Changes

===Thornthwaite Mather method===

===Thornthwaite Mather method===

The Thornthwaite Mather method of calculating water balance<ref>Thornthwaite, C. W., and Mather, J. R., Instructions and Tables for Computing Potential Evapotranspiration and the Water Balance, Drexel Institute of Technology, Laboratory of Climatology, 1957.{{#l:Thornthwaite1957.pdf}}</ref> is recommended within the [https://www.ontario.ca/document/stormwater-management-planning-and-design-manual 2003 Ontario Stormwater Management Planning and Design Manual]. The original paper (linked below) provides the required calculations as a series of lookup tables. The following equations are derived from these, and are widely documented elsewhere e.g.<ref>Sellinger,C.E. Computer Program for Estimating Evapotranspiration using the Thornthwaite Method NOAA Technical Memorandum ERL GLERL-101, Great Lakes Environmental Research Laboratory 1996 [https://www.glerl.noaa.gov/pubs/tech_reports/glerl-101/tm-101.pdf] Accessed 8 Jan 2018 </ref>.  

The Thornthwaite Mather method of calculating water balance<ref>Thornthwaite, C. W., and Mather, J. R., Instructions and Tables for Computing Potential Evapotranspiration and the Water Balance, Drexel Institute of Technology, Laboratory of Climatology, 1957.{{#l:Thornthwaite1957.pdf}}</ref> is recommended within the [https://www.ontario.ca/document/stormwater-management-planning-and-design-manual 2003 Ontario Stormwater Management Planning and Design Manual]. The original paper (linked below) provides the required calculations as a series of lookup tables. The following equations are derived from these, and are widely documented elsewhere<ref>Sellinger,C.E. Computer Program for Estimating Evapotranspiration using the Thornthwaite Method NOAA Technical Memorandum ERL GLERL-101, Great Lakes Environmental Research Laboratory 1996 [https://www.glerl.noaa.gov/pubs/tech_reports/glerl-101/tm-101.pdf] Accessed 8 Jan 2018 </ref>.  

We are in the process of writing an xls tool to semi-automate these; please feel free request a draft copy, or to contribute your own [[How to contribute]].  

 

We are in the process of writing a tool to semi-automate these; please feel free request a draft copy, or to contribute your own [[How to contribute]].  

'''Step 1.''' Calculate the monthly heat index (''i''):

'''Step 1.''' Calculate the monthly heat index (''i''):