06 Sep 2022
06 Sep 2022
Status: this preprint is currently under review for the journal ACP.

Impact of cruising speed on the ship-based sampling of marine fog frequency

Li Yi1 and King-Fai Li2 Li Yi and King-Fai Li
  • 1Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Physical Oceanography, Ocean University of China, Qingdao, Shandong, China
  • 2Department of Environmental Sciences, University of California, Riverside, California 92521, USA

Abstract. Understanding secular changes in marine fog frequency is crucial for marine traffic planning under global change. Voluntary ship-based weather reports from community activities provide unique decadal records of marine weather conditions over world’s oceans, including visibility that implies the presence of marine fog. However, slowly changing external factors (such as the voyage technology, vessel types, etc.) may interfere with the secular changes in ship-based weather reports. Here we identify the cruising speed as an example of “target-induced” sampling biases in ship-based weather reports, where the fog itself causes the bias in its own sampling due to human’s decision. As a demonstration, we rectify the sampling bias in the marine fog frequency by multiplying the ratio of the cruising speeds under fog over the average cruising speeds under all weather conditions. The target-induced sampling biases may cause significant errors in the long-term trends of fog occurrences in the Okhotsk Sea, the Grand Banks, and the North Sea. Similar target-induced sampling biases may also be defined in the ship-based measurements of other weather phenomena.

Li Yi and King-Fai Li

Status: open (until 22 Oct 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • AC1: 'Typos in Line 90', King-Fai Li, 06 Sep 2022 reply
  • RC1: 'Comment on acp-2022-593', Anonymous Referee #1, 15 Sep 2022 reply

Li Yi and King-Fai Li

Li Yi and King-Fai Li


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Short summary
Thorough understanding of the climatology of marine fog is highly relevant to marine traffic safety under global change. The definition of marine fog frequency commonly used in previous research has ignored the fact that marine fog itself impacts the cruising speeds of the ships due to human’s decisions on safety, which lead to a sampling bias in fog conditions and hence the apparent frequency of the marine fog occurrences, especially in coastal regions with heavy marine traffic.