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Geothermal heat flow (GHF), which contains integrated information on geothermal gradient, thermal conductivity, and heat productivity of rocks as well as crustal/mantle heat flow, is a crucial parameter in many studies including the evaluation of geothermal resources in a region and the prediction of ice sheet mass loss. The GHF measurements in the Bohai Bay Basin are insufficient and unevenly distributed, and no model has been developed to predict the GHF distribution. In this paper, using eight geological features as input data and output GHF predictions, four different machine learning algorithms were evaluated and implemented to predict the GHF data in this area: (1) a generalized linear model (GLM), (2) a deep neural network (DNN), (3) a gradient boosted regression tree (GBRT), and (4) a support vector machine (SVM). The DNN model, in which the number of neurons is a multiple of the number of features, tended to perform better than the others. Both the SVM and DNN algorithms demonstrated better accuracy, with average relative prediction errors of 13.3 and 12.7%, respectively. The accuracy improved when using a hybrid SVM and DNN approach, with an average relative prediction error of 12.2%. Based on the above models, we produced three new GHF maps of the Bohai Bay Basin. They showed similar local anomaly features but with different ranges and degrees. The new GHF maps are more detailed and rational than the map produced by kriging interpolation. The predicted GHF had much higher accuracy, which is more consistent with the measured geothermal gradient in the related areas. Finally, we reclassified the basin into four different levels of geothermal exploration target areas based on the new GHF maps. [ABSTRACT FROM AUTHOR]

The Holocene hydrological regime on the Heixiazi Island is critical for understanding the evolution of the East Asian summer monsoon (EASM) for the island's climate-sensitive location on the northern fringe of the EASM domain. In this paper, a marsh depression on the central island was selected to reconstruct the locally hydrological variation and to discuss its indications for the Holocene EASM evolution. This work is based on multi-proxy (magnetic susceptibility, grain size, loss-on-ignition, and carbonate content) analyses of 22 modern sedimentary samples with a water-level gradient of 0–66 cm and 100 cored sedimentary samples covering last ~ 9.0 ka BP. The proxies' hydrological significance was previously interpreted by the 22 modern samples using linear regression equations to construct their relationships to water-level changes. Among these proxies, the magnetic susceptibility, carbonate content, as well as the Md and sand fraction of grain size exhibit high-level relationships against the water-level changes with R2 > 0.6. Thus, these four proxies' linear-regression equations were selected and used on the 100 cored samples, and the Holocene water-level changes in the studied depression were quantitatively reconstructed. It shows that two relatively high water-level stages with strengthened EASM occurred during 8.0–4.5 ka BP and 3.0–1.4 ka BP, which were alternated by three low water-level stages with declined EASM during ~ 9.0–8.0 ka BP, 4.5–3.0 ka BP, and 1.4–0 ka BP, respectively. Among these fluctuations, the highest water-level stage with most strengthened EASM which is defined as the Holocene Monsoon Maximum occurred during 6.4–4.5 ka BP. Such a new evolution pattern of the EASM can be further supported by a large variety of records from monsoon-margin regions. We suggest the Holocene EASM evolution was generally associated with the thermal conditions in both the inner Eurasia landmass and the West Pacific Ocean, with an exception of the weak EASM before 8.0 ka BP due to the enhanced Siberia High with the dominance of the Eurasia ice sheet in the early Holocene. [ABSTRACT FROM AUTHOR]

The Arctic air mass is the cold, dry body of air slowly moving eastwards around the North Pole in the northern hemisphere. Its southern boundary consists of four planetary waves known as the Rossby waves that mark the interface with subtropical air bringing heat polewards. The Arctic air mass is constantly being modified by the addition of heat and moisture over the oceans, as well as by winter cooling over the land masses due to limited incoming solar radiation and constant reradiation of heat into the atmosphere. The coldest air in winter is located over northeastern Siberia and moves east, cooling Canada. Warm ocean currents add large quantities of heat to the air mass moving over them, but without this addition of heat, the Arctic air mass becomes significantly colder. Research in Tibet and Northeast Asia on depression of sea level shows that during the Late Wisconsin cold event (65–10 ka B.P.), vast quantities of sea water were sequestered on land primarily as ice sheets, exposing the sea bed in the Bering Strait from 50–10 ka B.P. together with the bottom of the South China Sea between 30–20 ka B.P.. The East China Monsoon failed to reach Tibet and much of Northeast China, resulting in severe cooling of northeast Siberia and northern Tibet. This, in turn, caused severe cooling in eastern Canada together with the development of a vast, predominantly cold-based ice sheet. As the sea levels started to rise (about 19 ka B.P.), the East China Monsoon slowly redeveloped and a gradual warming took place on both continents. However, along the west side of the North American Cordillera, the Late Wisconsin glaciation only began in 29 ka B.P. but continued along the west coast until about 10 ka B.P. This paper explores the relationship of the Late Wisconsin history on the two continents, together with the mechanisms causing the landforms and climatic differences. Finally, the probable effects of these climatic changes on the early peopling of North America are discussed. [ABSTRACT FROM AUTHOR]

