Last Millennium Reanalysis (LMR) Seasonal: A Millennium of Climate Data

LMR Seasonal Reanalysis Dataset

Attention:

This repo only contains ensemble mean, if you need ensemble members, please go to 

• Dataset portal: https://atmos.uw.edu/~zilumeng/LMR_Seasonal/

Description:
The Last Millennium Reanalysis (LMR) Seasonal dataset provides a global, seasonal-resolution reconstruction of climate variability over the past 1200 years (800–2000 CE). It is generated using a coupled, “online” data assimilation framework that integrates forecasts from a fully coupled ocean–atmosphere–sea-ice Linear Inverse Model (LIM) with a comprehensive network of paleoclimate proxy records. The resulting reanalysis offers a physically consistent, high-skill reconstruction of past climate dynamics across multiple Earth system components.

Key Features:

• Seasonal Resolution: Four seasons per year, capturing the evolution of climate phenomena such as El Niño events and orbitally forced temperature changes.

• Coupled Data Assimilation: Combines model forecasts and proxy observations through a Kalman filter approach for dynamically consistent reconstructions.

• Comprehensive Variables: Includes atmosphere (surface air temperature), ocean (sea surface temperature, ocean heat content), and sea ice (concentration and thickness).

• Millennium-Scale Coverage: 800–2000 CE, providing 1200+ years of global climate variability.

• High Fidelity: Validated against independent instrumental and proxy data, demonstrating robust performance across the reconstruction period.

Dataset Information:

• Temporal coverage: 800–2000 CE

• Temporal resolution: Seasonal

• Spatial resolution: 2° × 2° global grid (90 × 180)

• Ensemble size: 800 members

• Data volume: ~2 TB total (ensemble mean available here due to size limits)

Structure:

      Ensemble-Mean Gridded Fields (mean/) — Seasonal averages for key variables (tas, tos, sic, sit, ohc300). 
     This repo only contains ensemble mean, if you need ensemble members, please go to https://atmos.uw.edu/~zilumeng/LMR_Seasonal/

Access and Code:

• Dataset portal: https://atmos.uw.edu/~zilumeng/LMR_Seasonal/

• Code repository: https://github.com/ZiluM/LMR_Seasonal

Citation:
Meng, Z., G. J. Hakim, and E. J. Steig, 2025: Coupled Seasonal Data Assimilation of Sea Ice, Ocean, and Atmospheric Dynamics over the Last Millennium. Journal of Climate, https://doi.org/10.1175/JCLI-D-25-0048.1

License:
Creative Commons Attribution 4.0 International (CC BY 4.0)

Contact:

• Zilu Meng — zilumeng@uw.edu (https://zilum.github.io)
  Department of Atmospheric Sciences, University of Washington

• Gregory Hakim — ghakim@uw.edu
  Department of Atmospheric Sciences, University of Washington