CUI Shanggong,LI Xue,YANG Yi,WANG Shaopeng,QIN Xue,LI Hongjun

National Marine Data and Information Service,Tianjin 300171,China

Abstract:Based on the WoS and CNKI databases,this paper provides statistical analysis of Chinese and international polar research from 2013-2018 in terms of the number of publications,citations,institutions,disciplinary distribution,collaborations,source journals,and highly cited papers by bibliometric methods.Combining the differences of the traditional disciplinary advantages and natural geographical locations of China and the West,the current research hotspots in the polar field are summarized.(1)"Polar ice cap instability and sea level change","sensitivity and vulnerability of polar ecosystems","Arctic sea-ice-air interactions and climate effects"are the focus of research in the world.(2)Political environment research such as"National Strategy and Cooperation under the'Silk Road on Ice'Initiative"has become a unique polar strategic topic in China.At the same time,insights and suggestions are put forward from three aspects,such as increasing policy support,building cooperation system and optimizing strategic layout

Keywords:polar sciences,bibliometrics,cooperative relations,research hotspots

1 Introduction

Owing to their unique geographical location and ecological features,as well as the important role they play in global climate change,the Arctic and Antarctic regions have been ranked by many countries as key research areas in earth and environmental sciences[1].With the increasing attention to polar geopolitical issues[2]and the intense competition among countries for polar resources and strategic interests,research on polar management,in addition to scientific activities,has become a hot topic in academia domestic and abroad[3].The exploration of polar regions is important for understanding the changes in the earth's environment and fighting for natural resources and strategic rights and interests for China.Therefore,it is crucial to identify and predict the polar development orientation,compare the science and technology policies and strategies of China and other countries,and clarify the hot spots,frontiers and development trends of polar scientific research.

Bibliometrics is a quantitative analysis method based on mathematical statistics,which studies the external characteristics of scientific literature.lt examines the distribution structure and quantitative relationships of literature,and then explores certain structures,characteristics and laws of science and technology[4].Many scholars have analyzed the research hotspots and trends of polar science from the bibliometric perspective[5].Based on the literature database of North and South Polar regions,Binxian Fang et al.made a preliminary analysis of the volume of publications and focus on disciplines in the polar field[6].Xuemei Wang and Yibo Niu et al.analyzed the development patterns and trends of polar research from 1971-2010 and 2010-2016 based on WoS database,respectively[7,8].Li Wang et al.analyzed the comprehensive characteristics of Chinese and international Arctic scientific research fields from 2000-2017 based on CNKI and WoS databases[9].Many other scholars conducted bibliometric studies for a particular journal or a specific polar-related discipline[10-14].These studies summarized the polar researches and promoted the development of polar literature and intelligence to a certain extent,but they have the limitation of not being able to reflect the overall situation comprehensively and objectively due to the problems such as the early age of the data,not taking into account both Chinese and English literature,and focusing only on a single aspect of Antarctica or the Arctic.

Based on the Web of Sciences and CNKI databases,this paper presents a statistical analysis of Chinese and international polar scientific research from 2013,when China became an observer state of the Arctic Council,to 2018,through bibliometric methods,in terms of polar scientific research strengths,partnerships,relative advantages of disciplines and research hotspots,to reveal the progress and hotspots of international research in the polar region.lt will also help China's polar science management and researchers to understand their own situation,learn about the space to be developed,and identify potential cooperation partners.

2 Data and methods

2.1 Data sources and search strategies

The data for this study were obtained from the Web of Science Core Datasets Science Citation lndex Expanded(SCl-EXPANDED)1998-present,Social Sciences Citation Index(SSCI)2002-present,and China Knowledge Network CNKI databases.

For English literature,the search was based on the common English expressions for"Antarctic"and"Arctic",with Antarctic and Arctic as the main terms,and supplemented by"south ocean","King Grorge Island","Zhongshan(zhan)station"and other polar-related ma rine,geographical and expedition station terms.We also excluded geological and astronomical terms such as"palearctic"and"Polaris/north star",which are easily confused.

For Chinese literature,Antarctica and the Arctic were used as core search terms,supplemented by polar-related marine,geographic and expedition station terms,and unrelated terms such as"Qinghai-Tibet Plateau"were excluded.

