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This paper introduces a unique multiyear dataset and the monitoring capability of the PANDA automatic weather station network, which includes 11 automatic weather stations (AWSs) across the Prydz Bay–Amery Ice Shelf–Dome A area from the coast to the summit of the East Antarctic Ice Sheet. The ∼ 1460 km transect from Zhongshan to Panda S follows roughly along ∼ 77∘ E longitude and covers all geographic units of East Antarctica. Initial inland observations, near the coast, started in the 1996/97 austral summer. All AWSs in this network measure air temperature, relative humidity, air pressure, wind speed and wind direction at 1 h intervals, and some of them can also measure firn temperature and shortwave/longwave radiation. Data are relayed in near real time via the Argos system. The data quality is generally very reliable, and the data have been used widely. In this paper, we firstly present a detailed overview of the AWSs, including the sensor characteristics, installation procedure, data quality control protocol and the basic analysis of each variable. We then give an example of a short-term atmospheric event that shows the monitoring capacity of the PANDA AWS network. This dataset, which is publicly available, is planned to be updated on a near-real-time basis and should be valuable for climate change estimation, extreme weather events diagnosis, data assimilation, weather forecasting, etc. The dataset is available at https://doi.org/10.11888/Atmos.tpdc.272721 (Ding et al., 2022b).

This article aims to examine alternative explanations of social disadvantage on the university-to-work transition experiences of science, technology, engineering and mathematics (STEM) students. ‘Becoming employable’ during the university-to-work transition is reflected in three ways: students’ cognition/patterns of thinking (i.e., perceived employability); affect/emotion (i.e., anxiety); and career-related behaviour (i.e., job search and networking). To understand how social disadvantage affects ‘becoming employable’, we examine three potential explanations: students’ social background, type of higher education institution attended and individual financial strain. A cross-sectional survey design targeted at final year students in two UK Higher Education Institutions provided 288 survey responses. Findings show support for an institutional explanation to ‘becoming employable’. The study contributes to our understanding of social disadvantage during preparation for labour market entry and the ‘employable graduate’ identity construction process. Practical recommendations focus on alleviating some of the pressures on socially disadvantaged students.

Project governance is an important activity in agile software development (ASD) projects for project success. Middle managers are part of the governance structure in ASD projects. Despite the efficacy of project governance and existence of middle managers in agile teams, project governance and middle management in ASD projects are under-researched. This multiple-case study investigates the roles of middle managers in agile project governance activities within two Nigerian ASD projects through the lens of activity theory. We collected data in semi-structured interviews, observations, questionnaires, and company documents. Our findings show that middle managers performed 25 roles related to planning and coordination for project alignment and execution, continuous improvement and organisational change, agile and technical leadership, monitoring, and capability building. We conclude that middle managers are pivotal to project governance practice and the effectual functioning of agile teams in ASD projects. The study will help agile practitioners to better understand the roles of middle managers in agile project governance. Results from this work contribute to the ‘middle management in agile’ debate and offer an alternative view that may change beliefs about middle managers in agile project settings.

The International Association of Cryospheric Sciences (IACS) became the eighth and most recent association of IUGG at the general assembly in Perugia, Italy, in July 2007. IACS was launched in recognition of the importance of the cryosphere within the Earth system, particularly at a time of significant global change. It was the first new association of the union to be formed in over 80 years and IACS celebrated its 10th anniversary only a year before the IUGG centennial. The forbearers of IACS, however, stretch back even further than IUGG, starting with the formation of the Commission Internationale des Glaciers (CIG) by the International Geological Congress in 1894. Here we record the history of the transition from CIG to IACS, the scientific objectives that drove activities and changes, and some of the key events and individuals involved.

Nine density-dependent empirical thermal conductivity relationships for firn were compared against data from three Automatic Weather Stations at climatically-different East Antarctica sites (Dome A, Eagle and LGB69). The empirical relationships were validated using a vertical, one-dimensional thermal diffusion model and a phase-change based firn diffusivity estimation method. The best relationships for these East Antarctica sites were identified by comparing the modeled and observed firn temperature at the depth of 1 m and 3 m, and from the mean heat conductivities over two depth intervals (1–3 m and 3–10 m). Among the nine relationships, that proposed by Calonne et al. (2011) appears to have the best performance. This study provides useful reference for firn thermal conductivity parameterizations in land modeling or snow-air interaction studies on the Antarctica Ice Sheet.

