The National Center for Atmospheric Research (NCAR) Community Earth System Model Large Ensemble (CESM LENS) dataset includes a 40-member ensemble of climate simulations for the period 1920-2100. All model runs were subject to the same radiative forcing scenario: historical up to 2005, and RCP8.5 thereafter. (RCP8.5 - Representative Concentration Pathway 8.5 - refers to the worst-case scenario considered in the Fifth Assessment Report of the Intergovernmental Panel on Climate Change - IPCC). Each of the 40 runs begins from a slightly different initial atmospheric state (created by randomly perturbing temperatures at the level of round-off error). The data comprise both surface (2D) and volumetric (3D) variables in the atmosphere, ocean, land, and ice domains.
The total LENS data volume is ~500 TB, and is traditionally accessible through the NCAR Climate Data Gateway (CDG) for download or via web services. A subset (currently ~70 TB compressed) including the most useful variables is now freely available on S3 thanks to the AWS Public Dataset Program.
Slides from an informational briefing about this dataset are available at 20200212.CESM_LENS.AWStelecon.pdf.
S3 bucket: ncar-cesm-lens in us-west-2 region
Amazon Resource Name arn:aws:s3:::ncar-cesm-lens
Bucket contents list: https://ncar-cesm-lens.s3.amazonaws.com/
The intent is for users to compute directly on the data in AWS rather than downloading from S3 (traditional download is available from the NCAR CDG link above).
A Jupyter Notebook illustrating how to read the LENS data on AWS, and reproducing Figures 2 and 4 from Kay et al. (2015), has been developed. This Notebook and other resources on GitHub will be gradually improved and augmented.
Zarr format: The LENS data on AWS are structured according to the Zarr storage format. There are independent Zarr stores for each
component, frequency, experiment, and variable. The naming convention is:
The table below shows the available Zarr stores, including the experiments, variables, time ranges, and 2D or 3D nature (3D means multiple atmosphere levels or ocean depths are present). See also Collection Description and Catalog File used by Intake-esm.
|atm/monthly/CESM-LE-*||20C, RCP85, HIST, CTRL, CTRL_SLAB, CTRL_AMIP||2D: FLNS, FLNSC, FLUT, FSNS, FSNSC, FSNTOA, ICEFRAC, LHFLX, PRECC, PRECL, PRECSC, PRECSL, PSL, SHFLX, TMQ, TREFHT, TREFHTMN, TREFHTMX, TS 3D: T, U, V, Q, Z3||1920-01 (20C)
|lnd/monthly/CESM-LE-*||20C, RCP85||FSNO, H2OSNO, QRUNOFF, RAIN, SNOW, SOILLIQ, SOILWATER_10CM||2D|
|ocn/monthly/CESM-LE-*||20C, RCP85, CTRL||2D: SSH, SST 3D: SALT||2D, 3D|
|ice_nh/monthly/CESM-LE-*, ice_sh/monthly/CESM-LE-*||20C, RCP85, CTRL||aice, hi||2D|
|atm/daily/CESM-LE-*||20C, RCP85||FLNS, FLNSC, FLUT, FSNS, FSNSC, FSNTOA, ICEFRAC, LHFLX, PRECL, PRECSC, PRECSL, PRECT, PRECTMX, PSL, Q850, SHFLX, TMQ, TREFHT, TREFHTMN, TREFHTMX, TS, UBOT, WSPDSRFAV, Z500||1920-01-01 (20C)
|lnd/daily/CESM-LE-*||20C, RCP85||FSNO, H2OSNO, QRUNOFF, RAIN, SNOW, SOILWATER_10CM||2D|
|ice_nh/daily/CESM-LE-*, ice_sh/daily/CESM-LE-*||20C, RCP85||aice_d, hi_d||2D|
|atm/hourly6-1990-2005/CESM-LE-*||20C||2D: PRECT, PS, PSL, QREFHT, TREFHT, TS 3D: T, U, V, Q, Z3||1990-01-01T00 (20C)||2005-12-31T18 (20C)||2D, 3D|
|atm/hourly6-2026-2035/CESM-LE-*||RCP85||2D: PRECT, PS, PSL, QREFHT, TREFHT, TS 3D: T, U, V, Q, Z3||2026-01-01T00 (RCP8.5)||2035-12-31T18 (RCP8.5)||2D, 3D|
|atm/hourly6-2071-2080/CESM-LE-*||RCP85||2D: PRECT, PS, PSL, QREFHT, TREFHT, TS 3D: T, U, V, Q, Z3||2071-01-01T00 (RCP8.5)||2080-12-31T18 (RCP8.5)||2D, 3D|
|FLNS||Net longwave flux at surface|
|FLNSC||Clearsky net longwave flux at surface|
|FLUT||Upwelling longwave flux at top of model|
|FSNS||Net solar flux at surface|
|FSNSC||Clearsky net solar flux at surface|
|FSNTOA||Net solar flux at top of atmosphere|
|ICEFRAC||Fraction of sfc area covered by sea-ice|
|LHFLX||Surface latent heat flux|
|PRECC||Convective precipitation rate (liq + ice)|
|PRECL||Large-scale (stable) precipitation rate (liq + ice)|
|PRECSC||Convective snow rate (water equivalent)|
|PRECSL||Large-scale (stable) snow rate (water equivalent)|
|PRECT||Total (convective and large-scale) precipitation rate (liq + ice)|
|PRECTMX||Maximum (convective and large-scale) precipitation rate (liq+ice)|
|PSL||Sea level pressure|
|Q||3D Specific humidity|
|Q850||Specific Humidity at 850 mbar pressure surface|
|QREFHT||Reference height humidity|
|SHFLX||Surface sensible heat flux|
|TMQ||Total (vertically integrated) precipitable water|
|TREFHT||Reference height temperature|
|TREFHTMN||Minimum reference height temperature over output period|
|TREFHTMX||Maximum reference height temperature over output period|
|TS||Surface temperature (radiative)|
|U||3D Zonal wind|
|UBOT||Lowest model level zonal wind|
|V||3D Meridional wind|
|WSPDSRFAV||Horizontal total wind speed average at the surface|
|Z3||3D Geopotential Height (above sea level)|
|Z500||Geopotential Z at 500 mbar pressure surface|
|FSNO||fraction of ground covered by snow|
|H2OSNO||snow depth (liquid water)|
|QRUNOFF||total liquid runoff (does not include QSNWCPICE)|
|SOILLIQ||soil liquid water (vegetated land units only)|
|SOILWATER_10CM||soil liquid water + ice in top 10cm of soil (veg land units only)|
|SSH||Sea Surface Height|
|Ice Variables (Note: northern and southern hemisphere grids are stored separately as ice_nh and ice_sh)|
|aice||ice area (aggregate)|
|aice_d||ice area (aggregate)|
|hi||grid cellmean ice thickness|
|hi_d||grid cellmean ice thickness|
Users should consult the list of known issues in the CESM LENS dataset.
We also urge users to watch the CESM LENS GitHub repo for additions or changes to data and tools, and to notify cesm-lens-aws at ucar.edu if you are using these data so that we can justify continued maintenance on S3. All LENS model runs have been completed, so we do not expect to add data on an ongoing basis, but may be able to include additional fields upon request.
Last update of this page: 2020 Feb 12.