English literature was selected from rticle and Review category,based on publication time,and the search time range was one year in 2018,and the TOP 5% highly cited literature search time range was 2013-2018,and after excluding irrelevant and duplicate literature,we finally obtained 6 179 articles that met the search criteria in 2018;and for 2013-2018,36 070 articles that met the search criteria in 2018,and the top 5% were ranked by citation frequency,totaling 1 804 articles,retrieved on November 18,2019.Chinese literature was selected for search in the category of journal articles,and in the subject category of philosophy and humanities,only the categories of geography and archaeology were selected;in the social science ll series,the categories of preschool education,primary education,and secondary education were excluded.Based on the year of publication,the search time range was one year in 2018,and the TOP 5% highly cited literature search time range was 2013-2018,and 642 articles in 2018 were finally obtained after excluding authors as empty,irrelevant,duplicate and English literature;3 532 articles in 2013-2018 were selected from the top 5%,a total of 177 articles(highest cited frequency 123,lowest cited frequency 13)retrieved on October 12,2019.

It should be noted that although the"ESI citation percentage"tool is included in the WOS database,which can rank the disciplines and institutions specified in the database according to the citation frequency of papers and automatically export the ESl hot papers and highly cited papers.However,this function does not support user-defined disciplines,and polar science is a comprehensive discipline,so the results of relying on the ESl tool cannot fully meet the scope of the search results in this paper.Therefore,we choose to rank all the papers filtered by the search formula and select the top 5% as the highly cited papers.

2.2 Analysis tools and methods

This paper uses VOSviewer documentation processing software to process the resulting data and visualize and analyze them to visualize the collaborative relationships between countries and institutions.

The competitiveness and comparative advantage of each discipline is judged by calculating the disciplinary relative advantage index.The disciplinary comparative advantage index is derived from the Revealed Comparative Advantage Index(RCA),which was proposed by American economist Barraza in 1965.This index is the most convincing indicator to measure the competitiveness of a country's products or industries in the international market,and later used by international intelligence in the disciplinary advantage evaluation system.ln this paper,based on the principle of RCA index,the disciplinary comparative advantage index is defined as the ratio of the number of papers published in a disciplinary field in a region to the total number of papers published in that region,to the total number of papers published in that disciplinary field to the total number of papers published in all disciplines in all regions：

Pi,jis the number of papers in subject area j in region i is the number ofpapers in all subject areas in region i； is the number of papers in all regions of subject area j；is the total number of papers for all disciplines in all regions.If the RCA>1,it indicates that the discipline ha s a relative advantage in the region;if the RCA=1,it indicates that there is no relative superiority or inferiority;and if the RCA<1,it indicates that the discipline is not relatively competitive in the region.

3 Results and analysis

3.1 Analysis of international research strength in the field of polar science

3.1.1 Country and regional analysis

In 2018,there were 6 179 international publications in English in the field of polar science and 1 804 international publications in highly cited literature from 2013-2018.The top 10 countries in terms of the number of publications are shown in Tab.1.ln terms of both the number of publications and the number of highly cited literature in recent years,both the United States and the United Kingdom are in the top two positions,indicating that they are the world leaders in polar science.Canada and Germany ranked 3rdand 4th,constituting the second camp.With reference to the previous literature,the strength layout in the field of polar science research has been basically stable in the past 10 years.

Tab.1 Top 10 countries with English paper publications about polar science in 2018

China published 634 papers in English in 2018,ranking 6thin the world in terms of the number of papers issued,indicating that the volume of polar research in China has kept pace with the world.However,the number of highly cited literature in recent years is only 11th.By calculating the average number of citations per article in 2018,it is found that China ranked 31stwith 2.62 citations,which is lower than the world average of 3.26.Although the number of publications in China has grown steadily in recent years,the quality and impact of publications still need to be improved.

3.1.2 Institutional analysis

The TOP 10 institutions in the international polar science field in English literature in 2018 are shown in Tab.2.The German Helmholtz Association and the French CNRS,as the leading forces in the polar science field in recent years,firmly occupy the top two positions in the total number of articles published and the number of highly cited articles published.The United States has 3 institutions in the TOP 10,showing a strong national strength.

Tab.2 Top 10 institutions with English paper publications about polar science in 2018

In China,1 unit of Chinese Academy of Sciences was selected to the TOP10,ranking 6thin terms of the number of articles published.lt is worth noting that the H-index of Chinese Academy of Sciences is only 10,which is still a big gap compared with other European and American institutions,and the Chinese Academy of Sciences only ranks 34thin the list of highly cited articles in recent years,which suggests that we should also follow the disciplinary hotspots in polar frontier areas in time,make efforts to improve thequality of publications,and strive to build a research institution with strong academic influence.