Within the past 125,000 years, variations in Earth’s climate have resulted in global sea levels fluctuating from 130 to 140 m lower than present day to 6 to 9 m higher. Presently, global mean sea level is rising at its fastest rate in the past 6,000 years (~3 mm/year). In this chapter, we discuss both the causes and implications of sea-level rise from the perspective of a cryospheric hazard. We also survey the best estimates of sea-level rise and cryospheric mass change from a variety of monitoring techniques. The transfer of terrestrial ice into the sea has contributed about 50 percent of the sea-level rise since 1993, and probably exceeded the combined sea-level changes due to thermal expansion, changes in terrestrial water storage, and changes in ocean basin size since 2003. This cryospheric contribution to sea-level rise is approximately equally split between the combined ice sheets of Greenland and Antarctica, and the global population of about 200,000 glaciers. The societal effects of sea-level rise will be highly varied throughout the world, with some locations experiencing relative sea-level drop, whereas others experience a relative sea-level rise several times the global mean. Perhaps counter-intuitively, the sea-level rise due to terrestrial ice loss will be most substantial in areas furthest from the source of melting ice. Although this cryospheric hazard will unfold over a much longer time scale than many of the other hazards discussed in this volume, the ramifications of sea-level rise will likely be more widespread and profound. Some implications discussed here include coastal inundation, increased coastal flood frequency and groundwater salinization.

This paper explores the emergence and adoption of cloud computing by enterprises in sub-Saharan Africa. Several studies have shown the benefits of cloud technologies for enterprises. Using qualitative techniques we obtained and analyzed data from nine enterprises regarding the adoption of cloud computing as an IT strategy. These enterprises span the finance, information and communication technology (ICT) training, research, construction and manufacturing sectors in Ethiopia. We found that, contrary to the literature on cloud computing adoption in the global north, these enterprises are yet to adopt cloud computing as an IT provisioning method and they lack awareness of the advantages and disadvantages of adopting the cloud. The enterprises are concerned with challenges like security, privacy and trust issues as well as government telecommunications infrastructure policies and cloud technology skills acquisition. This research is part of a wider study that has taken place in Nigeria and Ghana, where we have observed higher levels of adoption. This research raises awareness of the challenges and potential benefits of cloud adoption.

The term "cryosphere" (deriving from the Greek word kryos for frost or icy cold) is used to describe collect­ively those portions of the Earth's surface where water is in a solid form. It includes sea, lake, and river ice, snow cover, glaciers, ice caps and ice sheets, and frozen ground (including permafrost). While the focus of this chapter is on geodetic issues and Future Earth, which primarily involves ice sheets and glaciers on land and their role in global mass redistribution and sea level, the cryosphere as a whole is an integral part of the global climate system with important links and feedbacks gen­erated through its influence on surface energy and mois­ture fluxes, clouds, precipitation, hydrology, and atmospheric and oceanic circulation. The basic proper­ties that determine these roles are the high albedo of snow and ice surfaces; the latent heat involved in phase changes of ice/water; the height-mass balance feedback, which results from the great elevation of ice sheets and resultant effects on temperature and precipitation; and the insulating effect of snow cover on land and of floating ice on fresh water or seawater. Other major factors include the water volume stored in ice sheets and glaciers, the greenhouse gases locked up in perma­frost, and the delays in annual energy and water cycles due to seasonal snow and ice cover. Through these and associated feedback processes, the cryosphere plays a significant role in global climate. Cryospheric processes therefore need to be included explicitly and correctly in climate models to project future response to global change. Change in the cryosphere is also an important indicator of climate variability and change.

The differing response of ice extent in the Arctic and Antarctic to global average temperature change, over approximately the last three decades, highlights the importance of reconstructing long-term sea ice history. Here, using high-resolution ice core records of methanesulfonate (MS−) from the East Antarctic Ice Sheet in Princess Elizabeth Land, we reconstruct southern Indian Ocean sea ice extent (SIE) for the sector 70° E–100° E for the period 1708–2000 A.D. Annual MS− concentration positively correlates in this sector with satellite-derived SIE for the period 1973–2000 (P < 0.05). The 293 yr MS− record of proxy SIE shows multi-decadal variations, with large decreases occurring in two warm intervals during the Little Ice Age, and during the 1940s. However, after the 1980s there is a change in phase between Antarctic SIE and global temperature change, with both increasing. This paradox is probably attributable to the strong anomaly in the Southern Annular Mode (SAM) in the recent three decades.

