Version 5 (modified by laurent, 13 months ago) (diff)

ASINTER-05_Brodeau_Advanced_Bulk

Last edition: 12/06/19 11:32:15 by laurent

The PI is responsible to closely follow the progress of the action, and especially to contact NEMO project manager if the delay on preview (or review) are longer than the 2 weeks expected.

  1. Summary
  2. Abstract
  3. Description
  4. Implementation
  5. Reference manual update
  6. Progress
  7. Review
  8. MP ready
  9. Tests
  10. Review

Summary

See ticket #2159 https://forge.ipsl.jussieu.fr/nemo/ticket/2159

Action ASINTER-05_Brodeau_Advanced_Bulk
PI(S) Laurent Brodeau @ Ocean Next

Digest

More accurate air-sea flux estimates through the implementation of a cool-skin/warm-layer parameterization in NEMO, also more advanced bulk formulae over sea-ice.

Dependencies
Expected for December, 2019
Ticket #2159
Branch NEMO/branches/2019/dev_r11085_ASINTER-05_Brodeau_Advanced_Bulk
Previewer(s)
Reviewer(s)
Link

'.' => '/nemo/wiki/2019WP/ASINTER-05_Brodeau_Advanced_Bulk'

Abstract

  • 1/ Implement different state-of-the-art bulk formula parametrizations used to compute transfer coefficients (CD, CE, and CH) for estimates of turbulent air-sea fluxes:
    • a/ NCAR (previously known as "CORE", Large and Yeager, 2004)
    • b/ ECMWF (IFS@ECWMF)
    • c/ COARE 3.0 (Fairall et al, 2003)
    • d/ COARE 3.6 (Fairall et al, 2019)
  • 2/ Implement, when relevant, their respective cool-skin and warm-layer parametrization for better estimate of the water temperature at the air-sea interface (which is the relevant temperature to estimate heat flux to the atmosphere).
    • a/ NCAR → irrelevant
    • b/ ECMWF → cool-skin & warm-layer
    • c/ COARE → cool-skin only
    • d/ COARE 3.6 → cool-skin & warm-layer
  • 3/ Improve the accuracy of various physical parameters used in the estimate of surface fluxes and previously assumed constant.
  • 4/ Implement more advanced bulk parametrization for turbulent "air-ice" fluxes of momentum, heat and freshwater over sea-ice

Description

See Abstract (above) and Implementation (below).

Implementation

Modified modules aka source files

(Forked from NEMOGCM trunk at rev 11085)

  • DOM/phycst.F90
    • Moved/merged all physical parameters previously declared into sbcblk.F90 into phycst.F90 (keeping the name they had in phycst.F90 when previously declared in both modules with a different name)
  • SBC/sbc_oce.F90
    • Added tsk, public 2D array to contain the sea-surface skin temperature from the cool-skin/warm-layer parametrization [Celsius]
    • Added rhoa, public 2D array to contain the air density at z=zu [kg/m3]
  • SBC/sbcblk.F90
    • Moved/merged all physical parameters previously declared into sbcblk.F90 into phycst.F90 (keeping the name they had in phycst.F90 when previously declared in both modules with a different name)
    • Moved all the functions for air thermodynamics into a new module: SBC/sbcblk_phy.F90
    • New namelist parameters to namelist's section namsbc_blk:
      • ln_skin (if true: use the cool-skin/warm-layer parametrization if supported by selected bulk algorithm)
      • ln_humi_sph (if true: air humidity in the forcing files is specific humidity [kg/kg])
      • ln_humi_dpt (if true: air humidity in the forcing files is dew-point temperature [K])
      • ln_humi_rlh (if true: air humidity in the forcing files is relative humidity [%])
      • ln_COARE_3p6 replaces the old ln_COARE_3p5, because we upgraded from COARE 3.5 to COARE 3.6 (3.5 was intermediate and not "official").
    • Added function sbc_blk_cswl_alloc() to allocate array tsk (declared into sbc_oce.F90).
    • Added part where turb_ecmwf (and soon turb_coare*) is called with Qlw, rad_sw, & slp (optional arguments) in case of ln_skin==.true.
    • 0.98 now becomes rdct_qsat_salt (into phycst.F90)
    • Longwave radiative flux component zqlw now computed after turbulent fluxes are, because needs the updated skin temperature which comes out the turb_ecmwf (and soon turb_coare*) function
    • Corrected mistake: no rdct_qsat_salt factor for q_sat over ice! (zqi_sat)
    • Added XIOS iom_put for density of air (rho_air), and skin temperature
    • Added local arrays zqair to contain specific humidity of air at height rn_zqt
    • When ln_humi_sph=.true., zqair is simply what is read into sn_humi file (spec. hum.). When ln_humi_dpt=.true., zqair is deduced from the dew-point temperature (read into sn_humi file) and the SLP. When ln_humi_rlh=.true., zqair is deduced from the relative humidity (read into sn_humi file), air temperature, and SLP.
    • rhoa (air density at height rn_zu, declared into sbc_oce.F90) is updated once for all in blk_oce() instead of being computed their and their in different locations.
  • SBC/sbcblk_algo_ecmwf.F90
    • Increased numerical stability to handle non-realistic values over land points, which caused systematic crash in old version (such as in 4.0)
    • The use of the cool-skin/warm-layer parametrization is triggered when optional arguments Qsw, rad_lw, slp are specified when calling turb_ecmwf
      • In each iteration step, estimation of solar and non-solar components of net surface heat flux is done prior to call to subroutine CSWL_ECMWF (defined into SBC/sbcblk_skin.F90)
    • Some variables renamed for clarity, ex: sst → T_s
    • Function visc_air moved to sbcblk_phy.F90
    • Use of function Ri_bulk() defined into SBC/sbcblk_skin.F90
  • SBC/sbcblk_algo_coare.F90 is gone, it is now SBC/sbcblk_algo_coare_3p0.F90 for the sake of consistency
  • SBC/sbcblk_algo_coare_3p0.F90 (ex sbcblk_algo_coare.F90)
    • Increased numerical stability to handle non-realistic values over land points, which caused systematic crash in old version (such as in 4.0)
    • The use of the cool-skin/warm-layer parametrization is triggered when optional arguments Qsw, rad_lw, slp are specified when calling turb_coare
    • In each iteration step, estimation of solar and non-solar components of net surface heat flux is done prior to call to subroutine CSWL_ECMWF (defined into SBC/sbcblk_skin.F90)
    • Some variables renamed for clarity, ex: sst → T_s
    • Function visc_air moved to sbcblk_phy.F90
    • Use of functions One_on_L() and Ri_bulk() defined into SBC/sbcblk_skin.F90
  • SBC/sbcblk_algo_coare_3p5.F90 is gone, it is now SBC/sbcblk_algo_coare_3p6.F90
  • SBC/sbcblk_algo_coare_3p6.F90 (ex sbcblk_algo_coare_3p5.F90)
    • upgraded from COARE 3.5 to COARE 3.6 (3.5 was intermediate and not "official") following Fairall et al. 2019 (in prep.) and Edson et al. 2013
    • applied all improvements mentioned for SBC/sbcblk_algo_coare_3p0.F90.
  • SBC/sbcblk_algo_ncar.F90
    • use of sbcblk_phy.F90 for functions virt_temp() and One_on_L()

