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:
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 94556 yjhuang@xxxxxxxxxxxxxxxxxxxxxxxx http://weather.whiteboxtechnologies.com for simulation-ready weather data (o) (925)388-0265 (c) (510)928-2683 "building energy simulations at your fingertips"
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 94556 yjhuang@xxxxxxxxxxxxxxxxxxxxxxxx http://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 AijaziPhD Student, Building Science and Sustainability(m) 703-508-6535 | (e) arfa@xxxxxxxxxxxx
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