Antarctic ice sheet mass loss has been linked to an increase in oceanic heat supply, which enhances basal melt and thinning of ice shelves. Here we detail the interaction of modified Circumpolar Deep Water (mCDW) with the Amery Ice Shelf, the largest ice shelf in East Antarctica, and provide the first estimates of basal melting due to mCDW. We use subice shelf ocean observations from a borehole site (AM02) situated ?70 km inshore of the ice shelf front, together with open ocean observations in Prydz Bay. We find that mCDW transport into the cavity is about 0.22?±?0.06 Sv (1 Sv?=?106 m3 s?1). The inflow of mCDW drives a net basal melt rate of up to 2?±?0.5 m yr?1 during 2001 (23.9?±?6.52 Gt yr?1 from under about 12,800 km2 of the north-eastern flank of the ice shelf). The heat content flux by mCDW at AM02 shows high intra-annual variability (up to 40%). Our results suggest two main modes of subice shelf circulation and basal melt regimes: (1) the “ice pump”/high salinity shelf water circulation, on the western flank and (2) the mCDW meltwater-driven circulation in conjunction with the “ice pump,” on the eastern flank. These results highlight the sensitivity of the Amery's basal melting to changes in mCDW inflow. Improved understanding of such ice shelf-ocean interaction is crucial to refining projections of mass loss and associated sea level rise.

With the omnipresence of softwares in our Society from Information Technology (IT) services to autonomous agents, their systematic and efficient development is crucial for software developers. Hence, in this paper, we present an approach to assist intelligent agents (IA), whatever human beings or artificial systems, in theirs task to develop and configure softwares. The proposed method is an ontological, developer-centred approach aiding a software developer in decision making and interoperable information sharing through the use of the ODYSSEY ontology we developed for the software development life cycle (SDLC) domain. This ODYSSEY ontology has been designed following the Enterprise Ontology (EO) methodology and coded in Descriptive Logic (DL). Its implementation in OWL has been evaluated for case studies, showing promising results.

The differing response of ice extent in the Arctic and Antarctic to global average temperature change, over approximately the last three decades, highlights the importance of reconstructing long-term sea-ice history. Here, using high-resolution ice-core records of methane-sulfonate (MS–) from the East Antarctic ice sheet in Princess Elizabeth Land, we reconstruct southern Indian Ocean sea-ice extent (SIE) for the sector 62–92° E for the period AD 1708–2000. Annual MS– concentration positively correlates in this sector with satellite-derived SIE for the period 1979–2000 (r2 = 0.25, P < 0.02). The 293 year MS– record of proxy SIE shows multi-decadal variations, with large decreases occurring in two warm intervals during the Little Ice Age, and during the 1940s. It is very likely that the global temperature is the controlling factor of Antarctic sea-ice variation at the centennial scale, although there has been a change in phase between them in recent decades.

The accuracy of daily mean surface pressure from five meteorological reanalyses is assessed against in situ observations from automatic weather stations in East Antarctica for 2005 to 2008. The in situ observations are from Zhongshan, LGB69, EAGLE, and Dome A. The five reanalyses all explain more than 87% of the average variance and have annual root mean square errors between 15 hPa and 45 hPa. The ERA Interim reanalysis performs best against both criteria. The NCEP-1, NCEP-2, and 20CRv2 reanalyses have negative biases of 29.7 hPa, 25.9 hPa, and 11.1 hPa, respectively, while ERA Interim and JCDAS have positive biases of 4.9 hPa and 14.9 hPa. The reanalyses do not show obvious seasonal differences. The errors generally tend to decrease from the coast to the interior of the East Antarctic ice sheet, although there are regional differences between the performance of the different reanalyses. ERA Interim is superior to other reanalyses, probably because of its 4D assimilation scheme, which is strongl...

This paper explores the emergence and adoption of cloud computing by small and medium-sized enterprises (SMEs) and points towards its implications for developing countries in sub-Saharan Africa. Several studies have shown the importance of technologies to SMEs and the potentials of SMEs for economic growth. Using qualitative techniques we obtained and analysed data from ten SMEs that have adopted cloud computing as an IT strategy. These SMEs span across various sectors including finance, information and communication technology (ICT), and manufacturing in Nigeria, a developing country in sub-Saharan Africa. We found that, contrary to the literature on cloud computing adoption in the global north, these SMEs are less concerned with challenges like security, privacy and data loss rather; they continue to show optimism in using the potential opportunities that cloud computing presents to them. We envisage that as cloud computing evolves, more SMEs in sub-Saharan Africa will adopt it as an IT Strategy. This could positively contribute to the successes of these SMEs and consequently contribute to the economic growth desired by these developing countries.

