Requested Diagnostics

Version 1.0  Drafted by John Scinocca, Tim Stockdale & Francois Lott

Input to this and a discussion of the rationale has been provided by Francois Lott: see  The text is reproduced below for convenience. This will need to be turned into a specific list of variables and pressure levels to be saved, for both “standard” and “high frequency” diagnostics, and agreement on which parts of EXPTS 1-5 should have high-frequency output archived. This document will be updated with a specific proposal in due course.

Storage is available at BADC, and it is proposed that groups upload their data in a common format (CF compliant netCDF) to BADC. This will involve registering to obtain an account, and preparing datasets to the specified common format. Please contact Scott Osprey for further details.

It will facilitate comparisons if the data are on a common lat-long grid, as well as being on standard pressure levels. SNAP specified a 1.5 deg grid, which is probably adequate for this project, too. (ERAI uses a 0.75 deg standard lat-long grid).

Are there any fields which should be supplied on the original model grid as well as a standard lat-long grid?

Text from Francois Lott:

Here is a table of diagnostics, which include the diagnostics requested by the ISSI group initiated by Joan Alexander a couple of years ago, and from which I started. What I remember from our discussions during the QBOi workshop, is that each group makes a simulation with its best QBO (not necessarily a version suited to CMIP6), and over 30 years (more maybe for histograms and spread?) store at pressure levels as near as they can be from the model levels and between 0.01 and 1000hPa, monthly-mean zonal mean data of:

u,  du/dt, T, v*, w*, F_phi, F_z, divF, G_ogw, G_ngw

Here the time derivative of the mean velocity (dynamical tendency) is to try to make the difference between the advective terms we can deduce from the TEM equations, and the advective plus forcing terms due to explicit/numerical diffusions which are sometimes difficult to extract from models. Also, we nead the EPF divergence (EPFD), and the tendencies due to the orographic and non-orographic gravity waves G_ogw, G_ngw

Also, it is useful to have the eastward and westward component of the non-orographic GWs momentum fluxes, rho_0*\bar{u'w'}_egw, rho_0*\bar{u'w'}_wgw

We could repeat this in 2XCO2+2K SST and 4XCO2+4K SST to see how our QBOs respond to climate change: there seems to be large spread amoing models.

Now, from the QBOi workshop I remember that we need to no know if our models simulate the QBO for the right (or the same reasons) and in particular the fraction of the resolved waves in each models. For this, the EPFD may not be sufficient, and the EPF themselves can include large opposing balance so we have to calculate time-wavenumber spectra of EPF, and this request storage of instantaneous values of u, w, v, and T at pressure levels, every three hours (to be discussed, 1hr?) and during at least one QBO period (for instance over three years). In my opinion, this needs to be done over a good number of levels in the QBO regions, above and below, for instance (to be discussed):

Why many levels: 1) to make better than the spectra in Horinoushi et al.~(2003) on top of the fact that we now all have a QBO (which was not the case in the 2003, paper); 2) A big question is to know how fast the equatorial waves dissipate in the vertical in the QBO region, 3) understand the behaviour around the TTL and in the SAO region. Differences between vertical levels may also help reduce the contribution of the tidal signals in the time-lon spectra, something that can be problematic at sub-diurnal periods (true?).

My rough estimate for one model is almost 500GB if we stay on netcdf format. But this opens the debate (3years of u,v,w,T at 12 vertical levels, 160x90 horizontal levels, every 3hrs).

Also, we would need a good deal of 2D fields, like precipitation, convective prec, OLR, etc. Information on the vertical structure of the tropical heating would be useful also, but I have no especially precise idea right now of about this should be done.

All diagnostics are done according to the TEM formalism as described in, Middle atmosphere dynamics. By D. G. Andrews, J. R. Holton and C. B. Leovy. Academic Press, San Diego, 1987 

Horinouchi, T., S. Pawson, K. Shibata, E. Manzini, M.A. Giorgetta, F. Sassi, R. J. Wilson, K.

Hamilton, J. DeGrandpe and A.A. Scaife, 2003: Tropical cumulus convection and upward propagating waves in middle-atmospheric GCMs, J. Atmos. Sci. , 60, 2765—2782.

Some spectra/composites from CMIP5 models are in:

Lott, F. S. Denvil , N. Butchart, C. Cagnazzo , M. Giorgetta, S. Hardiman, E. Manzini, T. T. Krishmer , J.-P. Duvel, P. Maury, J. Scinocca, S. Watanabe, S. Yukimoto, 2014: Kelvin and Rossby gravity wave packets in the lower stratosphere of some high-top CMIP5 models, J. Geophys. Res., 119, 5, 2156-2173, DOI: 10.1002/2013JD020797

1 comment:

  1. It might be a good idea for groups to compare their diagnostics lists against those suggested for DYNVARMIP. It would be advisable not to have any obvious gaps.