SW Flow Research Articles

A theoretical analysis on the operating and design parameters affecting the performance of a sewage wastewater sourced heat pump system

Sewage wastewater heat exchanger (SWHE) has a significant role in the performance of sewage wastewater sourced heat pump (SWSHP) system as it provides to transfer the energy of wastewater to intermediary fluid or working fluid. Thus, a theoretical analysis of the SWSHP system was carried out to investigate the effects of SWHE design parameters on the system ’s performance. For this purpose, a simulation program based on the proposed mathematical model of the SWSHP system was developed in MATLAB. Afterward, the indirect type SWSHP system that can meet 50 kW heating load was theoretically designed. The influences of SW temperature, its mass flow rate, the inner diameter of the heat exchanger tube, and intermediary fluid mass flow rate on the performance of the designed SWSHP system were analyzed. The results indicate that variation of SW temperature affects the COPsys more than the variation of SW mass flow rate. Considering the ranges of parameters investigated, the COPsys raises from 2.56 to 4.51 and 2.89 to 4.27 with the variations of SW temperature and SW flow rate, respectively. Moreover, an increase in the intermediary fluid mass flow rate provides an improvement on the COPsys and COPunit. However, SWSHP performance is adversely affected by the increasing value of the inner diameter of the tubes. As a result, small changes in the design parameters of the SWHE directly affect the system performance and system operating conditions.

Synoptic circulation patterns associated with foehn days in Sofia in the period 1979–2014

Foehn is a well-known example of local atmospheric circulation and is an extreme weather event for wind gusts. It can cause rapid snowmelt in spring or spread of forest fire in summer, as well as significant economic losses. The foehn in Bulgaria is observed on the northern slopes of the mountains. For the period 1979–2014, 261 foehn days are registered north of the Vitosha mountain, where Sofia valley is located. The average annual number of foehn days is 8.1, 8.3, and 4.5 for the periods 1985–1994, 1995– 2004, and 2005–2014. After 2004, the average annual number of days with foehn decreases, and the lowest maximum wind gusts are registered. To check whether atmospheric circulation changes, could be the reason for this change two objective circulation classifications and a manual one are used to study the foehn occurrence in the Sofia valley. Based on the GrossWettertypen (GWT) catalogue of circulation patterns produced by the COST Action 733 and ten circulation types of the Jenkinson-Collison (JCT) catalogue of weather types the largest number of foehn days occur at the SW, W, and NW circulation patterns. GWT and JCT classifications with 26 types confirm the foehn occurrence during the W and SW flows, but add two more cyclonic types, the CW and CSW. For the foehn days in March 1979–2014, best agreement was found with the manual circulation classification with 26 types. A comparison between the decades 1995–2004 and 2005–2014 shows a substantial decrease in western and northwestern circulation types during the foehn days. An analysis of circulation types for all days confirms an overall reduction of W and NW circulation types after 2004.

A green strategy for obtaining anthraquinones from Rheum tanguticum by subcritical water

AbstractRheum tanguticum is a traditional Chinese herbal medicine, which contains abundant anthraquinones. In this study, anthraquinones were efficiently extracted from Rheum tanguticum by subcritical water extraction (SWE). The parameters of extraction time (33–67 min), temperature (100–200°C), and SW flow rate (1.4–4.6 mL/min) were optimized so as to achieve a high yield of the target product. A high yield of the total anthraquinones was achieved under the optimized SWE conditions of extraction time 54 min, extraction temperature 170°C, and the flow rate 2.0 mL/min. The comparison between the SWE and traditional extraction techniques implied that the SWE is an efficient and green alternative method for the extraction of anthraquinones. Four anthraquinone glycosides were purified from the SWE extract by high-speed counter-current chromatography and identified as emodin-1-O-β-D-glucoside, physcion-8-O-β-D-glucopyranoside, chrysophanol-1-O-β-D-glucoside, and chrysophanol-8-O-β-D-glucoside.

