[Bldg-sim] Simulation or historic weather files for Northern Pakistan

Mon Mar 4 11:55:47 PST 2019

Joe, thank you very much this effort and the detailed explanation!

*Arfa Aijazi*
PhD Student, Building Science and Sustainability
Center for the Built Environment <http://cbe.berkeley.edu/> | Architecture
<https://ced.berkeley.edu/academics/architecture/> | UC Berkeley
<http://www.berkeley.edu/>
(m) 703-508-6535 | (e) arfa at berkeley.edu

On Mon, Mar 4, 2019 at 6:15 AM Joe Huang via Bldg-sim <
bldg-sim at lists.onebuilding.org> wrote:

> After a number of hours I've created a "typical year" weather file for
> Skardu using the data source that I describe below, along with some
> tweaking, or bias correction if I want to sound technical, using climatic
> information from Wikipedia.
>
> The file is available for free at this link on my company server:
>
>
> http://weather.whiteboxtechnologies.com/custom-np-link-download?F1=7806138414*PAK_SKARDU_415170_35.25-75.65mod_TYP.zip
>
> For those interested, I like to explain the technique I used that I had
> thought about for more than a year, but never actually tried out until now,
> with results that I'm very pleased to see, although those who are more
> critical might say that there's no hard evidence like actual measurements,
> but then that's a circular argument because this technique is being used
> only in cases when there's no measured data!
>
> The two sources I'm using are (1) satellite-derived solar radiation, and
> (2) meteorological reanalysis data.  The first is pretty self-explanatory,
> but the second needs a bit of explanation. Reanalysis is using massive
> climate forecasting models in a retrospective mode after the time is past
> and all the observational data have been incorporated.  There are several
> of these reanalysis efforts around the world, whose outputs cover the
> entire globe at a half-degree grid and span a time period going back a
> couple of decades. Look up reanalysis on the Web if you want more
> information.
>
> While the information is public, both of these types of data can be
> difficult to access, especially reanalysis, but in this case the location
> in Pakistan is covered by NREL's National Solar Radiation Database (NSRDB)
> courtesy of a India - US solar project that ended 5 years ago.  Since I use
> the NSRDB quite extensively, I've already downloaded  both the satellite
> solar and MERRA reanalysis data (NREL puts them together on the same file)
> for Skardu for 2000-2014. There are no issues with the satellite-derived
> solar, but the MERRA reanalysis data can be quite different from measured
> data, and particularly off for locations in India and Pakistan.  Therefore,
> I've been hesitant in using it verbatim, but found it helpful to fill data
> gaps once the data has been correlated with some type of "ground truth".
>
> In this case, the only measured data, a few months in Skardu in 2011, was
> also found to be very poor and unreliable.  Turning to the Wikipedia, I
> found the following summary climatic table for Skardu:
>
> I then calculated the same monthly statistics from 15 years of the MERRA
> reanalysis data, and found that monthly temperatures were about 12 C too
> cold, although the daily range (difference between the daily max and min)
> seemed quite similar.
>
> The average monthly relative humidity at 5 pm were also quite different
> except during July and August.
>
> What I then did was to adjust the dry bulb temperatures by calculating a
> difference in the mean daily average per month, and  a percent different in
> the mean daily range by month, and then used these to adjust or bias
> correct the MERRA data,  producing this plot for all 15 years of data:
>
> Adjustment for the humidity must be done after the dry-bulb temperatures,
> since relative humidities are dependent on the air temperature.  The other
> complication is that since the raw weather file contains only dewpoint
> temperatures,  a trial and error process with the dewpoint temperature had
> to be done.  After three iterations, the humidities also match quite
> closely.
>
> SInce the NREL files were given for India time, another small routine was
> used to shift up the data by two hours, which also brought the solar
> radiation in line with the calculated sun angles.
>
> The last step was to create a typical year weather file from these 15
> years of weather data. That was quite quick because I have all the software
> in house.
>
> A final look at the "typical year" file showed that it all looked
> reasonable.  There's no real way to say how good is this file, but the
> solar should be quite reliable, and the monthly statistics are almost
> exactly the same as those from the Pakistan Met Office.
>
> Joe
>
> Joe Huang
> White Box Technologies, Inc.
> 346 Rheem Blvd., Suite 205A
> Moraga CA 94556yjhuang at whiteboxtechnologies.comhttp://weather.whiteboxtechnologies.com for simulation-ready weather data
> (o) (925)388-0265
> (c) (510)928-2683
> "building energy simulations at your fingertips"
>
> On 3/1/2019 1:08 PM, Joe Huang via Bldg-sim wrote:
>
> As you probably realize, this is an  area of the world with almost no
> observed weather data.  The only remotely usable data I have from the ISD
> (Integrated Surface Hourly Database)  are nine months of data (April -
> October) 2011 in Skardu. However, there are satellite-derived solar
> radiation and computer-modeled weather conditions from the MERRA-1 Climate
> Forecast Model for anywhere in South Asia from 2000 through 2014 available
> as part of NREL's National Solar Radiation Database on line at
> https://nsrdb.nrel.gov/nsrdb-viewer .  Unless you want to spend several
> weeks doing so, I would not suggest that you delve into either data
> sources, nor would I recommend using the modeled weather data from MERRA-1,
> which I have found can be wildly off, especially in South Asia locations.
>
> Since I've already got the data for Skardu for both data sets, I can see
> if I can use the partial 2011 data for Skardu to bias correct the MERRA-1
> data,   which would then get you a weather file for 2011.  I'm not
> promising anything though, as I've got a lot of others things to do as well.
>
> Joe
>
> Joe Huang
> White Box Technologies, Inc.
> 346 Rheem Blvd., Suite 205A
> Moraga CA 94556yjhuang at whiteboxtechnologies.comhttp://weather.whiteboxtechnologies.com for simulation-ready weather data
> (o) (925)388-0265
> (c) (510)928-2683
> "building energy simulations at your fingertips"
>
> On 3/1/2019 11:35 AM, Arfa Aijazi via Bldg-sim wrote:
>
> Hi everyone,
>
> I'm working on a project to design affordable housing and temporary
> shelters for refugees and disaster recovery in Pakistan. One of our target
> areas is the remote northern areas of the country, called Hunza Valley.
> Some larger cities here include Gilgit and Skardu. The nearest weather
> files available from EnergyPlus are 200-300 miles away. The Hunza Valley
> region is mountainous, so given the influence of altitude and microclimate
> effects I'd like to at least find historical weather data  to validate
> simulation weather file selection.
>
> Let me know if you have any thoughts on where I can get weather data. It's
> a student project, so we don't have budget to purchase weather files from a
> commercial service.
>
> Best,
> Arfa
>
> *Arfa Aijazi*
> PhD Student, Building Science and Sustainability
> Center for the Built Environment <http://cbe.berkeley.edu/> | Architecture
> <https://ced.berkeley.edu/academics/architecture/> | UC Berkeley
> <http://www.berkeley.edu/>
> (m) 703-508-6535 | (e) arfa at berkeley.edu
>
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