3.1.3 Subject distribution analysis

International polar scientific research involves a total of 14 disciplinary categories and 165 disciplinary subcategories,showing obvious interdisciplinary characteristics.In view of the special environment of polar regions,their natural phenomena are often the result of multi-disciplinary and multifactorial influences,and technically,polar research also requires the coordination and application of different technical tools,so a wide range of interdisciplinary crossover has emerged.

In this paper,we only list the results of the distribution of the highly cited literature belonging to the disciplines ranked according to the number of articles issued from 2013 to 2018,see Tab.3.From the broad categories of disciplines,international polar science research is dominated by Geosciences,Environmental Science and Ecology,Multidisciplinary Sciences,Biology and Engineering Technology,mainly concentrated in Geosciences Multidisciplinary,Meteorology Atmospheric Sciences,Environmental Sciences,Ecology,Geography Physical,and Oceanography,etc.

Tab.3 Distribution of discipline of highly cited articles about polar science

3.1.4 Analysis of source journals

The TOP10 of the main source journals of highly cited literature from 2013 to 2018are shown in Tab.4.The level of international polar science literature in journals is mostly concentrated in the Q1 area of each discipline,indicating that the overall literature in polar science is of high quality and the related research has been relatively mature.ln terms of their subdivisions,these journals are mainly concentrated in the fields of Geosciences,Meteorology Atmospheric Sciences,Geography Physical and Environmental Sciences.

Tab.4 Top 10 source journals of English highly cited articles

3.2 Analysis of China's scientific research strength in the field of polar science

3.2.1 Institutional analysis

The TOP 10 institutions in the field of polar science in China in 2018 are shown in Tab.5.The Chinese Academy of Sciences took the absolute lead in the number of publications in 2018 and the number of highly cited literature published in recent years.The Former State Oceanic Administration and the Ocean University of China ranked 2ndand 3rd,respectively.ln terms of literature language,the Former State Oceanic Administration,Ocean University of China,and Wuhan University mainly published Chinese literature,and the rest of the institutions mainly published English literature.

Tab.5 Top 10 Chinese institutions and the number of cited and published papers about polar science in 2018

3.2.2 Analysis of source journals

The TOP10 of the main source journals of Chinese highly cited literature from 2013 to 2018 are shown in Tab.6 and they are all in"Guide to the Core Journals of China(GCJC)".Unlike English literature,most of the source journals of Chinese literature are social science journals,and relatively few natural science research results are published.

Tab.6 Top 10 source journals of Chinese highly cited articles from 2013 to 2018

3.3 Analysis of international polar scientific research cooperation relations

3.3.1 Country partnership analysis

The collaboration between the 47 countries that published 10 or more polar science papers in 2018 is shown in Fig.1,in which data for China include mainland China and Taiwan,while data for the United Kingdom include England,Scotland,Wales and North lreland.

Fig.1 The collaboration network of 47 countries and regions about polar science in 2018

Five circles of cooperation in polar research were formed in 2018 among the countries of the world according to their traditional disciplinary strengths and natural geographical locations.

(1)Red Cluster－a network of co-occurring relations consisting of Russia and many traditional European science and technology powers,with an average number of 33.82 collaborations and an average intensity of cooperation(sum of linkage weights)of 415.24.

(2)Green Cluster－a network of co-occurring relationships consisting of the UK,India,Saudi Arabia,etc.and Pacific Rim countries such as the U.S.,Australia,China and Japan,with an average number of 32 collaborations and an average cooperation intensity of 613.92.

(3)Blue Cluster－a network of co-occurring relationships consisting of southern European countries such as France and Spain and near-Antarctic countries such as Argentina and South Africa,with an average number of 30.5 collaborations and an average cooperation intensity of 301.8.

(4)Orange Cluster－a network of co-occurring relationships consisting of Greenland Rim countries such as Canada and Norway-has an average number of 35.4 collaborations and an average collaboration intensity of 792.8.

(5)Purple Cluster－a network of co-occurring relationships consisting of two countries,Belgium and Turkey,with an average number of 25.5 collaborations and an average collaboration intensity of 224.

