Niels Gylling Mortensen

Best Practices now available at http://www.risoe.dtu.dk/en/WAsP/Support/FAQ.aspx WAsP web site in general is now at http://www.risoe.dtu.dk/wasp.aspx

Link now changed to http://www.risoe.dtu.dk/en/WAsP/Support/FAQ.aspx WAsP web site in general is now at http://www.risoe.dtu.dk/wasp.aspx

Pages have been moved to http://www.risoe.dtu.dk/WAsP/Support/FAQ.aspx

Hmm, that depends on what you mean by "soon"... Much of the R&D that will go into WAsP 11 has been done already over the last couple of years, and it is being implemented now. According to our plans, WAsP 11 is still scheduled for 2011, but whether that will be the public release or it will reach some beta-version stage only, remains to be seen. A public release 3-5 months from now seems to be the most realistic estimate at the moment. We'll review the progress shortly and will try to update this estimate.

In an ideal world, the wind atlas shouldn't change the results, because it would then contain a very comprehensive and detailed description of the generalised wind climate that drives the predictions. However, with only 5 heights and 5 roughness classes, this is not so... It has always been the case that the wind atlas configuration should span and represent the conditions you want to model. So, the data and prediction sites should be within the ranges of height and roughness length in the atlas, and the configuration should be changed to best represent the modelling scenario. For years, most users didn't bother to change this, though. Recently, we have stressed this aspect of the modelling more, not least because modern wind turbines often have a hub height between the two standard heights of 50 and 100 m a.g.l. So, it's a known issue (it's not a bug) and we do recommend to change the configuration. In most cases, the changes in the results are quite small, on the order of one per cent. Do you see bigger changes? PS. This may well be changed in a future version of WAsP.

The 'XYZ format' is a bit confusing because the term is used for both vector and raster type data. WAsP and the Map Editor can only process vector data, so if your XYZ file contains raster (grid) roughness data, the procedure you use is not going to work. AFAIK, there is no standard procedure for transforming raster (grid) land cover data to WAsP roughness maps, though I have seen some 'experimental' solutions to this. For elevation data it's much simpler because tools for contouring are readily available (SAGA GIS, Surfer, ArcGIS, etc.)

Land cover (roughness length) maps are a little trickier to construct and often require some digitising by hand. Coastline contours may be constructed from the SWBD (SRTM Water Body Data) data set or using e.g. the Coastline Extractor (http://www.ngdc.noaa.gov/mgg/coast/); the Map Editor can import both formats. SWBD data also contains lakes and rivers. The land cover may be digitised from scanned, large-scale topographic map sheets, satellite imagery or aerial photographs. Some people use Google Earth directly for the digitising (Add | Path or Polygon) and convert the resulting KML file to MAP format. The roughness values have to be added manually afterwards. Remember that all maps and imagery correspond to a specific date; the land cover map should reflect the conditions you are modelling (say, use a historic map for the met. station site, recent Google Earth imagery for the wind farm site and so on). Lots of land cover data are available in raster format, but to my knowledge there is no standard procedure for transforming such data to WAsP vector maps. It is straightforward to import such data into GIS software, but it takes some analysis and GIS modelling to make a good roughness map in a format that can be used by WAsP. – Would be interesting to hear about experiences using raster land cover data!

Please note, that the WAsP Utility Programs have been discontinued now. The functionality has been (or will be) implemented in the latest (or future) versions of WAsP, the Map Editor and the Climate Analyst.

jfcorbett's post pretty much sums up what the WAsP team would recommend with respect to elevation maps, I guess. But I would like to add a few details: Digital elevation maps (contour lines or grids) may be quite expensive, so a combination of data is often the most cost-effective solution. Say, buy hi-res accurate contours for the wind farm site and its immediate surroundings, and use SRTM data for the terrain some distance away. SRTM data are usually a very good starting point, but beware of areas of 'white space' (no data) in some parts of the world. You can add detail (additional contours and spot heights) to an SRTM map from a commercial database or a large-scale topographical map (some hand-digitising required). For elevation maps, detail and accuracy are most important close to the wind turbine and met. station sites. SRTM data (the SWBD data set) can also give you the coastlines and lakes in an area, though it may take some editing to prepare these roughness change lines for WAsP. Digitising by hand is indeed a slow and tedious process, though there is also a 'zen' aspect to the process that some people like ;-) If you can get hold of the printed contours only (say, the contour layer in the traditional printing process), it is also possible to scan and vectorise the contours using a software tool.

You're welcome! The new database file will of course be included in the Map Editor and WAsP installation packages as soon as possible, but that may take a little while (for sure more than 22 hours ;-)

The GeoProjection database used by the Map Editor and Geo-projection tool has now been updated from version "10" to "11" to include the a) Argentinian projection (zone 1 .. 7), and b) the associated datums "Pampa del Castillo", POSGAR94 and POSGAR98. The update may be downloaded from the WAsP web site http://www.risoe.dtu.dk/WAsP/Download/Software/WAsP10_Installation.aspx. The ZIP file should simply be saved to the folder C:\Program Files (x86)\Wasp\Bin or similar.

A new installation file for the WAsP Map Editor has been uploaded to the WAsP web site; maybe this will solve the problem? Download it from http://www.risoe.dtu.dk/WAsP/Download/Software/WAsP10_Installation.aspx

The 'upper-air tab' is an old option that has been reactivated in the latest version of WAsP 10. It describes the statistics of the geostrophic wind and is the observed wind climate that can be obtained from analysis of radiosonde observations. This wind climate is not influenced by the details of the terrain surface in the same way as mast observations, and the data must be treated accordingly. The European Wind Atlas contains a number of upper-air stations lke this. When using an upper-air observed wind climate, the measurements height is specified as a non-numeric value such as '*'.

