eprintid: 1436748 rev_number: 35 eprint_status: archive userid: 608 dir: disk0/01/43/67/48 datestamp: 2014-08-06 11:17:41 lastmod: 2021-12-13 02:24:10 status_changed: 2014-08-29 15:20:44 type: article metadata_visibility: show item_issues_count: 0 creators_name: Haines, PE creators_name: Esler, JG creators_name: Carver, GD title: Technical Note: Adjoint formulation of the TOMCAT atmospheric transport scheme in the Eulerian backtracking framework (RETRO-TOM) ispublished: pub divisions: UCL divisions: B04 divisions: C06 divisions: F59 note: © Author(s) 2014. This work is distributed under the Creative Commons Attribution 3.0 License. http://creativecommons.org/licenses/by/3.0/ abstract: A new methodology for the formulation of an adjoint to the transport component of the chemistry transport model TOMCAT is described and implemented in a new model, RETRO-TOM. The Eulerian backtracking method is used, allowing the forward advection scheme (Prather's second-order moments) to be efficiently exploited in the backward adjoint calculations. Prather's scheme is shown to be time symmetric, suggesting the possibility of high accuracy. To attain this accuracy, however, it is necessary to make a careful treatment of the "density inconsistency" problem inherent to offline transport models. The results are verified using a series of test experiments. These demonstrate the high accuracy of RETRO-TOM when compared with direct forward sensitivity calculations, at least for problems in which flux limiters in the advection scheme are not required. RETRO-TOM therefore combines the flexibility and stability of a "finite difference of adjoint" formulation with the accuracy of an "adjoint of finite difference" formulation. date: 2014 official_url: http://dx.doi.org/10.5194/acp-14-5477-2014 vfaculties: VMPS oa_status: green full_text_type: pub language: eng primo: open primo_central: open_green verified: verified_manual elements_source: WoS-Lite elements_id: 966846 doi: 10.5194/acp-14-5477-2014 lyricists_name: Esler, James lyricists_id: JGESL00 full_text_status: public publication: Atmospheric Chemistry and Physics volume: 14 number: 11 pagerange: 5477 - 5493 issn: 1680-7316 citation: Haines, PE; Esler, JG; Carver, GD; (2014) Technical Note: Adjoint formulation of the TOMCAT atmospheric transport scheme in the Eulerian backtracking framework (RETRO-TOM). Atmospheric Chemistry and Physics , 14 (11) 5477 - 5493. 10.5194/acp-14-5477-2014 <https://doi.org/10.5194/acp-14-5477-2014>. Green open access document_url: https://discovery.ucl.ac.uk/id/eprint/1436748/1/acp-14-5477-2014.pdf