Minutes of the open meeting of the-

"Mesospheric Temperature Trend Assessment (MTTA)" Group

(Under IAGA /ICMA trend Working Group)

held at Sozopol , June 12, 2004

 

Dr.Beig has presented a brief overview of the progress made so far by MTTA after its inception in 2000. He has then made some proposal based on the feedback received from different members of MTTA for further continuation of the work under the MTTA umbrella. It mainly includes monthly trends and solar effect in long-term temperature data. As a future activity to promote the trend work, some points were made which involves active participation of GCM modeling community working in this field. A slide depicting the silent feature about his presentation is attached at the end as Appendix-1. He has invited Dr Offermann for his feedback about the future course of work.

Dr. Offermann has proposed to extend the work he presented at the Trend 2004 workshop about summer duration and their trends to other data sets and models. He has also mentioned the wave activity through EP flux or fluctuation estimates (see Appendix 2 for detail). Dr Jacobi has asked to specify the type of data sets because a lot about the dynamical data are available. Dr Offermann pointed out that it concerns not only mesopause but also the stratosphere.

Dr. Jacobi has shown great interest to participate in the MTTA activity and remarked that lot of dynamical data related to winds, waves etc are available and can be made use of to understand the trends. But he also pointed out that the data volume is huge and variable, so a proper selection of parameters and scope should be clearly defined for some meaningful outcome.

In response to the proposal made by Dr. Beig related to GCM runs, Dr Berger made a remark that these points are the dream goals for all modeler and argued that models have some problems to reproduce the actual state of the atmosphere. Dr Offermann has commented on it and mentioned that these may be difficult but not impossible and some groups like that of NCAR (using WECHAM model) have already started work in that direction. Dr Berger suggested that it is necessary to separate this issue with the zero trends of the mesopause. Dr Keckhut has supported the idea of Dr. Offermann in telling that these analyses will provide extra prognostics to compare models among themselves and the atmosphere through specific data sets.

Dr Lastovika has mentioned some additional data sets for Gravity waves. Dr Jacobi has support this approach on other data sets. Dr Schmidt has suggested that we should try to investigate the solar response using the smaller time scale as the 27-days solar rotation instead of the 11-years. But Dr. Beig has conveyed the difficulty of experimental data sets and pointed out that such resolution in long term mesospheric data sets is difficult at present with a high degree of confidence or significant level. Dr Lastovika has reported some difficulties associated with this time scale as phase shift between temperature and ozone, and the interferences with planetary waves. Finally Dr Fomichev has informed that at present his computer facility is being revamped and his Canadian GCM model is in a transition phase so performing immediate runs are difficult. Dr Beig has answered that it is ok because there is no any dead line fixed for this proposal.

 

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Appendix-1

MTTA ((Mesospheric Temperature Trend Assessment) under the IAGA /ICMA trend Working Group (http://www.tropmet.res.in/~lt-time)

Gufran Beig (MTTA Chair)

1. Progress /Achievements so far……

  • Establishment: 2000.

  • Work: Review of all experimental and model results available upto 2002 from 16 different groups on Annual Temperature trend at mesosphere and mesopause region temperature.

  • Peer Review Paper: Beig, G., P. Keckhut, R. P. Lowe, Ray Roble, M. G. Mlynczak, J. Scheer, V. Fomichev, D. Offermann, W.J.R. French, M. G. Shepherd, A. I. Semenov, E. E. Remsberg, C. Y. She, F. J. Lübken, J. Bremer, B. R. Clemesha, J. Stegman, F. Sigernes, and S. Fadnavis.

          Review of Mesospheric Temperature Trends. :  Review of Geophysics, 41(4), 1-1 to 1-41,            1015, doi:10.1029/2002RG000121, 2003.

  • Trend WG Publication: Gufran Beig, P. Keckhut, G.E. Thomas, A.I. Semenov, R.P. Lowe, F.J. Luebken, J. Bremer, G.B. Burns, E.E. Remsberg, C.Y. She, J. Stegman, D. Offermann, J. Scheer, S.P. Burton, M.G. Shepherd, C. Deehr, B.R. Clemesha, S. Fadanavis, M. Gadsden, J. Taubenheim, L.W. Thomason

  • Mesospheric Temperature Trend Assessment 1. Present Status and Issues.: Terchnical           Report No. II-F (1) of Joint working group LT-TIME "Long-Term Trends in the Ionosphere, Thermosphere and Mesosphere" of IAGA, ICMA and PS-MOS (SCOSTEP), 1-75, 2002.     

  • Models: Participation of modeling community poor so far.

 

2. Proposals for future Work:

  • Seasonal analysis: Monthly /seasonal long-term trend at the mesosphere and mesopause region temperature.

  • Solar Signals: Solar response in the mesospheric temperature

  • Some tempting immediate issues for modelers /data:

1. With reference to NLC findings, examine the trend in water vapor at the mesopause level to study whether it varies with seasons (or even months) and latitude and whether you can explain any increase (or decrease) in H2O to clarify Temperature trend hypothesis predicted earlier wrt NLC?

  • 2. Is there any solar response in temperature at high-latitude mesopause region and how the response varies with height in that region? Some model predicts a high degree of variation from 80 to 90 km.

  • Model simulations:

  1. Define and conduct trend studies with existing GCMs. Evaluate consistency and agreement between models on parameters of temperature, radiation, and chemistry. We really need a consistent picture from the modeling community to back our future measurement recommendations.

  2. Sample the GCM results along typical satellite orbital tracks to better understand the issues of aliasing due to asynoptic sampling.

  3. Evaluate optimal set of parameters and measurement techniques based on the consideration of the GCM study and remote sensing methods from space, including sampling and multiple satellite possibilities.

  4. Advocate the results in a "position paper" to be published as a follow on to the original trend paper.

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Appendix-2

Dirk Offermann

 

  • Questions (20 years) to Models /Measurements
  • How long is summer duration (SD)?

                   -at different altitudes

                   -at different latitudes

  • Does summer duration increase /decrease? If yes, then how much?

                   -at different altitudes?

                   -at different latitudes?

  • Does wave activity change?

                  -Fluctuation trends (standard deviations)

                  -Eliaren Palm Flux trends

                  -Changes of EP flux divergence

  • Questions (40 years)
  • Are there breakpoints in the trends?

 

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