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Drought projections on seasonal to annual time scales are presented for Canada over the twenty-first century, based on the Standardized Precipitation Evapotranspiration Index (SPEI). Results make u...

A devastating, flood-producing rainstorm occurred over southern Alberta, Canada, from 19 to 22 June 2013. The long-lived, heavy rainfall event was a result of complex interplays between topographic, synoptic, and convective processes that rendered an accurate simulation of this event a challenging task. In this study, the Weather Research and Forecasting (WRF) Model was used to simulate this event and was validated against several observation datasets. Both the timing and location of the model precipitation agree closely with the observations, indicating that the WRF Model is capable of reproducing this type of severe event. Sensitivity tests with different microphysics schemes were conducted and evaluated using equitable threat and bias frequency scores. The WRF double-moment 6-class microphysics scheme (WDM6) generally performed better when compared with other schemes. The application of a conventional convective/stratiform separation algorithm shows that convective activity was dominant during the early stages, then evolved into predominantly stratiform precipitation later in the event. The HYSPLIT back-trajectory analysis and regional water budget assessments using WRF simulation output suggest that the moisture for the precipitation was mainly from recycling antecedent soil moisture through evaporation and evapotranspiration over the Canadian Prairies and the U.S. Great Plains. This analysis also shows that a small fraction of the moisture can be traced back to the northeastern Pacific, and direct uptake from the Gulf of Mexico was not a significant source in this event.

Consensus is lacking as to the optimal radiotherapy dose and fractionation schedule for treating bone metastases.To assess the relative efficacy of high-dose, single-fraction stereotactic body radiotherapy (SBRT) vs standard multifraction radiotherapy (MFRT) for alleviation of pain in patients with mostly nonspine bone metastases.This prospective, randomized, single-institution phase 2 noninferiority trial conducted at a tertiary cancer care center enrolled 160 patients with radiologically confirmed painful bone metastases from September 19, 2014, through June 19, 2018. Patients were randomly assigned in a 1:1 ratio to receive either single-fraction SBRT (12 Gy for ≥4-cm lesions or 16 Gy for4-cm lesions) or MFRT to 30 Gy in 10 fractions.The primary end point was pain response, defined by international consensus criteria as a combination of pain score and analgesic use (daily morphine-equivalent dose). Pain failure (ie, lack of response) was defined as worsening pain score (≥2 points on a 0-to-10 scale), an increase in morphine-equivalent opioid dose of 50% or more, reirradiation, or pathologic fracture. We hypothesized that SBRT was noninferior to MFRT.In this phase 2 noninferiority trial of 96 men and 64 women (mean [SD] age, 62.4 [10.4] years), 81 patients received SBRT and 79 received MFRT. Among evaluable patients who received treatment per protocol, the single-fraction group had more pain responders than the MFRT group (complete response + partial response) at 2 weeks (34 of 55 [62%] vs 19 of 52 [36%]) (P = .01), 3 months (31 of 43 [72%] vs 17 of 35 [49%]) (P = .03), and 9 months (17 of 22 [77%] vs 12 of 26 [46%]) (P = .03). No differences were found in treatment-related toxic effects or quality-of-life scores after SBRT vs MFRT; local control rates at 1 and 2 years were higher in patients receiving single-fraction SBRT.Delivering high-dose, single-fraction SBRT seems to be an effective treatment option for patients with painful bone metastases. Among evaluable patients, SBRT had higher rates of pain response (complete response + partial response) than did MFRT and thus should be considered for patients expected to have relatively long survival.ClinicalTrials.gov identifier: NCT02163226.

Data obtained from a variety of sources including the Canadian Lightning Detection Network, weather radars, weather stations and operational numerical weather model analyses were used to address the evolution of precipitation during the June 2013 southern Alberta flood. The event was linked to a mid-level closed low pressure system to the west of the region and a surface low pressure region initially to its south. This configuration brought warm, moist unstable air into the region that led to dramatic, organized convection with an abundance of lightning and some hail. Such conditions occurred in the southern parts of the region whereas the northern parts were devoid of lightning. Initially, precipitation rates were high (extreme 15-min rainfall rates up to 102 mm h−1 were measured) but decreased to lower values as the precipitation shifted to long-lived stratiform conditions. Both the convective and stratiform precipitation components were affected by the topography. Similar flooding events, such as June 2002, have occurred over this region although the 2002 event was colder and precipitation was not associated with substantial convection over southwest Alberta.