Subcritical Water Extraction of Sesquiterpene Lactones from Inula racemose

AbstractInula racemose, a traditional Tibetan medicine with strong antifungal and anti‐inflammatory activities, contains large amounts of sesquiterpene lactones. In the current study, subcritical water extraction was employed for the efficient extraction sesquiterpene lactones from I. racemose. Various parameters, such as extraction time (23.2‐56.8 min), temperature (129.5‐230.5 °C) and SW flow rate (1.3‐4.7 mL/min) was investigated for optimizing the recovery of the targeted compounds. The optimal conditions for SWE were determined as follows: extraction time of 45 min, extraction temperature of 190 °C, and SW flow rate of 3.0 mL/min, and a recovery of 71.97% was achieved. Four sesquiterpene lactone isomers were separated by prep‐HPLC from the SWE extract and identified as igalan, isoalantolactone, alantolactone, and alloantolactone. A comparison of SWE with traditional extraction technologies showed that subcritical water could be a green and efficient substitution for the extraction of sesquiterpene lactones from I. racemose.

Subglacial and ice‐marginal landforms in south‐central Ontario: implications for ice‐sheet reconfiguration during deglaciation

Regional‐scale, high‐resolution terrain data permit the study of landforms across south‐central Ontario, where the bed of the former Laurentide Ice Sheet is well exposed and passes downflow from irregular topography on Precambrian Shield highlands to flat‐lying Palaeozoic carbonate bedrock, and thick (50 to >200 m) unconsolidated sediment substrates. Rock drumlins and megagrooves are eroded into bedrock and mega‐scale glacial lineations (MSGL) occur on patchy streamlined till residuals in the Algonquin Highlands. Downflow, MSGL pass into juxtaposed rock and drift drumlins on Palaeozoic bedrock and predominantly till‐cored drumlins in areas of thick drift. The Lake Simcoe Moraines, now traceable for more than 80 km across the Peterborough drumlin field (PDF), form a distinct morphological boundary: downflow of the moraine system, drumlins are larger, broader and show no indication of subsequent reworking by the ice, whereas upflow of the moraines, a higher degree of complexity in bedform pattern and morphology is distinguished. Discrete radial and/or cross‐cutting flowset terminate at subtle till‐cored moraine ridges downflow of local topographic lows, indicating multiple phases of late‐stage ice flow with strong local topographic steering. More regional‐scale flow switching is evident as NW‐orientated bedforms modify drumlins south of the Oak Ridges Moraine, and radial flowset emanate from areas within the St. Lawrence and Ottawa River valleys. Most of the drumlins in the PDF formed during an early, regional drumlinization phase of NE–SW flow that followed the deposition of a thick regional till sheet. These were subsequently modified by local‐scale, topographically controlled flows that terminate at till‐cored moraines, providing evidence that the superimposed bedforms record dynamic ice (re)advances throughout the deglaciation of south‐central Ontario. The patterns and relationships of glacial landform distribution and characteristics in south‐central Ontario hold significance for many modern and palaeo‐ice sheets, where similar downflow changes in bed topography and substrate lithology are observed.

Spatial variability of the relationships of runoff and sediment yield with weather types throughout the Mediterranean basin

Soil degradation by water is a serious environmental problem worldwide, with specific climatic factors being the major causes. We investigated the relationships between synoptic atmospheric patterns (i.e. weather types, WTs) and runoff, erosion and sediment yield throughout the Mediterranean basin by analyzing a large database of natural rainfall events at 68 research sites in 9 countries. Principal Component Analysis (PCA) was used to identify spatial relationships of the different WTs including three hydro-sedimentary variables: rainfall, runoff, and sediment yield (SY, used to refer to both soil erosion measured at plot scale and sediment yield registered at catchment scale). The results indicated 4 spatial classes of rainfall and runoff: (a) northern sites dependent on North (N) and North West (NW) flows; (b) eastern sites dependent on E and NE flows; (c) southern sites dependent on S and SE flows; and, finally, (d) western sites dependent on W and SW flows. Conversely, three spatial classes are identified for SY characterized by: (a) N and NE flows in northern sites (b) E flows in eastern sites, and (c) W and SW flows in western sites. Most of the rainfall, runoff and SY occurred during a small number of daily events, and just a few WTs accounted for large percentages of the total. Our results confirm that characterization by WT improves understanding of the general conditions under which runoff and SY occur, and provides useful information for understanding the spatial variability of runoff, and SY throughout the Mediterranean basin. The approach used here could be useful to aid of the design of regional water management and soil conservation measures.

