XXVIII OSTIV CongressJune 8 - 15, 2006Eskilstuna, Sweden |
 |
|
|
|
Abstracts of the papers presented within the Meteorology Session
- E. Hindman, S. Saleeby, O. Liechti, W. Cotton:
A system for planning soaring flights in northeastern Colorado USA
- Currently, USA glider pilots do not have an on-line, interactive
system to plan flights like their European counterparts. In Europe, a
glider pilot interacts with an atmospheric numerical model to
determine the most feasible flight for a given day: essentially the
pilot "flies" through the predicted weather to plan a flight. This
interaction is accomplished through the TopTask algorithm nested in
the on-line pilot briefing system called pc_met of the German Weather
Service. As a first step in the USA, the Regional Atmospheric Modeling
System (RAMS) at the Colorado State University has been coupled to the
A & K TopTask Competition (TTC) algorithm. The coupling was
accomplished following the Olofsson and Olsson lift-rate
procedures. The RAMS-TTC system was tested using 35 Colorado Soaring
Association On-line Contest flights. The flights occurred over 15 days
in 2004 and 2005 from Owl Canyon Gliderport (OCGP), Wellington CO. On
average, the RAMS-TTC system predicted a potential flight distance of
747 km while the actual flight distance was 289 km. The average
predicted task speed was 119 kph while the average actual speed was
104 kph. The average thermal top was predicted to be 4600 m MSL while
average achieved top was 4400 m MSL. These results demonstrate the
significant soaring conditions in northeast Colorado. Closer predicted
and actual task speeds are expected from the RAMS-TTC system using
results from a competition, as has been shown for Viking Glide 2005 by
Liechti using the TTC system in pc_met. Two competitions are planned
for OCGP, one in April 2006 and the other in May 2006. RAMS-TTC
results from these competitions will be presented at the Congress.
Back to Top of page
- O. Liechti:
Verification of thermal forecasts with glider flight data
- Post-processing of numerical weather prediction with a regional
convection model provides the meteorological information that is
crucial to soaring pilots: wind, lift rates, and climb
altitude. Regional forecasts are presented by showing the potential
flight distance for a standard class glider on a geographical map ? a
very intuitive form for pilots. Based on the regionalized forecasts
specific glider flight tasks can be planned and optimized by applying
a software tool named TopTask. The tool allows to specify the best
glide ratio and the corresponding glide speed of the glider to be used
- be it a paraglider or an open class sailplane. This flight planning
technique for gliding has been available for national and
international gliding championships such as Swiss Glide 2004 and
Viking Glide 2005. Task speeds obtained from to TopTask were compared
to scored speeds for these competitions. Recorded flights were
simulated with TopTask in order to compare the forecasted cloud base
altitude to the flight altitude and the task speeds of the flights to
the forecasts. Finally, flight plans based on different meteorological
models like LME-TOPTHERM and HIRLAM were compared to the scored
speeds. Results will be presented at the Congress. With the help of
TopTask recorded flights can be used to tune the forecasting
procedures for convective lift rates and for the depth of the
convective boundary layer. Operational numerical thermal forecasts
have reached a quality that is useful for soaring
practice. Self-briefing systems make these forecasts available and
provide the possibility of meteorological flight planning to the
gliding community.
Back to Top of page
- B. Olofsson:
Automatic Thermal Forecasts from the Swedish HIRLAM Model
- Thermal forecasts for glider pilots are produced automatically
from the operational NWP model in Sweden. Some extra algorithms are
used in the post-processing to calculate the thermal height and mean
rate of climb from the forecast vertical profile in every gridpoint.
Back to Top of page
- B. Sigrist:
Use of topographic radar scans to identify thermal hotspots in Alpine areas
- Thermals are part of the atmospheric energy flow caused by solar
irradiation. The question behind this project, called TherMap, has
been whether variations of the solar irradiance, caused by the local
topography, could be a valid predictor of thermals. Using digital
elevation data the local irradiance was therefore computed for each
mesh, date and time, and the results displayed on maps, leading to
first plausible results for the morning hours of mountain areas. In a
second step these models were refined to consider the thermal inertia
of the soil and the air, the different vegetation factors, as well as
the reflection of snow surfaces. For Alpine areas the resulting maps
turned out to show a high level of coincidence with superimposed
flighttracks. For topologically less differentiated regions, like the
Jura, the results were mixed. No conclusive results could be obtained
for topologically still smoother landscapes, where other factors are
likely to be predominant.
--> see Presentation (2.6 MByte)
Back to Top of page
- C. Lindemann: Convergences Mammatus
- Cloudstreets have been observed by satellite quite
often. Radiosoundings are evaluated for wind and temperature profiles
for these occasions. A first conclusion is that cloud streets must
form at a curved profile of Kuettners theory, but can form with
increasing wind velocity with hight also. Secondly convergence lines
over the central mountains of Spain are detected, which sometimes can
extend into the plain. Another interesting phenomena "mammatus
clouds" were observed and touched during a gliding flight over the
Andes.
Back to Top of page
Impressum / Imprint - Datenschutzerklärung / Privacy Policy