Where can I get quality weather files for the Southern Hemisphere?

weather-file

asked 2014-10-20 13:00:51 -0600

MikeBarker
81 ●4

updated 2017-05-29 17:41:37 -0600

__AmirRoth__

4436 ●5 ●17 http://bleedinggreenna...

Some of the automatically assembled weather files have weird data - where can I get good quality weather files for my hemisphere, especially Africa ?

Update:

My observation is based on a file I bought a few years ago - our attention was drawn to a high and constant level of snow over a city in South Africa. On further inspection we found :

Horizontal Infrared Radiation from Sky is a constant
All of the illuminance and luminance values are a constant
Sky cover values are also a constant
Precipitable water is a constant and also unrealistic.
Aerosol Optical Depth is a constant
Snow Depth is a constant and also unrealistic

BTW - this was not a DoE file - but a commercial file. More recently we have had good value from WhiteBox Technologies.

But that was just one file. My concern is that many Simulationists use these files in good faith but there does not seem to be a universal quality control method. Perhaps it's time we devise a ISO Standard ?

Also, any simulation should use a number of files - ASHRAE should demand not one result, but multiple results for different weather scenario - a typical scenario, and a few un-typical scenarios ? I quite like the idea of using a TMY file as a start, but then using say an artificial hot year and then a cold year ( or some combination of the extremes )

Does this make sense ?

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@MikeBarker. Typical? Specific year?

__AmirRoth__ ( 2014-10-20 13:17:39 -0600 )edit

@MikeBarker what are you seeing that is problematic with the South African weather data posted on the EnergyPlus website?

Neal Kruis ( 2014-10-21 10:06:32 -0600 )edit

@MikeBarker I took your recent post and appended it to your original question, since it was more of a clarification than an answer itself.

Neal Kruis ( 2014-11-23 10:01:12 -0600 )edit

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answered 2014-10-23 18:19:41 -0600

DancingDavidE

580 ●6 http://www.linkedin.co...

If you have found a particular issue, please let the group know. Sometimes these are traceable and correctable.

Weather files posted alongside modeling programs will have originated more or less from reputable sources although certainly there might be an error here or there due to faulty processing, missing data, or irregularity in the original source.

A couple of paid services are:

http://weather.whiteboxtechnologies.com/

http://www.weatheranalytics.com/get-w...

As far as Africa in particular, I can't say if these sources are better than others, or if the availability in general is going to be good. I can imagine that there might be difficulty with microclimate where the available sources are far apart if your modeled building is located somewhere between.

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answered 2014-10-24 19:01:48 -0600

Joe Huang
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updated 2014-10-28 13:27:04 -0600

The availablity of weather data for different parts of the world can vary tremendously, based largely on the activity of the local Meteorological Bureaus. The "automatically assembled weather files" to which Mike refers are not observed data, but generated by computer modeling, either reanalysis of weather forecasting programs or statistical procedures. Although much has been promised, these methods need more third-party scrutiny, especially comparison to observations. The few reports that I have seen have shown very mixed results.

I continue to follow developments in this area, but for now I'm still staying with measured weather data, which has gotten much more accessible over the past decade. In particular, the US National Climatic Data Center has made available data from close to 10,000 weather stations around the world going back to 1980. Data availability for locations in the Southern Hemisphere varies a lot country to country, but it's not as grim as you might think.

I've culled through the NCDC data, and was able to produce historical weather files for 97 locations in South Africa, 19 in Tanzania, 39 in Zimbabwe, 20 in Botswana, 27 in Zambia, etc. The numbers of IWEC2 "typical year" weather files for the same countries are quite a bit lower (17, 1, 7, 0, 0, respectively),which reflects when the IWEC2s were created (2008-2010) and the high criteria for data completeness. A complete list of all available locations in WMO1 (Africa) is available here.

Perhaps the biggest challenge with developing weather files for Subsaharan Africa is the poor quality of the Cloud Cover reports needed to estimate solar radiation. I've found stations in Nigeria and Cameroon where the CC was unchanged for months on end. This problem can actual ly be solved by using satellite data, which I understand is freely available from the Europeans as a way to promote solar energy, but only to researchers in Africa. If there are people in Africa interested to pursue this avenue, I would be happy to help in whatever way I can.

(Joe Huang is the president of White Box Technologies, which is a commercial provider of weather data for use in building energy simulations. WBT was the contractor to ASHRAE in developing the 3,012 IWEC2 weather files for international locations)