Green and efficient extraction of podophyllotoxin from Sinopodophyllum hexandrum by optimized subcritical water extraction combined with macroporous resin enrichment

Sinopodophyllum hexandrum is an important traditional Tibetan medicinal plant with great development potential in pharmaceutical industry because of the presence of major bioactive lignans such as podophyllotoxin (PT) that are widely used in combination therapy of cancer. In this study, a green and efficient method for the extraction of PT from S. hexandrum was established by optimized subcritical water extraction (SWE) combined with macroporous resin enrichment. Response surface methodology was introduced for SWE optimization to obtain the maximum yield of PT. The maximum extraction efficiency was achieved under the following conditions: extraction pressure 4 MPa, extraction solvent to feed ratio 18 mL/g, extraction temperature 180 °C, and SW flow rate 2.5 mL/min. Subsequently, an efficient macroporous resin enrichment method was developed to further purify PT in the crude extract obtained from SWE. D101 resin was selected as a proper adsorbent owing to its adsorption and desorption properties, whereas its adsorption process was found to be consistent with a pseudo-second-order model. The optimized loading amount was 3 BV of extract solution, and the desorption conditions were as follows: First, the product was eluted with deionized water until no sugar was detected in the effluent, followed by 6 BV of 20% aqueous ethanol elution and then by 15 BV of 60% aqueous ethanol elution. After the treatment with D101 resin, the concentration of PT increased from 8.3% in the crude extract to 61.5% in the final product. Moreover, the recovery yield of PT extracted with SW combined with D101 resin enrichment was 74.6%. The results show that SWE combined with macroporous resin enrichment is a green, effective, and low-cost technique for the extraction of PT from S. hexandrum.

Inversiones térmicas con advección cálida inferior en la Vega Media del Segura (Región de Murcia)

Anticyclonic situations fed by the maritime subtropical dorsal in winter are frequent in the South-east Spain. Under these conditions, the intrabaetic depressions and fluvial valleys are prone to thermal inversions. A clear example is the Middle Valley of the Segura River during winter months, especially when cooling at night appears to be accompanied by anticyclonic subsident air, warm advection SW flows at low atmospheric levels and cold katabatic winds proceeding from Sierra de Carrascoy. Such factors and the most temperature inversion situations registered in the study area during the period 2000-2011 are analyzed in this work. For this purpose data of meteorological stations and aerological soundings (e.g. temperature regime, vertical thermal stratification, indicators of atmospheric stability) were used.

Study Influence on Water and Sediment in Sandbank-Lagoon Harbor

Sandbank-lagoons are generally natural harbors for their good defense of wave, deep water near the coast and little source of sediments. Taking Bohe harbor locating on the sandbank-lagoon in South China as the example, water-sediment regime in the harbor block has been studied in this paper. It is shown that wave-induced long-shore current has a significant impact on the sediment movements in the planned harbor block and its back-silting is controlled by SW flow and wave power, and the training dike can trap sediment into the harbor block. And so in the harbor block planned around the west side of Bohe bay mouth not only can shelter the entrance of the lagoon and control wave-induced long-shore current, but also improve environment for back-silting.

Hydrogeological characterization of a tropical crystalline aquifer system

This research used a numerical groundwater flow model, calibrated under steady-state conditions to develop the groundwater flow system in the West Mamprusi District of Northern Ghana. It was aimed at conceptualizing the flow system to initiate a thorough hydrogeological study of the rocks in the area. Stable isotopes were used to relate groundwater recharge in the area to recent meteoric water that had been evaporated in transit down the surficial material. On this basis, direct vertical groundwater recharge from precipitation was applied in the numerical modeling. This study suggests that the prospects of commercial development of the aquifers are high as the estimated recharge ranges between 3.3% and 29% of the annual precipitation. Estimated horizontal hydraulic conductivity ranges between 3.2 and 48 m/d in the area. The variability in the horizontal hydraulic conductivity has led to the development of four prominent groundwater flowpaths in the area. However, a prominent NE–SW flow has been observed and is in consonance with the reported structural grain of the country. A groundwater flow divide noted in the southern part of the study area has been attributed to the structural heterogeneity rather than topographical complexities as the area is largely flat.

Implementation of Real Time Graphical User Interface Library for Dynamic Reconfigurable System

This work presents the implementation of real time GUI library for FPGA based run time reconfigurable system that is targeted to ML507 board. The presented work implements floating point arithmetic core as a reconfigurable IP and operands can be provide to the above core with GUI running on display monitor. User can interact with GUI with keyboard and mouse. GUI allows user to change the functionality of the circuit in run time by clicking on appropriate buttons. This approach combines both HW and SW flows. The HW module can be reconfigured on the fly by using partial dynamic reconfiguration.

