date: Thu, 3 Sep 2009 15:17:40 +0100 from: "Thorne, Peter (Climate Research)" subject: Maybe Pielke Sr. was right all along ... to: "Dian Seidel" , , "Ben Santer" , , "Imke Durre" , , "Parker, David" , "Phil Jones" History does not relate to whether these were day time or night time ascents but clearly the boundary layer is now seriously decoupled from the near-surface. You read it here first! Operational Radiosonde Network - data quality issues Towards the end of July, radiosonde operators and data users began to notice anomalous ascent data with a small number of the radiosondes used within the Met Office network. These sondes reported a jump in atmospheric temperature between surface and the 2-second data point, approximately 10m above the ground. Operators continued to monitor all flights, informing the forecasters when the data appeared suspicious. In the extreme cases, the temperature dropped by as much as 30 degrees! Analysis began immediately to try and identify any trends in the anomalous ascents. Archived high resolution data for the operational network was re-processed for all ascents between January and July 2009, to interrogate the surface to 2-second differentials. It was concluded that this problem was only evident in specific batches of radiosondes. The manufacturers were alerted and presented with the evidence and agreed to replace all remaining stock under warranty. This amounts to approximately 500 radiosondes 'sitting on the shelf' that are currently in the process of being replaced. The Met Office radiosonde operators were all made aware of the problem, and the operational network stopped using the suspect batches with immediate effect. Operators' experiences of using more recent stock suggests that this problem has been resolved. -- Peter Thorne, Climate Research scientist Met Office Hadley Centre, FitzRoy Road, Exeter, EX1 3PB. tel. +44 1392 886552 fax. +44 1392 885681 http://www.hadobs.org