The properties of ice strength have a significant impact on the design and safety of structures in ice-infested waters. To analyze the flexural strength of columnar saline model ice, we conducted circular plate center loading tests at the Small Ice Model Basin of the China Ship Scientific Research Center (CSSRC SIMB) in China. The tests involved varying the loading rate and ice temperature, and a numerical model was developed using FEM and LS-DYNA for validation and comparison. The results of the tests revealed the crack propagation process, stress distribution, load response, and failure mode of the model ice. The model ice displayed typical brittle failure, and the flexural strength was linearly related to ice temperature but not significantly correlated with loading rate. The porosity of the model ice affected the load response and time of failure but not the failure mode. The model ice with 7% porosity had a 7.8% reduction in load response compared to the nonporous model ice. This study provides a reliable method for measuring and analyzing the flexural strength of model ice. It also serves as a foundation for further research on the interaction between structures and ice sheets. [ABSTRACT FROM AUTHOR]

Nanopore metagenomic sequencing enables rapid annotating microbiological ecosystems, and the previous glacier-related sequencing applications (e.g., targeted ice sheets, ice lake, and cryoconite holes) inspire us to explore high-altitude glacier meltwater at Qilian Mountain, China (3000 to 4000 m above sea level, MASL). Our findings suggest that (1) despite only several hundred meters apart, the microbial communities and functionalities are quite different among vertical alpine distributions; (2) the high-altitude Qilian meltwater microbiome serve several main metabolic functions, including sulfur oxidation, selenite decomposing, photosynthesis, energy production, enzymic, and UV tolerant activities. Meanwhile, our Nanopore metagenomic results indicate that the microbial classifications and functionalities (e.g., chaperones, cold-shock, specific tRNA species, oxidative stress, and resistance to toxic compounds) of Qilian meltwater are highly consistent with the other glacial microbiome, emphasizing that only certain microbial species can survive in the cold environment and the molecular adaptions and lifestyles remain stable all over the world. Besides, we have shown Nanopore metagenomic sequencing can provide reliable prokaryotic classifications within or among studies, which therefore can encourage more applications in the field given faster turnaround time. However, we recommend accumulating at least 400 ng nucleic acids (after extraction) and maximizing Nanopore library preparation efficiency before on-site sequencing to obtain better resolutions. [ABSTRACT FROM AUTHOR]

The Holocene hydroclimate evolution and underlying mechanisms modulating the East Asian summer monsoon (EASM) remains controversial, especially in south eastern China. Here we present a multiproxy peat record of monsoon evolution from southeastern China covering the last 14 ka. Our new records show a relatively weaker EASM but wetter hydroclimate during the early (10 to 8 ka) and late Holocene (after 5.4 ka), while a stronger EASM and overall drier climate during the mid-Holocene (8 to 5.4 ka). In line with nearby speleothem records, our results reveal a dominant control of the northern-latitude ice-sheet meltwater forcing on millennial-scale East Asian hydroclimate variability during the last deglaciation and early Holocene. This dominant influence, however, likely waned once the global sea level had stabilized during the mid-to-late Holocene, giving way to other drivers of the monsoon and hydroclimate, including a combination of summer insolation and teleconnection patterns associated with vegetation-dust feedbacks. [ABSTRACT FROM AUTHOR]

Numerous high‐elevation alpine plants of the Qinghai‐Tibet Plateau (QTP) also have disjunct distribution in adjacent low‐altitude mountains. The out‐of‐QTP versus into‐the‐QTP hypothesis of alpine plants provide strong evidence for the highly disputed assumption of the massive ice sheet developed in the central plateau during the Last Glacial Maximum (LGM). In this study, we sequenced the genomes of most known populations of Megadenia, a monospecific alpine genus of Brassicaceae distributed primarily in the QTP, though rarely found in adjacent low‐elevation mountains of north China and Russia (NC‐R). All sequenced samples clustered into four geographic genetic groups: one pair was in the QTP and another was in NC‐R. The latter pair is nested within the former, and these findings support the out‐of‐QTP hypothesis. Dating the four genetic groups and niche distribution suggested that Megadenia migrated out of the QTP to adjacent regions during the LGM. The NC‐R group showed a decrease in the effective population sizes. In addition, the genes with high genetic divergences in the QTP group were mainly involved in habitat adaptations during low‐altitude colonization. These findings reject the hypothesis of development massive ice sheets, and support glacial survival of alpine plants within, as well as further migration out of, the QTP. [ABSTRACT FROM AUTHOR]

