C1 SNICAR-AD Shortwave Radiation for Sea Ice and Land Design Document
The Design Document page provides a description of the algorithms, implementation and planned testing including unit, verification, validation and performance testing. Please read Step 1.3 Performance Expectations that explains feature documentation requirements from the performance group point of view.
Design Document
In the table below 4.Equ means Equations and Algorithms, 5.Ver means Verification, 6.Perf - Performance, 7. Val - Validation, 
- competed, 
- in progress, 
- not done
Overview table for the owner and an approver of this feature
1.Description | SNICAR-AD Shortwave Radiation for Sea Ice and Land |
2.Owner | Cheng Dang (Unlicensed) |
| 3.Created | |
| 4.Equ | |
| 5.Ver | |
| 6.Perf | |
| 7.Val | |
| 8.Approver | |
| 9.Approved Date | |
| V2.0 | Pending |
Title: SNICAR-AD Shortwave Radiation for Sea Ice and Land
Requirements and Design
E3SM Cryosphere Group
Date:
Summary
ELM: modify the land shortwave code to include a subroutine that adopts the new radiative transfer algorithm.
MPAS-seaice: modify the sea-ice shortwave radiative transfer code to include a new subroutine that
- provides new input files for snow and ice optics adopted by ELM;
- expands the shortwave radiative calculation from three to five subdivided solar bands adopted by ELM;
- removes empirical adjustment for radiative-effective snow grain size;
- adopts a new algorithm to correct for the bias of near-infrared albedo and absorption when solar zenith angles are larger than 75 degrees.
Date last modified: Jun 1st, 2019
Contributors: Cheng Dang (Unlicensed) Charlie Zender
Algorithmic Formulations
Design solution: described in the following article
Dang, C., Zender, C. S., and Flanner, M. G.: Inter-comparison and improvement of 2-stream shortwave radiative transfer models for a unified treatment of cryospheric surfaces in ESMs, The Cryosphere Discuss., https://doi.org/10.5194/tc-2019-22, in review, 2019.
Date last modified: July 1st, 2019
Contributors: Cheng Dang (Unlicensed) Charlie Zender Mark Flanner
Design and Implementation
Implementation:
In the sea-ice and land shortwave code (ice_shortwace.F90, SnowSnicarMod.F90), we implemented SNICAR_AD that can be turned on/off by configuration toggles in the model namelists.
MPAS-source code: https://github.com/chengdang/MPAS-Model/tree/seaice/cdang_SnicarAD
ELM-source code: https://github.com/chengdang/E3SM/tree/chengdang/lnd/SNICAR_AD
Verification and Unit Testing:
- The offline radiative transfer model has been tested against a multi-stream benchmark model. (Dang, C., Zender, C. S., and Flanner, M. G.: Inter-comparison and improvement of 2-stream shortwave radiative transfer models for a unified treatment of cryospheric surfaces in ESMs, The Cryosphere Discuss., https://doi.org/10.5194/tc-2019-22, in review, 2019.)
Date last modified: July 1st, 2019
Contributors: Cheng Dang (Unlicensed)
Planned Validation Testing
Validation Testing:
- The modified E3SM model is tested with Pi-Control configuration, against the released Deckv1b simulation (mpas-analysis, e3sm diagnostics, and land comparison carried by the developer)
- 30-year MPAS-analysis: https://portal.nersc.gov/project/m2833/cdang/30yr.mpas_analysis.m2m.SNICAR_AD_landseaice_vs_DECKv1b.piControl.ne30_oEC.edison/
- 30-year E3SM diagnostics: https://portal.nersc.gov/project/m2833/cdang/30yr.e3sm_diags.m2m.SNICAR_AD_landseaice.SNICAR_AD_seaice.ne30_oEC.edison/viewer/
Date last modified: July 1st, 2019
Contributors: Cheng Dang (Unlicensed)
Planned Performance Testing
Performance Testing:
The new implementation is not expected to have a significant impact on the computational cost/performance of E3SM.