3.3.2 Analysis of international institutional partnerships

The collaborative relationships among the 211 institutions that published more than 20 papers related to polar science in 2018 are shown in Fig.2.Seven main collaborative circles were formed by world research institutions in polar research collaboration in 2018.

Fig.2 The collaboration network of 211 institutions about polar science in 2018

(a)Red Cluster－a collaborative circle consisting of the U.S.universities,government and research institutes.Among them,the University of Washington and the University of Colorado occupy the central position.ln addition,the University of Alaska Fairbanks,NASA,Columbia University,the National Oceanic and Atmospheric Administration(NOAA)and other universities and government agencies are also outstanding in terms of the number of publications and the intensity of cooperation,and they are the key institutions for polar research in the United States.lt is worth mentioning that among the 50 institutions in this cluster,only one(University of Zurich,Switzerland)is a non-U.S.institution,indicating the strong independence of U.S.polar research.The average number of collaborations in this cluster is 56.6,and the average intensity of collaboration is 107.44.

(b)Green Cluster－a collaborative circle consisting of 49 institutions in European countries such as Norway,Sweden,Russia,and Germany.Among them,the University of Copenhagen,Stockholm University and the University of Bergen are the centers of cooperation,and the Russian Academy of Sciences and the Norwegian Polar Research lnstitute are the important participating institutions.The average number of collaborations is 49.51 and the average intensity of collaboration is 103.63.

(c)Blue Cluster－a collaborative circle of 20 UK universities,research institutes and other European and American institutions comprising a total of 30 institutions.The British Antarctic Survey(BAS)is the core institution.The average number of collaborations was 58.4 and the average intensity of collaboration was 112.5.

(d)Yellow Cluster－a collaborative circle of 28 institutions from Australia,Japan,New Zealand and other countries.The University of Tasmania is the core institution.The average number of collaborations was 50.96 and the average intensity of collaboration was 90.07.

(e)Purple Cluster－a collaborative circle of Canadian and Danish institutions.With Aarhus University and Environment and Climate Change Canada as the core institutions.The average number of collaborations is 50.11 and the average intensity of collaboration is 94.56.

(f)Cyan Cluster－a cooperation circle composed of institutions from Spain and former Hispanic colonial countries such as Argentina and Chile,with the Argentine CONlCET as the core institution.The average number of collaborations was 29.5 and the average intensity of collaboration was 52.25.

(g)Orange Cluster－a collaborative circle consisting of institutions in mainland China.The Chinese Academy of Sciences is the core institution.The average number of collaborations is 29.64,and the average intensity of collaboration is 78.36.

3.4 Analysis of the relative strengths of polar science disciplines

The relative dominance indices of 11 countries in the field of polar research,including China and the United States,were calculated based on the total number of polar related publications in 2018.The total number of publications in each country in that year,and the total number of publications in the world are shown in Tab.7.

Tab.7 RCA of main countries about polar science in 2018

Russia has the highest disciplinary dominance index of 3.71,which indicates that polar research has a great weight in the research of that country.ln China,the disciplinary dominance index is lower,only 0.41,which indicates that polar research is still a niche discipline in China's scientific research field and is still not given enough attention.

3.5 Analysis of polar science research hotspots

For the English literature,1 635 articles published in 2018 by institutions ranked in the Top 10 of the H-index were selected,among which a total of 86 articles were cited no less than 13(the minimum H-index of the Top 10 institutions)times.After statistical analysis,these 86 articles were found to be mainly concentrated in 10 fields(Tab.8).It can be seen that Geosciences,Environmental Science and Ecology,and Biology are the mainstream of polar science research in the world,among which"instability of polar ice cap and sea level change","sensitivity and vulnerability of polar ecosystem","Arctic sea-ice-air interactions and their climate effects"are the main focuses of international polar research.Since Europe,America,Australia and Latin America are geographically closer to the polar regions than China,they are more sensitive to the changes of sea level,climate and environment in the polar regions,so the English-speaking countries focus more on ecological protection and resource development in scientific research,policy strategy and international organization.

For the Chinese literature,642 highly cited papers in CNKI in 2018 were selected,among which 67 papers were cited more than 3 times and mainly concentrated in six fields(Tab.8).lt can be seen that the research hotspots in Chinese literature are mainly concentrated in social science fields.In the context of China's polar strategy policy in recent years,as a global power,China's participation in polar affairs,especially in Arctic affairs,has gradually become an inevitable requirement to safeguard its own interests,and the relevant external environmental factors(such as political,social and technological environment)have profoundly influenced China's polar participation process,so it is urgent to study and investigate these factors,which is also the polar research direction that China has been trying to promote in recent years.