It is critical to understand the mechanisms and impacts of global climate change in cryosphere and polar environment. Here we describe the design and progress of the remote sensing products we have developed to monitor these changes. We obtain datasets by combining multi-sensor remote sensing systems with field validation systems, and then develop a methodological system that combines multiple sources and calibration technologies to address the challenges of data heterogeneity in dynamically monitoring key parameters. This global change and response special project supported by the National Key Research and Development Program of China, named 'observation and inversion of critical parameters of changes in the cryosphere and polar environment', providing comprehensive records of essential elements of the cryosphere through long-term satellite records. The multi-team is completing the project and collecting data from multi-sensor to create remote sensing data products that include records of changes in the cryosphere, such as permafrost, glaciers, ice sheet mass balance, seasonal snow accumulation, sea ice, and albedo changes. Finally, the existing ground- and space-based observing system can be improved to provide dynamic monitoring of key parameters in the cryosphere and changes in the polar environment. [ABSTRACT FROM AUTHOR]

The rainfall changes in East Asian summer monsoon (EASM) regions on the orbital timescale remain controversial due to the lack of reliable rainfall records. Here, we present new multiproxy records (δ18O, δ13C, Sr/Ca and Mg/Ca) of a 230Th-dated stalagmite from Hulu Cave in central eastern China. Multiproxy records reconstruct a regional hydroclimate history from 340 to 261 kyr BP (thousand years before present), approximately covering the antepenultimate glacial period. The δ18O record is dominated by the precessional cycles, suggesting that EASM responds to changes in Northern Hemisphere summer insolation (NHSI) on the orbital timescale. Significant correlations amongst the δ13C, Sr/Ca and Mg/Ca suggest that a common factor, i.e., the local hydrological cycle, controlled their variability, and their leading principal component can be used as a proxy linked to regional rainfall. This composite record bears a good similarity to those from the Chinese Loess Plateau, showing a gradually decreasing rainfall during the antepenultimate glacial period, consistent with changes in global ice volume. Superimposed on the long-term trend, three relative wetter intervals were responding to the higher NHSI periods, suggesting that EASM rainfall variability was induced by integrated effects of global ice volume and NHSI. The increased ice sheets and lower NHSI resulted in an increased meridional temperature gradient and southward shift of the westerlies, which shortened the duration of Meiyu and midsummer rainfall. The differences between the rainfall record and the stalagmite δ18O record indicate that the latter represents the overall EASM intensity linked to monsoon circulation, but does not directly reflect the rainfall changes at the cave sites. [ABSTRACT FROM AUTHOR]

The Gao Fen 7 (GF‐7) satellite is China's first submeter, high‐resolution Earth observation and remote sensing satellite for natural resource monitoring, land surveying, and other industrial applications in China. The GF‐7 laser altimeter system is the successor of the ZiYuan3‐02 (ZY3‐02 satellite) laser altimeter. The key objective of the GF‐7 laser altimetry system is to provide high‐precision ground elevation control points that assist in optical imaging to achieve 1:10000 mapping in China. This paper introduces the GF‐7 laser altimeter system payload specifications, mission objectives, in‐orbit calibration plan, data products, and service policy. In the future, the GF‐7 laser altimeter system will also serve multidisciplinary and professional applications through its precise elevation measurement capabilities. In addition, it will play a vital role in Earth observation, climate change monitoring, and environmental protection. Plain Language Summary: Spaceborne laser altimeters are widely used for planet surface measurements due to their high range accuracy. This paper details the GF‐7 laser altimeter system, which is China's first formal spaceborne laser altimeter system for Earth observations. This laser altimeter system will be used in scientific experiments for the first time in China. GF‐7 laser altimeter system is the first to be equipped with laser footprint cameras and a laser optical axis surveillance camera. The GF‐7 satellite will be launched in October 2019, and the scientific experiments will begin in November. All the data it gets will be released globally. In the future, these data will help researchers from different disciplines around the world to conduct scientific experiments and monitor the Earth's resources. The GF‐7 laser altimeter system will play a vital role in global climate change monitoring, environmental protection, disaster warning, etc. The content presented in this article will help students, researchers, and engineers in the fields of geography, oceanography, and glaciology understand and use GF‐7 satellite laser data, which will be of great significance. Key Points: A new laser altimeter system design consisting of a laser altimeter, two laser footprint cameras, and a laser optical axis surveillance camera equipped with the Gao Fen 7 satellite is introducedThe application of the Gao Fen 7 laser altimeter system including ground control point measurement, polar ice sheet monitoring, and forest biomass estimation is presentedScientific experiments on the Gao Fen 7 laser altimeter system to be performed in November 2019 are given. Six levels of data products are listed and will be provided to users worldwide [ABSTRACT FROM AUTHOR]