In June 2013, excessive rainfall associated with an intense weather system triggered severe flooding in southern Alberta, which became the costliest natural disaster in Canadian history. This article provides an overview of the climatological aspects and large-scale hydrometeorological features associated with the flooding event based upon information from a variety of sources, including satellite data, upper air soundings, surface observations and operational model analyses. The results show that multiple factors combined to create this unusually severe event. The event was characterized by a slow-moving upper level low pressure system west of Alberta, blocked by an upper level ridge, while an associated well-organized surface low pressure system kept southern Alberta, especially the eastern slopes of the Rocky Mountains, in continuous precipitation for up to two days. Results from air parcel trajectory analysis show that a significant amount of the moisture originated from the central Great Plains, transported into Alberta by a southeasterly low level jet. The event was first dominated by significant thunderstorm activity, and then evolved into continuous precipitation supported by the synoptic-scale low pressure system. Both the thunderstorm activity and upslope winds associated with the low pressure system produced large rainfall amounts. A comparison with previous similar events occurring in the same region suggests that the synoptic-scale features associated with the 2013 rainfall event were not particularly intense; however, its storm environment was the most convectively unstable. The system also exhibited a relatively high freezing level, which resulted in rain, rather than snow, mainly falling over the still snow-covered mountainous areas. Melting associated with this rain-on-snow scenario likely contributed to downstream flooding. Furthermore, above-normal snowfall in the preceding spring helped to maintain snow in the high-elevation areas, which facilitated the rain-on-snow event.

The Interior of Western Canada, up to and including the Arctic, has experienced rapid change in its climate, hydrology, cryosphere and ecosystems and this is expected to continue. Although there is general consensus that warming will occur in the future, many critical issues remain. In this first of two articles, attention is placed on atmospheric-related issues that range from large scales down to individual precipitation events. Each of these is considered in terms of expected change organized by season and utilizing climate scenario information as well as thermodynamically-driven future climatic forcing simulations. Large scale atmospheric circulations affecting this region are generally projected to become stronger in each season and, coupled with warming temperatures, lead to enhancements of numerous water-related and temperature-related extremes. These include winter snowstorms, freezing rain, drought as well as atmospheric forcing of spring floods although not necessarily summer convection. Collective insights of these atmospheric findings are summarized in a consistent, connected physical framework.

Faculty frequently express concerns about students’ personal use of information and communication technologies in today’s university classrooms. As a requirement of a graduate research methodology course in a university in Ontario, Canada, the authors conducted qualitative research to gain an in-depth understanding of students’ perceptions of this issue. Their findings reveal students’ complex considerations about the acceptability of technology use. Their analysis of the broader contexts of students’ use reveals that despite a technological revolution, university teaching practices have remained largely the same, resulting in ‘cultural lag’ within the classroom. While faculty are technically ‘in charge’, students wield power through course evaluations, surveillance technologies and Internet postings. Neoliberalism and the corporatisation of the university have engendered an ‘entrepreneurial student’ customer who sees education as a means to a career. Understanding students’ perceptions and their technolo...

In the spring and early summer of 2011, the Assiniboine River basin in Canada experienced an extreme flood that was unprecedented in terms of duration and severity. The flood had significant socioeconomic impacts and caused over $1 billion (Canadian dollars) in damage. Contrary to what one might expect for such an extreme flood, individual precipitation events before and during the 2011 flood were not extreme; instead, it was the cumulative impact and timing of precipitation events going back to the summer of 2010 that played a key role in the 2011 flood. The summer and fall of 2010 were exceptionally wet, resulting in above-normal soil moisture levels at the time of freeze-up. This was followed by record high snow water equivalent values in March and April 2011. Cold temperatures in March delayed the spring melt, resulting in the above-average spring freshet occurring close to the onset of heavy rains in May and June. The large-scale atmospheric flow during May and June 2011 favored increased cyclone activity in the region, which produced an anomalously large number of heavy rainfall events over the basin. All of these factors combined generated extreme flooding. Japanese 55-year Reanalysis Project (JRA-55) data are used to quantify the relative importance of snowmelt and spring precipitation in contributing to the unprecedented flood and to demonstrate how the 2011 flood was unique compared to previous floods. This study can be used to validate and improve flood forecasting techniques over this important basin; the findings also raise important questions regarding floods in a changing climate over basins that experience pluvial and nival flooding.

The National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR) reanalysis data have been used to compute the moisture flux convergence (MFC) over Central Southwest Asia (CSWA) between 45°–75° E and 25°–40° N. The present study focuses on the 1969–2007 period, and both horizontal distributions and vertical profiles of MFC have been calculated and compared. Moisture is transported into the region from the west throughout the year. In this region, winter is the wettest season with the most precipitation. Areas of high moisture convergence are observed in the east and southwest. Moisture convergence in the east and southwest are associated with topographic effects. Our study also examined composites of moisture flux convergence that characterized the wettest and the driest years in this area. The magnitude of the monthly MFC differs considerably between these two extremes. The spatial distribution of moisture flux convergence during the recent drought period (1999–2001) was also examined in order to understand how moisture transport affects drought. Deficiency of precipitation during drought periods appears to be due to deviation of moisture transport away from the region.

