Canadian Forest Service Publications

A high-resolution reanalysis of global fire weather from 1979 to 2018 – overwintering the Drought Code. 2020. McElhinny, M.; Beckers, J.F.; Hanes, C.; Flannigan, M.; Jain, P. Earth System Science Data 12(3):1823-1833.

Year: 2020

Issued by: Northern Forestry Centre

Catalog ID: 40800

Language: English

Availability: PDF (download)

Available from the Journal's Web site.
DOI: 10.5194/essd-12-1823-2020

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We present a global high-resolution calculation of the Canadian Fire Weather Index (FWI) System Indices using surface meteorology from the ERA5-HRS reanalysis for 1979-2018. ERA5-HRS represents an improved dataset compared to several other reanalyses in terms of accuracy, as well as spatial and temporal coverage. The FWI calculation is performed using two different procedures for setting the start-up value of the Drought Code (DC) at the beginning of the fire season. The first procedure, which accounts for the effects of inter-seasonal drought, overwinters 20 the DC by adjusting the fall DC value with a fraction of accumulated overwinter precipitation. The second procedure sets the DC to its default start-up value (i.e. 15) at the start of each fire season. We validate the FWI values over Canada using station observations from Environment and Climate Change Canada and find generally good agreement (mean Spearman correlation of 0.77). We also show that significant differences in early season DC and FWI values can occur when the FWI System calculation is started using the overwintered versus default DC values, as is 25 highlighted by an example from 2016 over North America. The FWI System moisture codes and fire behavior indices are made available for both versions of the calculation at (McElhinny et al., 2020), although we recommend using codes and indices calculated with the overwintered DC, unless specific research requirements dictate otherwise.