IMPACTS OF CLIMATE CHANGE ON MARINE AIR TEMPERATURE

Elizabeth Kent, David Berry ¹ and Julian Hill²

1 National Oceanography Centre, Southampton

2 Meteorological Office

Supporting Evidence

Marine air temperature over the ocean is measured from ships, buoys and marine platforms. Air temperature is not currently retrievable from satellites. The Hadley Centre produce 5˚ datasets of marine air temperature (MOHMAT, HadMAT1 & HadNAT2, Parker et al., 1995; Rayner et al., 2003; Hill et al., in preparation). This spatial resolution is not sufficient to show details of the spatial variability in air temperature near the UK, so here we use marine air temperature from a new dataset under development at the National Oceanography Centre, Southampton, which presents daily air temperatures on a 1˚ grid (although the true spatial resolution is somewhat coarser than 1˚). Confidence in the new dataset is gained through agreement with the well-established Central England Temperature timeseries (CET, Parker et al. 1992, panel lower right, red line) and through similarities with the Met Office datasets (panel lower left).

Adjustments have been applied to the marine air temperature to account for spurious daytime heating (Berry et al., 2004). This allows us to use daytime observations. In contrast the MetOffice datasets use night-time marine air temperature observations only.

Although relying on Voluntary Observing Ships (VOS) for information on marine air temperature we note that the number of observations collected, in UK waters and globally, has declined in recent years. Uncertainty in marine air temperature fields near the UK has increased by approximately 50% since the mid-1990s.

Please acknowledge this document as: Kent, E., Berry, D. and Hill, J. (2006). Impacts of Climate Change on Marine Air Temperature in Marine Climate Change Impacts Annual Report Card 2006 (Eds. Buckley, P.J, Dye, S.R. and Baxter, J.M), Online Summary Reports, MCCIP, Lowestoft, www.mccip.org.uk

References

Berry, D. I., E. C. Kent and P. K. Taylor, (2004). An analytical model of heating errors in marine air temperatures from ships, J. Atmos. Ocean. Tech., 21(8), 1198 - 1215.

Hill, J.G.T., Brohan, P.B., Rayner, N.A., Kennedy, J., Parker, D.E., Kent, E.C., Berry, D.I. and Tett, S.F.B. (In Preparation) Is night-time marine air temperature a better measure of global climate change than sea surface temperature

Kent, E.C. and D. I. Berry, (2005). ICOADS Data Quality Version 1, Unpublished Document, 42pp. [available from http://www.noc.soton.ac.uk/JRD/MET/noindex/JGS/icoads_quality_v1.pdf]

Parker, D. E. and Folland, C. K. and Jackson, M. (1995) Marine surface temperature: observed variations and data requirements, Clim. Change, 31, 559 – 600

Rayner, N. A., D. E. Parker, E. B. Horton, C. K. Folland, L. V. Alexander, D. P. Rowell, E. C. Kent and A. Kaplan (2003). Global Analyses of SST, Sea Ice and Night Marine Air Temperature Since the Late 19th Century, Journal of Geophysical Research 108(D14), DOI: 4407,10.1029/2002JD002670