Information for depthcalc.m and depthcalcET.m (version 201912) calculating 10Be and 26Al depth
profile exposure ages. The calculator is fixed by Jakob Heyman (jakob.heyman@gu.se) 2015-2019 mainly
based on the CRONUS calculator (Balco et al. 2008) and the LSD production rate scaling (Lifton et
al. 2014).

depthcalc.m:
Depth profile calculator for calculating the best-fit 10Be and/or 26Al exposure age.

depthcalcET.m
Depth profile calculator for calculating the best-fit 10Be and/or 26Al erosion rate / exposure age
chi-square domain for a range of defined erosion rates and exposure durations.


TO USE THE CALCULATORS (depthcalc.m / depthcalcET.m):
1. Fix the input.txt file (see below).
2. Run depthcalc.m / depthcalcET.m in Octave or Matlab.
3. Best-fit exposure ages and plots (if on) are displayed.


General information for both calculators:
* Nuclide-specific LSD spallation and muon production rate scaling based on simulated cosmic ray
  fluxes (Lifton et al. 2014) similar to the other expage calculators.
* Time-dependent spallation production rate with reference production rates based on global average
  from calibration studies published 2009-2019 calibrated using prodrate.m.
* Time-constant muon production rate parameterization (modified to reduce near-surface artifacts),
  including depth dependence for samples with an assumed erosion rate, based on Antarctica depth
  profile data (Borchers et al. 2016; Marrero et al. 2016; Phillips et al. 2016; Balco 2017) with
  fstar and sigma0 calibrated using muclib.m.
* Adjustment of the time-dependent production rate to the year of sampling (assuming a constant
  production since 2010).
* Atmospheric pressure based on sample elevation and ERA-40 re-analysis dataset ('std'), Antarctica
  best-fit interpolation ('ant') (Balco et al. 2008), or given directly ('pre') in hPa.
* Attenuation length for calculating the spallation production rate adjustments for sample thickness
  and erosion rate interpolated from atmospheric pressure and cutoff rigidity (Marrero et al. 2016).

depthcalc.m:
* Depth profile exposure age estimated with error minimization of simulated and measured sample
  concentrations (10Be and/or 26Al) using relative concentration uncertainties as weights. Standard
  chi-square minimization (with absolute concentration uncertainties as weights) can be used by
  setting absunc = 1 in line 19.
* Internal uncertainty based on best-fit individual sample exposure ages and uncertainties (weighted
  average). Reference production rate uncertainty added in quadrature to derive external
  uncertainty.

depthcalcET.m:
* Calculation of 10Be and/or 26Al concentration reduced chi-square values for a mesh of erosion
  rates and exposure ages defined by Emin-Emax and Tmin-Tmax (number of grid points defined by
  ETgrid at line 23).
* Spline interpolation of the chi-square matrix (to 1000 x 1000 points) to smooth the surface,
  identification of the minimum chi-square value and associated E and T, and plotting of that best-
  fit point plus contours for the minimum reduced chi-square value plus the values in vector cl
  (line 312).


INPUT INSTRUCTIONS:
The input is given in the file input.txt and the format can be one of two options. For both options
the data for each sample is specified in one row (rows can be commented out with '%').

Option 1:
Similar input as for the CRONUS calcuator version 2 (Balco et al. 2008) with the addition of
sampling year. The input should contain 15 columns with the following information:
1. Sample name - (strange characters may cause problems).
2. Latitude [DD (WGS84)] - North latitudes are positive. South latitudes are negative.
3. Longitude [DD (WGS84)] - East longitudes are positive. West longitudes are negative.
4. Elevation/pressure [m a.s.l. / hPa].
5. Elevation/pressure flag - std/ant/pre (ERA40 elev interpol/Antarctica elev/atmospheric pressure).
6. Sample thickness [cm].
7. Sample density [g/cm3].
8. Correction factor - Unitless factor used for topo/geom shielding correction (no shielding -> 1).
9. Erosion rate [mm/ka]. NOTE: different unit than in the CRONUS calculator.
10. 10Be concentration [atoms/g] - (if no 10Be measurement: use 0).
11. 10Be concentration uncertainty [atoms/g] - (if no 10Be measurement: use 0).
12. 10Be standardization - See make_consts_expage.m lines 34-38 for acceptable names and values.
13. 26Al concentration [atoms/g] - (if no 26Al measurement: use 0).
14. 26Al concentration uncertainty [atoms/g] - (if no 26Al measurement: use 0).
15. 26Al standardization - See make_consts_expage.m lines 41-42 for acceptable names and values.
16. Sampling year [CE].

Option 2:
Data in columns with row 1 specifying the data of each columns. The following specifiers are
allowed (the order of the data/columns is irrelevant):
sample - Sample name - (strange characters may cause problems).
lat - Latitude [DD (WGS84)] - North latitudes are positive. South latitudes are negative.
long - Longitude [DD (WGS84)] - East longitudes are positive. West longitudes are negative.
elv - Elevation/pressure [m a.s.l. / hPa].
Pflag - Elevation/pressure flag - std/ant/pre (see above). If not specified std will be used.
thick - Sample thickness [cm].
dens - Sample density [g/cm3].
shield - Correction factor - Unitless factor used for topo/geom shielding correction.
erosion - Erosion rate [mm/ka]. If not specified a zero erosion rate is assumed.
N10 - 10Be concentration [atoms/g].
N10unc - 10Be concentration uncertainty [atoms/g].
std10 - 10Be standardization - See make_consts_expage.m lines 34-38 for acceptable names and values.
N26 - 26Al concentration [atoms/g].
N26unc - 26Al concentration uncertainty [atoms/g].
std26 - 26Al standardization - See make_consts_expage.m lines 41-42 for acceptable names and values.
samplingyr - Sampling year [CE].
pressure - Atmospheric pressure [hPa] - If pressure is included, data in elv is not used.

Only in depthcalcET.m (rows 16-23) =================================================================
Tmin - Minimum exposure age to test (yr before sampling).
Tmax - Maximum exposure age to test (yr before sampling).
Emin - Minimum erosion rate to test (mm/ka).
Emax - Maximum erosion rate to test (mm/ka).
ETgrid - Number of E and T points to make an ET mesh for testing the fit to measured concentrations.
====================================================================================================


OUTPUT depthcalc.m:
The calculator displays the best-fit exposure age (internal uncertainty in parenthesis), reduced
chi-square value, and associated P-value. If plotting is on, a pĺot with individual sample
concentrations (red points) and best-fit depth profile concentration (black line) is displayed for
the 10Be and/or 26Al data. No output file is saved.

OUTPUT depthcalcET.m:
The calculator displays the range of exposure duration (T-range) and erosion (E-range), the best-fit
erosion (E), exposure age (T), reduced chi-square value (Rchi2), and associated P-value for the 10Be
and/or 26Al data. A plot with the best-fit E and T value (point) and contour lines for the minimum
reduced chi-square value plus [0.05 0.5 1.0 2.0] (defined by cl at line 312) is displayed for the
10Be and/or 26Al data. No output file is saved.
