理解GFS参数平均倍-地球科学堆栈交换江南电子竞技平台江南体育网页版 最近30从www.hoelymoley.com 2023 - 07 - 10 - t12:35:33z //www.hoelymoley.com/feeds/question/24235 https://creativecommons.org/licenses/by-sa/4.0/rdf //www.hoelymoley.com/q/24235 2 理解GFS参数平均时间 约旦 //www.hoelymoley.com/users/27501 2022 - 08 - 25 - t04:35:55z 2022 - 12 - 13 - t11:41:08z < p >我相信一些全球预测系统(GFS) < a href = " https://www.nco.ncep.noaa.gov/pmb/products/gfs/gfs.t00z.pgrb2.0p25.f003.shtml " rel = " nofollow noreferrer " > < / >参数点值而另一些则平均在一个区间值。For example, the parameter DSWRF (Downward Short-Wave Radiation Flux) is labeled as a "0-3 hour ave". Does this mean that for forecast hour 3 from the GFS, the DSWRF value is the average for the interval of hour 3 to hour 6? Is anything not labeled as an average a point value? Is there documentation that answers these questions (I can't find any)? I ask because the documentation for solarforecastarbiter-core claims that "Cloud cover from GFS is an interval average with ending label" (line 88). If this were true for my DSWRF example above, the forecast for hour 3 would be the average for the interval of hour 0 to hour 3 rather than from hour 3 to hour 6.

Thank you for your help!

 //www.hoelymoley.com/questions/24235/-/24624 # 24624 2 答案为理解FelixD GFS参数平均时间 FelixD //www.hoelymoley.com/users/28138 2022 - 12 - 13 - t11:21:51z 2022 - 12 - 13 - t11:41:08z < p > <强>这些GFS参数存储运行平均,每6小时重置。< / >强这有点不寻常,需要一些特殊处理回到小时预测。

The value you have, time-tagged 03:00 (3h) and labeled as "0-3 hour ave" in GRIB is indeed the average of the forecasts from 0-3 hours ahead, time-tagged interval ending. Or could be understood as the average of what one would typically like to have as three one-hour averages labelled 01:00 (0-1 hour ahead average), 02:00 (1-2 hour ahead average) and 03:00 (2-3 hour ahead average), time-tagged interval ending.

This is as follows for each the different time steps found in GFS data:

  • 01:00 (labeled as "0-1 hour ave"): the forecast for 01:00 (tagged interval ending, 1 hour average).
  • 02:00 (labeled as "0-2 hour ave"): the average of the 01:00 and 02:00 forecasts (interval ending 1 hour averages).
  • 03:00 (labeled as "0-3 hour ave"): the average of the 01:00, 02:00, 03:00 forecasts.
  • 04:00 (labeled as "0-4 hour ave"): the average of the 01:00, 02:00, 03:00, 04:00 forecasts.
  • 05:00 (labeled as "0-5 hour ave"): the average of the 01:00, 02:00, 03:00, 04:00, 05:00 forecasts.
  • 06:00 (labeled as "0-6 hour ave"): the average of the 01:00, 02:00, 03:00, 04:00, 05:00, 06:00 forecasts.
  • 07:00 (labeled as "6-7 hour ave"): the 07:00 forecast. The averaging has been reset after 6h.
  • 08:00 (labeled as "6-8 hour ave"): the average of the 07:00 and 08:00 forecasts.
  • and so on.

To get back to hourly forecasts (or 3-hourly for 3-hourly datasets), you either need to do the math yourself or you can use the wgrib2 option -ncep_norm. See https://www.cpc.ncep.noaa.gov/products/wesley/wgrib2/ncep_norm.html .

To convert back yourself, you need to use the previous average and substract it with proper weighting. Here is short instructions by Shrinivas Moorthi from this thread http://gradsusr.org/pipermail/gradsusr/2016-November/040397.html :

Let us denote the data from 6 hourly output as C1, C2, C3, C4, C5, C6. To get hourly mean, then for hour 1, the mean is C1, for hour 2, the mean is 2C2-C1 for hour 3, the mean is 3C3-2C2 for hour 4, the mean is 4C4-3C2 for hour 5, the mean is 5C5-4C4 and for hour 6, it is 6C6-5C5 This pattern repeats every six ours.

There also is an NCEP/NOAA paper on the model data, where this is explained somewhere deep down, but I couldn't find it right now. The two links above however give a bit of explanation/guidance as well.

And always a good idea to compare your results to the output of a tool doing the conversion automatically.
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