Caloric insolation

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Description

Computes caloric summer insolation for a given astronomical configuration and latitude.

Usage

1
 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

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## 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