Soaring Forecast Science
The science behind XC Skies is based in merging the best of modern forecast model output data with parameterization schemes that attempt to say something in more detail for a given region based on using the large scale atmospheric variables.
Saying it another way, XC Skies tries to 'solve / guess' the best soaring potential solution to a problem that involves the following:
- Known atmospheric variables from the large scale model runs (GFS,RUC,NAM,etc).
- Known sun angles for the exact location and time of day.
- Quantified vegetation types for each given square km on the planet and their affiliated heat capacity constants for the season.
- Known 1km and 90m elevation for any region on the planet and how this impacts parameterizing small scale variations from the large scale data.
- And of course everything in between getting this to work.
Alternative ways to arrive at soaring forecasts is to run a fully functional mesoscale numerical weather prediction
system such as the WFR
) from NOAA and NCAR research efforts. This model is a state-of-the-art system designed to be flexible enough for many types of forecasting needs. These models can be computationally intensive for fine grid scales, even in relatively small domains. Without a doubt, this is a better way to truly and fully solve the nonhydrostatic dynamics and surface physics to produce a more accurate forecast in a time-step method which considers small scale terrain features. However, this approach cannot be used to provide highly detailed forecasts at a global level due to the compute resources needed. A distributed compute system would need to be established to fascilitate such a large endeavor for global coverage. The RASP
soaring forecast program created by Dr. Jack is the most prominent effort of these which is gaining popularity among Unix savvy pilots who have resources available to setup 'compute nodes' for regions frequently flown. This is really cool stuff, but it's not for the average PG and HG pilot, although some cross-over is slowly happeneing. Tech-minded sailplane pilots are exploiting this free resource as best they can.
Hence, XC Skies is attempting to parameterize small scale soaring potential based on the large scale output from coarser model runs, such as the GFS 0.5 degree model run.
This includes a 'best of' suite of code that allows for parameterization of variables that relate to soaring potentials, where we leave some of the unnecessary output parameters alone. Plus, we can use any language that provides the best results for the given type of computation necessary. Python and IDL are being used right now due to their good ability of parallel computing, but if something else comes along that offers better performance, that will be used. Several C routines are used for some of the heavy lifting.
Some specific approaches to traditional and non-traditional algorithms are used. An overview can be found here