There is no way of specifying your own projection transformation parameters in the Map Editor or Geo-projection Utility tool. But we can add this projection type to the database used by these softwares. I believe this is being done now, so there will be an update to the programs in the near future. This will be published on the WAsP web site.

I always use three stations for the interpolation and have never experienced any 'funny looking' interpolated wind atlases. If you haven't already done so, I suggest you contact WAsP support directly at waspsupport@risoe.dtu.dk, including your data files. This seems to be a problem for the Lib Interpolator developer.

Hi Jose, Ok, it was a long shot, but I thought I'd give it a go. It seems to be a problem for the programming team; I'll let them know.

Haven't seen this error message before... but I wonder if it has to do with this: If WAsP does not find an elevation or roughness contour within 20 km of a site, it can come up with a error. This distance (calculation radius) is governed by one of the parameters in the projects "Edit project configuration…" menu. If you go to "Edit project configuration… / WAsP wind modeling / Max. interpolation radius in BZ model", you can change this radius to, say, 25,000 m or even more. Now your resource grid or wind farm will (hopefully) calculate. You could also make an elevation/roughness contour in the area where the problem is, e.g. around and close to the wind farm site. – This is what I do all the time: make a roughness / elevation line (with values 0, 0, 0) at the border of the offshore wind farm site.

Write an email to wasp@risoe.dtu.dk and ask for a student licence; they will know if and under what conditions such a licence is available.

There's a WAsP 10.1 release C now, see http://www.risoe.dtu.dk/WAsP/Download/Software/WAsP10_Installation.aspx. Could you possibly mail the entire error message to waspsupport@risoe.dtu.dk?

Check out the literature in general on the WAsP web site: http://www.risoe.dtu.dk/en/WAsP/Support/Literature.aspx. There are several papers and reports on complex terrain, RIX and dRIX.

The basics of using several anemometers and/or masts with WAsP has been discussed in another thread (http://www.wasptechnical.dk/forum/viewtopic.php?id=255). Interpolation, as in blending the results from several anemometers and/or masts, cannot be done with any presently available WAsP version. However, in addition to jfcorbett's post-processing way, there are a couple of other ways you can go: "No interpolation" way: reorganise the WAsP hierarchy, so each of your met. masts (i.e. "wind atlas / met. station / observed wind climate" branch) becomes a child of a wind farm or a turbine site group. In a big wind farm, one group of turbines can then be calculated using one mast, another group of turbines using a second mast, and so on. All the turbine site groups must be children of the same overall wind farm if you want to calculate the wake effects for all turbines. "Interpolation" way: In WAsP 10, there's a small tool, the "Lib interpolator”, which can interpolate between the generalised wind climates calculated at three masts. This is a 'mathematical' tool rather than a 'flow modelling' tool, and therefore must be used with the utmost care.

There' some help in this document http://www.wasp.dk/Support/DownloadFiles/A%20note%20on%20the%20use%20of%20SAGA%20GIS.pdf from the WAsP web site (http://www.wasp.dk/Support/FAQ.html)

1) No, WAsP doesn't use the KAMM or any other mesoscale model internally. WAsP's flow model and model for roughness changes are microscale and only take the terrain within ten's of km into consideration. 2) This projection may be used by mesoscale models that model much larger areas of the earth, but is not used by WAsP, which only models smaller areas. WAsP uses metric and Cartesian maps, usually of the UTM type or similar. 3) You can use the zone that covers most of your area and then refer all coordinates and map information to this zone. Then the map is metric and Cartesian as it should be. FYI, there are many mesoscale models around; WRF is one common example. To run such a model takes skilled staff and a fairly powerful cluster, so most WAsP users don't do this at all. What we do in the KAMM/WAsP methodology is to transform the mesoscale modelling results in each grid point into WAsP-compatible wind atlas data sets (*.lib files). These files can then be used to make predictions using WAsP.

1) This approach is correct in the sense that the predictor and predicted site(s) need not be in the same map (only within the same generalised or regional wind climate). So, you can have one map for the met. station (as a child of the wind atlas or met. station) and another map for the turbine sites (as a child of the project or wind farm). Two maps are allowed and even sometimes recommended, since the met. station map should reflect the measurement conditions (of the past) and the wind farm / resource grid map should reflect present and future conditions. With two maps you also have a dynamical wind atlas and don't need to worry about saving and inserting the wind atlas file. 2) with the two-map set-up described above, the delta RIX values are calculated immediately by WAsP. Remember, that the maps should be bigger than 5 by 5 square km; there should be at least about 10 km of map around each site (predictor or predicted) and even more when it comes to roughness, if large roughness changes occur at some distance.

Did you download and install the latest version of the Licence Manager software? Find it on the web page http://www.wasp.dk/Download/Software.html as [02.10.2009] WAsP Licencing System Standard 2.1.0.01 WaspLicencingSystemStandard2.1Build01.zip (7,228 KB) Also, make sure that you use the latest version of WAsP, see http://www.wasp.dk/Download/Software.html (WAsP 10) or http://www.wasp.dk/Download/Software/PreviousInstallations.html (WAsP 9.1 or 8.4)