From 2009 to 2011, the Canadian Prairies were subjected to exceptionally variable precipitation regimes, ranging between record drought and unprecedented flooding. Adjacent regions concurrently experienced droughts and floods, and individual areas transitioned rapidly from pluvial to drought conditions and vice versa. Such events had major impacts; for example, damages from floods in the Assiniboine River Basin (ARB) have exceeded $1 billion, and forest fires ravaged the town of Slave Lake, Alberta. This study first characterizes, and then assesses, these devastating natural hazards in terms of their physical processes (across multiple spatial and temporal scales) related to both the spatially contrasting precipitation states and rapid temporal transitions between these states. Subtle differences in large-scale atmospheric flow had marked impacts on precipitation. Primary factors controlling the distribution and amount of precipitation included the location and persistence of key surface and upper-air features, as well as their interaction. Additionally, multiple events—rather than individual extremes—were responsible for the flooding over the Saskatchewan River Basin and the ARB. Very heavy rainfall events (≥25 mm d−1) accounted for up to 55 % of warm season rain at some locations, and the frequency of heavy rainfall events was critical for determining whether a region experienced drought or pluvial conditions. This study has increased our knowledge of the characteristics, impacts and mechanisms of rapidly transitioning disparate precipitation states on the Canadian Prairies and will aid in better understanding both past and projected future hydro-climatic extremes in the region.

Importance Consensus is lacking as to the optimal radiotherapy dose and fractionation schedule for treating bone metastases. Objective To assess the relative efficacy of high-dose, single-fraction stereotactic body radiotherapy (SBRT) vs standard multifraction radiotherapy (MFRT) for alleviation of pain in patients with mostly nonspine bone metastases. Design, Setting, and Participants This prospective, randomized, single-institution phase 2 portion of a phase 2/3 noninferiority trial conducted at a tertiary cancer care center randomized 160 patients with radiologically confirmed painful bone metastases from September 19, 2014, through June 19, 2018. Patients were randomly assigned in a 1:1 ratio to receive either single-fraction SBRT (12 Gy for ≥4-cm lesions or 16 Gy for Main Outcomes and Measures The primary end point for this analysis was pain response, defined by international consensus criteria as a combination of pain score and analgesic use (daily morphine-equivalent dose) at 3 months. Pain failure was defined as worsening pain score (≥2 points on a 0-to-10 scale), an increase in morphine-equivalent opioid dose (MED) of 50% or more, reirradiation, or pathologic fracture. Failure, defined by worsening pain score, increase in MED, reirradiation, or radiographic disease progression was calculated with a subdistribution hazard ratio (SHR) using a competing risks model. We hypothesized that SBRT was noninferior to MFRT. Results In this phase 2 portion of a phase 2/3 noninferiority trial of 96 men and 64 women (mean [SD] age, 62.4 [10.4] years), 81 patients received SBRT and 79 received MFRT. Among evaluable patients who received treatment per protocol, the single-fraction group had more pain responders than the MFRT group (complete response + partial response) at 2 weeks (34 of 55 [62%] vs 19 of 52 [36%]) (P = .01), 3 months (32 of 44 [73%] vs 17 of 35 [49%]) (P = .04), and 9 months (17 of 22 [77%] vs 12 of 26 [46%]) (P = .04). An SHR of 0.71 (95% CI, 0.36-1.39) indicated that SBRT had 29% less risk of failure relative to the MFRT after considering death as a competing risk. The upper 95% CI for SHR was less than the noninferiority margin of 1.5, indicating that SBRT was noninferior to MFRT. No differences were found in treatment-related toxic effects or quality-of-life scores after SBRT vs MFRT. Conclusions and Relevance Delivering high-dose, single-fraction SBRT seems to be an effective treatment option for patients with painful bone metastases. Among evaluable patients, SBRT had higher rates of pain response (complete response + partial response) than did MFRT and thus should be considered for patients expected to have relatively long survival. Trial Registration ClinicalTrials.gov Identifier:NCT02163226

Water budgets terms, evapotranspiration (E), precipitation (P), runoff (N), moisture convergence (MC) and both surface as well as atmospheric residual terms have been computed with National Centers for Environmental Prediction (NCEP) (1948-2007) and European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-40 (1958-2001) reanalysis data sets for Central Southwest Asia (CSWA).The domain of the study is 45° - 75°E & 25° - 40°N. Only the land area has been used in these calculations. It is noted in the comparison of both reanalysis data sets with Global Precipitation Climatology Centre (GPCC) that all three data sets record different precipitation before 1970. The maximum is from NCEP and the minimum with ERA-40. However, after 1970 all the data sets record almost the same precipitation. ERA-40 computes two phases of MC. Before 1975, the domain acts as a moisture source, whereas after 1975 it behaves as a moisture sink. The region CSWA is divided into six sub areas with rotational principle factor analysis and we distinguish them by different approached weather systems acting on each area. Finally, NCEP yearly precipitation is further divided into seasons; winter (November to April) and summer (May to October) and two phases have been noted. The variation in winter precipitation is more than summer during last 60-year analysis.

