Data were provided by J. Cappelen (Danish Meteorological Institute), D. Kiktev (Russian Hydrometeorological Institute), R. Ray (National Climatic Data Center), M. J. Salinger [NIWA New Zealand: Asia–Pacific network (APN) data], L. Vincent (Environment Canada), and P. Zhai (China Meteorological Administration). C. K. Folland provided useful comments. This work was supported by the U.K. Government Research Program and this paper is U.K. Crown Copyright.
Arnfield, A. J., 2003: Two decades of urban climate research: A review of turbulence, exchanges of energy and water, and the urban heat island. Int. J. Climatol., 23 , 1–26.
Elliott, W. P., , and D. J. Gaffen, 1991: On the utility of radiosonde humidity archives for climate studies. Bull. Amer. Meteor. Soc., 72 , 1507–1520.
Elliott, W. P., , R. J. Ross, , and B. Schwartz, 1998: Effects on climate records of changes in National Weather Service humidity processing procedures. J. Climate, 11 , 2424–2436.
Folland, C. K., and Coauthors, 2001a: Global temperature change and its uncertainties since 1861. Geophys. Res. Lett., 28 , 2621–2624.
Folland, C. K., and Coauthors, 2001b: Observed climate variability and change. Climate Change 2001: The Scientific Basis, J. T. Houghton et al., Eds., Cambridge University Press, 99–181.
GCOS, 2004: Implementation plan for the Global Observing System for Climate in support of the UNFCCC. Global Climate Observing System GCOS-92, WMO Tech. Doc. 1219, 136 pp. [Available online at http://www.wmo.int/web/gcos/gcoshome.html.].
Hansen, J., , R. Ruedy, , J. Glascoe, , and M. Sato, 1999: GISS analysis of surface temperature change. J. Geophys. Res., 104 , D24. 30997–31022.
Hansen, J., , R. Ruedy, , M. Sato, , M. Imhoff, , W. Lawrence, , D. Easterling, , T. Peterson, , and T. Karl, 2001: A closer look at United States and global surface temperature change. J. Geophys. Res., 106 , D20. 23947–23963.
Horton, E. B., , C. K. Folland, , and D. E. Parker, 2001: The changing incidence of extremes in worldwide and Central England temperatures to the end of the twentieth century. Climatic Change, 50 , 267–295.
Hurrell, J. W., , and H. van Loon, 1997: Decadal variations in climate associated with the North Atlantic Oscillation. Climatic Change, 36 , 301–326.
Johnson, G. T., , T. R. Oke, , T. J. Lyons, , D. G. Steyn, , I. D. Watson, , and J. A. Voogt, 1991: Simulation of surface urban heat islands under “ideal” conditions at night. Part 1: Theory and tests against field data. Bound.-Layer Meteor., 56 , 275–294.
Jones, P. D., , and A. Moberg, 2003: Hemispheric and large-scale surface air temperature variations: An extensive revision and an update to 2001. J. Climate, 16 , 206–223.
Jones, P. D., , P. Ya Groisman, , M. Coughlan, , N. Plummer, , W. C. Wang, , and T. R. Karl, 1990: Assessment of urbanization effects in time series of surface air temperature over land. Nature, 347 , 169–172.
Jones, P. D., , T. J. Osborn, , and K. R. Briffa, 1997: Estimating sampling errors in large-scale temperature averages. J. Climate, 10 , 2548–2568.
Jones, P. D., , E. B. Horton, , C. K. Folland, , M. Hulme, , D. E. Parker, , and T. A. Basnett, 1999: The use of indices to identify changes in climate extremes. Climatic Change, 42 , 131–149.
Karl, T. R., , C. N. Williams, , P. J. Young, , and W. M. Wendland, 1986: A model to estimate the time of observation bias associated with monthly mean maximum, minimum and mean temperatures for the United States. J. Climate Appl. Meteor., 25 , 145–160.
Klein Tank, A. M. G., and Coauthors, 2002: Daily dataset of 20th-century surface air temperature and precipitation series for the European Climate Assessment. Int. J. Climatol., 22 , 1441–1453.
Laursen, E. V., 2002: Observed daily precipitation, maximum temperature and minimum temperature from Ilulissat and Tasiilaq, 1873–2000, version 2. Danish Meteorological Institute Tech. Rep. 02-15, 10 pp.
Lin, X., , K. G. Hubbard, , E. A. Walter-Shea, , and J. R. Brandle, 2001: Some perspectives on recent in situ air temperature observations: Modeling the microclimate inside the radiation shields. J. Atmos. Oceanic Technol., 18 , 1470–1484.
Manton, M. J., and Coauthors, 2001: Trends in extreme daily rainfall and temperature in southeast Asia and the South Pacific: 1961–1998. Int. J. Climatol., 21 , 269–284.
Mason, P. J., and Coauthors, 2003: The second report on the adequacy of the Global Observing Systems for Climate in support of the UNFCCC. Global Climate Observing System GCOS-82, WMO Tech. Doc. 1143, 74 pp.
Parker, D. E., , T. P. Legg, , and C. K. Folland, 1992: A new daily central England temperature series. Int. J. Climatol., 12 , 317–342.
Peterson, T. C., 2003: Assessment of urban versus rural in situ surface temperatures in the contiguous United States: No difference found. J. Climate, 16 , 2941–2959.
Peterson, T. C., , K. P. Gallo, , J. Lawrimore, , A. Huang, , and D. A. McKittrick, 1999: Global rural temperature trends. Geophys. Res. Lett., 26 , 329–332.
Razuvaev, V. N., , E. G. Apasova, , and R. A. Martuganov, cited. 1993: Daily temperature and precipitation data for 223 USSR stations. ORNL/CDIAC-56, NDP-040, ESD Publication 4194, Carbon Dioxide Information Data Center, Oak Ridge National Laboratory, Oak Ridge, TN. [Available online at http://cdiac.ornl.gov/ftp/ndp040/ndp040.txt.].
Simmons, A. J., and Coauthors, 2004: Comparison of trends and low-frequency variability in CRU, ERA-40, and NCEP/NCAR analyses of surface air temperature. J. Geophys. Res., 109 .D24115, doi:10.1029/2004JD005306.
Vincent, L. A., , X. Zhang, , B. R. Bonsal, , and W. D. Hogg, 2002: Homogenization of daily temperatures over Canada. J. Climate, 15 , 1322–1334.
Vose, R. S., , T. R. Karl, , D. R. Easterling, , C. N. Williams, , and M. J. Menne, 2004: Impact of land-use change on climate. Nature, 427 , 213–214.
Zhou, L., , R. E. Dickinson, , Y. Tian, , J. Fang, , Q. Li, , R. K. Kaufmann, , C. J. Tucker, , and R. B. Myneni, 2004: Evidence for a significant urbanization effect on climate in China. Proc. Natl. Acad. Sci. USA, 101 , 9540–9544.