www.Autodiff.org - Publication: MITgcm-AD v2: Open source tangent linear and adjoint modeling framework for the oceans and atmosphere enabled by the Automatic Differentiation tool Tapenade

MITgcm-AD v2: Open source tangent linear and adjoint modeling framework for the oceans and atmosphere enabled by the Automatic Differentiation tool Tapenade

- Article in a journal -

Area
Oceanography

Author(s)
Shreyas Sunil Gaikwad , Sri Hari Krishna Narayanan , Laurent Hascoët , Jean-Michel Campin , Helen Pillar , An Nguyen , Jan Hückelheim , Paul Hovland , Patrick Heimbach

Published in
Future Generation Computer Systems

Year
2025

Abstract
The Massachusetts Institute of Technology General Circulation Model (MITgcm) is widely used by the climate science community to simulate planetary atmosphere and ocean circulations. A defining feature of the MITgcm is that it has been developed to be compatible with an algorithmic differentiation (ad) tool, TAF, enabling the generation of tangent-linear and adjoint models. These provide gradient information which enables dynamics-based sensitivity and attribution studies, state and parameter estimation, and rigorous uncertainty quantification. Importantly, gradient information is essential for computing comprehensive sensitivities and performing efficient large-scale data assimilation, ensuring that observations collected from satellites and in-situ measuring instruments can be effectively used to optimize a large uncertain control space. As a result, the MITgcm forms the dynamical core of a key data assimilation product employed by the physical oceanography research community: Estimating the Circulation and Climate of the Ocean (ECCO) state estimate. Although MITgcm and ECCO are used extensively within the research community, the ad tool TAF is proprietary and hence inaccessible to a large proportion of these users. The new version 2 (MITgcm-ad v2) framework introduced here is based on the source-to-source ad tool TAPENADE, which has recently been open-sourced. Another feature of TAPENADE is that it stores required variables by default (instead of recomputing them) which simplifies the implementation of efficient, ad-compatible code. The framework has been integrated with the MITgcm model’s main branch and is now freely available.

AD Tools
TAPENADE

AD Theory and Techniques
Adjoint

BibTeX
@ARTICLE{
         Gaikwad2025MAv,
       author = "Shreyas Sunil Gaikwad and Sri Hari Krishna Narayanan and Laurent
         Hasco\"{e}t and Jean-Michel Campin and Helen Pillar and An Nguyen and Jan
         H{\"u}ckelheim and Paul Hovland and Patrick Heimbach",
       title = "{MITgcm-AD} v2: Open source tangent linear and adjoint modeling framework for the
         oceans and atmosphere enabled by the {A}utomatic {D}ifferentiation tool {T}apenade",
       journal = "Future Generation Computer Systems",
       volume = "163",
       pages = "107512",
       year = "2025",
       issn = "0167-739X",
       doi = "10.1016/j.future.2024.107512",
       url = "https://www.sciencedirect.com/science/article/pii/S0167739X2400476X",
       keywords = "Automatic Differentiation, Differentiable programming, Adjoints, Ocean modeling,
         Data assimilation, Climate science, MITgcm, Tapenade",
       abstract = "The Massachusetts Institute of Technology General Circulation Model (MITgcm) is
         widely used by the climate science community to simulate planetary atmosphere and ocean
         circulations. A defining feature of the MITgcm is that it has been developed to be compatible with
         an algorithmic differentiation (AD) tool, TAF, enabling the generation of tangent-linear and adjoint
         models. These provide gradient information which enables dynamics-based sensitivity and attribution
         studies, state and parameter estimation, and rigorous uncertainty quantification. Importantly,
         gradient information is essential for computing comprehensive sensitivities and performing efficient
         large-scale data assimilation, ensuring that observations collected from satellites and in-situ
         measuring instruments can be effectively used to optimize a large uncertain control space. As a
         result, the MITgcm forms the dynamical core of a key data assimilation product employed by the
         physical oceanography research community: Estimating the Circulation and Climate of the Ocean (ECCO)
         state estimate. Although MITgcm and ECCO are used extensively within the research community, the AD
         tool TAF is proprietary and hence inaccessible to a large proportion of these users. The new version
         2 (MITgcm-AD v2) framework introduced here is based on the source-to-source AD tool Tapenade, which
         has recently been open-sourced. Another feature of Tapenade is that it stores required variables by
         default (instead of recomputing them) which simplifies the implementation of efficient,
         AD-compatible code. The framework has been integrated with the MITgcm model’s main branch and
         is now freely available.",
       ad_tools = "TAPENADE",
       ad_area = "Oceanography",
       ad_theotech = "Adjoint"
}

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