Droughts are among the world's most costly natural disasters and collectively affect more people than any other form of natural disaster. The Canadian Prairies are very susceptible to drought and have experienced this phenomenon many times. However, the recent 1999–2005 Prairie drought was one of the worst meteorological, agricultural and hydrologic droughts over the instrumental record. It also had major socio-economic consequences, adding up to losses in the billions of dollars. This recent drought was the focus of the Drought Research Initiative (DRI), the first integrated network focusing on drought in Canada. This article addresses some of the key objectives of DRI by providing a collective summary, understanding and synthesis of the 1999–2005 drought. Bringing together the many datasets used in this study was in itself a major accomplishment. This drought exhibited many important, and sometimes surprising, features. This includes, for example, (1) a non-steady large-scale atmospheric circulation (an...

A catastrophic rain event occurred in early June 2002 during a major drought over the Canadian Prairies. The storm brought record-breaking rainfall and major flooding to many locations in the region. Given the importance of this event, this study's overall objectives are to characterize and to understand the physical nature of the rainstorm better. The event was associated with a major extratropical cyclone which acted in concert with the Great Plains low-level jet to transport a tremendous amount of moisture into the eastern Prairies producing intense diurnal mesoscale convective systems over the region. At the same time, moisture was transported to the western Prairies by a strong easterly low-level jet which produced heavy and long-lived orographic precipitation near the foothills. Several working hypotheses were developed to explain the severity and longevity of the rainstorm; it was found that the Rockies played a central role in the organization and development of the system. Atmospheric features th...

This study documents and assesses the atmospheric and oceanic variability associated with growing season (May to August) droughts on the Canadian Prairies. For comparison, extreme wet seasons or pluvials are also examined. Using the Palmer Z-Index as a drought indicator, extreme dry and wet seasons are first identified for the period 1950 to 2007. Interrelationships among several atmospheric parameters including large- to synoptic-scale circulation patterns, low-level moisture transport, moisture convergence, precipitable water content and cyclone frequency are then assessed during extreme drought and pluvial periods. In addition, links to the previous winter's global sea surface temperature (SST) patterns are identified using the multivariate technique of singular value decomposition. Results show that moisture from the Gulf of Mexico is notably decreased during the identified drought seasons. Stronger than normal subsidence associated with anomalously high pressure over northwestern North America also l...

This study represents the first attempt at developing a comprehensive climatology of atmospheric and surface water and energy budgets for the Mackenzie River basin (MRB). Different observed, remotely sensed, (re)analyzed, and modeled datasets were used to obtain independent estimates of the budgets. In particular, assimilated datasets, including the National Centers for Environmental Prediction Global Reanalysis 2 (NCEP-R2), the global 40-yr European Centre for Medium-Range Weather Forecasts Re-Analysis (ERA-40), the NCEP North American Regional Reanalysis (NARR), and the Canadian Meteorological Centre (CMC) operational regional analysis as well as results from the Canadian Regional Climate Model (CRCM) simulations, are used in the study. Apart from the development of state-of-the-art budget estimates for the MRB, the relative merits of current models, data assimilation systems, and global blended datasets in representing aspects of the water and energy cycle of this northern and data-sparse region were also assessed. In addition, the levels of uncertainty in assessing the budgets as well as their sources are discussed. The regional water budget for the MRB is closed within 10% of the observed runoff by using the moisture flux convergence from ERA-40, NARR, CMC, or CRCM. While these are noted improvements over previous water closure assessments for the region, magnitudes of the residuals in balancing the budgets are often comparable to the budget terms themselves in all the model and analysis datasets, and the spreads of budget estimates from the different datasets are also typically large, suggesting that substantial improvements to the models and observations are needed before the assessments of water and energy budgets for this northern region can be vastly improved.