Study of Corotating Interaction Regions in the Ascending Phase of the Solar Cycle: Multi-spacecraft Observations

We combined simultaneous solar wind observations from five different spacecraft: Helios 1, Helios 2, IMP-8, Voyager 1 and Voyager 2, from November 1977 to February 1978 (Carrington rotations 1661 – 1664, ascending phase of Solar Cycle 21). The concurrence of the five trajectories makes this interval unique for the purpose of studying solar wind dynamics during this phase of the cycle. We analyzed the observations identifying five corotating interaction regions (CIRs) and produced maps of interplanetary large-scale features, unifying and summarizing the data. The maps show the compressive events and the magnetic sectors associated with the solar wind streams causing the CIRs. We analyzed the relative position of the stream interfaces immersed within the CIRs. About 70 % of the stream interfaces in this study were located closer to the forward edge of the CIR. From the analysis of the geometry of the stream interfaces, we found that all the CIRs presented latitudinal tilts, having their fronts pointing towards the ecliptic plane and their tails northwards or southwards. These results are in agreement with the origin of the fast streams coming from mid-latitude coronal holes and the predominance of forward shocks over reverse shocks bounding the CIRs, which characterize this phase of the cycle. From the analysis of the ratio of dynamic pressures between fast and slow solar wind streams associated with the CIRs, we found that in about 60 % of the cases the fast stream was transferring momentum to the slow one ahead, but in the rest of the cases the momentum was flowing sunward. This result indicates significant inhomogeneities in the solar wind streams during the ascending phase of the cycle that affect the local form and evolution of CIR events. We did a limited comparison between a global magneto-hydrodynamic (MHD) model of SW flows and the orientation of the SI from in-situ observations, we found, in general, a qualitative agreement between the pressure profiles at 1 AU predicted by the model and the inclinations of the stream interfaces deduced from the data analysis.

Implementation of Dynamic Reconfigurable Audio Player and Spectrum Analyzer

This work presents the implementation of FPGA based run time reconfigurable audio player system that is targeted to ML507 board with frequency component display of the stored audio data. The presented work combines both HW and SW flows where the complex parts of the architecture are designed to HW modules. These HW modules can be reconfigured on the fly by using partial dynamic reconfiguration. In our work, we are using filter block as partial reconfiguration module, 16 point FFT to decimate audio sample data in frequency in SW logic and displaying the spectrum of the audio signal on the display monitor. Our aim is to implement reconfigurable complex audio player as an application of reconfiguration computing, proving how this technique may be helpful to decrease resource utilization of the device with negligible performance overhead.

Implementation of Dynamically Reconfigurable Systems on Chip with OS Support

This work presents the implementation of dynamically reconfigurable system with operating system support specifically Linux. The presented work combines both HW and SW flows where the complex parts of the architecture are designed to HW modules. These HW modules can be reconfigured on the fly by using partial dynamic reconfiguration. In our work, we are using floating point computation unit as partial reconfiguration module. Our aim is to show the idea how an operating system can be involved in the area of reconfiguration computing. The application that manages the reconfiguration can be developed either as standalone software that is specific for the system or with an operating system support, to achieve code reusability and code portability. Finally, a prototype is implemented on Xilinx ML507 board, where a general Linux open source kernel has been used to handle dynamic reconfigurable hardware recourses.

Conceptualization of the hydrogeological system of some sedimentary aquifers in Savelugu–Nanton and surrounding areas, Northern Ghana

AbstractGroundwater resources play a pivotal role in the rural water delivery system in Ghana. The hydrogeological system of Middle Voltaian terrain was simulated using available data on hydraulic heads and boundary conditions. The objective was to characterize the general groundwater flow pattern and provide local estimates of the distribution of hydraulic conductivity and recharge fields. The results suggest a predominant NE–SW flow direction, which ties in with the general regional structural trend and indicates that the hydrogeological conditions of the rocks are controlled by structural entities created in the wake of fracturing and/or weathering of the rocks whose primary permeabilities are considerably reduced because of high compaction and low‐grade metamorphism. Calibrated hydraulic conductivities range between 1.90 and 10.81 m/d. The spatial distribution appears to reflect the intensity of fracturing and/or weathering of the rock and the proportion of the clay fraction of the weathered zone. Vertical groundwater recharge has been estimated to range between 0.3% and 4.1% of the annual rainfall. This recharge rate is quite low and reflects the imperviousness of the thick overburden because of high clay content in some places and high compaction in others. Despite this apparently low recharge rate, groundwater resources potential in the area appear to be high, and increased abstraction from existing abstraction wells by up to 50% does not appear to register significant effects on groundwater budgets at the simulated recharge rates. This suggests that the well yields are much lower than the potential of the aquifer system. The apparently low yields might be associated with poor well development and the choice of inappropriate well completion materials. This study recommends a monitoring system to be developed for a much more regional groundwater flow simulation under transient conditions. Copyright © 2012 John Wiley & Sons, Ltd.

