{"id":128,"date":"2026-04-10T02:53:10","date_gmt":"2026-04-10T02:53:10","guid":{"rendered":"https:\/\/books.gw-project.org\/age-dating-young-groundwater\/chapter\/ch049-xhtml\/"},"modified":"2026-05-11T22:27:30","modified_gmt":"2026-05-11T22:27:30","slug":"6-5-sensitivity-of-age-to-input-parameters","status":"publish","type":"chapter","link":"https:\/\/books.gw-project.org\/age-dating-young-groundwater\/chapter\/6-5-sensitivity-of-age-to-input-parameters\/","title":{"raw":"6.5 Sensitivity of Age to Input Parameters","rendered":"6.5 Sensitivity of Age to Input Parameters"},"content":{"raw":"
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\r\n\r\nThe procedure outlined in the previous section for calculating a tracer age from a measured concentration of CFCs involves numerous parameters (recharge temperature, salinity, elevation) that are uncertain to some degree. In this section, we summarize the sensitivity of the computed age to uncertainty in recharge temperature and elevation.\r\n\r\n<\/div>\r\n
\r\n\r\nFigure 27<\/span><\/a> shows the relationship between the CFC tracer age and various input parameters for a water sample having aqueous concentrations of 1.5, 0.7, and 0.1\u00a0pmole\/kg for CFC\u201111, CFC\u201112, and CFC\u2011113 respectively. The sample was assumed to have been collected in the year 2015, and the age was calculated as 2015 minus the computed recharge year. The recharge temperature and recharge elevation were varied to illustrate the sensitivity of the computed age to these parameters.\r\n\r\n<\/div>\r\n
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\r\n\r\n<\/span>Figure 27\u00a0\u2011<\/strong>\u00a0Sensitivity of CFC tracer ages to input parameters. The tracer age of a hypothetical sample having CFC concentrations of 1.5, 0.7, and 0.1\u00a0pmole\/kg for CFC\u201111, CFC\u201112, and CFC\u2011113, respectively, were computed for various values of recharge temperature and recharge elevation as indicated. The sensitivities\u2014change in age per change in parameter\u2014are shown in red.\r\n\r\n<\/div><\/blockquote>\r\n<\/div>\r\n
\r\n\r\nThe sensitivity of the tracer age to recharge temperature is about \u2212 <\/em>0.52\u00a0year\/\u00b0C for recharge temperatures ranging from 0 to 40\u00a0\u00b0C. In other words, if the assumed recharge temperature was 1\u00a0\u00b0C warmer than the true value, the tracer age would be 0.5\u00a0years younger than the true age. The sensitivity to recharge elevation is about \u2212 <\/em>0.15\u00a0year\/100\u00a0m, so using a recharge elevation that is 100\u00a0m greater than the true elevation results in an age that is 0.15\u00a0years younger. The relationship is not smooth because of an artifact of the numerical simulation that uses annual average atmospheric concentrations instead of continuous values.\r\n\r\n<\/div>\r\n<\/div>","rendered":"
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The procedure outlined in the previous section for calculating a tracer age from a measured concentration of CFCs involves numerous parameters (recharge temperature, salinity, elevation) that are uncertain to some degree. In this section, we summarize the sensitivity of the computed age to uncertainty in recharge temperature and elevation.<\/p>\n<\/div>\n

\n

Figure 27<\/span><\/a> shows the relationship between the CFC tracer age and various input parameters for a water sample having aqueous concentrations of 1.5, 0.7, and 0.1\u00a0pmole\/kg for CFC\u201111, CFC\u201112, and CFC\u2011113 respectively. The sample was assumed to have been collected in the year 2015, and the age was calculated as 2015 minus the computed recharge year. The recharge temperature and recharge elevation were varied to illustrate the sensitivity of the computed age to these parameters.<\/p>\n<\/div>\n

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<\/span>Figure 27\u00a0\u2011<\/strong>\u00a0Sensitivity of CFC tracer ages to input parameters. The tracer age of a hypothetical sample having CFC concentrations of 1.5, 0.7, and 0.1\u00a0pmole\/kg for CFC\u201111, CFC\u201112, and CFC\u2011113, respectively, were computed for various values of recharge temperature and recharge elevation as indicated. The sensitivities\u2014change in age per change in parameter\u2014are shown in red.<\/p>\n<\/div>\n<\/blockquote>\n<\/div>\n

\n

The sensitivity of the tracer age to recharge temperature is about \u2212 <\/em>0.52\u00a0year\/\u00b0C for recharge temperatures ranging from 0 to 40\u00a0\u00b0C. In other words, if the assumed recharge temperature was 1\u00a0\u00b0C warmer than the true value, the tracer age would be 0.5\u00a0years younger than the true age. The sensitivity to recharge elevation is about \u2212 <\/em>0.15\u00a0year\/100\u00a0m, so using a recharge elevation that is 100\u00a0m greater than the true elevation results in an age that is 0.15\u00a0years younger. The relationship is not smooth because of an artifact of the numerical simulation that uses annual average atmospheric concentrations instead of continuous values.<\/p>\n<\/div>\n<\/div>\n","protected":false},"author":7,"menu_order":33,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-128","chapter","type-chapter","status-publish","hentry"],"part":35,"_links":{"self":[{"href":"https:\/\/books.gw-project.org\/age-dating-young-groundwater\/wp-json\/pressbooks\/v2\/chapters\/128","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/books.gw-project.org\/age-dating-young-groundwater\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/books.gw-project.org\/age-dating-young-groundwater\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/books.gw-project.org\/age-dating-young-groundwater\/wp-json\/wp\/v2\/users\/7"}],"version-history":[{"count":3,"href":"https:\/\/books.gw-project.org\/age-dating-young-groundwater\/wp-json\/pressbooks\/v2\/chapters\/128\/revisions"}],"predecessor-version":[{"id":420,"href":"https:\/\/books.gw-project.org\/age-dating-young-groundwater\/wp-json\/pressbooks\/v2\/chapters\/128\/revisions\/420"}],"part":[{"href":"https:\/\/books.gw-project.org\/age-dating-young-groundwater\/wp-json\/pressbooks\/v2\/parts\/35"}],"metadata":[{"href":"https:\/\/books.gw-project.org\/age-dating-young-groundwater\/wp-json\/pressbooks\/v2\/chapters\/128\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/books.gw-project.org\/age-dating-young-groundwater\/wp-json\/wp\/v2\/media?parent=128"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/books.gw-project.org\/age-dating-young-groundwater\/wp-json\/pressbooks\/v2\/chapter-type?post=128"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/books.gw-project.org\/age-dating-young-groundwater\/wp-json\/wp\/v2\/contributor?post=128"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/books.gw-project.org\/age-dating-young-groundwater\/wp-json\/wp\/v2\/license?post=128"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}