09 September 2016, Volume 27 Issue 4

    

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  Contents of No.4 Vol.27 2016

  Editorial Office of Advances in Polar Science

  Advances in Polar Science. 2016, 27(4): 0-0.

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Reviews
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  Chinese investigation and research in Southern Ocean physical oceanography and meteorology during the Chinese Polar Programs 2011–2015

  GAO Libao, WEI Zexun , GUO Guijun & SHI Jiuxin

  Advances in Polar Science. 2016, 27(4): 209-218. https://doi.org/10.13679/j.advps.2016.4.00209

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  Within the context of developing a research presence in the Antarctic region, the first phase of the Chinese Polar Programs covered the period 2011–2015, which almost coincided with the 12th Five-Year Plan (2011–2015). For the promotion of full understanding of the progress of Chinese expeditions and research in Antarctica, the observations and achievements of cruises during 2011–2015 are summarized in this paper. Four Antarctic cruises (28th–31st) were performed in the Prydz Bay and Antarctic Peninsula regions during the first phase of the Polar Programs. These cruises performed systemic collections of physical oceanographic and meteorological data to support further research on the ice–ocean–atmosphere interactions in Antarctica. Overall, 248 CTD/LADCP stations, 66 microstructure profiles, 507 XBT/XCTDs, 181 air sounding balloons, 58000 total gaseous mercury (TGM) concentrations, 452 aerosol samples, 294 atmospheric samples, 11 moorings, and 28 surface drifters were acquired or deployed during the four cruises. Using these extensive observations and other data, Chinese scientists have achieved new recognition in the fields of Southern Ocean physical oceanography and meteorology, as well as in other interdisciplinary subjects. These studies, which have been associated with scientific techniques, instrumentation, ocean circulation, water mass formation, energy transformation, and carbon uptake, have elucidated the dynamic mechanisms and potential effects of climate change in Antarctica. Finally, some observations based on experience gained during previous Chinese Antarctic Research and Expedition campaigns are summarized with advice for the improvement of future investigations in the Antarctic region.
  
  
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  Recent progress in Chinese polar upper-atmospheric physics research: review of research advances supported by the Chinese Arctic and Antarctic expeditions

  HE Fang, HU Hongqiao, YANG Huigen, ZHANG Beichen, HUANG Dehong, LIU Yonghua, HU Zejun&LIU Jianjun

  Advances in Polar Science. 2016, 27(4): 219-232. https://doi.org/10.13679/j.advps.2016.4.00219

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  It has been more than 30 years since the first Chinese Antarctic Expedition took place. Polar upper atmospheric observations started at this time. First began at Great Wall Station and then at Zhongshan Station in Antarctica, and later in the Arctic at Yellow River Station, Kjell Henriksen Observatory on Svalbard, and at the China-Iceland Joint Aurora Observatory in Iceland. In this paper, we reviewed the advances in polar upper atmosphere physics (UAP) based on the Chinese national Arctic and Antarctic research over the last five years. These included newly deployed observatories and research instruments in the Arctic and Antarctic; and new research findings, from ground-based observations, about polar ionosphere dynamics, aurora and particle precipitation, polar plasma convection, geomagnetic pulsations and space plasma waves, space weather in the polar regions, simulations of the polar ionosphere-magnetosphere. In conclusion, suggestions were made for future polar upper atmosphere physics research in China.
  
  
  
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  Sources of organic matter and paleo-environmental implications inferred from carbon isotope compositions of lacustrine sediments at Inexpressible Island, Ross Sea, Antarctica

  WEI Yangyang , JIN Jing , NIE Yaguang , CHEN Xin , WU Libin , FU Pingqing , LIU Xiaodong & Steven D. Emslie

  Advances in Polar Science. 2016, 27(4): 233-244. https://doi.org/10.13679/j.advps.2016.4.00233

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  The carbon isotopic composition of organic matter (δ¹³C_org) was determined in two sediment cores (IIL1 and IIL9) recovered from Inexpressible Island, Ross Sea, Antarctica, and analyzed to identify the sources of that organic matter. The δ¹³C_org values of sediments of IIL9 were found to vary between −14.6‰ and −11.6‰, with a mean of −13.4‰ (n=48). These values were significantly higher than those of IIL1 sediments which varied between −23.2‰ and −20.4‰, with a mean of −21.8‰ (n=55). The variation in δ¹³C_org values in these two sediment cores indicate different sources of organic matter. The relatively high δ¹³C_org values in IIL9 are in accordance with a source from algae, while the low δ¹³C_org values in IIL1 evince significant influence from penguin guano with algae as the secondary source. Compared with the reference data from other high-latitude lake sediments and plants, the δ¹³C_org values in IIL9 were extremely high, a result likely related to intense competition for CO₂ assimilation among algal species during the growing season in this relatively shallow pond. These results indicate that sedimentary δ¹³C_org is a reliable proxy for paleo-primary productivity in ponds at Inexpressible Island.
  
