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Sushban

Hydrometeorolgy Data for Long Term Simulation in GSSHA

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For long term simulation in GSSHA, where can we download direct and global radiation? I downloaded other hydrometeorology parameters (Pressure, Sky Cover, Wind Speed and Temperature) from NCDC website (http://gis.ncdc.noaa.gov/map/viewer/#app=cdo).

Relative Humidity was estimated based on dew point and average temperature using this formula:

RH: =100*(EXP((17.625*TD)/(243.04+TD))/EXP((17.625*T)/(243.04+T)))

Is there any other recommended method for Relative Humidity estimation?

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Sushban,

If solar radiation data values are not available at your meteorological station, you can either find data for the closest station or let GSSHA approximate the amount of solar radiation based on the location of the watershed, day of the year, and time of day. See the following pages on gsshawiki.com for more information:

http://gsshawiki.com/Continuous:Hydrometeorological_Data

http://gsshawiki.com/Long-term_Simulations:Hydrometeorological_data

Alternatively, you could try to find solar radiation data for the closest station with radiation data and then use the data from that station, as long as it's not too far away. Here's a web site I found that has a repository of sites with historical solar radiation data:

http://www.nrel.gov/rredc/solar_data.html

Most meteorological sites record the relative humidity with the temperature and other information. You should be able to get the humidity from the NCDC. If you cannot get the humidity, the above equation should work as long as you have a good reference for this equation.

Chris

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I would like to understand how GSSHA deals with missing data in HMET file in case of a long term simulation. Also, is there a possibility to use daily data instead of hourly data ? What is the loss in accuracy expected while using daily HMET data?

Thank you

Fadoua

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Fadoua,

I don't think there is an option to use daily data instead of hourly data. The time series editor, included with WMS, includes tools that should help you create the required hourly HMET data, interpolate between data values, and format your HMET data. Some values, such as temperature and humidity, fluctuate during the day and you need to include this fluctuation in your HMET data.

A good overview of the data that's required in an HMET file and how missing data is handled is located on the gsshawiki here:

http://gsshawiki.com/Long-term_Simulations:Hydrometeorological_data

Regards,

Chris

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