Description Usage Arguments Details Value References Examples
Calculate folded aspect, heatload, and potential direct incident radiation (PDIR) of a slope based on topographic measures.
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asp |
vector of aspect, in degrees 0-360 |
... |
further arguments passed to other methods |
lat |
vector of latitude, in degrees 0-90 |
slo |
vector of slope, in degrees 0-60 |
lognat |
logical, should result be on natural log scale? |
digits |
default=3, integer number of digits for rounding |
Aspect units are degrees. Follows pg. 605 of McCune and Keon (2002).
Heatload is unitless. Follows Equation 2 of McCune and Keon (2002).
PDIR units are MJ cm-2 yr-1. Follows Equation 2 of McCune and Keon (2002).
Vector of values based on topographic attributes.
McCune, B., and D. Keon. 2002. Equations for potential annual direct incident radiation and heat load. Journal of Vegetation Science 13:603-606.
McCune, B. 2007. Improved estimates of incident radiation and heat load using nonparametric regression against topographic variables. Journal of Vegetation Science 18:751-754.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 | # simple example:
lats <- c(41.2, 44.7, 45.8)
slopes <- c(10, 0.1, 34)
aspects <- c(12, 146, 240)
foldasp(aspects)
htld(lats, slopes, aspects, lognat=FALSE)
pdir(lats, slopes, aspects, lognat=FALSE)
# from Table 2 in McCune & Keon (2002):
htld(lat=40, slo=30, asp=0, lognat=TRUE)
htld(lat=40, slo=30, asp=180, lognat=TRUE)
htld(lat=40, slo=0, asp=0, lognat=TRUE)
# from Table 2 in McCune & Keon (2002):
pdir(lat=40, slo=30, asp=0, lognat=TRUE) # expect -0.889
pdir(lat=40, slo=30, asp=180, lognat=TRUE) # expect -0.005
pdir(lat=40, slo=0, asp=0, lognat=TRUE) # expect -0.202
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