| Summary: | ### Overview This dataset contains the Arctic Subpolar gyre sTate Estimate, Release 1 (ASTE\_R1) (Nguyen et al., JAMES, 2021), a medium-resolution data-constrained ocean-sea ice model-data synthesis spanning the period 2002-2017. This product was achieved through adjoint-based nonlinear least-squares optimization, whereby the misfit of the model to an extensive (O(10^9)) set of satellite and in situ observations was iteratively minimized. ASTE\_R1 is unique in its dynamical and kinematic consistency, which distinguishes the state estimate from existing ocean reanalyses. Through strict adherence to conservation laws, all sources and sinks within ASTE\_R1 can be accounted for, permitting meaningful analysis of closed budgets, such as contributions of horizontal and vertical convergence to the tendencies of heat and salt. The primary product consists of monthly means of state variables, as well as monthly mean and snapshot fields required for accurate budget calculations. ### Access Data files can be accessed via: [https://arcticdata.io/data/10.18739/A2CV4BS5K](https://arcticdata.io/data/10.18739/A2CV4BS5K) ### Structure The dataset contains top level directories for the following: **nctiles\_monthly/ and nctiles\_monthly\_snapshots/ - Time varying fields as monthly averages and monthly snapshots** These directories contain contains all monthly mean fields (nctiles\_monthly) and monthly snapshots (nctiles\_monthly\_snapshots). Each subdirectory inside these folders contains NetCDF files for each model variable, as indicated by the name of the subdirectory. Inside each variable folder, there are 29 files covering the 29 tiles that comprise the entire ASTE geographical domain. The tile number, ranging from 0001 to 0029, is accessible from the file name (e.g., inside ETAN/ there are ETAN.0001.nc to ETAN.0029.nc). Each file contains all 192 records of monthly output, spanning Jan/2002-Dec/2017. See Sections 4.4-4.5 in the ASTE\_R1 User Guide for descriptions of the model output fields. **nctiles\_monthly\_integrated/ and nctiles\_monthly\_snapshots\_integrated/ - Depth-integrated time varying fields as monthly averages and monthly snapshots** These directories contain 2D depth-integrated time varying fields as monthly averages (nctiles\_monthly\_integrated) and monthly snapshots (nctiles\_monthly\_snapshots\_integrated). Each subdirectory inside these folders contains NetCDF files for each model variable, as indicated by the name of the subdirectory. Inside each variable folder, there are 29 files covering the 29 tiles that comprise the entire ASTE geographical domain. The tile number, ranging from 0001 to 0029, is accessible from the file name (e.g., inside SALT/ there are SALT.0001.nc to SALT.0029.nc). Each file contains all 192 records of monthly output, spanning Jan/2002-Dec/2017. See Section 4.6 in the ASTE\_R1 User Guide for descriptions of the model output fields. **nctiles\_daily/ - Selected time varying state variables as daily averages** This dataset contains selected time varying 2D and 3D fields as daily averages (nctiles\_daily). Each subdirectory inside these folders contains NetCDF files for each model variable, as indicated by the name of the subdirectory. Inside each variable folder, there are 29 files covering the 29 tiles that comprise the entire ASTE geographical domain. The tile number, ranging from 0001 to 0029, is accessible from the file name (e.g., inside SALT/ there are SALT.0001.nc to SALT.0029.nc). Each file contains all 5844 records of daily output, spanning Jan/2002-Dec/2017. See Section 4.7 in the ASTE\_R1 User Guide for descriptions of the model output fields. **nctiles\_climatology/ - 12-month climatological averages** This directory contains the 12-month climatological fields (nctiles\_climatology). Each subdirectory inside these folders contains NetCDF files for each model variable, as indicated by the name of the subdirectory. Inside each variable folder, there are 29 files covering the 29 tiles that comprise the entire ASTE geographical domain. The tile number, ranging from 0001 to 0029, is accessible from the file name (e.g., inside SALT/ there are SALT.0001.nc to SALT.0029.nc). Each file contains 12 records of corresponding to the twelve calendar months. The year range used to create the climatology is 2002-2017. See Section 4.8 the ASTE\_R1 User Guide for descriptions of the model output fields. **profiles/ - Vertical profiles of in-situ measurements and model-equivalent** This directory contains the model equivalent of vertical profiles of in situ data in NetCDF format. The model fields are sampled on the fly during model integration at the time and location of the in situ data to generate the model equivalent. See Section 4.9 in the ASTE\_R1 User Guide for more details. **nctiles\_grid/ - ASTE\_R1 grid files** This dataset contains the model grid (nctiles\_grid), User Guide, sample figures and sample matlab scripts to help analyze the model output fields. The ASTE domain is split into 29 regional tiles, with each variable saved in 29 separate files in NetCDF format (GRID.0001.nc to GRID.0029.nc) in the directory nctiles\_grid. See Sections 4.1-4.2, 5, and 6 in the ASTE\_R1 User Guide for more details. **docs/ - documentation** **matlab\_tools/ - MATLAB toolbox to help analyze the output fields** **rerun\_ASTE\_R1/ - Compile-time and run-time parameter files necessary to reproduce ASTE\_R1 with the MITgcm** This directory contains all files in raw binary formats and instruction for how to download the atmospheric forcing that are needed to reproduce ASTE\_R1. See Sections 4.10-4.11 in the ASTE\_R1 User Guide for more details.
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