  
  
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  Outflow from under the Pine Island Bay Ice Shelf: finescale structure and its temporal variability

  Robin Robertson,

  Advances in Polar Science. 2016, 27(4): 245-263. https://doi.org/10.13679/j.advps.2016.4.00245

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  The water column structure of the ice shelf cavity outflow from under Pine Island Glacier and its temporal variability were investigated using a hourly time series of yo-yo CTD and LADCP data collected over ~24 h at the southern end of the ice shelf front. The primary water types present over the continental shelf off Pine Island Bay were Circumpolar Deep Water (CDW), modified Circumpolar Deep Water (mCDW), Shelf Water (SW), and Ice Shelf Water (ISW). As CDW transited the shelf, it transitioned into cooler, mCDW. In the upper 200 m, ISW dominated within 100 km of the ice shelf and SW further offshore. Within Pine Island Bay, the water column was partitioned into two primary layers based on their behavior: an upper outflowing layer from 100 m to 450 m composed of ISW with a significant meltwater component, 1%–2%, over an inflowing layer from ~550 m to the sea bed composed of mCDW. Due to the small cavity extent, the outflowing water was warmer than the seawater freezing point. The upper ISW layer was further split into upper ISW layer #1 (100–300 m) and upper ISW layer #2 (320–450 m) with the transition coinciding with the ice shelf draft. Small step-like features with heights from 1–50 m existed within both the ISW layers and were more prominent in upper ISW layer #1. A baroclinic signal at the semidiurnal frequency existed within both primary layers with the strongest signal, ~ 10 cm·s^-1, propagating vertically in the upper ISW layer.
  
  
  
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  Estimating sea ice albedo feedback in a regional climate modeling sensitivity experiment

  LIAN Yu, LI Yaosun, CAI Lei

  Advances in Polar Science. 2016, 27(4): 264-271. https://doi.org/10.13679/j.advps.2016.4.00264

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  Surface albedo feedback (SAF), or sea ice albedo feedback over the Arctic Ocean, has an important effect on the Arctic climate, even though it is not the leading contributor to polar amplification. Previous model-based studies on SAF have primarily used global climate models to exploit their global coverage and favorable configurations. This study verified the capability of using regional climate models (RCMs) to investigate SAF by designing a sensitivity experiment in terms of sea ice coverage. This study modeled two control cases of the years 1980 and 2012, as well as two sensitivity cases performed by switching the sea ice coverages in the control cases. The results proved the Weather Research and Forecast model capable of separating and quantifying the respective contributions of the atmosphere and the surface albedo to the surface radiation budget. Supported by the ALL/CLR model, the balanced surface shortwave radiation absorption was used to calculate SAF. The experiments overestimated SAF, largely because of the canceled cloud effect during model initialization. This study highlights a new possibility of designing experiments for studying climatic sensitivity and feedback using RCMs.
  
  
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  A preliminary dayglow model for summer auroral images from Polar/UVI

  WANG Lingmin, & LUAN Xiaoli,

  Advances in Polar Science. 2016, 27(4): 272-279. https://doi.org/10.13679/j.advps.2016.4.00272

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  In this study, we developed a summer dayglow model using auroral emissions acquired by the ultraviolet imager (UVI) onboard the Polar satellite. In the summer polar region, dayglow varies as a cosine-like function of the solar zenith angle (SZA). The shape of this function can be characterized by its amplitude (Amp) and phase (Phi) factors. We first obtained the hourly Amp and Phi factors in summers from 1996 to 2000, and then investigated the universal time (UT) and solar activity variations of these two shape factors. It was found that both factors were non-linearly dependent on the solar flux for all years, and the Amp factor showed clear UT variations under both low and high solar flux years. Thus, a dayglow model was constructed to consider the above dependencies. After the dayglow was removed automatically from the original UVI images via our model, the remaining auroral precipitation energy flux was in good agreement with previously reported magnetic local time–latitude (MLT–MLAT) patterns. Our model provides a fast way to statistically process summer auroral precipitation of Polar/UVI and its variations.