Till geochemical signatures of magmatic Ni–Cu deposits, Thompson Nickel Belt, Manitoba, Canada

ABSTRACT Sampling around the Ni–Cu deposits in the northern Thompson Nickel Belt (TNB), central Canada, was conducted to document Ni–Cu mineralization signatures in till. Samples used in this study include archived material collected in 1996 and new samples collected in 2005 and 2006. During the Late Wisconsinan, the Laurentide Ice Sheet flowed southwestward and subsequently westward across the TNB striating outcrops and transporting metal-rich till. Exploration along the belt and in the surrounding terranes should consider both the older SW and younger westward ice flow events when interpreting and following up till geochemical results. Till geochemistry of the 3 offer further discrimination of significant till geochemical anomalies. Using the deposit signatures in till as a guide, five anomalous till samples outside the belt represent new exploration targets because they contain significant elevated concentrations of, in various combinations, Pt, Pd, Cu, Cr, Mo, Sb, Bi and Fe.

Summer daily precipitation variability over the East Anglian region of Great Britain

AbstractDaily precipitation totals for five consecutive summers (1994–1998) were obtained for 136 stations in East Anglia to explore geographic variations in rainfall. S‐mode principal components analysis (PCA) was used to identify the main spatial modes of variability in the region's precipitation field. The components were interpreted physically by examining synoptic charts and the British Isles' circulation variables for the days with high PC scores. Whilst seven principal components have eigenvalues greater than 1, and collectively explain 86.3% of the variance, only the first 5 PCs have well defined rainfall patterns that can be attributed to specific circulation patterns. The most dominant pattern (PC 1) shows a gradient between wetter conditions in NE Norfolk and drier conditions in Cambridgeshire and Essex, which is favoured by a cyclonic northerly airflow. PC 2 is almost as dominant, and shows a west to east decay in rainfall totals that is typically associated with active zonal W–SW flows. PC 3 sees the highest totals occurring in Essex. Wetter conditions in the south of East Anglia tend to occur when areas of low pressure follow a southerly track along the English Channel and southern North Sea. PC 4 shows a maximum in convective activity that occurs furthest inland in SE Cambridgeshire and west Suffolk, with the convection being triggered or accentuated by the East Anglian Heights (the highest land in East Anglia). PC 5 shows the rainfall distribution under a cyclonic N–NW, whereby showers generated over The Wash penetrate inland and produce the most rainfall in west Norfolk. Finally, a summer precipitation regionalization was derived by applying agglomerative hierarchical cluster analysis to the loadings of PCs 1–7. It is concluded that a location's precipitation climatology is more strongly determined by the orientation of the nearest coastline rather than simply the site's distance from the North Sea. Copyright © 2008 Royal Meteorological Society

Variability in the Slope Water and its relation to the Gulf Stream path

Sea Surface Temperature (SST) and Sea Surface Height (SSH) data for 1993–2007 for the North Atlantic are combined with hydrographic data at 69W to investigate the relation between the Gulf Stream (GS) position and the Slope Water properties. SST anomalies north of the GS are correlated with changes in its path. The lag of this correlation is such that positive temperature anomalies precede northward shifts of the GS, and suggests that SST anomalies move westward with speeds of several cm/s. EOF analysis of the SST and SSH fields shows that cooling and strengthening of the SW flow are in phase over the Slope Water, which is mirrored in the vertical structure of these fields at 69W, indicating larger transports in the Deep Western Boundary Current lead to southward shifts of the mean GS path. This relation between the Slope Water and the GS path provides some predictability for the latter.