对比分析2005~2008年五种再分析资料和东南极地区气象站实测的日平均2 m气温，结果表明: 五种再分析资料都能够解释超过70%的方差，年均方根误差为3.4~6.9℃. 三种NOAA再分析资料NCEP-1，NCEP-2和20CRv2呈现冷偏差（分别为-2.5，-1.4和-1.5℃），ERA Interim和JCDAS呈现暖偏差（分别为1.7和2.0℃）. 五种再分析气温通常在（南半球）春季适用性强，冬、秋季适用性差；在海拔2800 m高原内陆EAGLE地区适用性最强，在东南极冰盖最高点Dome A地区适用性最差. ERA Interim适用性优于其他再分析资料，可能源于其4D同化体系；三种NOAA再分析资料适用性最差，因为其同化体系更多地受控于有限的观测资料，20CRv2同化数据更少，仅仅同化了表面气压观测资料. 虽然再分析气温具有一定的不足和局限性，但是，仍然不失为南极地区气候研究的有效工具. 在南极，尤其是在广袤的南极内陆地区，进一步加强更多的实地观测显得尤为重要.

Oceanographic instruments suspended beneath the Amery Ice Shelf, East Antarctica, have recorded sporadic pressure decreases of 10–20 dbar over a few days at three sites where basal marine ice growth is expected. We attribute these events to flotation due to platelet ice accretion on the instrument moorings. Some events were transient, rapidly returning to pre-event pressures, probably through dislodgement of loosely attached crystals. Driven by these pressure changes, temperatures recorded by the shallowest instruments (within 20 m of the shelf base) tracked in situ freezing temperatures during the events. These observations provide indirect evidence for the presence of frazil ice in the sub-ice-shelf mixed layer and for active marine ice accretion. At one site we infer that a dense layer of platelet ice ˜1.5 m thick was accreted to the ice shelf over a 50 day period. Following some permanent abrupt pressure decreases (which we interpret as due to the lodgement of the uppermost instrument at the ice-shelf base), altered background trends in pressure suggest compaction rates of 3–4 m a–1 for the accreted basal platelet layer. Attachment of platelet ice and resulting displacement of moorings has ramifications for project design and instrument deployment, and implications for interpretation of oceanographic data from sub-ice-shelf environments.

[1] Marine ice is an important factor in ice shelf stability. An extensive marine ice layer is present under the Amery Ice Shelf (AIS), East Antarctica. This paper documents observations on the seasonal variability of the AIS-ocean interaction beneath the marine ice layer. We focus on data collected during 2002 through a borehole at AM01, 100 km from the ice shelf calving front, and use additional data from two other boreholes to complement the study. At AM01, the top ∼20 m of the water column is super-cooled almost year round, protecting the marine ice layer and promoting frazil ice formation. The mixed layer thickness varies from ∼50 m in February to at least 160 m by June, as the water column cools and freshens. High Salinity Shelf Water (HSSW) abruptly arrives at AM01 in June–August as an eddy-like flow. We suggest that the flow characteristics are a result of baroclinic instabilities. In addition, the inflow of HSSW results in a steepening of the isopycnals that enhances the upwelling of Ice Shelf Water. This study documents, for the first time, a seasonal signal in the formation of marine ice under the AIS. Our results highlight the vulnerability of the marine ice layer to ocean variability with potential consequences for the overall ice shelf mass balance.

The accuracy of daily mean 2 meter air temperatures from five reanalyses are assessed against in-situ observations from Automatic Weather Stations in East Antarctica for 2005 to 2008. The five reanalyses all explain more than 70% of the average variance, and have annual root mean square errors (RMSE) between 3.4 and 6.9°C. The NOAA reanalyses, NCEP-1, NCEP-2 and 20CRv2, have cool biases of 2.5, 1.4 and 1.5°C, respectively. The ERA Interim and JCDAS reanalyses have warm biases of 1.7 and 2.0°C. All reanalyses generally perform better in the austral spring and worse in winter and autumn. They also show the best performance at an inland plateau site at 2800 m elevation, but are worst at Dome A, the summit of the East Antarctic ice sheet. In general, ERA Interim is superior to the other reanalyses, probably because of its 4D assimilation scheme. The three NOAA reanalyses perform worst; Their assimilation scheme is more constrained by limited observations and 20CRv2 has less input data, assimilating only surface pressure observations. Despite deficiencies and limitations, the reanalyses are still powerful tools for climate studies in the Antarctic region. However, more in-situ observations are required, especially from the vast interior of Antarctica.

