The Stable Boundary Layer And Climategate #2

In the Climategate #2 e-mails, Peter Thorne is shown joking about the concept that the surface temperatures can be decoupled from the temperatures higher in the atmosphere and this could have an important effect on the interpretation of multi-decadal surface  and lower tropospheric temperature trends. This is an issue that we have explored quantitatively in our papers; e.g. see

Klotzbach, P.J., R.A. Pielke Sr., R.A. Pielke Jr., J.R. Christy, and R.T. McNider, 2009: An alternative explanation for differential temperature trends at the surface and in the lower troposphere. J. Geophys. Res., 114, D21102, doi:10.1029/2009JD011841

Klotzbach, P.J., R.A. Pielke Sr., R.A. Pielke Jr., J.R. Christy, and R.T. McNider, 2010: Correction to: “An alternative explanation for differential temperature trends at the surface and in the lower troposphere. J. Geophys. Res., 114, D21102, doi:10.1029/2009JD011841″, J. Geophys. Res., 115, D1, doi:10.1029/2009JD013655.

Steeneveld, G.J., A.A.M. Holtslag, R.T. McNider,  and R.A Pielke Sr, 2011: Screen  level temperature increase due to higher atmospheric carbon dioxide in calm and  windy nights revisited. J. Geophys. Res., 116, D02122,   doi:10.1029/2010JD014612.

The e-mail from Climategate 2 FOIA 2011 Searchable Database  is and reads [highlight added]

date: Thu, 3 Sep 2009 15:17:40 +0100
from: “Thorne, Peter (Climate Research)” <REDACTED>
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.

Peter Thorne now works with Tom Karl and Tom Peterson at NCDC.  His e-mail was, of course,  a joke, but it also highlights a lack of knowledge (and an arrogance) about the issues with respect to accurately modeling and explaining observed surface air temperature trends over land. However, as of 2011, our findings remain unrefuted in the peer-reviewed literature.

Recently there was a Worksop at ECMWF in Exeter, UK that updates the science community on the significant limitations of the representation of the nighttime (including winter arctic and antarctic) boundary layer of  climate models. This includes the ability to skillfully model the vertical temperature profile near the surface. The workshop was

Workshop on Diurnal cycles and the stable atmospheric boundary layer

with the description [highlight]

 22 November 2011 A workshop was held at ECMWF on “Diurnal cycles and the stable atmospheric boundary layer” from 7 to 10 November 2011. The workshop attracted about 60 participants, from Europe and other parts of the world, including Japan, North and South America and Australia.

The workshop was organised together with the GEWEX Atmospheric Boundary Layer Studies (GABLS) working group and co-sponsored by ECMWF, the World Climate Research Programme (WCRP), the Global Energy and Water Cycle Experiment (GEWEX), and GABLS.

One of ECMWF’s strategic goals is to improve the quality of near-surface weather products like temperature and wind and atmospheric composition. It is well known that the diurnal cycles of temperature and wind are strongly influenced by small-scale atmospheric processes in the stable boundary layer, in particular by turbulent diffusion, gravity waves and radiation, but also by the thermal coupling with the underlying soil through vegetation and snow. Most large-scale atmospheric models utilize rather diffusive boundary layer schemes resulting in stable boundary layers that are too thick and which show too little wind turning. Climate projections also show strong temperature signals at high latitudes which are affected by the processes mentioned above.

More details can be seen at ECMWF/GABLS Workshop including the presentations here.

As an example of the specific conclusions from the talks at this workshop, Dick McNider summarized observed data that documents that warming has been much larger in minimum temperatures than maximum temperatures, and that the global climate models do not accurately simulate this asymmetry in his talk

Response and Sensitivity of the Stable Boundary Layer to Added Downward Long-wave Radiation

As he showed

This asymmetry in warming is one of the most significant signals in the observed climate record

His conclusions, based on his modeling study are that most of this warming is from  a vertical redistribution of heat, not an overall warming of the lower atmosphere. His conclusion slide reads

  • The positive feedback due to a redistribution of heat when the SBL is destabilized by added downward radiation may be part of the reason for the differential rise in observed minimum temperatures.
  • The models/processes presented here that have increased temperature of 0.5-1.0K would explain a significant part of the differential minimum temperature warming.
  • Global models don’t have the mechanisms or resolution to capture this feed back.
  • Downward radiation by aerosols which is also not handled well in GCMs may play a major role in the warming of minimum temperatures.

In terms of Peter Thorne’s statement “Maybe Pielke Sr. was right all along …”,  apparently so. :-)

source of image

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