Winter Storms in the Central Himalayas

Based on observations from a hydrometeorological network on the eastern slopes of the Annapurna Range, nearly all the annual precipitation at low elevations ( 3000 m MSL) can receive up to 40% of their annual precipitation as snowfall during the winter, with the highest altitude stations (@4000 m MSL and above) having the most total winter precipitation (which can exceed 100 cm). Significant snowstorms are associated with terrain-locked low-pressure systems that form when an upper-level disturbance passes over the notch formed by the Himalayas and Hindu Kush mountains (the so-called Western Disturbances), causing upper-level SW flow over central Nepal and orographically forced precipitation. Based on these results, a 30-year (1973‐2002) climatology of these notch depressions is developed and reveals that significant interannual variability in central Himalayan winter storms exists. Weak but statistically significant correlation between notch depressions and the Polar/Eurasia teleconnection pattern was found, suggesting that the strength of the circumpolar vortex may affect the number of depressions passing through the Himalayan region. A typical snow event (11 February 2000) was the subject of an observational and modeling case study. Local precipitation (snow and rain) and other meteorological observations, as well as satellite (Meteosat-5 and TRMM) and NCEP/NCAR Reanalysis data were used, along with a cloud-resolving model with realistic topography. This study shows that significant wintertime precipitation only occurs in the central Himalayas when the large-scale flow evolves to a favorable geometry with respect to the mountains.

The 500 and 1000 hPa weather type circulations and their relationship with some extreme climatic conditions over southern South America

AbstractDifferent circulation types for southern South America are derived from the circulation anomaly maps at 500 hPa corresponding to a 9 year period. The series of daily maps was obtained from the ECWMF reanalysis. These data are particularly useful, since real data, especially the radiosonde network, are sparse in this region. The properties to be studied are selected in such a way that they describe different flow conditions over the region, in order to obtain a statistical diagnosis useful for modelling an objective forecast.The circulation types were obtained by a correlation–map‐based pattern classification technique. Lund's method is used in this paper to identify the most frequent circulation patterns.The classification method was applied to daily Z anomalies at 500 hPa over the whole record (1980–88). This allows one to analyse the evolution and presence of a particular type over different months and years. The most outstanding circulation‐type structures, represented by only eight types, explain about 63% of the total number of cases in the sample. The most frequent type, Type 1 (Z), shows an almost zonal circulation with a strong meridional gradient, associated with a trough in the west of the region. Type 2 (LCE) is represented by a low‐pressure system in the centre of the region (approximately at 37° S, 65° W). In general, this type is related to the occurrence of blocking situations in the South Atlantic Ocean and the passage of cold fronts over the region. Types 3 (SW) and 4 (WNW) show a SW and WNW atmospheric circulation over the whole region with a meridional gradient lower than in Type 1. Type 5 (TNS) shows an NW–SE trough axis over the continent. Type 6 (WW) has an intense SW flow over the southern part of the continent. Type 7 (NW) shows a very deep trough to the west of the continent, located over the Pacific Ocean at 80° W and 34° S. The continent is affected by a NW atmospheric circulation. Type 8 (R) represents a ridge over the continent with an intense NW flow in the south. The frequency of Types 1 to 8 is about 63%. None of the circulation types mentioned accounts for more than 12% of the sample. There is a considerable variability in monthly circulation type distributions; the first six types only account for approximately 50% of the variability. This suggests that the use of probability models related to circulation type occurrence in the middle troposphere should be analysed on a monthly basis.The results attempt to summarize the region's synoptic regime through a small number of circulation types at 500 hPa and the corresponding 1000 hPa maps. The frequency distribution of each type during warm, neutral and cold phases in the equatorial Pacific Ocean was analysed. These results partially explain the best dynamic conditions (cyclonic vorticity), for the Argentine humid and semi‐humid region, southern Brazil, Paraguay and Uruguay, that lead to the harvest precipitation events in spring (October–December 1982) with SOI < 0. In winter these circulation types are more important during cold phases with advection of cold and dry air (July–September 1982).The circulation types at 500 hPa and the corresponding maps at 1000 hPa associated with mean maximum and minimum monthly temperature and precipitation in the region are studied. The monthly maximum and minimum precipitation recorded in stations near the Uruguay River basin in southeastern South America and the mean monthly maximum and minimum temperatures from three stations in Argentina during 1980–88 are used in the analysis. Some of the daily patterns are strongly associated with the occurrence of maximum and minimum monthly temperature and precipitation in different places of the country. In reference to the maximum and minimum precipitation records, the behaviour of the variables under study is observed to be physically consistent with the associated circulation patterns. Copyright © 2003 Royal Meteorological Society