date: Thu, 3 Sep 2009 15:17:40 +0100
from: "Thorne, Peter (Climate Research)" <peter.thorne@metoffice.gov.uk>
subject: Maybe Pielke Sr. was right all along ...
to: "Dian Seidel" <dian.seidel@noaa.gov>, <John.Lanzante@noaa.gov>, "Ben Santer" <santer1@llnl.gov>, <Thomas.C.Peterson@noaa.gov>, "Imke Durre" <Imke.Durre@noaa.gov>, <Russell.Vose@noaa.gov>, "Parker, David" <david.parker@metoffice.gov.uk>, "Phil Jones" <p.jones@uea.ac.uk>

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
