The 12th International Workshop on Modeling the Ocean (IWMO 2022) was hosted by the Cooperative Institute for Great Lakes Research (CIGLR) and NOAA Great Lakes Environmental Research Laboratory (GLERL). The meeting was held on the campus of the University of Michigan, Ann Arbor, Michigan, USA, on June 28-July 1, 2022.

The 11th International Workshop on Modeling the Ocean (IWMO 2019) was hosted by Tsinghua University, National Supercomputing Center in Wuxi, China, on June 17–20, 2019. Wuxi is situated northwest of Shanghai, between the Yangtze River delta and Lake Tai, which is the third largest freshwater lake in China and a popular tourist attraction. The historical and cultural city, which traced its origin habitants to before 1000BC, is today a city of about 5 million people and a center for industry, manufacturing, and scientific research.

The 10th International Workshop on Modeling the Ocean (IWMO 2018) was hosted by the University of Sao Paulo and held on June 25–28, 2018, at the beautiful coastal city of Santos, Brazil. This old city was founded by the Portuguese in the 1500s and is known for its world’s longest beach garden, the Coffee Museum and the Pele Museum (featuring the famous football player and a local hero). Since the inaugural IWMO meeting in Taiwan in 2009, meetings were held in Asia, Europe, North America, and Australia, but this was the first meeting to be held in South America. With the 10th anniversary of IWMO, we would like to acknowledge the foremost contribution and dedication of Prof. L.-Y. Oey who was one of the founding fathers of IWMO in 2009 (Oey et al. 2010a, b) and who led the organization for 10 successful years, before passing the leadership baton to a new generation of scientists. During this meeting, a special session was held to honor Professor Emeritus George L. Mellor for his pioneering contribution to ocean modeling, which started some 6 decades ago and continues today with his own contribution to this special issue (Mellor 2019). We would like thus to dedicate this special issue to Professor Mellor and his legacy.

The 9th International Workshop on Modeling the Ocean (IWMO 2017) was held in the modern campus of Yonsei University, Seoul, Korea, from July 3–6 2017. The workshop was attended by about 80 participants from countries all around the world, many of whom were young and earlier-career scientists: students and postdocs. Papers were presented covering a broad range of topics on field observations, analyses, and modeling: wave and air-sea interaction dynamics, climate variability, basin-scale processes and coastal oceanography, sea-ice dynamics, sediment transport, tropical cyclones, biogeochemical-physical coupling, boundary currents, sea-level rise, extreme events, ocean prediction and others. We were pleased to witness very high-quality research and presentations, many from young students and scientists. Thirty three (33) young scholars participated in the Outstanding Young Scientist Award (OYSA) competition; congratulations to all of them!

The 8th International Workshop on Modeling the Ocean (IWMO 2016) was held on June 7–10, 2016, at one of the oldest universities in Europe—the University of Bologna in Italy (founded 1088 A.D.). The workshop returned to Europe for the second time (the other European IWMO was held in Norway in 2013; Berntsen et al. 2014). Since the establishment of the IWMO in 2009 (Oey et al. 2010a, b), meetings were held four times in Asia, two times in Europe, two times in North America, one time in Australia, and for the 10th anniversary of IWMO, the 2018’s meeting will be held in South America (Brazil) for the first time.

IWMO 2015 was held in the pristine campus of the Australian National University, Canberra, Australia, from June 1–5, 2015. Despite the negative Coriolis spin that many of us from the northern half of the globe experienced for the first time, we were positively impressed by the vastness and beauty of Australia and the kindness and friendliness of its people. Late fall in Canberra displayed spectacular starry nights and brisk sunny days. The workshop was attended by more than 80 participants from 16 countries around the globe. Seventy papers including both oral and posters were presented, covering a very broad range of topics on observations and models: climate variability, basin circulation and coastal oceanography, air-sea interaction, sea-ice dynamics, sediment transport, tropical cyclones, biogeochemical-physical coupling, boundary currents, sea level rise, extreme events, ocean prediction, and others. As in the past years, many of the participants were students and young scientists—all presented very high-quality research, and three were selected to receive the Outstanding Young Scientist Awards (OYSA). In order that some of us may have a chance to also receive some recognition for our hard work, new this year were three Best Presentation Prizes (BPP), given to any presenters deemed qualified by the audience to receive the honors. Also, new this year were special lunch-time sessions when young and more senior scientists exchanged ideas on a wide range topics.

The 6th International Workshop on Modeling the Ocean (IWMO 2014) was held on June 23–27, 2014, at Dalhousie University in Halifax, Nova Scotia, Canada. After three meetings in Asia (Oey et al. 2010, 2013a, b) and one in Europe (Berntsen et al. 2014), the IWMO returned to North America for the second time (since IWMO 2010 in the USA; Ezer et al. 2011). Readers are referred to https://www.dal.ca/sites/iwmo.html for more information on IWMO 2014 and http://www.ccpo.odu.edu/POMWEB /meetings.htm for information on the past meetings and future planned meetings.

