2023.04.24 Mon

Release of JAXA-RIKEN Ocean Analysis through JAXA’s P-Tree System

Japan Aerospace Exploration Agency (JAXA) and RIKEN have conducted joint research to create an ensemble ocean analysis product called LETKF-based Ocean Research Analysis (LORA) and released it through the following website:

JAXA-RIKEN Ocean Analysis

JAXA and RIKEN aim to unify satellite data and ocean simulation and create an ensemble ocean analysis product, LORA, by assimilating satellite and in-situ observations from JAXA and various institutions at a 1-day interval in a high-resolution regional ocean data assimilation system, sbPOM-LETKF*, developed by RIKEN. LORA has the advantages of 1) being a three-dimensional gridded dataset without missing values, 2) having high accuracy especially in the mid-latitude regions, and 3) quantifying uncertainty. The uncertainty is estimated from the standard deviation of 128 ensemble members (i.e., ensemble spread). In addition to the daily averaged ensemble mean and spread of basic variables, LORA provides daily-averaged all ensemble members at the sea surface and ensemble mean of each term in mixed-layer temperature and salinity budget equations, respectively, to be utilized for boundary conditions in atmospheric models and for quantitative analyses of spatiotemporal variations in sea surface temperatures and salinity.

* Data assimilation system consisting of a regional ocean model, sbPOM, and an ensemble Kalman filter, LETKF (Ohishi et al. 2022a, b, 2023)

Duration August 1, 2015 ~
*LORA will be updated one month behind real time.
Area Western North Pacific(108°E-180°、12°N-50°N)
Maritime Continent(95°E-136°E、18°S-30°N)
Temporal resolution 1 day
Spatial resolution About 10 km (0.1 degree), 50 σ-layers
Data – Daily averaged ensemble mean and spread (2D-variable×1, 3D-variables×5): Sea surface height, temperature, salinity, and zonal, meridional, and vertical velocities
– Daily averaged all sea surface ensemble (2D-128 ensemble variables×5): Sea surface height, temperature, salinity, and zonal and meridional velocities
– Ensemble mean of each term in the daily averaged mixed layer temperature and salinity budget equations and of the daily averaged related variables (2D-variables×41)

* See details in User Guide.

NetCDF files of LORA can be downloaded through the P-Tree website after user registration.