Table 1.
Details of sites included in the study. Sites shown with bold text have at least 20 years of data between 1996 and 2018.
| Site | °Lat | °Long | Alt (m) | Years | Agency |
|---|---|---|---|---|---|
| Summit, Greenland | 73 N | 38 W | 3202 | 2004–2017 | BSI/NSF |
| Barrow, Alaska | 71 N | 157 W | 8 | 1991–2016 | BSI/NSF |
| Villeneuve-d’Ascq, France | 51 N | 3 E | 70 | 2000–2018 | LOA/UDL |
| Hoher Sonnblick, Austria | 47 N | 13 E | 3106 | 1997–2018 | BOKU |
| Haute-Provence Obs., France | 44 N | 6 E | 688 | 2009–2018 | LOA/UDL |
| Thessaloniki, Greece | 41 N | 23 E | 60 | 1990–2018 | AUTH |
| Boulder, Colorado | 40 N | 105 W | 1650 | 1998–2018 | NIWA/NOAA |
| San Diego, California | 33 N | 117 W | 22 | 1993–2008 | BSI/NSF |
| Mauna Loa Obs., Hawaii | 20 N | 156 W | 3400 | 1995–2018 | NIWA/NOAA |
| Saint-Denis, Réunion Island | 21 S | 55 E | 80 | 2009–2018 | LOA/UDL |
| Alice Springs, Australia | 24 S | 134 E | 547 | 2003–2018 | NIWA/BoM |
| Melbourne, Australia | 38 S | 145 E | 110 | 2001–2018* | NIWA/BoM |
| Lauder, New Zealand | 45 S | 170 E | 370 | 1990–2018 | NIWA |
| Ushuaia, Argentina | 55 S | 68 W | 30 | 1988–2008 | BSI/NSF |
| Palmer Station, Antarctica | 65 S | 64 W | 21 | 1990–2018 | BSI/NSF/NOAA |
| Arrival Heights, Antarctica | 78 S | 167 E | 190 | 1989–2018 | BSI/NSF/NOAA |
| South Pole | 90 S | — | 2835 | 1991–2018 | BSI/NSF/NOAA |
Abbreviations:AUTH, Aristotle University of Thessaloniki; BOKU Universität für Bodenkultur, Vienna (Austria); BoM, Bureau of Meteorology (Australia); BSI, Biospherical Instruments Incorporated (USA); LOA, Laboratoire d’Optique Atmosphérique (France); NOAA, National Oceanic and Atmospheric Administration (USA); NSF, National Science Foundation (USA); UDL, Université de Lille, Faculté des Sciences et Technologies, Villeneuve d’Ascq (France). *There were no data at Melbourne from 2003 to 2008.