<p>I'm confused with the GFS model data products, presented at <a href="https://www.nco.ncep.noaa.gov/pmb/products/gfs/" rel="nofollow noreferrer">NCEP Products Inventory website</a>. There are two types of products for analysis: <strong>ANL</strong> (&quot;**.anl&quot;) and <strong>FH000</strong> (&quot;*.f000&quot;).  As the inventory suggests, they are both analysis, but <strong>ANL</strong> containing less data, than <strong>FH000</strong> (in partucular, ANL has no data for altitudes 2 meters and 10 meters, while FH000 has).
<a href="https://i.sstatic.net/oiZgWhA4.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/oiZgWhA4.png" alt="enter image description here" /></a></p>
<p>Both <strong>ANL</strong> and <strong>FH000</strong> have some shared data, but the fact is <em>there are differences between them within the shared datasets</em>.</p>
<p>For example, I've taken similar datasets from <strong>ANL</strong> and <strong>FH000</strong> to check whether they are the same or not. The datasets are Temperature at altitudes 80 m and 100 m. The subsets for 80 m temperature showed, that the data arrays are different (<strong>ANL</strong> (&quot;**.anl&quot;) on the left, <strong>FH000</strong> (&quot;*.f000&quot;) on the right):
<a href="https://i.sstatic.net/f5sIMed6.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/f5sIMed6.png" alt="enter image description here" /></a></p>
<p>Could you please help find out, what are the <strong>ANL</strong> and <strong>FH000</strong> products, what are the differences between them, and why are the seemingly common datasets diferent? Which data to rely on in research?</p>

CC BY-SA 4.0
2024-06-09T17:01:10.793Z
Does https://earthscience.stackexchange.com/a/10142/6298 particularly the second part help with your question?
JeopardyTempest
CC BY-SA 4.0
2024-06-10T11:17:29.560Z
@JeopardyTempest I'm not sure about "GFS" and "FNL" definitions. It is said that "Forecasts contain the same parameters as analysis AND accumulated forecast variables such as precipitation." Still, it turned out to be that the shared parameters values in both anl and f000 are not the same. Also, "FNL analysis incorporates ~10% more data than the GFS by waiting for ~3 hours longer for the data stragglers." while in fact in the original GFS data catalogue "*.anl" and "*.f000" files both come 3 hours away from the run-cycle time and are like 3 minutes away from each other ("*.f000" comes first).
Outlaw
CC BY-SA 4.0
2024-06-10T11:25:32.190Z
I kind of think, that maybe the given info is all about Research Data Archive (RDA) and how they store data. Also, the questeion itself and the source links are a bit old. Still, there is no clear answer to what is the difference between ANL ("**.anl") and FH000 ("*.f000") analyses in the original GFS data products catalogue (https://www.nco.ncep.noaa.gov/pmb/products/gfs/) and why the shared dataarrays (like temperature at 80 m) are different.
Outlaw
CC BY-SA 4.0
2024-06-11T06:51:42.490Z
Yeah, I had to deal with such things like 15 years ago.  I don't miss them :-(  Sorry, wish I had more input, know it can be obnoxious to navigate :-/
JeopardyTempest
CC BY-SA 4.0
2024-06-11T07:05:28.563Z
My only other guesses focus around ANL either starting later by eliminating some variables (and so including more "late" data), which would be somewhat in line with the quote...
JeopardyTempest
CC BY-SA 4.0
2024-06-11T07:12:56.820Z
...or perhaps it's related to spinup (I don't know if GFS still does spinup, but many models have done), where basically it mixes the previous model run with current data, then with some smoothing/scaling to get stable initial conditions so that things that may be dynamically unstable at the resolution of the model aren't kept (even if realistic)?  And so maybe analysis (and then GDAS FNL) are focused on representing the true current data???  Just a wild guess...
JeopardyTempest
CC BY-SA 4.0
2024-06-11T07:17:40.470Z
Though it's weird to me that 2 meter temperature (the standard "surface" level) isn't in the ANL.  I guess the focus is on the higher atmosphere???  But then, things like SBCAPE are very dependent on 2m temperature, so how does it have that but not 2m T.  Blah.
JeopardyTempest
CC BY-SA 4.0
2024-06-12T10:55:16.337Z
@JeopardyTempest Yep, that all is weird. And guesses are all we have... Yet I continue my investiogation for answer.
Outlaw
CC BY-SA 4.0
2024-06-13T08:10:36.703Z
hope you'll remember to come back and post it as an answer if/when you get some progress!  Cheers
JeopardyTempest
CC BY-SA 4.0
2024-06-13T15:02:47.140Z
@JeopardyTempest Absolutely, thanks!
Outlaw
<meteorology><models><weather-forecasting><numerical-modelling><gfs>
NCEP GFS data products: ANL and FH000
Outlaw
# NCEP GFS data products: ANL and FH000

