[{"name":"stockholm-historical-monthly-temperature-1","title":"Stockholm Historical Weather Observations \u2014 Monthly mean air temperatures since 1756","summary":"Weather observations of several meteorological variables have been made continuously at the old astronomical observatory in Stockholm since 1756. As a part of a collection of data for selected variables, the dataset provided here contains monthly mean air temperatures for the period 1756\u20132018. Three variants are available: (i) non-homogenized monthly mean temperatures, as estimated from the local temperature observations, (ii) homogenized monthly mean temperatures, adjusted after 1870 to exclude the urban warming trend in the city, and (iii) homogenized monthly mean temperatures having an additional adjustment applied to data for May\u2013August in the period before 1859, to correct for a supposed warm bias of the observed temperatures due to likely poor protection of thermometers against radiation.","citations":"Moberg A, Bergstr\u00f6m H, Ruiz Krigsman J, Svanered O. 2002: Daily air temperature and pressure series for Stockholm (1756\u20131998). Climatic Change 53: 171\u2013212. DOI:10.1023\/A:1014966724670\r\n\r\nMoberg A, Alexandersson H, Bergstr\u00f6m H, Jones PD. 2003: Were Southern Swedish summer temperatures before 1860 as warm as measured? Int. J. Climatol. 23: 1495\u20131521. DOI:10.1002\/joc.945\r\n\r\nMoberg A, Tuomenvirta H, Nordli \u00d8. 2005: Recent climatic trends. In: Physical Geography of Fennoscandia. (Ed: Sepp\u00e4l\u00e4 M). Oxford Regional Environments Series, Oxford University Press, Oxford: 113\u2013133","comments":"The observation site is included in the national station network managed by the Swedish Meteorological and Hydrological Institute (SMHI), with station number 98210 (manual station) and 98230 (automatic station), but data in the current dataset can differ from those in the SMHI database. \r\n\r\n\r\nThe three variants of monthly mean air temperatures presented here are derived from the associated dataset with daily mean temperatures.\r\n\r\n\r\nThe first variant (non-homogenized data, see Moberg et al. 2002) accounts for changes in observation times and also includes the following adjustments:\r\n\r\n\r\n1. Adjustments in 1819\u20131825 for an incorrectly calibrated thermometer probably being used.\r\n\r\n2. Adjustments in 1756 and 1763 for missing or poor daily observations.\r\n\r\n\r\nNote: In the corresponding dataset with daily mean temperatures, these two particular adjustments are not applied to the non-homogenized data, but they are applied there to the homogenized data.\r\n\r\n\r\nThe second variant (homogenized data, see Moberg et al. 2002) additionally includes an adjustment after 1870 to eliminate an urban warming trend and the effect of other inhomogeneities detected in homogeneity tests against surrounding reference station data. The main purpose of applying this adjustment is to obtain a homogenized record that, throughout its entire length, is approximately respresentative of the rural conditions that prevailed before the mid\u201319th century. The size of the adjustment changes with time and varies over the year. It causes homogenized temperature data after 1967 being on average 0.8\u00b0C colder than non-homogenized temperatures.\r\n\r\n\r\nThe third variant (with additional adjustment to data for May\u2013August in the period 1756\u20131858), has been derived as in Moberg et al. (2005) based on conclusions in Moberg et al. (2003). It includes the following additional adjustments, relative to the second variant:\r\n\r\n\r\nMay and August: \u22120.3\u00b0C.\r\n\r\nJune and July: \u22120.7\u00b0C.\r\n\r\n\r\nThe motivation for this additional adjustment is based on the available knowledge about the position of the old thermometer in combination with results from homogeneity testing and other statistical modelling. However, it should be seen as an ad hoc judgement rather than a result from a strict statistical analysis. Nevertheless, this variant of monthly mean temperatures is judged to be the one that currently best represents the true temperature history for the May\u2013August season. Further research would be needed to better assess the need for adjustments in the early period and to determine their size and how they should be applied. Actually, there is a need also to undertake further analysis of how to better adjust the temperature data for the modern urban heat island effect.\r\n\r\n\r\nData from before 2013 are based on manual observations. Data from 2013 onward are derived on the automatic weather station (SMHI station 98230). Monthly mean temperatures presented here may differ from those that can be obtained directly from the SMHI due to differences in calculation procedures. \r\n\r\n\r\nFurther information about instrument positions and original data sources is available in the comments to the associated dataset with thermometer observations.","category":"Atmosphere","subcategory":"Weather observations","keywords":"Air temperature; Monthly data; Early instrumental data; Homogenized data; Sweden; Stockholm","scientist":"Anders Moberg","firstname":"Anders","lastname":"Moberg","address":"Department of Physical Geography, Stockholm University","postalcode":"SE-106 91","city":"Stockholm","province":"","country":"Sweden","parameters":"Earth science > Atmosphere > Atmospheric temperature > Surface temperature > Air temperature","location":"Continent > Europe > Northern Europe > Scandinavia > Sweden","progress":"Completed","language":"English","project":"Digitization, quality control and development of daily and monthly air temperature and pressure data series until 1998 was undertaken as part of the project IMPROVE \u2014 Improved Understanding of Past Climatic Variability from Early Daily European Instrumental Sources. Project funding: EU 4th Framework Programme, 1998\u20131999. Contract: ENV4-CT97-0511. Co-ordinator: Dario Camuffo, Consiglio Nazionale delle Ricerche, Istituto di Scienze dell'Atmosfera e del Clima, Padova, Italy. PI at Stockholm University: Anders Moberg.","publisher":"Bolin Centre Database","version":"1","constrains":"None","access":"Free"}]