Despite the Amery Ice Shelf (AIS) being the third largest ice shelf in Antarctica, the seasonal variability of the physical processes involved in the AIS-ocean interaction remains undocumented and a robust observational, oceanographic-based basal melt rate estimate has been lacking. Here we use year-long time series of water column temperature, salinity, and horizontal velocities measured along the ice shelf front from 2001 to 2002. Our results show strong zonal variations in the distribution of water masses along the ice shelf front: modified Circumpolar Deep Water (mCDW) arrives in the east, while in the west, Ice Shelf Water (ISW) and Dense Shelf Water (DSW) formed in the Mackenzie polynya dominate the water column. Baroclinic eddies, formed during winter deep convection (down to 1100 m), drive the inflow of DSW into the ice shelf cavity. Our net basal melt rate estimate is 57.4 ± 25.3 Gt yr−1 (1 ± 0.4 m yr−1), larger than previous modeling-based and glaciological-based estimates, and results from the inflow of DSW (0.52 ± 0.38 Sv; 1 Sv = 106 m3 s−1) and mCDW (0.22 ± 0.06 Sv) into the cavity. Our results highlight the role of the Mackenzie polynya in the seasonal exchange of water masses across the ice shelf front, and the role of the ISW in controlling the formation rate and thermohaline properties of DSW. These two processes directly impact on the ice shelf mass balance, and on the contribution of DSW/ISW to the formation of Antarctic Bottom Water.

The Sea Ice Physics and Ecosystem eXperiment (SIPEX) was conducted in the East Antarctic pack ice zone between 115-130 degrees E from 9 September - 11 October, 2007. In situ measurements of sea-ice and snow properties were conducted at 15 ice stations, together with ship-based ASPeCt observations. The ice and snow thickness varied considerably in different regions of the pack ice, with particularly thick ice associated with deformation and a strong slope jet in the southwest of the study region. The mean ice thickness was 0.99 m (1.57 m excluding the northern marginal ice zones), but varied from 0.61 m along the southern leg to 1.80 m along the western leg, with pockets of considerably thicker ice in some regions. Swell was observed on two occasions penetrating more than 330 km south of the ice edge into regions with 80-100% ice concentration. Ice thicknesses calculated from near coincident ICESat laser altimetry (1.74 m) are similar to the in-situ observations in the central pack (1.57 m). (C) 2010 Elsevier Ltd. All rights reserved.

In austral spring 2007, two meso-scale (of the order of 10–100 km) drifting buoy arrays were deployed to investigate the sea-ice kinematics off East Antarctica during the Sea Ice Physics and Ecosystem eXperiment ( SIPEX ). Deployment locations were within the one oceanic surface-drift regime with similarly high ice concentrations, the two arrays were about 440 km apart. Deployments of the two arrays were separated by 18 days. During spring 2007 the sea ice in the region was under the influence of enhanced atmospheric forcing, associated with an unprecedented seasonal increase in cyclone intensity. This atmospheric anomaly also led to repeated winter breakouts of the fast ice around much of East Antarctica (112–134°E), which, in turn, enabled the southward advection of pack ice into zones of quasi-stationary ice. Consequently, synoptic-scale atmospheric activity strongly influenced the characteristics of the regional fast-ice zone. Despite the intensified atmospheric forcing, only 73% of the variability in sea-ice motion is explained by direct atmospheric forcing, compared to 85% derived in previous studies for the same region and time of year. This reduction of synoptic-scale (multi-daily period) variability agrees with relatively high levels of semi-diurnal motion variance (compared to previous studies). Non-linear ice mechanics enable this energy cascade to higher frequencies. Both arrays experienced significant divergence, which enlarged their area by 230% (eastern array, 28 days) and 267% (western array, 30 days) without significant decrease of ice concentration within the enclosed area, indicating that active ice growth was still prevalent in the region. Divergence and shear deformation dominated the deformation parameters.

Seasonal variation of temperature, pressure, snow accumulation, winds, and their harmonic analysis are presented by using the data from Zhongshan Station and three Automatic Weather Stations deployed between the East Antarctic coast and the summit of the ice sheet at Dome A for the period 2005–07. Results show that: 1) temperature, snow accumulation and specific humidity decrease with increasing elevation and distance from the coast, with snow accumulation decreasing from 199 mm water equivalent (w.e.) yr-1 at LGB69 (180 km from the coast) to 31 mm w.e. yr-1 at Dome A, 2) Dome A experiences an extremely low minimum temperature of -82.5°C with the monthly mean temperature below -50°C for eight months in contrast to Zhongshan Station which does not show any monthly mean temperatures below -20°C, 3) mean surface wind speed increases from the coast to the escarpment region, and then reduces rapidly towards the interior plateau with the strongest winds occurring at katabatic sites with the greatest surface slopes, 4) temperature and pressure all shows a distinct biannual oscillation with a main minimum in spring and a secondary minimum in autumn, differing slightly from station to station, and 5) winter temperature corelessness increases as a function of elevation and distance from the coast, from 0.260 at the coastal Zhongshan Station to 0.433 at Dome A.