Abstract: Previous studies show that the area of a moraine-dammed lake can provide a good indicator of the significance of its outburst. For a glacier-dammed lake however, because its area and depth fluctuates with the melting of its ice dam, it is difficult to predict the outburst of the glacier‐dammed lake by using its area alone. A characteristic of the surface of Lake Merzbacher is a large amount of floating ice therefore, a method is proposed in this article to extract the area of floating ice on the lake and the area of ice free water in the lake by using Environment and Disaster Monitoring Small Satellite images respectively. Furthermore, based on the area of floating ice extracted through the image information of Lake Merzbacher in 2009 and 2010, we determined the relationship between the ice area and the outburst of the lake, then formulated the Index for hazard of Glacier Lake Outburst Flood (IGLOF) of Lake Merzbacher, which cannot only predict the flood outburst, but also determine the specific outburst period after the lake drainage had occurred. This can be shown in a recalculation of the lake drainages in the years 2009 and 2010. Research results indicate that when IGLOF is less than 0.5 and the lake area is larger than 3km2, the outburst process is in early-warning period and GLOF will occur in the next 5–8days. Also, the successful outburst prediction of Lake Merzbacher in 2011 showed that the index described in this paper provides a quick methodology for forecasting and warning against Lake Merzbacher outburst floods. However，as our research was based on a short observation period (2009-2011) and also cannot be supplemented by other images, it will still be needed to be checked and validated by continuous observation and improvement in future. [Copyright &y& Elsevier]

Abstract: Field observations conducted on oil platforms in the Bohai Sea revealed that the offshore jacket structures, which can withstand the maximum static ice force, might suffer from severe vibrations when ice sheets pass through the legs of the structure. It has been proved that, when the natural frequency of narrow or flexible structures is close to or coincides with the predominant frequency of cyclical ice forces, severe ice-induced vibrations will be evoked. Excessive and consistent vibration will cause the discomfort of working crew, failure of deck facilities even structural fatigue failure. Therefore, it is imperative to seek economical ways to reduce the vibrations to an acceptable level. Based on full-scale tests and technical feasibility, the strategies of vibration mitigation are investigated and compared in this paper. The primary studies demonstrate that adding a Tuned Mass Damper (TMD, also called a Dynamic Vibration Absorber, DVA) is a feasible and practical approach to reduce vibrations. The efficiency of optimally designed TMD and one-directional conceptual TMD device has been presented in this study. Field ice load time history was used as loading scenario to assess the performance of TMD system. The results show that the supplemental device can favorably reduce the dynamic response of platform. [Copyright &y& Elsevier]

The East Asian summer monsoon and the precipitation it brings are relevant for millions of people. Because of the monsoon's importance, there has been a substantial amount of work attempting to describe the driving mechanisms behind its past variability. However, discrepancies exist, with speleothem-based East Asian monsoon reconstructions differing from those based on loess records from the Chinese Loess Plateau during the late Quaternary. The periodicity of wet and dry phases experienced by desert areas that lie on the periphery of the East Asian monsoon's influence offer another independent view of monsoonal variability. Here, we provide environmental records based on magnetic parameters for the last 3 million years from the Tengger Desert, China, one such marginal arid region. Our results reveal wet-dry cycles at a dominant frequency of 405 kiloyears, with drier intervals corresponding to eccentricity minima. These findings are consistent with previous reconstructions of East Asian summer and North African summer monsoon precipitation variability. Our records emphasize the dominant role of eccentricity in forcing East Asian monsoonal precipitation as well as monsoonal-derived environmental fluctuations experienced in peripheral desert areas. These results challenge the traditional view that high-latitude ice sheets are the primary driver of East Asian monsoon precipitation during the Quaternary based on Chinese loess records. [ABSTRACT FROM AUTHOR]

