Workshop Meteorological Panel
25 - 27 September 2009
Pfaffstaetten near Vienna, Austria
PRESENTATIONS Saturday 26th
- Use of the Java TopTask Weather Browser
Olivier Liechti (Switzerland)
TopTask is an interactive Java based web application embedded in pc-met.
It displays the Top-Therm forecasts for the actual and next day of
potential flight distance (PFD) in Europe and some regions in the USA.
The forecasts are based on the model chain of DWD, for Europe COSMO-EU
and COSMO-DE forecasts are used, for other regions the global model GME
is used. PFD's can interactively be selected for different glider
classes. The forecast data can be archived for later analysis. In
addition, this tool allows for the task planning based on PDF's and
post-analysis of the flight after importing the IGC files. It also
supports direct export/import into SeeYou.
Presentation PDF (2 Mbyte)
- Improving Atmospheric Numerical Models using Meteorological and
GliderFlight Recorded Data
Edward Hindman (USA)
In order to improve the forecast quality of TopTask for the USA, the
forecasts of the Colorado State University RAMS model are used. However
incorrect temperature and dew-point predictions caused unreliable PDF
forecasts. In the course of 2008 several improvements related to the
incoming solar radiation and soil moisture were conducted to RAMS.
Comparison of the forecast with RAMS and with the DWD global model GME
showed good agreement, but still some improvements of surface dew point
predictions are necessary.
Presentation PDF (1.2 Mbyte)
- Convective Structures in Clear-Air Echoes seen by a Weather Radar
Martin Hagen (Germany)
Modern weather radar systems are not only able to observe signals from
precipitation, but they also show echoes from the cloud-free boundary
layer. These echoes have low reflectivities and are normally not shown
in the operational data. During summer time these echoes can be observed
within a range of up to 50 km around the radar. The sources for the
clear-air echoes can either be Bragg-scatter or insects. Observations by
polarimetric weather radar give a strong indication that mainly insects
cause clear-air echoes. Since insects act as passive tracers it is
possible to visualize convective structures and motions.
Presentation PDF (2.2 Mbyte)
- Climb Rate - Altitude Correlation from Analysis of IGC Files
Christof Maul (Germany)
IGC files form 3 championships are used to correlate climb rate with
altitude. In order to access maximum meteorological climb rates only
data from the distance flight phase were used, i.e. the pre-departure
and the post-finish flight phase was manually removed. It is also
necessary to separate circling from straight-climb flight phases. It was
found that mean vertical speeds are essential independent of altitude
which is in contrast to the accepted theory (e.g. T. Bradbury
"Meteorology and Flight"). However a deeper analysis and using a 3rd
order polynomial fit to maximum climb rates and then compared to the
mean climb rates gave an excellent agreement with Bradbury's theory. A
further analysis of the climb-rate data showed that a Gaussian normal
distribution can be confirmed.
Presentation PDF (0.9 Mbyte)
- Identification of Waves in IGC files
Alfred Ultsch (Germany)
Application of databionics to IGC files: pilots search for updrafts. The
task is to develop an unsupervised classifier for climbs in IGC files
and separation of thermals and waves. Based on flights in the Andes a
classifier was developed. It is validated for the Alps using a manual
analysis by Philip Ohrndorf of 160 flights. This was a cumbersome work
since only 10 downloads per day from OLC are allowed.. An accuracy of
76% was achieved with the unsupervised classifier. These flights were
used to present a wave climatology for the Alps. It can be assumed that
the classifier gives similar accuracy for the Andes. For the Alps also
an Artificial Neural Network could be constructed since training data
sets are available.