The basal melting and freezing rates under the Amery Ice Shelf, East Antarctica, are evaluated, and their spatial distributions mapped. Ice velocity, surface elevation and accumulation rate datasets are employed in the analysis, along with a column-averaged ice density model. Our analysis shows that the total area of basal melting is 34 700 km2, with a total annual melt of 62.5 ± 9.3 Gt and an average melting rate of 1.8 ± 0.3 m a−1. Basal freezing mainly occurs in the northwestern part of the ice shelf, over a total area of 26 100 km2 and with a maximum freezing rate of 2.4 ± 0.4 m a−1. The total marine ice that accretes to the ice-shelf base is estimated to be 16.2 ± 2.4 Gt a−1. Using a redefined grounding line and geometry of the Amery Ice Shelf, we estimate the net melt over the ice-shelf base is about 46.4 ± 6.9 G ta−1, which is higher than previous modeling and oceanographic estimates. Net basal melting accounts for about half of the total ice-shelf mass loss, with the rest being from iceberg discharge. Our basal melting and freezing distribution map provides a scientific basis for quantitative analysis of ice–ocean interaction at the ice-shelf–ocean interface.

Determining the mass balance of the Greenland and Antarctic ice sheets (GIS and AIS) has long been a major challenge for polar science. But until recent advances in measurement technology, the uncertainty in ice sheet mass balance estimates was greater than any net contribution to sea level change. The Fourth Assessment Report of the Intergovernmental Panel on Climate Change (AR4) was able, for the first time, to conclude that, taken together, the GIS and AIS have probably been contributing to sea level rise over the period 1993–2003 at an average rate estimated at 0.4 mm yr-1. Since the cut-off date for work included in AR4, a number of further studies of the mass balance of GIS and AIS have been made using satellite altimetry, satellite gravity measurements and estimates of mass influx and discharge using a variety of techniques. Overall, these studies reinforce the conclusion that the ice sheets are contributing to present sea level rise, and suggest that the rate of loss from GIS has recently increased. The largest unknown in the projections of sea level rise over the next century is the potential for rapid dynamic collapse of ice sheets.

The Amery Ice Shelf, East Antarctica, undergoes high basal melt rates near the southern limit of its grounding line where 80% of the ice melts within 240 km of becoming afloat. A considerable portion of this later refreezes downstream as marine ice. This produces a marine ice layer up to 200 m thick in the northwest sector of the ice shelf concentrated in a pair of longitudinal bands that extend some 200 km all the way to the calving front. We drilled through the eastern marine ice band at two locations 70 km apart on the same flowline. We determine an average accretion rate of marine ice of 1.1 ± 0.2 m a−1, at a reference density of 920 kg m−3 between borehole sites, and infer a similar average rate of 1.3 ± 0.2 m a−1 upstream. The deeper marine ice was permeable enough that a hydraulic connection was made whilst the drill was still 70–100 m above the ice-shelf base. Below this marine close-off depth, borehole video imagery showed permeable ice with water-filled cavities and individual ice platelets fused together, while the upper marine ice was impermeable with small brine-cell inclusions. We infer that the uppermost portion of the permeable ice becomes impermeable with the passage of time and as more marine ice is accreted on the base of the shelf. We estimate an average closure rate of 0.3 m a−1 between the borehole sites; upstream the average closure rate is faster at 0.9 m a−1. We estimate an average porosity of the total marine ice layer of 14–20%, such that the deeper ice must have even higher values. High permeability implies that sea water can move relatively freely through the material, and we propose that where such marine ice exists this renders deep parts of the ice shelf particularly vulnerable to changes in ocean properties.

Lowest temperature and snow accumulation rate are preconditions for retrieving the oldest ice core from the polar ice sheets. The 10-m depth firn temperature at Dome A, the summit of the Antarctic Ice Sheet, recorded by an automatic weather station (AWS) was −58.3°C in 2005 and −58.2°C in 2006, respectively. The 10-m firn temperature is an approximation of the annual mean air temperature (AMAT), and this is the lowest AMAT that has been recorded on the surface of the Earth. The stable isotopic ratios (δ 18O and δD) of surface snow at Dome A are also lower than at other ice sheet domes along the East Antarctic Ice Divide such as Dome C, Dome F, Dome B and Vostok. These facts indicate that Dome A is the “pole of cold” on the Earth. The total amount of snow accumulation rate in 2005 and 2006 was only 0.16 cm, equaling 0.016 m water equivalent per year, the lowest precipitation ever recorded from Antarctica. Preliminary evidences indicate that Dome A is a candidate site for recovering the oldest ice core.