Much has been learned regarding orbital and millennial timescale climate changes after the onset of Northern Hemisphere glaciations (NHG) at ca. 2.7 Ma. By contrast, little is known about these variations before the NHG due to lack of high‐resolution records. Here we report first millennial resolution quantified East Asian summer monsoon (EASM) precipitation record from the north eastern Tibetan Plateau. The record supports astronomical forcing of EASM during the late Miocene, except for the period of 8.13–8.03 Ma when EASM experienced high amplitude variations at the 100‐, 20‐kyr, and suborbital bands, which is in sharp contrast with the damped astronomical forcing. Detection of strong 100‐kyr and millennial cycles during low eccentricity intervals of the warm late Miocene with ephemeral NH ice sheets cast doubt on NH ice sheet size variations as their exclusive forcing in the late Miocene and late Quaternary paleoclimatic records. Plain Language Summary: Millennial and 100‐kyr cycles in paleoclimate records are normally attributed to Northern Hemisphere ice sheet size variations. Here we present the first 1‐kyr resolution quantitative East Asian summer monsoon precipitation record from the northeastern Tibetan Plateau during the late Miocene, when Northern Hemisphere ice sheets were ephemeral. The record demonstrates strong 100‐kyr and clear millennial cycles. Detection of 100‐kyr and millennial cycles in this warm time interval cast doubt on Northern Hemisphere ice sheet size variations as their exclusive forcing in paleoclimatic records. Key Points: First 1‐kyr resolution quantitative northern China precipitation record during the late MioceneThe record reveals strong 100‐kyr and clear millennial cyclesDetection of 100‐kyr and millennial cycles in this warm interval challenges Northern Hemisphere (NH) ice sheet size variations as their exclusive forcing [ABSTRACT FROM AUTHOR]

The climatic drivers of tropical rainfall and atmospheric circulation in the late Pleistocene are still debated. Some studies suggest that tropical precipitation primarily responded to precession (23–19 ky cycle), whereas others propose that glacial‐interglacial (100 ky) changes in ice sheets and sea level dominate. Here, we reexamine orbital influences on tropical‐to‐subtropical precipitation isotopes using singular spectrum analysis to isolate leading oscillatory modes from proxy records across the Indo‐Pacific Warm Pool (IPWP) and Asian monsoon domain. We find that the IPWP, Bay of Bengal, and South China Sea are dominated by the 100 ky glacial‐interglacial mode of variability, whereas eastern China clearly follows precession, suggesting that precipitation isotopes over the mid‐latitude Asian continent respond to different mechanisms than those in the IPWP or Indian and East Asian monsoon regions. This study demonstrates that glacial cycles, rather than changes in local insolation, are the dominant drivers of Pleistocene IPWP hydroclimate. Plain Language Summary: Reconstructions of past changes in rainfall, derived from cave deposits and ancient leaf waxes, provide an opportunity to understand how the tropical Indo‐Pacific Warm Pool, located between Southeast Asia and Australia, responds to large‐scale changes in global climate. Here, we statistically analyze five long records of rainfall and atmospheric circulation across the Warm Pool, the Indian and East Asian monsoon regions, and eastern China to isolate different external drivers of change between regions for the last 600,000 years. We find that the signal over eastern China is dominated by seasonal changes in solar radiation over mid‐latitudes in the Northern Hemisphere, whereas the signal in the Warm Pool and monsoon regions are dominated by changes in sea level and high latitude ice sheet growth. This clear spatial difference in the external drivers of regional circulation changes suggests that the cave records from China do not exclusively reflect East Asian monsoon rainfall. Additionally, this study supports a strong connection between high and low latitude climates during the last several hundred thousand years. Key Points: Indo‐Pacific precipitation isotopes are dominated by glacial‐interglacial climate shifts for 560 kyPrecipitation isotope records from eastern China are dominated by the 23 and 19 ky precessional cycles for 640 kyIndo‐Pacific climate is linked to high latitude processes, cautioning against assuming local insolation dominates [ABSTRACT FROM AUTHOR]

Modelling of glacier and ice sheet micro-topography is meaningful for the understanding of interactions between local ice mass and climate. Here, we used an Unmanned Aerial Vehicle (UAV) platform composed of a DJI Phantom 4 and a D-RTK mobile station to model the surface micro-topography around Zhongshan Station of China, East Antarctica. Two UAV survey types (vertical and oblique aerial photogrammetry) were performed during the China's 35th Antarctic expedition (CHINARE) in 2018–2019. Six surveys were obtained by the SfM-MVS technology. Then, we extracted the features of glacier surface micro-topography (blue ice, crevasses, ice doline and melt-water). It's noteworthy that traces of melt-water and a large ice doline appeared on the surface of Dalk Glacier in December 2018. Finally, we concluded that surface micro-topographic features, observable in the UAV-derived models but unavailable on satellite images, may reveal hints for interactions between surface and beneath processes in regional polar glacier. [ABSTRACT FROM AUTHOR]