(Asked by: username_0 on 2024-06-09)

I'm confused with the GFS model data products, presented at [NCEP Products Inventory website](https://www.nco.ncep.noaa.gov/pmb/products/gfs/). There are two types of products for analysis: **ANL** ("\*\*.anl") and **FH000** ("\*.f000"). As the inventory suggests, they are both analysis, but **ANL** containing less data, than **FH000** (in partucular, ANL has no data for altitudes 2 meters and 10 meters, while FH000 has).
[![enter image description here](https://i.sstatic.net/oiZgWhA4.png)](https://i.sstatic.net/oiZgWhA4.png)

Both **ANL** and **FH000** have some shared data, but the fact is *there are differences between them within the shared datasets*.

For example, I've taken similar datasets from **ANL** and **FH000** to check whether they are the same or not. The datasets are Temperature at altitudes 80 m and 100 m. The subsets for 80 m temperature showed, that the data arrays are different (**ANL** ("\*\*.anl") on the left, **FH000** ("\*.f000") on the right):
[![enter image description here](https://i.sstatic.net/f5sIMed6.png)](https://i.sstatic.net/f5sIMed6.png)

Could you please help find out, what are the **ANL** and **FH000** products, what are the differences between them, and why are the seemingly common datasets diferent? Which data to rely on in research?

**Tags:** meteorology, models, weather-forecasting, numerical-modelling, gfs

> **Comments:**
> **username_1**: Does https://earthscience.stackexchange.com/a/10142/6298 particularly the second part help with your question?  
> **username_0**: @username_1 I'm not sure about "GFS" and "FNL" definitions. It is said that "Forecasts contain the same parameters as analysis AND accumulated forecast variables such as precipitation." Still, it turned out to be that the shared parameters values in both anl and f000 are not the same. Also, "FNL analysis incorporates ~10% more data than the GFS by waiting for ~3 hours longer for the data stragglers." while in fact in the original GFS data catalogue "*.anl" and "*.f000" files both come 3 hours away from the run-cycle time and are like 3 minutes away from each other ("*.f000" comes first).  
> **username_0**: I kind of think, that maybe the given info is all about Research Data Archive (RDA) and how they store data. Also, the questeion itself and the source links are a bit old. Still, there is no clear answer to what is the difference between ANL ("**.anl") and FH000 ("*.f000") analyses in the original GFS data products catalogue (https://www.nco.ncep.noaa.gov/pmb/products/gfs/) and why the shared dataarrays (like temperature at 80 m) are different.  
> **username_1**: Yeah, I had to deal with such things like 15 years ago.  I don't miss them :-(  Sorry, wish I had more input, know it can be obnoxious to navigate :-/  
> **username_1**: My only other guesses focus around ANL either starting later by eliminating some variables (and so including more "late" data), which would be somewhat in line with the quote...  
> **username_1**: ...or perhaps it's related to spinup (I don't know if GFS still does spinup, but many models have done), where basically it mixes the previous model run with current data, then with some smoothing/scaling to get stable initial conditions so that things that may be dynamically unstable at the resolution of the model aren't kept (even if realistic)?  And so maybe analysis (and then GDAS FNL) are focused on representing the true current data???  Just a wild guess...  
> **username_1**: Though it's weird to me that 2 meter temperature (the standard "surface" level) isn't in the ANL.  I guess the focus is on the higher atmosphere???  But then, things like SBCAPE are very dependent on 2m temperature, so how does it have that but not 2m T.  Blah.  
> **username_0**: @username_1 Yep, that all is weird. And guesses are all we have... Yet I continue my investiogation for answer.  
> **username_1**: hope you'll remember to come back and post it as an answer if/when you get some progress!  Cheers  
> **username_0**: @username_1 Absolutely, thanks!  

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## 0 answers

