Dear Donna, Matteo, all,
Thanks for pointing out this issue and the reference.
Can either of you elaborate on which product you mean with "ERA5
forecast" / where we can find information on this dataset?
It seems to elude at least my online search queries.
Thanks & Best,
Johannes Hampp (he/him)
Justus Liebig University Giessen (JLU)
Center for international Development and Environmental Research (ZEU)
Am 14/08/2021 um 13:10 schrieb Matteo De Felice:
> Dear Umed,
> as Donna pointed out, this is a well-known issue due to the assimilation
> cycles. It's quite annoying and the only solution is using the forecasts
> rather than the analysis,
> Best regards,
> On Saturday, August 14, 2021 at 8:42:05 AM UTC+2 peng...@gmail.com
>> Hi Umed,
>> I have come across this before in this paper:
>> The most relevant section is below.
>> 4.1 Issue in ERA5 diurnal cycles
>> The author discovered an issue with the diurnal cycles of wind speeds in
>> ERA5. The wind speeds at 10 m, 100 m and also on lower model levels,
>> exhibit gaps at 10:00 UTC and following hours and similarly but in a lesser
>> extent at 22:00 UTC. The wind deficit at 10:00 UTC may be larger than 0.5 m
>> s−1 on average.
>> The issue was reported to ECMWF which acknowledged the problem, which is
>> linked to the assimilation process, affects mostly low latitude oceanic
>> regions but also Europe and North America, and is not possible to correct
>> (ERA5 data documentation
>). The issue
>> appears at both 10:00 and 22:00 UTC but is more visible in convective
>> atmospheric conditions thus appearing mostly at 10:00 UTC, during the day,
>> over continental France.
>> To address this issue, ERA5 forecasts (denoted “fc” hereafter) were
>> downloaded and studied in addition to the usual analysis data
>> (denoted “an”). The forecasts do not exhibit the issue at 10:00 and 22:00
>> UTC but there may be jumps at 07:00 and 19:00 UTC when moving from one
>> forecast stream onto the next. These jumps are small or not visible over
>> continental France.
>> On 14 Aug 2021, at 03:28, Umed Paliwal <paliwa...@gmail.com
>> Hi All,
>> I am trying to do some analysis on offshore wind potential in the US and
>> China. I am using 100m wind speeds from ERA5. I found a very weird pattern
>> in the offshore wind speeds, the wind speeds always drop significantly from
>> 9AM to 10 AM and 9 PM to 10 PM. This happens in all offshore locations
>> whether the lat lon is on the coast of US, China, Japan and India. I have
>> pulled out the data for 6 of the offshore points from across the globe and
>> plotted the hourly wind speeds and diurnal mean in this tableau