CHRONO SHCal20 Database

About the SHCAL database

It is visualized that if you are interested in climate modelling you will use the cooked datasets. If you are interested in modelling calibration curve construction you will use the raw datasets. See below for how the cooked data is derived from the raw data.

Historically, the Quaternary Isotope Laboratory in Seattle kept data for different trees in different MS Excel sheets, and these are denoted by divisions in this database. In general, divisions in the tree ring data refer to organization put in place by the laboratory.

This paragraph explains the difference between the raw and cooked data tables. When database maintenance occurs it is generally done in the raw table. The cooked data table is then updated from the raw table with the following commands:

cooked.c14age=raw.c14age + reservoirage;
cooked.c14sig=sqrt(pow(raw.c14sig*c14mulsig,2) + pow(c14addsig,2) + pow(reservoirsig,2));
cooked.calsig=sqrt(pow(calsigI,2) + pow(calsigD,2) + pow(calsigC,2));

The calage refers to the midpoint of a calendar time interval of width calspan. To obtain the starting point of the time interval instead of the midpoint, use a query like:

select calage-(calspan-1)/2,calspan,c14age,c14sig from raw