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Global Temperature News

Classé dans: — group @ 6 décembre 2011

There are two interesting pieces of news on the global temperature evolution.

First, today a paper by Grant Foster and Stefan Rahmstorf was published by Environmental Research Letters, providing a new analysis of the five available global (land+ocean) temperature time series. Foster and Rahmstorf tease out and remove the short-term variability due to ENSO, solar cycles and volcanic eruptions and find that after this adjustment all five time series match much more closely than before (see graph). That’s because the variability differs between the series, for example El Niño events show up about twice as strongly in the satellite data as compared to the surface temperatures. In all five adjusted series, 2009 and 2010 are the two warmest years on record. For details have a look over at Tamino’s Open Mind.
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References

  1. G. Foster, and S. Rahmstorf, "Global temperature evolution 1979–2010", Environmental Research Letters, vol. 6, 2011, pp. 044022-. DOI.

On record-breaking extremes

Classé dans: — stefan @ 6 novembre 2011

It is a good tradition in science to gain insights and build intuition with the help of thought-experiments. Let’s perform a couple of thought-experiments that shed light on some basic properties of the statistics of record-breaking events, like unprecedented heat waves. I promise it won’t be complicated, but I can’t promise you won’t be surprised.
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The Climate Data Guide

Classé dans: — Jim @ 30 octobre 2011

The National Center for Atmospheric Research (NCAR) has, in the last few months, developed an interesting and potentially very useful website The Climate Data Guide devoted to the ins and outs of obtaining and analyzing the various existing climatic data sets. The site describes itself as “…a focal point for expert-user guidance, commentary, and questions on the strengths and limitations of selected observational data sets and their applicability to model evaluations.”

There are already many climate data set websites in existence, and lists of links to same, including at this site. Some of them host the actual data, while others provide various statistical analysis or graphing/visualization tools, all of which are helpful. What makes this new site unique is: (1) expert users contribute pages describing and pointing to various existing data sources within certain topic areas, (2) explanations of various existing data formats, gridding approaches, etc, (3) an online discussion forum dealing with the appropriateness of particular data sets for addressing particular scientific questions, and (4) a news section as well as links to a very wide range of data repositories, among other things. Here for example, is the page summarizing the existing reanalysis data sets.

The site, sponsored by the NSF, appears to be a unique and valuable approach to advancing climate data analysis. We encourage everyone to check it out, register as members as appropriate, etc. This would also be a good place to discuss or point to other useful data and analysis oriented sites that are out there.

NPP lift off

Classé dans: — gavin @ 28 octobre 2011

The launch of the NASA/NOAA NPP satellite seems to have gone off without a hitch this morning which is great news. This satellite has instruments that are vital to continuing data streams that were pioneered on the aging TERRA (1999), AQUA (2002) and AURA (2004), satellites – including the CERES instrument for monitoring the Earth’s radiation budget, a microwave sounder to continue the AMSU data and a visible/IR camera to complement the work of MODIS.

We really need to apologise for the acronym soup though – it is an endemic disease in satellite discussions. Indeed, NPP is a recursive acronym, standing for NPOESS Preparatory Project, where NPOESS stands for the National Polar-Orbiting Operational Environmental Satellite System.

Another satellite mission we’ve mentioned here, Aquarius (launched in June), has recently released its first results on ocean salinity:




The patterns are not particularly surprising, there is higher salinity in the sub-tropical evaporative regions, lower salinity near the equator (because of the rain!), and particularly low salinity near big river outflows (the Amazon plume stands out clearly). However, as we noted earlier, the main interest is going to be in the variability.

Results from the NPP mission will take a while to come out and be cross-calibrated with the existing records, but given other recent disappointments (GLORY and OCO), this is a huge boost to the effort to monitor the Earth System.

Global warming and ocean heat content

Classé dans: — gavin @ 3 octobre 2011

The connection between global warming and the changes in ocean heat content has long been a subject of discussion in climate science. This was explicitly discussed in Hansen et al, 1997 where they predicted that over the last few decades of the 20th Century, there should have been a significant increase in ocean heat content (OHC). Note that at the time, there had not been any observational estimate of that change (the first was in 2000 (Levitus et al, 2000)), giving yet another example of a successful climate model prediction. At RC, we have tracked the issue multiple times e.g. 2005, 2008 and 2010. Over the last few months, though, there have been a number of new papers on this connection that provide some interesting perspective on the issue which will certainly continue as the CMIP5 models start to get analysed.
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References

  1. S. Levitus, "Warming of the World Ocean", Science, vol. 287, pp. 2225-2229. DOI.

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