Tab.8 Research areas and the number of Chinese-English top papers

4 Conclusion and insights

4.1 Conclusion

Based on the Web of Sciences and CNKI databases,this paper presents a statistical analysis of Chinese and international polar research from 2013-2018,with the following conclusions：

(1)Judged by both the number of national publications and the number of highly cited literature publications,the United States and the United Kingdom are world leaders in polar science.China ranked 6th in the world in terms of the number of publications in 2018,while the average number of citations per article was lower than the world average.lt can be seen that although the number of publications in China has increased steadily in recent years,the quality and impact of publications still need to be improved.

(2)The German Helmholtz Association and the CNRS are the leading institutions in the field of international polar science in recent years,while China has not yet formed a scientific institution with strong influence in the world in this field.The Chinese Academy of Sciences is the absolute leader in Chinese polar science research,but there is still a big gap compared with European and American institutions.

(3)International polar scientific research is mainly focused on Meteorology Atmospheric Sciences,Environmental Sciences,Ecology,Geography Physical and Oceanography,while Chinese literature is mainly focused on Arctic waterways,polar politics and law,and other social sciences.

(4)In 2018,research institutions around the world formed several cooperation circles in the field of polar research based on their traditional disciplinary strengths and natural geographical locations,and Chinese research institutions also formed nine cooperation circles,including"polar aquaculture and fisheries,""polar meteorology,"and"polar oceanography,"based on their disciplinary focus.

(5)By calculating the disciplinary advantage index of polar science in each country,we found that China's disciplinary advantage index is only 0.41,which indicates that polar research is still a niche discipline in China's scientific research field,and the degree of attention is still far from adequate.

(6)Through the research of top papers,we found that the current international polar science mainly focuses on 10 fields,among which"Polar ice cap instability and sea level change","Sensitivity and vulnerability of polar ecosystems",and"Arctic sea-ice-air interactions and climate effects"are the hot spots and frontiers of research.These are also the directions that China should focus on.The research in Chinese paper mainly focuses on six areas,among which the topic of"National Strategy and Cooperation under the'Silk Road on Ice'Initiative"has attracted the most attention of scholars.

4.2 Insights and recommendations

Since China acceded to the Antarctic Treaty in 1983,China's polar scientific research has been carried out for 37 years,forming a strategic pattern and basic platform of"Two Ships,Four Stations,Three Aircraft and One Base",and making important progress in polar scientific research.However,there are still gaps between China and European and American countries in terms of academic influence,and the following suggestions and insights are put forward in this paper through bibliometric analysis.

(1)Increase the support to polar research and steadily improve academic influence.ln view of China's low academic strength and weak academic influence in polar science,China should actively encourage scientific activities in the north and south poles to improve its academic status and international discourse.Under the"Belt and Road"and"Silk Road on lce"initiatives,we should develop a comprehensive Arctic cooperation and research sys tem,and provide strong support for the construction of the"Arctic Seaway"from political,geographical,historical and military aspects.At the same time,we will continue to strengthen research related to Antarctic scientific research.Since the Antarctic Treaty has temporarily frozen the issue of territorial sovereignty,the share of the country in the future development of Antarctic resources depends on its investment in and contribution to Antarctic science,so we should increase the basic investigation and research on Antarctic resources to prepare for the future acquisition of national interests.

(2)Build a polar cooperation network system and strengthen the construction of polar academic journals.Cooperation among domestic research institutions and international cooperation in response to common needs and challenges should be encouraged,so that China can play the role of"backbone network"in bilateral,multilateral and regional scientific and technological cooperation in polar research.The current high-level"strong-strong"international cooperation is not obvious,and the cooperation of some important organizations is still incomplete,so systematic planning is needed to coordinate the relationship between the level,intensity and direction of cooperation.At the same time,we need to encourage and support the development of polar academic journals and cultivate relevant academic editorial teams.

(3)Take into account both natural and social sciences,and coordinate the long-term development of polar research.China's polar research involves both natural science and social science with Chinese characteristics,so we should clarify strategies,optimize the layout,guide trends,and maintain the development of the characteristics of social science research in the Arctic region while taking both aspects into account to enhance the overall strength of China's polar research.