Presentation PDF (3.8 Mbyte)
- Mountain Waves - DWD's new Tool to Forecast Lee Waves
Erland Lorenzen (Germany)
The DWD high resolution model COSMO-DE (2.8 km horizontal resolution)
allows the forecast of mountain waves at the German Mittelgebirge (small
mountains up to 1500 m MSL). Waves up to 7000 m MSL have been forecasted
at the Harz, Thüringer Wald, Schwarzwald and Riesengebirge. The
Forecasts are consistent with the cloud structure observed by
Presentation PDF (2.4 Mbyte)
- Are Cross-Country Wave-Flights possible almost without Mountains?
Ralf Thehos (Germany)
Especially during winter the DWD COSMO-DE model indicates wave
structures without any relation to terrain. Wave structures are also
sometimes visible in high resolution visible satellite images. Some
flights by Ralf and colleagues in the Rhine Valley confirmed the wave
structures. It is assumed that the waves are initiated at inversion
layers with high wind speeds above.
Presentation PDF (1.5 Mbyte)
- Stable and Convective wave clouds
Julian West (Germany)
Julian presented a number of impressive photos from wave clouds, rotors
and morning glory clouds. Their stable and unstable appearance did leave
a lot of questions which can not be answered in detail.
Presentation PDF (0.6 Mbyte)
- Stratified Flows over the Sierras
Larry Armi (USA)
Larry presented results from the T-REX campaign (2006) over the Sierra
Nevada. Airborne observation with an instrumented King Air within
stratified flow showed that only gap flow is able to descent into the
Owens Valley. The analysis of flight track and measured 3-dimensional
wind was done with Google Earth. An impressive graphical presentation is
possible with this new technology. The same kind of analysis was
repeated for some flights within Föhn during the MAP campaign in 1999.
Armi, L. and G. Mayr, 2011: The Descending Stratified Flow and Internal Hydraulic Jump in the Lee of the Sierras. J. Appl. Meteor. Climatol., 50, 1995-2011
- Enhancement of Convection in Arid Areas
Markus Stracke (Austria)
In savannah regions convection and thus precipitation can be enhanced by
changing the surface properties, i.e. by enhancing the sensible heat
flux. The evaporating water from irrigated areas will be recycled if the
irrigated areas are surrounded by i.e. black tires.
- Gilding Safari Adventures without Crew
Thomas Seiler (Germany)
Thomas presented his experience from some safari flights within the last
years. Without a supporting team he managed (in most cases) to fly tours
through Germany for several days and to return to the starting point.
The challenging goal of such flights is the weather forecast for several
days. Each evening an airfield with towing possibility has to be
Presentation PDF (2.3 Mbyte)
- The Role of Climate Changing on Organisation of Thermals
Ahmet Tokgözlü (Turkey)
The authors from Turkey could not come themselves to Pfaffstätten to
present their papers, but they did sent a presentation.
Daily programs of gliding activities are based on convection potential
in flight area. Vertical velocity, air temperature, wetness, vegetation
cover, daily heating rate, instability condition and heat fluxes have a
key role on prediction of flight lengths. The main aim of this study is
to analyze temporal and spatial variations of air temperature and
rainfall rate and climate changing effects on soaring conditions in
Presentation PDF (1.4 Mbyte)
DISCUSSION Sunday 27th
The next SAA Convention will be held in Little Rock, Arkansas, USA,
January 28-30, 2010.
The next OSTIV congress will be during the World Gliding
Championship in Szeged, Hungary. The dates for the OSTIV event are July
21 - 28, 2010
The next workshop of the OSTIV Meteorological Panel will be in
Ward Hindman did announce that the "Technical Soaring" Journal is now
Hermann presented a message from the OSTIV president Loek Boermans.
On that occasion Hermann announced that OSTIV will invite us for the
dinner Saturday evening. Special Thanks to Loek from all
The upcoming European regulations for pilot licences are currently
under discussion. To avoid an unnecessary load on meteorological themes
for glider pilots, suggestions on the structure of meteorological
education have to be suggested to EASA. A working group lead by
Ghislaine Facon was established during the workshop and will investigate
meteorological themes for glider pilots within the next year.
Summary by Hermann Trimmel and Martin Hagen