GPS-derived IWV Data Assimilation (nudging scheme) – in #8: General Questions

Dear colleagues

I am attempting to perform Data Assimilation of GPS -derived IWV in the COSMO model (v. 5.01). So far I am working in the production of the netCDF files that have the right format to be assimilated by the model.
I would like to have some advice about the following points.

- In the description of the format of the input files for assimilating GPS data, a list of optional and mandatory variables is given. Among the ones needed for assimilating GPS data there are three, which I lack of, these are: Pressure ( MPPP ), Temperature ( MTN ) and Relative Humidity ( MUUU ). My question is, could the values of these three needed quantities directly extracted from the simulated fields of the COSMO model? in other words, can I use simulated values of Pressure, temperature and Rel. Hummidity instead of observational data while assimilating data?, if so, how should I set the model in order to do that?

- In the Part III of the COSMO documentation (Data Assimilation) it is described that the model requires in some cases the IWV to be assimilated in in other it needs the Zenith total Delay ( ZTD ). The explanation is that the model can, itself, calculate the values of IWV , in those cases where the values are missing, or easily assimilate thos introduced via the input files. Given that, in the description of format of the input files, found in the User guide both variables ( IWV and ZTD ) are identified as ‘needed’ is there any way I can only input IWV data, without having to introduce as well the ZTD values?

- Finally it could come in handy having an example netCDF file (already finished) with the correct fields and the correct format used for GPS data assimilation. Does somebody know where could I obtain one of these?

Thank you for your time and cooperation

Alberto

  @albertocaldas-alvarez in #80080f4

Dear colleagues

I am attempting to perform Data Assimilation of GPS -derived IWV in the COSMO model (v. 5.01). So far I am working in the production of the netCDF files that have the right format to be assimilated by the model.
I would like to have some advice about the following points.

- In the description of the format of the input files for assimilating GPS data, a list of optional and mandatory variables is given. Among the ones needed for assimilating GPS data there are three, which I lack of, these are: Pressure ( MPPP ), Temperature ( MTN ) and Relative Humidity ( MUUU ). My question is, could the values of these three needed quantities directly extracted from the simulated fields of the COSMO model? in other words, can I use simulated values of Pressure, temperature and Rel. Hummidity instead of observational data while assimilating data?, if so, how should I set the model in order to do that?

- In the Part III of the COSMO documentation (Data Assimilation) it is described that the model requires in some cases the IWV to be assimilated in in other it needs the Zenith total Delay ( ZTD ). The explanation is that the model can, itself, calculate the values of IWV , in those cases where the values are missing, or easily assimilate thos introduced via the input files. Given that, in the description of format of the input files, found in the User guide both variables ( IWV and ZTD ) are identified as ‘needed’ is there any way I can only input IWV data, without having to introduce as well the ZTD values?

- Finally it could come in handy having an example netCDF file (already finished) with the correct fields and the correct format used for GPS data assimilation. Does somebody know where could I obtain one of these?

Thank you for your time and cooperation

Alberto