The Mackenzie River basin (MRB) in northwestern Canada is a climatologically important region that exerts significant influences on the weather and climate of North America. The region exhibits the largest cold-season temperature variability in the world on both the intraseasonal and interannual time scales. In addition, some of the strongest recent warming signals have been observed over the basin. To understand the nature of these profound and intriguing observed thermal characteristics of the region, its atmospheric heat budget is assessed by using the NCEP–NCAR reanalysis dataset. The composite heat budgets and large-scale atmospheric conditions that are representative of anomalous winters in the region are examined in unison to study the processes that are responsible for the development of extreme warm/cold winters in the MRB. It is shown that the large winter temperature variability of the region is largely a result of the strong variability of atmospheric circulations over the North Pacific, the selective enhancement/weakening of latent heating of the cross-barrier flow for various onshore flow configurations, and synoptic-scale feedback processes that accentuate the thermal response of the basin to the changes in upwind conditions. The improved understanding of mechanisms that govern the thermal response of the basin to changes in the upstream environment provides a theoretical basis to interpret the climate change and modeling results for the region. In particular, the large recent warming trend observed for the region can be understood as the enhanced response of the basin to the shift in North Pacific circulation regime during the mid-1970s. The strong cold bias that affected the region in some climate model results can be attributed to the underprediction of orographic precipitation and associate latent heating of the cross-barrier flow, and the subsequent weakening of mean subsidence and warming over the basin in the models.

The boreal region has a subarctic climate that is subject to considerable inter-annual variability and is prone to impacts of future warming. Climate influences the seasonal streamflow regime which typically exhibits winter low flow, terminated by spring freshet, followed by summer flow recession. The effects of climatic variation on streamflow cannot be isolated with confidence but the impact of human regulation of rivers can greatly alter the natural flow rhythm, changing the timing of flow to suit human demands. The effect of scenario climate change on streamflow is explored through hydrological simulation. Example of a Canadian basin under warming scenario suggests that winter flow will increase, spring freshet dates will advance but peak flow will decline, as will summer flow due to enhanced evaporation. While this simulation was site specific, the results are qualitatively applicable to other boreal areas. Future studies should consider the role of human activities as their impacts on streamflow will be more profound than those due to climate change.

The Mackenzie Global Energy and Water Cycle Experiment (GEWEX) Study (MAGS) is one of the continental-scale experiments approved specifically by GEWEX to better understand and model water and energy cycling at high latitudes. The project has gone through two phases since its inception in 1994 and conclusion in December 2005. Many scientific results have been achieved through MAGS research to advance our understanding of the Mackenzie River basin climate system. This article is a synthesis of its atmospheric research achievements through an integrative description of the basin's climate system, along with highlights of MAGS research that has advanced our knowledge and understanding of various key aspects of the system. In particular, the significance of MAGS research is discussed in the hancing knowledge of the basin's hydroclimate with focuses on i) the large-scale atmospheric processes that control the transport of water and energy into the basin, and ii) the interactions of the large-scale atmospheric flows with physical features of the basin's environment in affecting the weather and climate of the basin.

The Saskatchewan River Basin (SRB) in Canada is one of the most important agricultural regions for the country. Despite the critical dependency of the region’s agricultural and societal activities to climate variability and change, no comprehensive water and energy budget assessment has yet been developed for this drought-prone region. This study represents the first attempt at developing a comprehensive climatology of water and energy budgets for the SRB. Different observed, remotely-sensed, (re-)analyzed and modeled datasets were used to obtain independent estimates of the budgets. In particular, flux measurements from the Boreal Ecosystem Research and Monitoring Sites (BERMS) Coordinated Enhanced Observing Period (CEOP) reference site provide valuable validation data for the surface flux assessments. Budget results for the SRB are compared to those assessed for the Mackenzie River Basin to gain insights into the differences in water and energy cycling, and challenges in their quantifications, for these two neighboring major basins in North America. Apart from the development of state-of-the-art budget estimates for the SRB, the relative merits of current models, data assimilation systems and global blended datasets in representing aspects of the water and energy cycle of this semi-arid region were also assessed. Although some of the assessed component budgets compared quite well with observations, magnitudes of the residuals in balancing the budgets are often comparable to the budget terms themselves in all the analysis datasets, suggesting that substantial improvements to the models and observations are needed before we can vastly improve the assessment of water and energy budgets for the region.

The 54-yr (1948–2001) NCEP–NCAR reanalysis data as well as other information were used to study the moisture transport and associated circulation features for the severe 2000/01 drought over the western and central Canadian Prairies. Most of the moisture for precipitation over the region is from the Pacific Ocean in winter (November–March) and from the Gulf of Mexico in summer (May–August). An analysis shows that the zonal moisture transport from the Pacific Ocean into both the North American continent and the western and central Canadian Prairies during the winter of the 2000/01 agricultural year was the least over the entire study period, and there was no significantly enhanced moisture influx from the Gulf of Mexico into the region to compensate. Very low winter precipitation was produced over the western and central Canadian Prairies as a consequence. During the ensuing summer period, moisture transport from the Gulf of Mexico was significantly less than normal and no significantly enhanced m...