The northeastern Qinghai‐Tibetan Plateau (QTP) of China is located at the triple junction of the Asian winter and summer monsoons and the westerlies, where paleoclimatic evolution has an important scientific significance for recognizing the spatial‐temporal pattern of Asian monsoons in the past and predicting environmental change in the future. Nevertheless, the framework of the Holocene moisture variation and related mechanisms remain controversial, owing to complex hydroclimatic conditions triggered by the landform of the large mountain‐arid basin. Here, we employed geochemical proxies from typical aeolian sand‐palaeosol sequences in the Gonghe Basin, northeastern QTP, together with Optically Stimulated Luminescence (OSL) dating, to reconstruct the pattern of effective moisture variation and associated mechanisms in this region. Our results indicate that the regional effective moisture was at its lowest until 9–8 ka, and approached a maximum during 8–4/3 ka of the middle Holocene. Afterwards, the climate became relatively dry in general, but with a transient humid interval around 2–1 ka. Our geochemical evidence indicates that the dry early Holocene probably can be attributed to a strong winter monsoon forced by remnant ice sheet, combined with the high evaporation caused by solar insolation. Also, shifts of humid‐dry are closely linked to the Asian summer monsoonal strength and therefore the balance of evaporation‐precipitation in the middle and late Holocene. Thus, the pattern of the Holocene effective moisture variation is characterized as the 'monsoon model' in a closed intermontane arid and semi‐arid basin near the western Asian monsoonal limit. [ABSTRACT FROM AUTHOR]

As a first qualitative assessment tool, LOVECLIM has been used to investigate the interactions between insolation, ice sheets and the East Asian Monsoon at the Marine Isotopic Stage 13 (MIS-13) in work by Yin et al. (Clim Past 4:79-90, , Clim Past 5:229-243, ). The results are in need of validation with a more sophisticated model, which is done in this work with the ARPEGE atmospheric general circulation model. As in the Earth system Model of Intermediate Complexity, LOVECLIM, ARPEGE shows that the northern hemispheric high insolation in summer leads to strong MIS-13 monsoon precipitation. Data from the Chinese Loess Plateau indicate that MIS-13 was locally a warm and humid period (Guo et al. in Clim Past 5:21-31, ; Yin and Guo in Chin Sci Bull 51(2):213-220, ). This is confirmed by these General Circulation Model (GCM) results, where the MIS-13 climate is found to be hotter and more humid both in the presence and absence of any added ice sheets. LOVECLIM found that the combined effects of the ice sheets and their accompanying SSTs contribute to more precipitation in eastern China, whilst in ARPEGE the impact is significant in northeastern China. Nonetheless the results of ARPEGE confirm the counter-intuitive results of LOVECLIM where ice sheets contribute to enhance monsoon precipitation. This happens through a topography induced wave propagating through Eurasia with an ascending branch over northeastern China. A feature which is also seen in LOVECLIM. The SST forcing in ARPEGE results in a strong zonal temperature gradient between the North Atlantic and east Eurasia, which in turn triggers an atmospheric gravity wave. This wave induces a blocking Okhotskian high, preventing the northwards penetration of the Meiyu monsoon front. The synergism between the ice sheets and SST is found through the factor separation method, yielding an increase in the Meiyu precipitation, though a reduction of the Changma precipitation. The synergism between the ice sheets and SST play a non-negligible role and should be taken into consideration in GCM studies. Preliminary fully coupled AOGCM results presented here further substantiate the finding of stronger MIS-13 monsoons and a reinforcement from ice sheets. This work increases our understanding of the signals found in the paleo-observations and the dynamics of the complex East Asian Summer Monsoon. [ABSTRACT FROM AUTHOR]

The article offers information on a study based on contemporary glacier systems of continental Eurasia. It mentions that continental Eurasia was distinguished into 32 regional glacier systems for the purpose of study including Karakorum range, Kunlun mountains and Nyangchentanglha. It adds that the "World Atlas of Snow and Ice Resources" depicting the maps of heights of equilibrium line and the regional glacier system regimes was used in the study for the determination of the feeding sources of distinguished regions. It mentions, the study reveals that area of glaciations has decreased in last 150 years.

By using ANSYS/LS-DYNA explicit dynamical analysis software, finite element models for an ice sheet and a T-frame bridge were set up individually. On the basis of the deformation compatibility condition and momentum equation, the impact force of a drift ice sheet on a bridge pier was computed. The effects of ice-breaking nose shapes on the ice impact force were investigated. The parameters studied included the nose angle of a wedge-shaped ice-breaking nose, the inclination angle of both wedge-shaped and bow-shaped ice-breaking noses, and the curvature of a bow-shaped ice-breaking nose. The research results indicated that the inclination and nose angle of a wedge-shaped ice-breaking nose and the curvature and inclination angle of a bow-shaped ice-breaking nose are important factors affecting the drift ice impact force. On the basis of the study results, design parameters for the ice-breaking nose shapes were proposed. [ABSTRACT FROM AUTHOR]

