-latitude westerly), and exhibit an overall good potential for explaining the variability of regional seasonal precipitation. Moreover, the climate shift signals in the late 1970s over the eastern Pacific/North Pacific Oceans could also be reflected by both the variability of some circulation types and their correspondingly composite precipitations. This study extends our understandings for the large-scale atmospheric dynamics and their linkages with regional precipitation and is beneficial for the climate change projection and related adaptation activities in the highest and largest plateau in the world.

STUDY ON σ PHASE PRECIPITATION OF HR3C STEEL USED IN ULTRA-SUPERCRITICAL BOILER

HR3C steel is a new type of austenitic heat-resistant steel which has been widely used for super- heater and re-heater tubes in the ultra-supercritical (USC) boiler. The mechanical properties of HR3C steel were de- pendent on the stability of the microstructure, particularly the large amount of precipitates formed during service. The precipitation of s phase in HR3C steel during long-term aging for 2000 h at temperature of 700 and 750 ℃ was investigated by OM, SEM and TEM. The phase calculation method was applied to understand the factors in- fluencing the precipitation. After 1000 h of the aging duration, irregular mass second phase was found to pre- cipitate at the grain boundary, followed by the subsequent increasing and coarsening with time. The constituent ele- ments of the phases were determined as Fe and Cr through SEM equipped with EDS. Further SAED analysis re- sults led to the confirmation that these phases were basically s-FeCr compound. Combined with the prediction made through New PHACOMP method, the microstructure or phase structure in initial state may affect the subse-

Comparison of the 2011 Mississippi River Flood to the MR-T Project Design Flood

AbstractDuring the period of April 19 to May 4, 2011, an unusually large amount of precipitation fell across the middle to lower portion of the Mississippi River basin and resulted in record flooding in many locations. The greatest amount of moisture, with rainfall totals near or in excess of 508 mm (20 in.), was located throughout northern Arkansas, southern Missouri, far southern Illinois, and western Kentucky. This study determined, using the procedures outlined in the Manual on Estimation of Probable Maximum Precipitation of the World Meteorological Organization (WMO), the extent of how much more precipitation could have occurred in the same region from the same storms if the maximum possible amount of moisture had been available. A detailed examination of the synoptic weather conditions from mid-April through early May in 2011 indicated that two distinct systems affected the region with heavy rainfall during that period. National Weather Service radar and surface observation data from each storm was ...

Enhanced flux pinning properties in Bi-2212 high temperature superconductors with nano-sized precipitates

Al doped Bi-2212 superconducting bulks with large amounts of nano-sized precipitates have been fabricated by spark plasma sintering (SPS) and subsequent annealing under oxygen. Due to the interferences of Al doping, alkali earth cuprates (AEC, (Ca, Sr)xCuyOz) have precipitated and formed the nanoparticles distributed uniformly in the Bi-2212 matrix. The influences of these precipitates and Al doping on the microstructures, transport and superconducting properties, especially the flux pinning properties have been systematically investigated. The point flux pinning mechanism has been obviously enhanced with the appearance of precipitates. The effects of these nano-sized precipitates on the enhancements of flux pinning properties in Bi-2212 bulks under magnetic field have been proved by both the increased activation energy and the improved flux pinning force.

Influence of eastern Pacific and central Pacific El Niño events on winter climate extremes over the eastern and central United States

ABSTRACTDifferent influences of the eastern‐Pacific (EP) El Niño and central‐Pacific (CP) El Niño on nine winter extreme indices over the eastern and central United States are examined through composite analysis of high‐resolution daily maximum temperature, minimum temperature, and precipitation for the period 1950–2010. During EP El Niño winters, there are usually more warm days and warm nights, fewer frost days, cold days, and cold nights over the eastern and central United States than in winters with a CP El Niño, especially for the Ohio Valley, around the Great Lakes, and southern New England. For precipitation extremes, compared with CP El Niño, EP El Niño usually brings more extreme precipitation amounts, more days with large precipitation amounts, larger amounts of maximum consecutive 5‐day total precipitation, and a shorter duration of consecutive dry days around the Great Lakes and Ohio Valley. The 500 hPa geopotential height anomalies show that wave train patterns differ when the maximum tropical sea surface heating locations are displaced. The corresponding wind field and moisture convergence anomalies are examined to analyse the mechanisms that drive the anomaly fields associated with the two types of El Niño events.

Microstructural control and hardening response of Mg–6Zn–0.5Er–0.5Ca alloy

The effects of heat treatment on microstructures and hardening response of Mg–6Zn–0.5Er–0.5Ca (wt%) alloy were investigated by optical microscope (OM), scanning electron microscope (SEM), and transmission electron microscope (TEM) in this paper. The results show that the Mg–6Zn–0.5Er–0.5Ca alloy contains Mg3Zn6Er1 quasicrystalline phase (I-phase) and Ca2Mg6Zn3 phase under as-cast condition. Most of the Ca2Mg6Zn3 phases and I-phases dissolve into matrix during heat treatment at 475 °C for 5 h. After the as-solution alloy was aged at 175 °C for 36 h, a large amount of MgZn2 precipitate with several nanometers precipitate. It is suggested that the trace addition of Ca results in refining the size of the precipitate, and the presence of the nanoscale MgZn2 phase is the main factor to improve the peak-aged hardness greatly to 87 HV, which increases about 40 % compared with that of as-cast alloy.

Composition Optimization and Experimental Characterization of a Novel Steel Based on CALPHAD

A new steel with high Cr and low W, Mo contents for forged cold work roll was designed based on the composition system of traditional high-speed steel roll. The Fe-C isopleths of the steel and the mass fraction of equilibrium phases versus temperature were calculated by Thermo-Calc, and the effects of different alloying elements (W, Mo, Cr, V) on austenite, ferrite, and carbides (MC, M6C, M7C3, M23C6) were also established to optimize the composition and structure. The designed and optimized specimens were both quenched at 1100 °C and then tempered twice at 560 °C. The hardness and wear resistance of the samples were measured. The microstructures of quenched tempered and forged specimens were studied. The results show that ferrite crystallization, peritectic reaction, austenite crystallization, and the precipitation of MC, M6C, M7C3, M23C6 occur during equilibrium solidification process. The alloying elements W, Mo mainly affect the precipitation of M6C, while Cr affects the precipitated region and mass fraction of M7C3. Higher V content widens the high-temperature region of the peritectic reaction and results in a large amount of MC precipitation. The optimized composition (wt.%) for cold work roll steel is 1.30-1.35%C, 9-10%Cr, 2.5-3.0%Mo, 0.5-1.0%W, 2.5-3.0%V, 0.5-0.6%Mn, 0.5-0.6%Si. The hardness of the steel after quenching and tempering is 60.8 HRC and weight loss after 120 min is 6.2 mg. This meets the requirement of hardness and wear resistance requirements for cold work roll. The ledeburite in the optimized steel disappears after forging and the carbide network break into a large amount of tiny blocky ones dispersed in the matrix without cracks, which shows a good forgeability of the steel and rationality of the optimized composition.