topographic: Topographic measures

Description Usage Arguments Details Value References Examples

Description

Calculate folded aspect, heatload, and potential direct incident radiation (PDIR) of a slope based on topographic measures.

Usage

1
2
3
4
5
foldasp(asp = 0, ...)

htld(lat = 0, slo = 0, asp = 0, lognat = FALSE, digits = 3, ...)

pdir(lat = 0, slo = 0, asp = 0, lognat = FALSE, digits = 3, ...)

Arguments

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

Details

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).

Value

Vector of values based on topographic attributes.

References

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.

Examples

 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

phytomosaic/ecole documentation built on Jan. 2, 2022, 11:24 p.m.