An assessment of the glaciological and meteorological characteristics of Dome A, the summit of the East Antarctic ice sheet, is made based on field investigations during the austral summer of 2004/05. Knowledge of these characteristics is critical for future international studies such as deep ice-core drilling. The assessment shows that: (1) Dome A is characterized by a very low 10m depth firn temperature, –58.3˚C (nearly 3˚C lower than at EPICA Dome C and 1˚C lower than at Vostok). (2) Automatic weather station (AWS) measurements of snow surface height and reference layers in a snow pit indicate the present-day snow accumulation rate at Dome A is within the range 1–3cmw.e. a–1. Densification models suggest a range of 1–2cmw.e. a–1. This is lower than at other sites along the ice divide of East Antarctica (IDEA). Annual layers at Dome A are thus potentially thinner than at other sites, so that a longer record is preserved in a given ice thickness. (3) The average wind speed observed at Dome A (–1) is lower than at other sites along IDEA. Together, these parameters, combined with radio-echo sounding data and information on the subglacial drainage distribution beneath Dome A, suggest Dome A as a candidate site for obtaining the oldest ice core.

在极地冰盖, “低温、低积累率”是获取古老冰芯的必要条件之一. 通过南极冰盖最高点Dome A(冰穹A)自动气象站连续记录的2005年和2006年10 m深度雪温数据, 得到Dome A的多年平均气温约为-58.3℃, 较东南极冰盖分冰岭的其他冰穹如Dome C, Dome F, Dome B以及Vostok均低, 是迄今地球上实测最低年平均温度; 从雪冰气温代用指标 δ 18 O和 δ D测值看, Dome A在上述地点中亦最低.自动气象站记录的雪面高度数据表明2005~2006年间Dome A年积累率约0.01~0.02 m水当量, 是迄今在东南极冰岭测得的最小积累率. Dome A低温、低积累率特点是寻找年代超过1 Ma冰芯的必要条件.

This paper presents a framework that draws on Structuration theory and dialectical hermeneutics to explicate the dynamics of software process improvement (SPI) in a packaged software organisation. Adding to the growing body of qualitative research, this approach overcomes some of the criticisms of interpretive studies, especially the need for the research to be reflexive in nature. Our longitudinal analysis of the case study shows SPI to be an emergent rather than a deterministic activity: the design and action of the change process are shown to be intertwined and shaped by their context. This understanding is based upon a structurational perspective that highlights how the unfolding/realisation of the process improvement (intent) are enabled and constrained by their context. The work builds on the recognition that the improvements can be understood from an organisational learning perspective. Fresh insights to the improvement process are developed by recognising the role of the individual to influence the improvement through facilitating or resisting the changes. The understanding gained here can be applied by organisations to enable them to improve the effectiveness of their SPI programmes, and so improve the quality of their software.

Multi-tenancy is a vital cloud computing property that enables multiple tenants of an application to be served concurrently while guaranteeing isolation between the tenants. Current cloud deployment patterns catalogue for implementing multi-tenancy lack details which make it difficult to use in deploying applications to the cloud. This paper applies our existing catalogue template to the cloud multi-tenancy patterns, in particular the tenant-isolated and dedicated component pattern. Thereafter we demonstrated its applicability with a local company software application that involved the migration of a database driven business process management system to the cloud. The result shows that: (i) there is an improvement in the structure and clarity of the cloud deployment pattern catalogue; (ii) deployment patterns can help achieve migration in less time and with realistic results; (iii) the improved catalogue helps software engineers to understand the trade-off between each pattern.

Samples of marine ice were collected from the Amery Ice Shelf, a large embayed ice shelf in East Antarctica, during the Austral summer of 2001–2002. The samples came from a site ∼90 km from the iceberg calving front of the shelf, where the ice is 479 m thick and the lower 203 m is composed of accreted marine ice. Protists identified within the marine ice layer of the Amery Ice Shelf include diatoms, chrysophytes, silicoflagellates and dinoflagellates. The numerical dominance of sea ice indicator diatoms such as Fragilariopsis curta, Fragilariopsis cylindrus, Fragilariopsis rhombica and Chaetoceros resting spores, and the presence of cold open water diatoms such as Fragilariopsis kerguelensis and species of Thalassiosira suggest the protist composition of the Amery marine ice is attributable to seeding from melting pack and/or fast ice protist communities in the highly productive waters of Prydz Bay to the north.

Recent unexpected changes in the Antarctic Ice Sheet, including ice sheet thinning, ice shelf collapse and changes in ice velocities, along with the recent realization that as much as one third of ice shelf mass loss is due to bottom melt, place a new urgency on understanding the processes involved in these changes. Technological advances, including very new or forthcoming satellite-based (e.g. ICESat, CryoSat) remote sensing missions, will improve our ability to make meaningful determinations of changes in Antarctic Ice Sheet mass balance.This paper is the result of a workshop held to develop a strategy for international collaboration aimed at the collection and synthesis of Antarctic Ice Sheet mass balance data, and at understanding the processes involved so that we might predict future change. Nine sets of recommendations are made, concerning the most important and sensitive measurements, temporal ranges and study areas. A final tenth recommendation calls for increased synthesis of ice sheet data and communication between the field measurement, satellite observation and modelling communities. (C) 2004 Published by Elsevier B.V.

