Arctic 2k v1.1.1

These data are well described in the Nature Scientific Data data descriptor: "An extended Arctic proxy temperature database for the past 2,000 years". ***Version 1.1.1 update**** In addition to the revised datasets, three tables are also included 1) MetadataTablev1.1.1.xlsx Which lists the site information and metadata for each site as in table 1 of the Scientific Data articles 2) Revisions_v1.1.1.xlsx Which lists and describes the changes between versions 3) Reconstruction_Arc2kv1.1.1.xlsx Which includes the data for the annual, 30-year and 100-year mean Arctic temperature reconstruction based on the v1.1.1 data. Lastly, the text files were updated to reflect the publication date and DOI of the Scientific Data publication, and the former convention of inverting values in the records with negative temperature was changed to the much more natural approach of showing the original data and relying on the metadata to identify records with inverse temperature relations.