Teban54 wrote:Flwxguy86 wrote:I put a little less weight into the the interim models like 06z and 18z, They always seem to be off compared to what I'd call the "main runs". I don't know if maybe there is less data in them or something but it seems that way to me.
I thought someone said this year that 6z and 18z now have as much data as 0z and 12z, at least for global models, even though that wasn't the case before?
I don't believe this has been true for some time. There was some truth prior to 2008 with the way radiosonde data was ingested into the models and our reliance on weather balloon launches (most were done at 00z and 12z), but assimilation of data was switched to a 6 hour window around that time and our reliance on weather balloons has significantly decreased (while important, this also had a small footprint in terms of total data input). Aircraft data provides much more input in today's models, and it would be interesting to get a timestamp of flights between 00z,06z,12z,18z. Again though, with the amount of commercial flights and package carriers, I would imagine over CONUS the difference is rather small. Both of these could be variable, but their magnitude is significantly small compared to the observations listed below.
The bulk of our observations for any given 6-hour window really is remote instrument driven—satellite data, microwave, multi-channel IR, GPS radio occultations from space that track temperature profiles vertically, satellite derived atmosphere motion, surface observation networks, ships/buoys, etc. The order of magnitude for these is literally in the hundreds of millions. While there is a lot of overlap and redundancy here, the true number of bins assimilated is likely on the order of several million.
The likely major difference between 00z/12z runs and 06z/18z, where in-situ sampling makes a difference for severe impact events (Helene being an example, where a critical shortwave trough that is important for downstream development and steering). I am going to say this one is largely myth.