The Canadian Regional Climate Model has been used to estimate surface water balance over the Mackenzie River basin during the water year 1998–99 in support of the Canadian Global Energy and Water Cycle Experiment (GEWEX) Enhanced Study (CAGES). The model makes use of a developmental third-generation physics parameterization package from the Canadian Centre for Climate Modelling and Analysis GCM, as well as a high-resolution land surface dataset. The surface water balance is simulated reasonably well, though Mackenzie basin annual mean daily maximum and minimum temperatures were both colder than observed by 1.7°C. The cold bias contributed to a longer snow-covered season and larger peak snow water equivalent than was observed, though snow accumulated realistically compared with two independently observed estimates after 1 November. Mackenzie basin annual precipitation was simulated as 496 mm, about 9% larger than observed, and P − E was 225 mm. Net soil moisture change during this water year was f...

The Canadian Regional Climate Model has recently been coupled with an advanced, second generation land surface model - the Canadian Land Surface Scheme. In addition, high resolution land cover and soils data sets have been assembled on a 1 km horizontal resolution grid over North America. These data sets, along with the coupled model, provide a powerful tool for the examination of regional climate processes in complex, heterogeneous terrain. In a first application of the new modelling system, simulations of progressively higher horizontal resolution are performed over the Mackenzie Basin for the spring of 1995 in order to determine if turbulent fluxes associated with a heterogeneous land surface can generate mesoscale atmospheric circulations of relevance to the surface energy budget during the critical snow melt period. We have found that shallow, diurnally forced mesoscale circulations associated with surface flux heterogeneity developed regularly throughout the snow melt period in the higher resolution experiments. In one case, a localized downdraft associated with a low level isothermal layer was found to enhance turbulent heat exchange with the underlying snow. The net importance of this process to the overall energy balance of the snowpack did increase with resolution, but remained relatively small for the resolutions considered here.

The phenomena that occurred within and in the vicinity of the Mackenzie basin climate system during the 1994/95 water year are the focus of this study. This water year was characterized by a record low discharge and by a very early discharge into the Arctic Ocean. The low discharge arose because the efficiency with which the record‐low large‐scale moisture convergence over the Mackenzie basin was converted into discharge was also the lowest on record. This low efficiency occurred as a consequence of many atmospheric, surface and hydrological processes and feedbacks occurring during this period. The dry surface conditions that had developed just prior to the start of the water year were also a contributing factor. It is evident through the comprehensive examination of the overall climate system of this basin that many strongly coupled processes were occurring. Our models are able to account for some of these, but more research is needed to address a number of them.

Moisture recycling over the Mackenzie basin is investigated by estimating the precipitation recycling ratio (the ratio of precipitation derived from local evaporation to the total precipitation within the basin) for the region with the National Centers for Environmental Prediction (NCEP) reanalysis dataset and the Meteorological Service of Canada (MSC) precipitation climatology. The results suggest that recycling is very active over the region during the warm season (April – August) and extremely inactive during the cold season. The annual recycling ratio estimated for the basin is about 0.25, which is close to that estimated by others for the Mississippi and Amazon basins despite the lower annual evapotranspiration over the Mackenzie basin. The high recycling ratios and the recycling patterns estimated for the basin during the warm season are found to be consequences of the unique topographical and climatic settings characterizing the region. Analysis of conditions during the years having anomal...

A winter oceanic cyclonic cloud system was simulated by using the mesoscale compressible community (MC2) model with different combinations of model resolutions and cloud microphysics packages. Results from these simulations are intercompared to examine the effects of the coarse model grid and simplified model physics on the simulated large-scale storm environment. When aggregated to an area approximately equivalent to the size of a grid box in current GCMs, the results from the models differ significantly in the large-scale cloud and moisture profiles. Although the effects of using different stratiform cloud schemes on the coarse-grid results are appreciable, the effects of different model resolution are shown to be greater on the large-scale frontal cloud field. In particular, the coarse-grid models underestimated the cloudiness and atmospheric moisture content in the warm-frontal region. Such differences in the large-scale model storm environment were consequences of the stronger mean cross-fro...

The objectives of this study are to examine the effects of the 1994–96 Inpres Desa Tertinggal** (IDT) programme in Indonesia on the change in intra-provincial inequality between 1993 and 1996. Through regression analysis, it was found that per capita IDT grants per province have a significant ameliorating effect on the change in intra-provincial expenditure inequality between 1993 and 1996. The inclusion of other plausible explanatory variables further clarifies the robust effects of the IDT programme. Overall, the IDT programme appears to have been successful in improving the economic conditions of the poorer households and in reducing the overall level of inequality.

A winter oceanic cyclonic cloud system was simulated by using both a cloud-resolving model (CRM) and two single-column models (SCMs) utilizing different approaches to parameterize layer clouds. When driven with advective forcing derived from the CRM, the SCMs can capture the general developments of the large-scale cloud field during the warm-frontal passage. However, the vertical cloud structures differed significantly among the models. Some of the differences in the model cloud structures can be attributed to the lack of, or inappropriateness of the parameterizations of some cloud microphysical processes and subgrid cloudiness in current GCM prognostic cloud schemes. The high resolution CRM results will be valuable in identifying such deficiencies in current GCM cloud schemes and in the future developments and calibrations of these schemes.

