{'fraction_non_alphanumeric': 0.02081228531016367, 'fraction_numerical': 0.011719539300868862, 'mean_word_length': 5.530343007915567, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Tracking progress in marine climatology

This special section accumulates articles from the Fourth JCOMM Workshop on Advances in Marine Climatology (CLIMAR-IV) held in Asheville, NC, USA from 9 to 12 June 2014. Since the first workshop in Vancouver in 1999, CLIMAR Workshops track the progress in marine climatology comprehensively covering scientific, methodological and data management issues of marine climatology (see e.g. Gulev, 2005; Gulev and Woodruff, 2011). Marine climatological data play a crucial role in assessing past and ongoing climate variability and change. Without long-term global and regional time series of marine climatological data, we cannot track global climate and quantify the ocean’s role in climate variability and change. Besides estimation of variability of surface state variables, marine climatological data allow for computation of surface air–sea fluxes – the language of ocean and atmosphere communication. Also marine climatological archives provide invaluable contribution to the data assimilated by modern reanalyses, some of which are going back now to the 19th century, documenting the dynamically consistent history of the climate system. Marine climatological records (e.g. information about winds and waves) are also widely used for estimation of extreme events over the ocean, including storminess, storm surges and extreme sea level rise. These phenomena are of great importance for all types of marine structures, including operations of marine carriers and offshore engineering. Finally, marine climatological data provide an important source of in situ information for validation of satellite measurements of surface meteorological variables. However to be useful for all mentioned purposes, marine climatological data need to be accurately assembled, quality controlled and supplied with estimates of all types of uncertainties. These include measurement errors associated with the accuracy of instruments and with historical changes in observational practices which may affect not only climatological means but also estimates of climate variability. In addition to measurement errors, marine climatological data are subject to sampling uncertainties, originating from space and time inhomogeneities of sampling density, collected by merchant ships primarily along the major shipping routes. Unless these uncertainties are properly estimated, marine climatological data sets are more difficult to be effectively used for any purpose. For many years, starting from the late 1980s marine climatological data are assimilated in the International Comprehensive Ocean–atmosphere Data Set (ICOADS), representing now a unique freely available digital archive covering the period from the 17th century onwards including individual ship reports and Monthly Summary Group (MSG) statistical products. ICOADS has played a central role in all CLIMAR Workshops, and also with the alternate but associated Workshops on the Advances in the Use of Historical MARine Climate DATa (MARCDAT) focused on more technical issues of the analysis of marine data. Thus, it is very natural that CLIMAR-IV was organized in conjunction with the First ICOADS Value-Added Database (IVAD-I) Workshop held on 13 June 2014 at the same location. During CLIMAR-IV about 50 participants from around the world presented more than 50 oral talks and 10 posters organized in 8 sessions focused on all aspects of the use of marine climatological data from pre-processing and quality control to estimation of surface fluxes and assessment of climate variability and change. General and plenary discussions resulted in recommendations focused on best practices for estimation of uncertainties, developing metadata, cross-validation of marine climatological information and applications for different areas of climate and ocean science. Articles in this Special Section cover recent developments of ICOADS and guidance on the latest ICOADS Release 3.0 – the most recent and complete data set of marine climatological data (Freeman et al., 2017), problems of analysing spatially inhomogeneous data collected along the merchant ship routes (Berry and Kent, 2017; Carella et al., 2017) and impact of marine meteorological data on the estimates of variability in ocean heat content (Good, 2017). We note that many more results from the Workshop were and will be published in regular issues of International Journal of Climatology and the other relevant journals. We would like to take this opportunity to thank the World Meteorological Organization (WMO), Intergovernmental Oceanographic Committee (IOC) of UNESCO and the UK National Oceanography Centre in Southampton for supporting CLIMAR-IV Workshop. Our special thanks go to the NOAA Climate Program Office for their long-term support of ICOADS. We thank the Royal Meteorological Society and our publisher Wiley and Sons for nearly two decades of support for publications on marine climatology.