>This is brief introduction to the TAO Project Sea Air and Sea Surface Temperature data that’s available through the KNMI Climate Explorer.
The Monthly observations webpage of the KNMI Climate Explorer includes Sea Air Temperature and Sea Surface Temperature data from the NOAA Pacific Marine Environmental Laboratory (PMEL) Tropical Atmosphere Ocean (TAO) project. Refer to the TOA Project Home webpage. A Flash player overview of the TAO project is provided here: The TAO Story.
If you were to download the data from the KNMI Climate Explorer for the full area covered (8S-9N, 137E-95W), you’d note that data starts as early as 1980. But, like all datasets, the timing of partial and complete coverage needs to be understood. There may be TOA Project data available as far back as 1980, but it is very sparse in early years. The installation of the buoys was not completed until 1994. As an initial reference, Animation 1 shows the locations of available TOA Project sea air and sea surface temperature data for Januaries starting in 1989. It shows how sparse the coverage was of the tropical Pacific prior to 1994. So caution should be exercised when using TAO project data before 1994. And as you will note, there can be months after 1994 when data from individual buoys is not available, leaving incomplete coverage.
Keeping that in mind, Figure 1 compares Sea Surface and Sea Air Temperature data (not anomalies) for the NINO3.4 region (5S-5N, 170W-120W) of the central equatorial Pacific starting in 1995. As one would expect, monthly NINO3.4 SST is higher than NINO3.4 Sea Air Temperature.
If we subtract the NINO3.4 Sea Air Temperature from the NINO3.4 Sea Surface Temperature, Figure 2, the difference appears to be a noisy ENSO dataset. And it clearly illustrates that the monthly SST data stays above the monthly Sea Air temperature for the NINO3.4 region. The average monthly NINO3.4 Sea Surface Temperature is approximately 0.55 deg C warmer than the average Sea Air Temperature. Referring back to the animation, the sharp drop in 2008 could be caused by the loss of data in that area.
Smoothing the data with a 13-month running average filter to reduce the noise, the difference compares well to scaled NINO3.4 SST anomalies, Figure 3.
The TAO project Sea Surface and Sea Air Temperatures for the entire dataset (8S-9N, 137E-95W) are illustrated in Figure 4. SST is clearly higher then SAT on a monthly basis.
The difference is shown in Figure 5. Since 1995, the average monthly equatorial Pacific Sea Surface Temperature has been approximately 0.82 deg C higher than Sea Air Temperature.
And as one would expect, the variations in the difference between the TAO Project Sea Air and Sea Surface Temperatures is a function of ENSO. Refer to Figure 6, which compares the difference to scaled and ranged NINO3.4 SST anomalies.
The TAO Project data used in this post is available through the KNMI Climate Explorer: