Preface for the article collection “Land–Ocean Linkages under the Influence of the Asian Monsoon”

Preface Land–ocean interactions are an essential part of the climatic system, and monsoons are perhaps the most important example of such interactions. The Asian monsoon is by far the largest monsoon system on the globe, and its impact is felt worldwide. This monsoon system influences the lives of more than one half of the world’s population via the hydrological cycle and its variability over time. The Asian monsoon also exerts a significant impact on the condition of the oceans surrounding Asia through freshwater discharge, nutrient inputs, and strong winds. Such impacts are especially significant in marginal seas because of their high sensitivity to climate change. We hope that the articles collected in this issue in the Special Call for Excellent Papers on Hot Topics (SPEPS) series will stimulate and promote future research on land–ocean linkages in Asia and their relationship with the Asian monsoon. The eastern margin of Asia is unique because of the large number of marginal seas that were formed as a result of the collision between India and Eurasia that began at ca. 45 Ma. The collision also caused the uplift of the Himalaya and Tibet, which is considered to be one of the main causes of the establishment and intensification of the Asian monsoon during the Cenozoic. Consequently, it is worthwhile exploring (1) how the Asian monsoon was established and then evolved through time; (2) what kinds of land–ocean interactions the Asian monsoon has caused throughout the marginal sea regions; and (3) how the Asian monsoon has affected the oceanography of the marginal seas. Scientific ocean drilling has contributed to society’s understanding of monsoonal systems for decades. Most recently, a focused series of the Integrated Ocean Drilling Program and International Ocean Discovery Program (IODP) expeditions conducted drilling campaigns from 2013 to 2016 that targeted the Asian monsoon and its possible linkage with the uplift of the Himalaya and Tibet (Fig. 1). Thus, considerable advances in our understanding of monsoonal processes are expected over the coming years. Consequently, it seems worthwhile to summarize the present status of our knowledge on this theme and identify the major problems that remain to be solved. Soon after IODP Expedition 346 (named “Asian Monsoon”) was completed in 2013, a special session entitled “Land–Ocean Linkages in East Asian Marginal Seas” was held on April 29, 2014, during the Japan Geoscience Union (JpGU) annual meeting in Yokohama (Fig. 2). Twelve oral and four poster presentations were given at the special JpGU session, and the papers presented in this issue include three research articles and six reviews based on presentations from that session. These nine papers cover the evolution and variability of the Asian monsoon (Tada et al. 2016), the evolution of surface water and deep-water circulation in East Asian marginal seas (Gallagher et al. 2015; Kim et al. 2015; Itaki 2016), the impact of the East Asian summer monsoon on the composition of sediment discharged from the Yangtze River, surface water salinity in the East China Sea, flood records and typhoon tracks in southern Japan (He et al. 2015; Horikawa et al. 2015; Suzuki et al. 2016), and volcanic ash as a useful tool for land–ocean correlation and as a * Correspondence: [email protected] Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan Full list of author information is available at the end of the article Progress in Earth and Planetary Science