A severe ice storm affected the east coast of Canada during the Canadian Atlantic Storms Project II. A hierarchy of cloud-resolving model simulations of this storm was performed with the objective of enhancing understanding of the cloud and mesoscale processes that affected the development of freezing rain events. The observed features of the system were reasonably well replicated in the high-resolution simulation. Diagnosis of the model results suggests that the change of surface characteristics from ocean to land when the surface warm front approaches Newfoundland disturbs the (quasi-) thermal wind balance near the frontal region. The cross-frontal circulation intensifies in response to the thermal wind imbalance, which in turn leads to the development of an extensive above-freezing inversion layer in the model storm. Depending on the depth of the subfreezing layer below the inversion, the melted snow may refreeze within the subfreezing layer to form ice pellets or they may refreeze at the surf...

SUMMARY The rotation of the inner core (IC) is influenced by the rest of the Earth through a number of coupling mechanisms. Among four possible coupling mechanisms, gravitational, pressure, viscous and electromagnetic, the first two torques are dominant. Numerous existing IC gravitational torque estimates have been shown to agree very well with one another (Xu & Szeto 1996). It is shown in this paper that diVerent estimates of the IC pressure torque are also in good agreement.

Midlatitude cyclonic cloud systems are common occurrences that significantly impact our climate. In this review, attention is paid to those physical characteristics of these cloud systems with large-scale impacts that must be accounted for in climate simulations. Such attributes include atmospheric forcing, internal structure, surface influences, cloud layering, microphysics, precipitation, water cycling, and radiation. Because of their present limitations associated with, for example, grid sizes and simplified parameterizations, climate models cannot account for all the crucial impacts of these cloud systems. Future advances in the representation of these systems within climate models will need to rely in part on rigorous assessments of model capabilities in a variety of conditions.

Methamphetamine (METH) has long-lasting neurotoxic effects on the dopamine and forebrain serotonin systems. It was reported that METH would induce the release of glutamate within the striatum and that it also caused astrogliosis. The mechanisms of this release and subsequent neurotoxicity are not well defined. The aim of this study was to examine the response of cultured astrocytes after METH-induced injury. Astrocytes were cultured from neonatal C57B1/6 mice brains. Cells were obtained from the mesencephalon, striatum and cortex in order to examine any regional differences. Cells were treated with 4 mM METH for 4, 8, 12, 24 and 48 hr. Lactate dehydrogenase (LDH) levels were used as a measure of cell viability. At various time points, Western blot analyses were performed to study the change in GFAP and vimentin (markers for astrogliosis) levels. Change in glutamine synthase (GS), the enzyme that catalyzes the synthesis of glutamine from glutamate and ammonia in astrocytes, was also examined. The results showed that METH caused marked astrogliosis in striatal and mesencephalic astrocytes. Cells were transformed from protoplasmic (inactive) to fibrous (reactive) form after 48 hr treatment. There were also large amounts of vacuoles present in the cytoplasm of these cells. LDH results showed that there was only slight increase in enzyme levels after 48 hr treatment suggesting that the astrogliosis observed was not due to the decrease in cell viability. The amount of GS were depleted more rapidly in striatal astrocytes (50% of control by 8 hr treatment) followed by mesencephalic astrocytes (reaching 10% of control by 48 hr treatment). Cortical astrocytes showed only a 48% depletion by 48 hr treatment, indicating that they are more resistant to METH-induced toxicity. The rapid depletion of GS obtained in striatal and mesencephalic astrocytes suggested that astrocytes of the dopaminergic system are more sensitive to METH-induced injury. This may be due to the direct effects of METH-induced oxidative stress on the mitochondria of these cells resulting in GS depletion and astrogliosis.

Gravitational coupling within an axially symmetric, ellipsoidal Earth gives rise to torques among the mantle, outer core, and inner core. Such torques act along “lines of nodes”, i.e., orthogonal to axes of symmetry. In a triaxial Earth model, small deviations from axial symmetry modify the torques in direction as well as magnitude. The perturbative torques depend on three Euler angles specifying the long axis of the inner core relative to that of the mantle shell. Their magnitudes, excluding angular dependences, are ∼400 times (i.e., of the order of the inner core boundary flattening) smaller than their biaxial analogs. While triaxiality has a negligible impact on coupling considerations along the line of nodes, it creates gravitational coupling along orthogonal directions that have not been previously investigated. The gravitational coupling torques on the inner core and the mantle that take these triaxial perturbations into account are summarized. To the extent that fluid pressure and electromagnetic effects have not been explicitly modeled here, the present calculations are intended to provide only an order of magnitude estimate of coupling within the Earth along directions not previously examined. It is found that the axial torque on the inner core produces a differential rotation of less than 0.02°/yr and thus fails by at least one order of magnitude in supplying a mechanism for inner core differential rotation suggested by seismological evidence [Song and Richards, 1996]. This conclusion breaks down only if one is prepared to accept an inner core obliquity surpassing 10°.

