pycoare 2023.4a2

A Python implementation of the COARE bulk air-sea flux algorithm.

pyCOARE

COARE-algorithm

This is an alpha-quality fork of the Python version of the COARE algorithm that was written with the goal of standardizing testing, packaging, and distribution of the algorithm. Currently only COARE v3.5 is implemented - hopefully v3.6 will come soon!

The functionality of the code is ideally the same as that for the scripts found in the NOAA PSL repository linked above. My only intended contributions are towards formatting, testing, and packaging. To that end, tests have been constructed based on the output of the original MATLAB code for COARE v3.5. View the results of the tests or download the data and run them yourself. All results from this script agree to at least five significant figures with the MATLAB scripts in the NOAA repository, provided the testing badge above stays green.

Installation

The latest stable version (currently still an alpha) can be downloaded using Pip

pip install pycoare

You can install the most up-to-date version using

pip install git+https://github.com/andrew-s28/COARE-algorithm

Contribution

I welcome any contributions - please feel free to raise an issue or submit a pull request. My hope is that this implementation will get better as those with more knowledge on bulk air-sea fluxes or Python software development get involved.

Origins

The international TOGA-COARE field program which took place in the western Pacific warm pool over 4 months from November 1992 to February 1993 (Fairall et al. 1996a, 1996b and 1997) spurred the development of the COARE model. The algorithm is intended to provide estimates of momentum, sensible heat, and latent heat fluxes using inputs of bulk atmospheric variables (wind speed, SST, air temperature, air humidity). The algorithm contains subroutines/functions to handle near-surface gradients of temperature in the ocean.

Versions

• Version 2.5 was published in 1996.
• Version 3.0 was published in 2003; it was a major update from Version 2.5. This update was based on new observations at higher wind speeds (10 to 20 m/s). Available in MATLAB and FORTRAN only.
• Version 3.5 was released in 2013 following the publication of Edson et al. 2013, which made adjustments to the wind speed dependence of the Charnock parameter based on a large database of direct covariance stress observations (principally from a buoy). This led to an increase in stress for wind speeds greater than about 18 m/s. The roughness Reynolds number formulation of the scalar roughness length was tuned slightly to give the same values of Ch and Ce as Version 3.0. The diurnal warm layer model was structured as a separate routine instead of embedded in a driver program. COARE 3.5 was based on Edson’s buoy data (Edson et al. 2013) and was compared to a large database (a total of 16,000 hours of observations) combining observations from NOAA, WHOI, and U. Miami (Fairall et al. 2011). It is available in Python and MATLAB.
• Version 3.6 is slightly restructured and built around improvements in the representation of the effects of waves on fluxes. This includes improved relationships of surface roughness, $z_o$, and whitecap fraction, $W_f$, on wave parameters. More details can be found in coare3.6_readme_1.pdf. This version is available in Python, MATLAB and FORTRAN.

References:

• Edson, J.B., J. V. S. Raju, R.A. Weller, S. Bigorre, A. Plueddemann, C.W. Fairall, S. Miller, L. Mahrt, Dean Vickers, and Hans Hersbach, 2013: On the Exchange of momentum over the open ocean. J. Phys. Oceanogr., 43, 1589–1610. doi: http://dx.doi.org/10.1175/JPO-D-12-0173.1

• Fairall, C.W., E.F. Bradley, J.S. Godfrey, G.A. Wick, J.B. Edson, and G.S. Young, 1996a: The cool skin and the warm layer in bulk flux calculations. J. Geophys. Res. 101, 1295-1308. https://doi.org/10.1029/95JC03190

• Fairall, C.W., E.F. Bradley, D.P. Rogers, J.B. Edson, G.S. Young, 1996b: Bulk parameterization of air-sea fluxes for TOGA COARE. J. Geophys. Res. 101, 3747-3764. https://doi.org/10.1029/95JC03205

• Fairall, C. W., White, A. B., Edson, J. B., and Hare, J. E.: Integrated Shipboard Measurements of the Marine Boundary Layer, J. Atmos. Ocean. Tech., 14, 338–359, 1997. https://doi.org/10.1175/1520-0426(1997)014<0338:ISMOTM>2.0.CO;2

• Fairall, C.W., E.F. Bradley, J.E. Hare, A.A. Grachev, and J.B. Edson, 2003: Bulk parameterization of air-sea fluxes: Updates and verification for the COARE algorithm. J. Climate 16, 571-591. https://doi.org/10.1175/1520-0442(2003)016<0571:BPOASF>2.0.CO;2

• Fairall, C.W., Mingxi Yang, Ludovic Bariteau, J.B. Edson, D. Helmig, W. McGillis, S. Pezoa, J.E. Hare, B. Huebert, and B. Blomquist, 2011: Implementation of the COARE flux algorithm with CO2, DMS, and O3. J. Geophys. Res., 116, C00F09, https://doi.org/10.1029/2010JC006884