This study investigates the causes of severe ice conditions over the Bohai Sea, China, and mild ice cover over the North American Great Lakes under the same hemispheric climate patterns during the 2009/10 winter with a strong negative Arctic Oscillation (AO) and an El Niño event. The main cause of severe ice cover over the Bohai Sea was the strong negative AO. Six of seven winters with severe ice were associated with a strong negative AO during the period 1954-2010. The Siberian high (SH) in the 2009/10 winter was close to normal. The influence of El Niño on the Bohai Sea was not significant. In contrast, the mild ice conditions in the Great Lakes were mainly caused by the strong El Niño event. Although the negative AO generally produces significant colder surface air temperature (SAT) and heavy ice cover over the Great Lakes, when it coincided with a strong El Niño event during the 2009/10 winter the El Niño-induced Pacific-North America (PNA)-like pattern dominated the midlatitudes and was responsible for the flattening of the ridge-trough system over North America, leading to warmer-than-normal temperatures and mild ice conditions over the Great Lakes. This comparative study revealed that interannual variability of SAT in North America, including the Great Lakes, is effectively influenced by El Niño events through a PNA or PNA-like pattern whereas the interannual variability of SAT in northeastern China, including the Bohai Sea area, was mainly controlled by AO and SH. [ABSTRACT FROM AUTHOR]

We reconstructed a multiproxy record of the Holocene climate changes from a 9.53 m core from Bosten Lake in the southern Xinjiang of northwestern China based on a chronology supported by nine AMS 14C dates in the hope that the previous reconstructions can be improved. Our data exhibited three timescales of variation in the water salinity of the lake. First, the upward-increasing parallel trends of major salinity proxies suggest that the salinity has been gradually increasing in the past ∼8000 years. This constant increase in the salinity is most likely to have resulted from the shrinking of glacial cover in the central Tianshan Mountains where the inflowing river (i.e. Kaidu River) originated. Second, the C/S ratio and carbonate-based salinity proxies suggest that the lake was formed around ∼8060 cal. yr BP and reached its maximum depth around ∼7250 cal yr BP. The lake level then declined to the mid- and late-Holocene average level around ∼6370 cal. yr BP and has varied drastically around a relatively constant mean during the past ∼6370 years. Third, the past ∼8060 yr history of the Bosten Lake can be divided into five salinity stages. That is, three high salinity intervals are separated by two low salinity intervals. The two low salinity stages occurred between ∼6370 and ∼5170 cal. yr BP and between ∼3000 and ∼2170 cal. yr BP. Each one of the three high salinity stages can be further divided into less saline and more saline substages. Specifically, less saline time intervals are: substage 2-1 (∼8060-∼7250 cal. yr BP), substage 4-2 (∼4370-∼3830 cal. yr BP) and substage 6-2 (∼1250-∼0 cal. yr BP). Also, saltier time intervals are: substage 2-2 (∼7250-∼6370 cal. yr BP), substage 4-1 (∼5170-∼4370 cal. yr BP), substage 4-3 (∼3830-∼3000 cal. yr BP) and substage 6-1 (∼2170-∼1250 cal. yr BP). It should be stressed that the phase relationships between the carbonate-based salinity proxy and diatom-based temperature proxy suggest that the salinity was mainly controlled by temperature. Finally, the comparison between the Bosten Lake salinity record and the high northern latitudinal climate pattern suggests that the lower salinity and cooler periods in Bosten Lake area correspond with abrupt climatic events (i.e. cooling events) in the high northern latitudes. [ABSTRACT FROM AUTHOR]

Microbial community patterns vary in glaciers world wide, presenting unique responses to global climatic and environmental changes. Four bacterial clone libraries were established by 16S rRNA gene amplification from four ice layers along the 42-m-long ice core MuztB drilled from the Muztag Ata Glacier. A total of 152 bacterial sequences obtained from the ice core MuztB were phylogenetically compared with the 71 previously reported sequences from three ice cores extracted from ice caps Malan, Dunde, and Puruoganri. The six functional clusters Flavisolibacter, Flexibacter (Bacteroidetes), Acinetobacter, Enterobacter (Gammaproteobacteria), Planococcus/Anoxybacillus (Firmicutes), and Propionibacter/Luteococcus (Actinobacteria) frequently occurred along the Muztag Ata Glacier profile. Sequence analysis showed that most of the sequences from the ice core clustered with those from cold environments, and the sequences from the same glacier formed a distinct cluster. Moreover, bacterial communities from the same location or similarly aged ice formed a cluster, and were clearly separate from those from other geographically isolated glaciers. In a summary, the findings provide preliminary evidence of zone distribution of microbial community, support our hypothesis of the spatial and temporal biogeography of microorganisms in glacial ice. [ABSTRACT FROM AUTHOR]