The 5th International Workshop on Modeling the Ocean (IWMO http://www.uib.no/en/IWMO2013/-58927/iwmo-2013-bergen-norway) was held in June 17–20, in Bergen, Norway. The historic city of Bergen is the gateway to the fjords and a center for oceanic research. The workshop was hosted by the University of Bergen and also sponsored by the Research Council of Norway. Approximately 80 researchers worldwide participated in the workshop. Professor Mellor, Princeton University, gave the keynote lecture. The 5th IWMO meeting in Bergen was the first IWMO held in Europe, followed on the footsteps of previous meetings, IWMO-2009 in Taipei, Taiwan (Oey et al. 2010a, b), IWMO-2010 in Norfolk, USA (Ezer et al. 2011), IWMO-2011 in Qingdao, China (Oey et al. 2013a), and IWMO-2012 in Yokohama, Japan (Oey et al. 2013b). The participants presented approximately 60 oral talks and 20 posters, covering a wide range of ocean modeling and data analysis topics, as described below. In the spirit of promoting young scientists in their early career (graduate students and postdocs), about 15 young presenters participated in the Outstanding Young Scientist Award (OYSA) competition and three of them received awards.

The 4th International Workshop on Modeling the Ocean (IWMO; http://www.jamstec.go.jp/frcgc/jcope/htdocs/e/iwmo2012.html) was held on May 21–24, 2012 in the vibrant city of Yokohama on the Tokyo Bay, Japan. The Workshop was hosted by Japan Agency for Marine-Earth Science and Technology (JAMSTEC)—the home of the famous “Earth Simulator”—one of the world's most powerful supercomputers dedicated for simulating the complex interactive processes of the earth and its environment. Over 100 researchers worldwide participated in the Workshop, which included two keynote lecturers, by Professor Mellor of Princeton University and Professor Yamagata of the University of Tokyo, and more than 80 oral presentations and 20 posters. The topics covered in the Workshop, as in the past IWMO's, are wide-ranging, from small-scale waves and estuarine processes to large-scale eddy and multi-decadal climate dynamics. In part thanks to the generosity of the host, a new record of 30 graduate students and postdocs participated in the Outstanding Young Scientist Award Competition, some with truly outstanding presentations of top scientific rigors.

The 3rd International Workshop on Modeling the Ocean (IWMO; http://service.fio.org.cn/iwmo2011/iwmo2011.htm) was held on June 6–9, 2011 in the beautiful seaport city of Qingdao, hosted by the First Institute of Oceanography, China. The year was marred by the tragic March 11 Tōhoku earthquake a few months before the workshop. This special issue is dedicated to the Japanese people, who despite the enormity of their sufferings, showed immense resilience and fortitude.

The formation of the International Workshop on Modeling the Ocean (IWMO) in 2009 has been motivated by the rapid growth in ocean modeling research around the world. In particular, the spread of ocean modeling research in Asia during recent years and the establishment of many international collaborative modeling projects led to the first meeting, IWMO-2009, which was held in Taipei, Taiwan, 23–26 February 2009 (see the two special issues resulted from this meeting: Oey et al. 2010a, b). The second meeting (IWMO-2010; http://www.ccpo.odu.edu/∼tezer/IWMO_2010/) was hosted by the Center for Coastal Physical Oceanography at Old Dominion University in Norfolk, VA, USA, 24–26 May 2010. The collection of manuscripts resulted from this IWMO-2010 meeting are included in this special issue and have been published in Ocean Dynamics issues from May to this issue. Two important foci are highlighted in IWMO meetings: (1) international collaborations and (2) involvement of young scientists. As evident in the papers in this special issue, the co-authors of papers are often from different countries and include several graduate students and post-docs. To encourage young scientists to participate, IWMO hosts a special session for the Outstanding Young Scientist Award competition. Despite difficulties in international travel during the IWMO-2010 meeting due to the Iceland volcano eruption and increased security that prevented scientists from some countries to travel to the USA, participants from over 15 countries attended the meeting, including attendees from Europe, North and South America, Asia, and Australia. The meeting received considerable attention from the local media due to the BP oil spill in the Gulf of Mexico that happened just before the meeting; a paper on the oil spill was presented in the meeting and is included in the special issue (Chang et al. 2011). The IWMO returned to Asia for the third meeting (IWMO-2011; http://www.fio.org.cn/iwmo2011/iwmo2011.htm) that has been hosted by the First Institute of Oceanography, Qingdao, China, 6–9 June 2011. The next meeting (IWMO-2012) will be hosted by the Japan Agency for Marine-Earth Science and Technology (JAMSTEK), Japan.

This is part 2 of the Special Issue for the First IWMO (http://phyoce.es.ntnu.edu.tw/2009WMO/) held on Feb 23–26, 2009, at the National Taiwan Normal University (NTNU) campus in Taipei, Taiwan. Part 1 was published in May in Ocean Dynamics and consisted of 12 papers that covered a wide range of topics from numerical schemes to process studies and realistic simulations. Part 2 also includes many interesting papers and also covers a wide range of topics. As in part 1, all papers underwent the usual rigorous process of reviews and revisions. There were at least two reviewers for each paper. Some of the reviewers were from the Workshop attendees, but many were solicited from the scientific community at large. A summary of the papers follow.

The first International Workshop on Modeling the Ocean (IWMO; http://phyoce.es.ntnu.edu.tw/2009WMO/) was held on Feb. 23–26, 2009 at the National Taiwan Normal University (NTNU) campus in Taipei, Taiwan. The idea for the Workshop originated when Chau-Ron Wu from NTNU visited Lie-Yauw Oey at Princeton in 2007–2008. Ocean modeling research has rapidly spread worldwide and especially in Asia since the public release of the Princeton Ocean Model (POM; http://www.aos.princeton.edu/WWWPUBLIC/htdocs.pom/) in the 1990s. The time was right, we thought, to hold a dedicated Workshop to further encourage exchange between researchers from Asia and other continents and to involve young scientists. Moreover, we wanted the first IWMO to be in a vibrant city—Taipei, Taiwan.