Benchmarking CRUT3 and CRUT4 land only grid box temperature trends against AMSU lower troposphere data for East China, Russia, Africa and North AmericaApril 5th, 2012 by Warwick Hughes
After comparing land only CRUT3 vs the shiny new CRUT4 for some Australian grid boxes I examined again grid box areas in East China, Russia, Africa and also North America which I have checked in past years for trend differences between CRUT data and AMSU satellite data from UAH. For map of grid box areas. Data from KNMI Climate Explorer
For East China the differences are large and have increased in CRUT4.
Over Russia differences are less and have increased in CRUT4.
In the case of the grid box over Africa the trend per decade differences between CRUT3 and AMSU are huge and have eased slightly in CRUT4. These results imply large errors in surface data – unless some other reason can be found.
In 2006 I found close agreement between satellites and CRUT2 over the USA. Now we find that CRUT4 finds more warming trend in the USA than did CRUT3 – this chart shows evidence of huge adjustments in 1850′s data – and also CRUT4 has been tweaked warmer in recent years. The North American grid box area still shows the closest agreement with satellites – but CRUT4 finds increasing warmth by a variety of adjustments. An example is this 0.25 degree jump in the CRUT4 minus AMSU trace at 1997. I wonder if this tweak was “peer reviewed” ?
Perhaps the CRUT team thinks USA climate scientists are not watching – we are told the science is settled – not where I am looking.