We here present a detailed glacial geomorphological map covering 136,500 km² of the Bayan Har sector of the northeastern Tibetan Plateau - an area previously suggested to have nourished the most extensive Quaternary glaciers of the Tibetan Plateau. The map, presented at a scale of 1:650,000, is based on remote sensing of a 90 m SRTM digital elevation model and 15/30 m Landsat ETM+ satellite imagery. Seven landform types have been mapped; glacial valleys, glacial troughs, glacial lineations, marginal moraines, marginal moraine remnants, meltwater channels and hummocky terrain. A large number of glacial landforms exist, concentrated around mountain blocks protruding above the surrounding plateau area, testifying to former glacial activity. In contrast, large plateau areas of lower altitude lack glacial landforms. The mapped glacial geomorphology indicates multiple former glacial advances primarily by valley and piedmont glaciers, but lends no support to the hypothesis of ice sheet scale glaciation in the area. The presented glacial geomorphological map demonstrates the usefulness of remote sensing techniques for mapping the glacial geomorphology of the Tibetan Plateau, and it will be used for reconstructing the paleoglaciology of the Bayan Har sector of the northeastern Tibetan Plateau. [ABSTRACT FROM AUTHOR]

High-resolution speleothem records from China have provided insights into the factors that control the strength of the East Asian monsoon. Our understanding of these factors remains incomplete, however, owing to gaps in the record of monsoon history over the past two interglacial–glacial cycles. In particular, missing sections have hampered our ability to test ideas about orbital-scale controls on the monsoon, the causes of millennial-scale events and relationships between changes in the monsoon and climate in other regions. Here we present an absolute-dated oxygen isotope record from Sanbao cave, central China, that completes a Chinese-cave-based record of the strength of the East Asian monsoon that covers the past 224,000 years. The record is dominated by 23,000-year-long cycles that are synchronous within dating errors with summer insolation at 65° N (ref. 10), supporting the idea that tropical/subtropical monsoons respond dominantly and directly to changes in Northern Hemisphere summer insolation on orbital timescales. The cycles are punctuated by millennial-scale strong-summer-monsoon events (Chinese interstadials), and the new record allows us to identify the complete series of these events over the past two interglacial–glacial cycles. Their duration decreases and their frequency increases during glacial build-up in both the last and penultimate glacial periods, indicating that ice sheet size affects their character and pacing. The ages of the events are exceptionally well constrained and may thus serve as benchmarks for correlating and calibrating climate records. [ABSTRACT FROM AUTHOR]

Using radio echo sounder, ice thickness of Keqikaer Glacier tongue was measured in 1981 and 2004. Data obtained by comparing topographical maps, aerial and satellite photographs at different times, illustrates changes of the thickness and advance/retreat of Keqikaer Glacier. Keqikaer Glacier has been in intensive retreat since the 1990s and become thinner since the 1980s. Measured thickness of the ice tongue indicates reducing with a speed of 0. 5–1. 5 m a−1 since 1981. The shrinkage of the glacier terminus is less than 2% of the total length during the last 30 years; however, the retreat of terminus position and the thinning of the ice thickness provides significant information that these glaciers on the south slope of Mt. Tuomuer are in an intensively decreasing phase in recent time. [ABSTRACT FROM AUTHOR]

In order to understand the relationship between the community structure of bacteria in ice core and the past climate and environment, we initiated the study on the microorganisms in the three selected ice samples from the Malan ice core drilled from the Tibetan Plateau. The 16S ribosomal DNA (rDNA) molecules were directly amplified from the melt water samples, and three 16S rDNA clone libraries were established. Among 94 positive clones, eleven clones with unique restriction pattern were used for partial sequence and compared with eight reported sequences from the same ice core. The phylotypes were divided into 5 groups: alpha, beta, gamma proteobacteria; CFB, and other eubacteria group. Among them, there were many ‘typical Malan glacial bacteria’ pertaining to psychrophilies and new bacteria found in the ice core. At a longer time scale, the concentration distribution of '‘typical Malan glacial bacteria’ with depth showed negative correlation with temperature variations and was coincident with dirty layer. It implied the influence of temperature on the microbial record through impact on the concentrations of the '‘typical Malan glacial bacteria’. In addition, the nutrition contained in ice was another important factor controlling the distribution of microbial population in ice core section. Moreover, the result displayed an apparent layer distribution of bacterial community in the ice core section, which reflected the microbial response to the past climatic and environmental conditions at the time of deposition. [ABSTRACT FROM AUTHOR]