The Inconvenient Skeptic » More Monkey Business with the Mean Sea Level
UCAR's last bodge involving openly admitted GIA didnt go so well politically or in the media. I wonder if they will be quite as open about their 'adjustments' this time.
The University of Colorado Sea Level Research Group updated their data in July, but oddly enough the new data was only available through mid-April. In the past these updates have tended to bring the Mean Sea Level (MSL) up to date. That is the first oddity in this update, but it is also the most trivial. This update also reversed the isostatic adjustment that they put in earlier this year. I covered the isostatic adjustment here and the previous update here. In essence they intentionally inserted a 0.25 mm/yr trend into the MSL. The result of such a update is that it maintained the status quo 3.1 mm/yr that they have been advocating. That trend has ceased over the past 5 years.
The latest update eliminated the isostatic adjustment, but added in the following new one:
Replaced classical GDR Inverted Barometer correction on all missions with improved AVISO Dynamic Atmopshere Correction (DAC) that combines MOG2D high frequency and inverted barometer low frequency signals (Pascual et al., 2008)
They have also made previous versions of the data unavailable. Fortunately I am a pack rat and have all the original data. If the isostatic adjustment was overboard, this one is really over the top.
This chart shows that there is a 3.2 mm/yr trend in the MSL since 1993.
The first obvious difference in this data from previous data is a shift of ~10 mm for the data from 1993. There is absolutely no reason to shift data that is almost 20 years old, but they did. This chart shows the data that was available 1 year ago and the latest data. Both of them retain the seasonal signal.
The difference for the available data in 2010 is 14.66 mm difference. What started out as a 10mm shift is most recently an ~15mm shift in the most recent MSL. The trend in the difference is 0.18 mm/yr for the smoothed data. The funny thing is, even with all of this monkey business, the sea level trend for the past few years is dropping. Even with an added trend, a step function shift in 2004 and the overall shift since 1993, the trend for the past 5 years is only 2.0 mm/yr.
UCAR's last bodge involving openly admitted GIA didnt go so well politically or in the media. I wonder if they will be quite as open about their 'adjustments' this time.