Memo To : MLTCS Colleagues

From : Alan Manson, Co-convenor with Jeff Forbes

Topic : Summer Newsletter, following SENDAI

There are two major matters, following the events at Sendai. One is the nature of 1995 Campaigns, and the second is the MLTCS-5 data analysis.

1 Campaigns. Our bi-monthly 10d runs have been useful 1990-1994. Some of our simpler and less well funded radars have been able to schedule these and build up local climatologies---- this has helped with their funding prorities. However these data have not generally been of any value for our collaborative efforts. It does not seem that we should continue these in 1995. If you think otherwise please contact me, and we can reconsider the matter.

The major MLTCS/LTCS campaigns have been of greater value to us, and the ISR community have worked with these data to develop thermospheric climatologies and to compare radar systems. It seems that as long as the ISRs find this useful we should continue with that essential but not demanding task (for most of the MLT radars). See below on the "10d" run of 1993.

Recent newsletters have contained information on the CADRE campaigns and the 2d N.H. wave study. These have been very successful and inspired much more participation than the regular MLTCSs, which have not had much science in them for us. The modelling efforts have also definitely moved in that direction, with Jeff working on 16d P.W., Francois Vial on the 5d, and Maura Hagan on the 2d. These studies require also, of course, tidal/mean wind/GW data to be complete, and so they contain rich science. It is our intention to pursue this direction of "PW" campaigns for the next few years, as STEP moves to its latter half.

Hence we encourage all radars to operate continuously during the solstices-- of course the main MLTs run continuously---

a) July/Aug 1994, 1995 The northern hemisphere NH 2d wave peaks then, and SH radars can look for propagation into the winter circulation. The 16d wave may also be seen in the SH.

b) Dec/Jan/Feb 1994/1995 The SH 2d wave is more extended in its occurrence--- then NH radars can look for propagation in to the winter flows, and also for the 16d wave.

c) the 5d wave is less clear in its seasonal occurrence---at Saskatoon the solstices are favoured.

These then become our CAMPAIGNS for 1994/5.

Typical, and useful analysis methods have been mentioned in recent MLTCS letters. eg 24h means slid by 12h show the PW activity nicely and simply; 10d sliding spectra have been most useful for the 2d waves; mean winds throughout the wave event are useful for modelling purpose and comparisons; time series of hourly means at 90km have been sent to Saskatoon for the 2d waves and Steve (Urbana) and Chris (here) have used that for mode assessment; tidal fits throughout the wave events will also be used to clarify the wave -tide non-linear interactions. For the above, all MLT heights are of interest including the 100+ km ranges if available. Our plan would be to identify the waves in a particular campaign first, and then suggest specific examples of the above , appropriate to the period. We enclose examples from Saskatoon of the above for the 2d wave as guidance and for interest.

We hope the above will also attract the OPTICAL observatories in the community, who have often found the small MLTCS campaigns too restricting, given the problems with clouds etc..

2 MLTCS/LTCS campaign analyses: many of you will have received the letter from Roberta Johnson and Casandra Fesen on the planned meeting on the Jan 20-30 10d campaign. This is MLTCS-5 or LTCS-9. It would be most useful if you were to do these in normal fashion and send to Saskatoon so they can be ready as a set for the workshop--even if you are planning to go to it. Normally we prepare profiles of mean wind and tides (12, 24; 48h PW if there) for the interval; but also before, after and for the month centered on the 10d to assess( the variability. Analysis for any PW could follow suggestions in 1 above.

Ron McMurray and I believe we have all of the MLTCS 1,2,3 (March 1991, Dec 1991, March/April 1992), so while doing the 10d MLTCS-5 it would nice if you could do MLTCS-4 for Jul 30-Aug 5,1992. These will eventually be in an ISR MLT paper ---but the big MLTCS-5 DEFINITELY will have an excellent science involvement. (Once the first paper with MLTCS 1,2,3,4 in are underway, that small data quantity could go into CEDAR as have LTCS 1,2, 3,4.)

3 Conclusion These activities are likely to be the most productive we have engaged in with MLTCS, so we hope for your support! There will be a post STEP activity (1998-2002) focussing on the STEP data 1990-97, but we have/will have done much of the essential work, leaving the collaborations with others to follow: RAMP, Results, Analysis Modelling Phase. STEP Analysis Campaigns will be formed based upon the campaign data existing, so our MLTCSs will be useful. There will also likely be a significant Middle Atmosphere activity for us to work within in 1998-2002.

Thanks for your interest and help!

Alan Manson

P.S.

CRISTA/MAHRSI Campaign: Bittner and Offermann

Many of you will be aware of this campaign, featuring instruments on US-Space Shuttle (STS66, Oct 27, 1994 launch); some of you are already formally part of the associated ground based measurements team which will define the dynamical state of the atmosphere (20-140 km). The Shuttle instruments will measure small-scale structures in trace gases (~500 km), and high resolution profiles of OH and NO. Anyone else who wishes to contribute should operate continuously from Oct 20 - Nov 18, and inform us here of your "data-success" later. I would forward all such information to Derek Offermann.