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Fix the derivatives of the density of supersaturated moist air - #4836
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rho_pTX_der did not match rho_pTX for supersaturated moist air, where it was off by up to 60 % in the temperature direction: - The dry air density derivative was evaluated at the total pressure and its derivative, instead of the partial pressure of the dry air. - Below 273.16 K, the vapor density was missing from the gas density, and its derivative was instead added to the derivative of the specific volume. - xws_pT_der lacked the term for the pressure derivative of the saturation humidity ratio. The derivatives now agree with finite differences of rho_pTX. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
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hubertus65
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rho_pTX_derdid not matchrho_pTXfor supersaturated moist air, where it was off by up to 60 % in the temperature direction:xws_pT_derlacked the term for the pressure derivative of the saturation humidity ratio.The derivatives now agree with finite differences of
rho_pTX.@MatthiasBSchaefer: Note that unlike many other recently opened PRs addressing unit inconsistencies, this PR changes values. It makes it a good test case for CI testing of a PR, and if needed we should also re-generate reference results to avoid that tests break when this is merged.