Computes caloric summer insolation for a given astronomical configuration and
latitude.
Usage
calins (orbit,lat=65*pi/180,...)
Arguments
orbit
Output from a solution, such as ber78, ber90 or la04
lat
latitude
...
Other arguments passed to Insol
Details
The caloric summer is a notion introduced by M. Milankovitch. It is defined
as the halve of the tropical year
during for which daily mean insolation are greater than all days of the other halves.
The algorithm is an original algorithm by M. Crucifix, but consistent with
earlier definitions and algorithms by A. Berger (see examples). Do not confuse
this Berger (1978) reference with the Berger (1978), J. Atm. Sci. of the
astronomical solution.
Value
Time-integrated insolation in kJ/m2 during the caloric summer.
Author(s)
Michel Crucifix, U. catholique de Louvain, Belgium.
References
Berger (1978) Long-term variations of caloric insolation resulting from the earth's orbital elements, Quaternary Research, 9, 139 - 167.
Examples
## reproduces Table 2 of Berger 1978
lat <- seq(90, 0, -10) * pi/180. ## angles in radiants.
orbit_1 = ber78(0)
orbit_2 = orbit_1
orbit_2 ['eps'] = orbit_2['eps'] + 1*pi/180.
T <- sapply(lat, function(x) c(lat = x * 180/pi,
calins(orbit_2, lat=x, S0=1365) / (4.18 * 1e1)
- calins(orbit_1, lat=x, S0=1365) / (4.18 * 1e1) ) )
data.frame(t(T))
# there are still some differences, of the order of 0.3 %, that are probably related to
# the slightly different methods.
# 41.8 is the factor from cal/cm2 to kJ/m2