Short description of the VADYldai-Tool


1 Description of the LDAI

The project VADY1 – part DLR2 – deals with the representation of the atmospheric dynamics in the MiKlip model by looking at the activity of atmospheric waves. Therefore, a process-oriented and easy-to-calculate variable called LDAI (large-scale dynamical activity index) was developed. It is especially for travelling planetary waves. Details can be looked up in (Wuest et al.) [1].

2 Starting the tool

The program works as follows: For using VADYldai you need temperature data on pressure levels. That is the only input the tool requires. Choose the project, product, institute, model and experiment. For further information use the help command (freva --plugin ldai --help). In the preset dryrun mode, it creates a list of the input data which are usable for the tool. Then run the program.

freva --plugin ldai project=baseline1 product=output2 institute=mpi-m  
model=mpi-esm-lr experiment=decs4e2000 ensemble=r1i1p1

Please make sure that the data of your interest are not already calculated and findable trough freva or via https://www-miklip.dkrz.de/?login_required=1&next=/solr/data-browser/ (see also 1).

If input data are found, run the program without the dryrun option again:

freva --plugin ldai project=baseline1 product=output2 institute=mpi-m  
model=mpi-esm-lr experiment=decs4e2000 ensemble=r1i1p1 dryrun=‘‘FALSE’’

To run a whole decade for one ensemble member the procedure will take aprox. 6 hours. For further information use the help command (freva --plugin ldai --help).

Table 1: Overview of the LDAI calculations with different model setups.
MiKlip model Baseline 0 Baseline 1 Prototype/ Prototype/
ORA-S4 GECCO2
period decade 1999 1969 to 2013 1969 to 2013 1969 to 2013
ensemble runs 1 to 3 1 to 10 1 to 15 1 to 15
number of levels 17 24 24 24

Table 2: Overview of the different available LDAI calculations with the different reanalysis data with freva.
Reanalysis data ERA-Interim3 MERRA4 CFSR5 JRA256
Time range 1979 to 2011 1979 to 2011 1979 to 2010 1979 to 2010
number of levels 22 24 22 24
3ECMWF re-analysis Interim 4Modern-Era Retrospective Analysis for Research and Applications 5Climate Forecast System Reanalysis 6Japanese 25-year ReAnalysis

3 Where do I find the calculated results?

The calculated files can be found in your evaluation system folder e. g.:

~/evaluation_system/output/ldai/...

4 How does the result look like?

You get a netcdf file which includes the results of the LDAI for all the vertical level and the horizontal resolution you have choosen before. Due to specific analysis reasons (see [2]) it is recommendable to calculate a zonal mean of your results (for example with cdo zonmean inputfile outputfile). Figure 1 shows a typical example. For plotting the results or calculating skill scores please use other available tools.

PIC PIC

Figure 1: LDAI calculated for the ERA-Interim reanalysis for January 2008 (left) and July 2008 (right).

References

   S. Wüst, K. Piecha, R. Kramer, M. Bittner, J.-H. Yee, M. G. Mlynczak, and J. M. Rusell III. Investigating atmospheric waves in ECHAM6 - Part I: Introduction of two process-oriented indices for validation. in preparation.

   S. Wüst, K. Piecha, R. Kramer, M. Bittner, J.-H. Yee, M. G. Mlynczak, and J. M. Rusell III. Investigating atmospheric waves in ECHAM6 - Part II: Application of two process-oriented indices for validation. in preparation.