New modules aka source files

  • SBC/sbcblk_phy.F90 [ catalog of functions of some non constant physical parameters in the MBL (Marine Boundary Layer) ] → Gathers the following functions:
    • virt_temp (computes absolute/potential VIRTUAL temperature out of absolute/potential temperature and specific humidity)
    • Rho_air (computes density of air out of air temperature and spec. hum. and SLP)
    • Visc_air (computes kinematic viscosity of air out of air temperature)
    • L_vap (computes the latent heat of vaporization of water out of water temperature)
    • cp_air (computes the specific heat, aka Cp, of moist air out of specific humidity)
    • gamma_moist (computes the the adiabatic lapse-rate of moist air out of air temperature and spec. hum.)
    • One_on_L (computes 1/[Monin-Obukhov length])
    • Ri_bulk (computes the bulk Richardson number)
    • e_sat_sclr (computes "e_sat", the water vapor pressure of saturated air out of air temperature and SLP, scalar IO arguments)
    • q_sat (computes the specific humidity at saturation out of temperature of air and SLP)
    • q_air_rh (computes the specific humidity of air out of relative humidity and temperature of air and SLP)
  • SBC/sbcblk_skin.F90 [ cool-skin / warm-layer parametrization of ECMWF, contains function CSWL_ECMWF, which updates the value of the skin temperature out of previous guess of skin temperature, solar and non-solar components of surface heat flux and friction velocity u*] → Gathers the following subroutine:
    • `CSWL_ECMWF

Reference manual update

???

Progress

  • 1/ 90% completed
  • 2/ 75% completed
  • 3/ 100% completed
  • 4/ 0% completed

Review

Has the review been completed? I don't think so.

MP ready

Yes, very likely to be ready for MP 2019 in December.

Since the preview step must be completed before the PI starts the coding, the previewer(s) answers are expected to be completed within the two weeks after the PI has sent the request to the previewer(s).
Then an iterative process should take place between PI and previewer(s) in order to find a consensus

Possible bottlenecks:

  • the methodology
  • the flowchart and list of routines to be changed
  • the new list of variables wrt coding rules
  • the summary of updates in literature

Once an agreement has been reached, preview is ended and the PI can start the development into his branch.

Tests

Once the development is done, the PI should complete the tests section below and after ask the reviewers to start their review.

This part should contain the detailed results of SETTE tests (restartability and reproducibility for each of the reference configuration) and detailed results of restartability and reproducibility when the option is activated on specified configurations used for this test

Regular checks:

  • Can this change be shown to produce expected impact (option activated)?
  • Can this change be shown to have a null impact (option not activated)?
  • Results of the required bit comparability tests been run: are there no differences when activating the development?
  • If some differences appear, is reason for the change valid/understood?
  • If some differences appear, is the impact as expected on model configurations?
  • Is this change expected to preserve all diagnostics?
  • If no, is reason for the change valid/understood?
  • Are there significant changes in run time/memory?

Review

A successful review is needed to schedule the merge of this development into the future NEMO release during next Merge Party (usually in November).

Assessments:

  • Is the proposed methodology now implemented?
  • Are the code changes in agreement with the flowchart defined at preview step?
  • Are the code changes in agreement with list of routines and variables as proposed at preview step?
    If, not, are the discrepancies acceptable?
  • Is the in-line documentation accurate and sufficient?
  • Do the code changes comply with NEMO coding standards?
  • Is the development documented with sufficient details for others to understand the impact of the change?
  • Is the project literature (manual, guide, web, …) now updated or completed following the proposed summary in preview section?

Finding:

Is the review fully successful? If not, please indicate what is still missing


Once review is successful, the development must be scheduled for merge during next Merge Party Meeting.