Description Usage Arguments Value Note Author(s) References See Also Examples
View source: R/F_shape_calibration.R
Calibrates the shape of the night interpolating curve, either horizontalaxe parabola or line, by changing the exponent z (see reference). It functions according to the comparison of the daily thermal range and the climate (reference) monthly one.
1 2 3 4 5  shape_calibration(meas, date.format = "ymd",
cal_times_list, band_min = 0:23, band_max = 0:23,
ratio_dtr_range = c(0, 6), nr_cycles = 10,
min_mo.length = 21, full.24.hrs.span_min = TRUE,
silent = FALSE)

meas 
measured hourly values file (table), where the first column is the series' ID 
date.format 
input date format (formats for
function 
cal_times_list 
calibration list of "time"
parameters (output of 
band_min 
band of hours of occurrence of day
minimum in the daily series (continuous). See

band_max 
same for maximum time 
ratio_dtr_range 
range for seeking the optimal
value of 
nr_cycles 
number of calibration trials within the calibration ranges (all) 
min_mo.length 
minimum number of days to calculate
any monthly values of dtr (is passed to function

full.24.hrs.span_min 
logical, if set to

silent 
logical, if set to 
A list containing the optimum values of ratio_dtr
meas
must be organized as 4field records, all
series in the same file, no headers. Column order:
station ID, date, time (hour), T, [others fields, if
any...] separated by spaces. This field order is
mandatory.
Default date format is "ymd" (yyyy/mm/dd). Different
combinations can be passed to function with
date.format
, but separator must be "/"
band_min
and band_max
are the time bands
according to which the minimum and maximum temperature
were calculated in the daily series to be interpolated.
In general, they range from 0 to 23, unless the series
has had some restriction in the calculation of minimum
and maximum values. Hence, these bands can be different
from those used to calibrate the most frequent occurrence
of min and max.
The optimal value of ratio_dtr
(k
, eq. 7,
in the quoted reference Eccel (2010a)) is chosen as the
one with the (absolute) minimum value of the bias
(irrespective of its sign). ratio_dtr
is the ratio
between the daily thermal range of the day to be
interpolated and the mean monthly value for that series.
The corresponding values of mean absolute error and RMSE
can be checked in the resulting list.
min_mo.length
(passed to function
Mo.Th.Ra.
) refers to the sum of days along all the
series for each specific month, not for any single month
in one year.
full.24.hrs.span_min
is TRUE
as default. If
must be set to FALSE
only if minimum values of the
daily series have been calculated on a restricted time
band, which is included in band_min
(see function
par_calibration
). If this is the case, the minimum
of the interpolated curve will always fall within
band_min
(early hours of the day). If this option
is erroneously chosen, errors as large as 0.6 deg C can
arise in the average of mean daily T.
Emanuele Eccel, Emanuele Cordano emanuele.eccel@iasma.it
Eccel, E., 2010: What we can ask to hourly temperature recording. Part II: hourly interpolation of temperatures for climatology and modelling. Italian Journal of Agrometeorology XV(2):4550 http://www.agrometeorologia.it/documenti/Rivista2010_2/AIAM%2022010_pag45.pdf,www.agrometeorologia.it
Original algorithm from: Cesaraccio, C., Spano, D., Duce, P., Snyder, R.L., 2001. An improved model for determining degreeday values from daily temperature data. Int. J. Biometeorol. 45: 161169. http://www.springerlink.com/content/qwctkmlq3tebthek/
See also: Eccel, E., 2010: What we can ask to hourly temperature recording. Part I: statistical vs. meteorological meaning of minimum temperature. Italian Journal of Agrometeorology XV(2):4143. http://www.agrometeorologia.it/documenti/Rivista2010_2/AIAM%2022010_pag41.pdf,www.agrometeorologia.it
1 2 3 4 5 6 7 8 9  library(Interpol.T)
data(Trentino_hourly_T)
stations < c("T0001","T0010","T0129")
calibration_shape < shape_calibration(meas = h_d_t[h_d_t$V1 %in% stations,],
cal_times_list = calibration_l[stations],
band_min = 0:23, band_max = 0:23, ratio_dtr_range = c(0,4),
min_mo.length=21)

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