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Progress Towards a Pan-CMIP OSSE Capability for CLARREO

Explore international collaborations, NRC White Paper insights, and developments in the pan-spectral OSSE capability for climate models. Detailed progress report and first-phase model overview included.

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Progress Towards a Pan-CMIP OSSE Capability for CLARREO

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  1. Progress Towards a Pan-CMIP OSSE Capability for CLARREO Daniel Feldman1 Bill Collins1,2, Chaincy Kuo1, Bruce Wielicki3, Yolanda Roberts3, Constantine Lukashin3December 2, 2015 CLARREO Fall Science Team Meeting 1 Lawrence Berkeley National Laboratory, Earth Sciences Division 2 University of California-Berkeley, Department of Earth & Planetary Science 3 NASA Langley Research Center

  2. Outline • Strengthening of International Collaborations. • Recent research highlight. • NRC Decadal Survey White Paper Summary. • Overview and goals of a pan CMIP OSSE capability. • Pan CMIP OSSE development update. • First phase models. • The aerosol challenge. • Summary. • Discussion.

  3. International Collaborations • Building off PNAS (LBNL), GRL (Umich), and JC (Umich) papers on science value of surface emissivity measurements, collaboration with UK partners strengthened through NERC proposal. • Investigation will analyze CIRCCREX data over Greenland and the Denmark Strait and retrieve far-IR surface emissivity over ice-sheet and ocean. • Compare with calculations in emissivity database. • Investigation will quantify ice-emissivity feedback within models. • Preliminary diagnosis using kernel techniques for CESM1.2 is +0.07 W/m2/K (~1/3 ice albedo feedback), but is state-dependent. • Investigation will improve understanding of the controls on the polar radiative energy budget.

  4. Highlight: Pan-Spectral OSSEs • Summary of simulations of both the shortwave reflectance and longwave radiance clear-sky and all-sky CLARREO (OSSE), indicating the complementarity of the signals. Globally-averaged shortwave and longwave clear- and all-sky spectra from the CLARREO OSSE. Globally-averaged shortwave and longwave clear- and all-sky spectral trends from the CLARREO OSSE. Feldman, D.R., W.D. Collins, J.L. Paige (2014) Pan-Spectral Observing System Simulation Experiments of Shortwave Reflectance and Longwave Radiance for Climate Model Evaluation, Geoscientific Model Development, 8, 1943-1954, doi: 10.5194/gmd-8-1943-2015.

  5. Highlight continued … • We compare averages of random sampling of OSSE grid-cells vs calculations based on all grid cells. • Sampling results indicate that acceptable radiometric error is incurred with 1000x fewer calculations are needed for global 10-year averages, 60x fewer calculations for regional averages. Globally-averaged shortwave and longwave clear- and all-sky spectra from the CLARREO OSSE. Globally-averaged shortwave and longwave clear- and all-sky spectral trends from the CLARREO OSSE. Feldman, D.R., W.D. Collins, J.L. Paige (2014) Pan-Spectral Observing System Simulation Experiments of Shortwave Reflectance and Longwave Radiance for Climate Model Evaluation, Geoscientific Model Development, 8, 1943-1954, doi: 10.5194/gmd-8-1943-2015.

  6. NRC White Paper Summary • Born out of ongoing conversation with Bruce, Yolanda, Costy and others, and the CFMIP meeting in June, 2015. • White Paper Submitted November 2, 2015. • Co-authors William Collins, Bruce Wielicki, Jonathan Jiang (JPL), Isaac Moradi (UMD), Nikki Prive (GSFC). • Summarized the informal state of OSSEs for mission design and implementation. • Recommendations: • Formal, independent, and intramural OSSE capability for NASA. • Encouragement of participation from modelers: • Scientifically: Use OSSEs to explore hypothesis testing. • Financially: Provide resources for modelers to participate in OSSEs.