A weak high-latitude warm-frontal precipitation system was simulated by using a 2D cloudresolving model. It was found that many of the structural characteristics of the system were consequences of the subfreezing temperatures and enhanced planetary rotation in the region. The coupling of cloud microphysical processes to frontal scale dynamics caused the precipitation efficiency (defined as the ratio of integrated surface precipitation rate to the net water vapor influx into the storm) of the model storm to exhibit strong sensitivity to low-level humidity conditions. A relatively high (zero) precipitation efficiency is associated with a storm if it develops over regions having near surface relative humidity with respect to ice ≥ (

On 30 September 1994 an Arctic low pressure system passed over the southern Beaufort Sea area of northern Canada and research aircraft observations were made within and around the warm front of the storm. This study is unique in that the warm front contained subzero centigrade temperatures across the entire frontal region. The overall structure of the warm front and surrounding region was similar to midlatitude storms; however, the precipitation rates, liquid water content magnitudes, horizontal and vertical winds, vertical wind shear, turbulence, and thermal advection were very weak. In addition, a low-level jet and cloud bands were aligned parallel to the warm front, near-neutral stability occurred within and around the front, and conditional symmetric instability was likely occurring. A steep frontal region resulted from strong Coriolis influences that in turn limited the amount of cloud and precipitation ahead of the system. The precipitation efficiency of the storm was high (60%) but is beli...

Cold season warm-frontal systems are simulated with a 2-D cloud-resolving model. The organization of surface weather elements (precipitation type and intensity, factors affecting visibility, accretion, blowing snow and surface wind) in the vicinity of the surface front are investigated. The patterns of surface weather conditions in the model storms are in good agreement with those observed in real systems. The organization of weather elements is found to be sensitive to large-scale conditions such as background stability, temperature and frontal forcing. These surface weather conditions are also found to be affected significantly by cloud-scale and mesoscale dynamical processes. The implications of the model results to the improvement of quantitative forecasting of weather elements in winter storms are discussed.

Frontal precipitation systems are simulated with a 2D cloud model including ice-phase microphysics. Despite the use of idealized frontogenetic forcing in the simulations, some observed characteristics of frontal zones and their associated cloud and precipitation fields are reproduced in the simulations. The effects of melting snow on surface frontogenesis is investigated. It is found that the cooling effects of melting snow significantly accelerate surface frontogenesis in winter storm environments, especially when the melting layer is close to the surface. However, the steady-state surface frontal strength in the model is not sensitive to the melting effects. Finescale thermal and kinematic perturbations inside the frontal zone near the melting level, quite similar to those recently reported in the literature, are evident in the model results. Analysis of the model results suggests that cooling from melting snow may induce these thermal and kinematic perturbations and may enhance baroclinicity, ...

As the only two optical instruments appearing in its first fleet of instrumentation, the GEMINI MultiObject Spectrograph (GMOS) are indeed being developed as workhorse instruments. One GMOS will be located at each of the GEMINI telescopes to perform: a) exquisite direct imaging, b) 5.5 arcminute longslit spectroscopy, c) up to 600 object multislit spectroscopy, and d) about 2000 element integral field spectroscopy. The GMOSs are the only GEMINI instrumentation duplicated at both telescopes. The UK and Canadian GMOS team successfully completed their critical design review in February 1997. They are now well into the fabrication phase, and will soon approach integration of the first instrument. The first GMOS is scheduled to be delivered to Mauna Kea in the fall of'99 and the second to Cerro Pachon one year later. In this paper, we will look at how a few of the more interesting details of the final GMOS design help meet its demanding scientific requirements. These include its transmissive optical design and mask handling mechanisms. We will also discuss our plans for the mask handling process in GEMINI's queue scheduled environment, from the taking of direct images through to the use of masks on the telescope. Finally, we present the status of fabrication and integration work to date.

Seventeen horizontal aircraft passes were made across 0°C regions within 10 winter storms over Atlantic Canada. Regions of near freezing temperatures (±1°C) ranged from

The passage of a winter storm is accompanied by changes in many surface and near‐surface parameters including temperature, humidity, wind, pressure, precipitation rate and type, cloud base height, visibility and accretion. These parameters were measured in association with the passage of precipitation‐type transitions over Newfoundland during the Canadian Atlantic Storms Program II field experiment. Three simple summaries of the observed weather events were developed. These summaries depend on the observed large‐scale synoptic conditions, which include warm fronts, a cold front and a trough.