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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

 Click here for instructions to fill up the table below ......

The first table in Design Document gives overview of this document, from this info the Design Documents Overview page is automatically created.

In the overview table below 4.Equ means Equations and Algorithms, 5.Ver means Verification, 6.Perf - Performance, 7. Val - Validation

  • Equations: Document the equations that are being solved and describe algorithms
  • Verification Plans: Define tests that will be run to show that implementation is correct and robust. Involve unit tests to cover range of inputs as well as benchmarks.
  • Performance expectations: Explain the expected performance impact from this development
  • Validation Plans: Document what process-based, stand-alone component, and coupled model runs will be performed, and with what metrics will be used to assess validity

Use the symbols below (copy and paste) to indicate if the section is in progress or done or not started.

In the table below 4.Equ means Equations and Algorithms, 5.Ver means Verification, 6.Perf - Performance, 7. Val - Validation,   (tick) - competed, (warning) - in progress, (error) - not done


Overview table for the owner and an approver of this feature

1.Description

SNICAR-AD Shortwave Radiation for Sea Ice

2.Owner

Cheng Dang (Unlicensed)
3.Created 
4.Equ(error)
5.Ver(error)
6.Perf(error)
7.Val(error)
8.Approver
9.Approved Date
V2.0Pending
 Click here for Table of Contents ...

Table of Contents




Title: SNICAR-AD Shortwave Radiation for Sea Ice

Requirements and Design

E3SM Cryosphere Group

Date:  

Summary


The goal of this task is to improve the shortwave radiative transfer simulation of snow-covered sea ice by adopting the updated radiative scheme SNICAR-AD in the sea-ice component MPAS-seaice. A parallel modification has also been made to the land component ELM, together they provide consistent and improved shortwave radiative transfer computation for snow-covered surfaces.

Requirements

Modify the sea-ice shortwave code to include a new subroutine SNICAR_AD that

  1. provides new input files for snow and ice optics adopted by ELM;
  2. expands the shortwave radiative calculation to 5 subdivided solar bands adopted by ELM;
  3. removes empirical adjustment for radiative-effective snow grain size;
  4. 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)


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)


Design and Implementation

Implementation: 

In ice_shortwace.F90, we added a new subroutine SNICAR_AD to compute the shortwave radiative properties of snow-covered sea ice, which can be turned on by setting config_use_snicar_ad to true.

Pseudo code:

if snow-covered sea ice:

    if (SNICAR_AD):





Date last modified: July 1st, 2019

Contributors: Cheng Dang (Unlicensed)


This section should detail the plan for implementing the design solution for requirement XXX. In general, this section is software-centric with a focus on software implementation. Pseudo code is appropriate in this section. Links to actual source code are appropriate. Project management items, such as svn branches, timelines and staffing are also appropriate. How do we typeset pseudo code?


Planned Verification and Unit Testing 

Verification and Unit Testing: short-desciption-of-testing-here

Date last modified:  
Contributors: (add your name to this list if it does not appear)


How will XXX be tested? i.e. how will be we know when we have met requirement XXX. Will these unit tests be included in the ongoing going forward?

Planned Validation Testing 

Validation Testing: short-desciption-of-testing-here

Date last modified:
Contributors: (add your name to this list if it does not appear)


How will XXX be tested? What observational or other dataset will be used?  i.e. how will be we know when we have met requirement XXX. Will these unit tests be included in the ongoing going forward?

Planned Performance Testing 

Performance Testing: short-desciption-of-testing-here

Date last modified:
Contributors: (add your name to this list if it does not appear)


The new implementation is not expected to have a significant impact on the computational cost/performance of E3SM.



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