The net surface snow accumulation on the Antarctic ice sheet is determined by a combination of precipitation, sublimation and wind redistribution. We present a 1 year record of hourly snow-height measurements that shows its seasonal variability. The measurements were made with an ultrasonic sensor mounted on an automatic weather station (AWS) installed at LGB69, Princess Elizabeth Land, Antarctica (70.835˚S, 77.075˚E; 1850 ma.s.l.). The average accumulation at this site is approximately 0.70 m snow a–1. Throughout the winter, between April and September, there was little change in surface snow height. The strongest accumulation occurred during the period October–March, with four episodic increases occurring during 2002. These episodic events coincided with obvious humidity ‘pulses’ and decreases of incoming solar radiation as recorded by the AWS. Observations of the total cloud amount at Davis station, 160 km north-northeast of LGB69, showed good correlation with major accumulation events recorded at LGB69. There was an obvious anticorrelation between the lowest cloud height at Davis and the daily accumulation rate at LGB69. Although there was no correlation over the total year between wind speed and accumulation at LGB69, large individual accumulation events are associated with episodes of strong wind. Strong accumulation events at LGB69 are associated with major storms in the region and inland transport of moist air masses from the coast.

Surface mass-balance studies and climatic records from firn cores show remarkable differences between the east and west sides of the Lambert Glacier basin (LGB). The spatial distribution of the surface accumulation is influenced by the atmospheric moisture flux, and by the surface wind field, which is largely determined by topography. Atmospheric water-vapor budget data for the ice-sheet sector covering the basin (45–90˚ E) show that on the east side of the LGB the moisture flux is poleward, averaging 18 kgm–1 s–1 in 1988, while for the west side it is Equatorward, averaging 5 kgm–1 s–1. A similar pattern, but with much lower transport of vapor flux, is seen across 70˚ S. Two firn cores from the east side of the basin and two from the west side were analyzed to determine accumulation-rate and temperature-proxy variations for the past 50 years. The trends were opposite on the different sides of the basin. Similar opposing trends are seen in meteorological records from Davis and Mawson coastal stations, situated on the east and west sides of the LGB respectively. There is a good correlation between the accumulation/18O record in ice cores from the eastern LGB and the sea-level pressure (obtained from the US National Centers for Environmental Prediction/US National Center for Atmospheric Research (NCEP/NCAR) re-analyses) of a Southern Indian Ocean low (SIOL), but not between the SIOL and the records from the western LGB. This study reveals that variations in local circulation could alter at least the annual to decadal time-scale climate records, and may result in completely different climate histories between adjacent areas.

A coupled atmosphere–sea-ice model is used to assess the effect of Antarctic polynyas on the heat exchange between the surface and the atmosphere, the ice production rate within the polynyas, and the possible mechanisms of formation and maintenance of the polynyas. Results are presented for sensitivity studies with the model using prescribed minimum open-water fractions (25% and 30%) at a number of locations around the coast of East Antarctica and in the Amundsen, Ross and Weddell Seas. Although to some extent unphysical for the ocean, this technique allows the heat fluxes and freezing rates to be computed for the constrained conditions compared with an unconstrained control simulation. The model simulations suggest that Antarctic coastal polynyas, including the Mertz Glacier polynya, are primarily latent heat polynyas (where the heat loss from open water is balanced by the latent heat released with ice production) rather than sensible heat ones (where the heat loss is balanced by heat from the deep ocean). When a polynya exists, the turbulent latent heat flux from the ocean surface to the atmosphere can increase several times in magnitude and the average latent heat flux (over open-water and sea-ice fractions) can be sustained at over 60 W m −2 . The sensible heat flux changes sign and increases by about 2 orders of magnitude. This loss of turbulent heat (sensible plus latent) is offset only slightly by increased absorbed short-wave radiation in winter, but this offset increases greatly in spring when more short-wave radiation is available. In the polynyas, the large heat loss to the atmosphere is mostly balanced by the heat released due to ice formation, and this is accompanied by a high rate of salt rejection. The average ice production simulated in the polynyas is more than 11 m/year, with 5 m formed during 3 months of winter. These results provide quantitative support for the sustained high ice-freezing rates in polynyas estimated in other studies, which have used satellite and in situ observational data.