  7. Pan CMIP5 OSSE Capability • At Spring CLARREO meeting, Berkeley group received guidance to focus on development of a pan CMIP5 OSSE capability in support of CLARREO. • Berkeley group will build off current OSSE, develop model-agnostic OSSE capability for SW reflectance and LW radiance for CMIP5 and CMIP6 models. • Goals: • Determine relationship between model ECS and pan-spectral trends. • Establish pan-spectral variability across a broad range of climate models, with an eye towards observational constraint. • Support Decadal Survey 2017-2027 discussion.

  8. Progress Report • First Phase Models Overview. • Data Acquisition. • Boundary Conditions. • Vertical Interpolation. • Benchmark Testing • Execution on NAS facilities.

  9. First Phase Models • Model vertical-coordinate idiosyncrasies and data availability from Earth System Grid and mirroring servers have limited the feasible range of models for the first phase of the pan CMIP OSSE. • First phase contains nearly complete range of diagnosed ECS across full ensemble.

  10. Data Acquisition • Thermodynamic and condensate profiles downloaded from Earth System Grid and its mirrors. • MODIS 16-day averages of 7 bands of BRDF and albedo, and 6 bands of emissivity gathered for 2003-2014. • Model-agnostic NCL and Matlab routines developed to concatenate fields into appropriate input files for OSSE. • If you expect to work with multiple CMIP5 or CMIP6 fields, these routines will save you time.

  11. Boundary Condition Interpolation • Key component of Berkeley’s pan-spectral OSSE is surface boundary conditions built off of MODIS land-surface products. • Gridding required for MODIS Climate Modeling Grid (CMG) data for each model’s horizontal resolution. • Highly computationally-intensive, but parallelizable. Visible Near-IR

  12. Interpolation • OSSE is now model-agnostic for horizontal resolution, but it is less flexible for vertical resolution and inflexible on using layers, instead of levels. • Vertical interpolation routines are required for thermodynamic and condensate profiles. • Routines need to be mathematically stable, no edge cases. • Construction of a positive-definite, monotonic function is necessary for gaseous and condensate species. • For cloud amount, we use saturated specific humidity to create saturated precipitable water path, then multiplying by cloud amount to create function onto which interpolation should occur.

  13. Benchmark Testing • Multiple scattering line-by-line radiative transfer calculations (LBLRTM+CHARTS) coupled to a database of ice cloud optical properties enable versatile spectral flux calculations. • NERSC and NAS resources take advantage of embarrassingly parallel nature of these calculations. Currently calculations are disk limited … upcoming AGU poster.

  14. Execution on NAS • MPI library updates on NASA Advanced Supercomputing (NAS) facilities enable better scaling of OSSE to larger numbers of processors (i.e., 2048, 4096). • OSSE has been configured for new MPI library and now • Berkeley group received new 1-Million CPU NASA High-End Computing Award received for 2015-2016 for execution on NAS. • The vertical interpolation routines still need to be tested.

  15. The Aerosol Challenge • CMIP5 models generally do not archive sufficient information on aerosols to include them in the pan CMIP OSSE. • Clean-sky simulations are tractable, otherwise an aerosol placeholder is necessary. • Aerosol forcing, and clear-sky reflectance simulations will be inconsistent with CMIP5 model results. • CMIP6 will probably be better.

  16. Summary • International collaboration with Imperial College and UMich partners yielding exciting science in the far-IR. • Decadal Survey white paper recommends independent OSSE capability that entrains modelers. • Pieces for a pan CMIP OSSE are now in place. • Final testing and benchmarking needed. • With EVM2 done, we expect preliminary OSSE first phase model results of RCP8.5 in early 2016. • Time-series analysis of pan-spectral signals to follow. Acknowledgements:This research was supported by NASA grants NNH11AQ75I and NNH14ZDA001N-ACSCS. NERSC and NASA High-End Computing grants provided computational resources.

  17. Discussion • Feedback from CLARREO Science Team on what CMIP5 OSSE runs will lead to synergistic research activities. • Ongoing collaborations with NASA LaRC on PCRTM and fingerprinting should also be considered. • Thoughts on how the pan CMIP OSSE should address the under-specification of aerosols in CMIP5 are appreciated. • Feedback can be directly conveyed to Earth System Grid Federation at next week’s meeting.

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