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Merged Land-Ocean Surface Temperature Analysis

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The historical Merged Land-Ocean Surface Temperature Analysis (MLOST) is derived from two independent analyses, an extended reconstructed sea surface temperature (ERSSTv3b) analysis and a land surface air temperature (LST) analysis using the global historical climatology network (GHCN) temperature database. The ERSST analysis on a 2 deg grid is degraded to a 5 deg resolution to match the LST analysis. The MLOST anomalies are computed relative to a 1971-2000 baseline, following the World Meteorological Organization convention. The MLOST anomalies and error fields are available through the Climate Monitoring group.

The MLOST v3 processing is described in Smith et al. (2008). The LST is computed exactly as discussed in the paper. However, the current v3b ERSST analysis uses only in situ SST data (v3b implies that no satellite SST data are used). Consequently, the merged product is now also referred to as MLOST v3b. Thus, other than the exclusion of satellite SST data, the v3 and v3b processing are the same.

As described in Smith et al. (2008), there are 3 major changes of version 3 over version 2. First, we improved the tuning procedures using simulated data. The result of the change is that data have a stronger influence on the analysis prior to 1930. This can be seen in figure 6 of the reprint. In this figure the global surface temperature in shown for the merged version 2 and 3 as well as for the UK HadCRUTv analysis. The second change is that we now process the sea ice directly using our own sea-ice bias correction in ERSST. This change allows the analysis to be made in a more timely fashion. Analyses for the previous month are now available on the third day of the current month. The third change was the addition of satellite data to the ERSST analysis from 1985 onwards, but as mentioned above, this change has been withdrawn in v3b.

Global 5x5 binary data
Various regional averaged ASCII data

See also readme.status.changes. for information on recent changes and updates to this dataset.


Smith, T.M., R. W. Reynolds, T. C. Peterson, and J. Lawrimore, 2008: Improvements to NOAA's historical merged land-ocean surface temperature analysis (1880-2006). J. Climate, 21, 2283-2296.

Smith, T.M.and R. W. Reynolds, 2005: A Global Merged Land-Air-Sea-Surface Temperature Reconstruction Based on Historical Observations (1880-1997). J. Climate, 18, 2021-2036.

Contact Information

Boyin Huang

David Wuertz

Dick Reynolds

Tom Smith

Ron Ray

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NOAA NCDC / Satellite Data / Help