6 votes
Accepted

What is the meaning of step in ERA reanalysis data?

The "step" is the number of hours the ERA re-forecast has been run into the future from the "time" of the re-analysis. For example, asking for ERA data with time = 12:00 and step = 0 means asking for ...
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  • 1,662
6 votes

Odd structures in 66 year NCEP daily temperature reanalysis

It looks like a Gibbs oscillation, a basic feature of spectral analysis. In a spectral atmospheric model this means that near high orography artificial surface waves exist which may reflect in ...
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  • 318
6 votes
Accepted

ERA Interim, how to handle total precipitation

First of all, these netCDF files follow the CF Metadata Conventions, which describe the use of scale_factor and add_offset in ...
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  • 3,133
5 votes

Why is radiation and total precipitation not available in ERA Interim Reanalysis at step 0?

The ERA archive description document, Berrisford et al (2011) "The ERA-Interim archive Version 2.0", provides additional information about what is available. It's less explicit on the why, but we can ...
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  • 3,133
5 votes
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How to calculate 3-hour flux values in ERA-Interim?

After my original answer, and some back and forth in the comments, turns out I got the answer right by a bit of fools luck, and we sorted it out... The thing is, despite flux being commonly thought ...
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5 votes
Accepted

Extracting Regional Data from ERA5

To me I am not sure why the subset option should not work with a python script. According to me it does work. Here is a sample script. ...
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  • 6,208
4 votes
Accepted

Single-layer water content variables

The ERA Interim reanalysis is made by ECMWF and the other reanalysis is made by NOAA. Reanalyzes of the past are made by running global climate models and these differ because NOAA and ECMWF use ...
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  • 1,043
4 votes
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ERA Interim problem with Waves

I haven't looked into ERA-Interim wave data a huge amount but I know around 1991 it started to assimilate ocean wave data from satellite altimeters (ERS-1). See the first figure here https://...
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  • 201
4 votes
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Why is ferret giving me error that the region is not 2D while plotting

You need to use the following syntax yes? fill 't'[k=1,l=1] This is because ferret treats t variable name as time and to distinguish your variable name (if it is ...
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4 votes
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In meteorology, are satellite data "better" than reanalysis data?

Unfortunately, your question has no answer. Both have errors. Both can be unreliable. Your choice really depends on how you plan on using them. Satellites instrument contain sources of error, such as ...
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3 votes

Does Climate Data Store provide daily mean of ERA 5 reanalysis data?

tl;dr I would suggest using the Toolbox of the Copernicus CDS. Via the Toolbox, you can choose datasets, process them and download the processed results. You have to be registered and logged-in to ...
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3 votes
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Error trying to download ERA5 data: Exception: Missing/incomplete configuration file: C:\Users\username/.cdsapirc

I had the same problem but have just found the solution after an hour or so of trawling through forums! The problem was that the code 'api.py' could not find the '.cdsapirc' file. The file type has to ...
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3 votes
Accepted

Difference between NCEP's 20th Century daily Forecast and Analysis variables

Some variables in reanalyses have to be forecast and cannot be assimilated to allow the model to converse mass, momentum and energy. Precipitation is a good example. The model will assimilate ...
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  • 201
3 votes
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What is the height above ground of NCEP/NCAR Reanalysis 1 variables?

The height coordinate varies and is described for the various variables on the site you link. For example: Levels: Surface or near the surface (.995 sigma level), or entire atmosphere (eatm) ...
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2 votes
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shortwave and longwave radiation terminology, direct, beam, PAR, flux?

Beam radiation is direct radiation, e.g. photons that have not been scattered. Diffuse radiation is indirect and has been scattered. Examples of beam radiation from the sky would be from the sun ...
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2 votes
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What's the difference between snow cover and fractional snow cover?

Fractional Snow Cover (FSC) is a property of snow cover. The fractional snow cover property is used in a variety of contexts, most common of which is meteorological models. Snow cover algorithms ...
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  • 12.7k
2 votes

ERA-Interim how to select only grid-points over land area?

The simplest way is to download another variable in which data is only available over the ocean, such as Sea Surface Temperature (SST). You should be able to download it in the very same way you do ...
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  • 587
2 votes
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Temperature at 2 m MERRA2

When I visit that link, the first option at the top ("Data Product") defaults to inst3_3d_asm_Np, which is atmospheric variables in pressure levels. I suspect you ...
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  • 3,133
2 votes

MERRA-2 Reanalysis data V and U wind are missing values over land at 1000 hPa pressure level

TL;DR: It is not a problem, it is a feature. As it was pointed in the comments, 1000 hPa over land (and sometimes over ocean) is below the surface. MERRA is just fair enough not to put any values ...
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  • 121
2 votes
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How reanalysis data influence our research/results?

Welcome to StackExchange SE! I don't think I fully understand your question, but I'll try to answer it. Reanalysis data is the use of weather models and data assimilation to piece back the weather. ...
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2 votes

How can I account for rainfall effects on air pollution?

Sounds like you want a dataset that is unadjusted for rainfall. I'm not sure what you have to gain from that, but there are ways to do it. One way to do this would be to find the inverse correlation ...
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  • 12.7k
1 vote

How to calculate 'real-world' geometric height from ERA reanalysis data

I have two solutions. Use MetPy to calculate the height from the geopotential height. Use the hypsometric equation, averaging the temperature below the level.
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1 vote

How to calculate 'real-world' geometric height from ERA reanalysis data

If I understood the question right: CDO can interpolate from model level to height level with the operator ml2hl infile.nc outfile.nc additionally, for the lower atmospheric levels, you can add an ...
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1 vote

How reliable is sea-ice concentration (fraction) data in ERA-Interim?

I would recommend changing from ERA-Interim to ERA-5, since ERA-Interim will be outdated soon. This is the information currently given by the data provider: ERA Interim is being phased out. Users ...
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  • 379
1 vote

ERA-Interim how to select only grid-points over land area?

The land-sea mask for ERA Interim is available here.
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  • 379
1 vote

Extracting Regional Data from ERA5

Any Python/R packages that can extract and plot these data in an efficient way? I can highly recommend using the Python package xarray or iris for data analysis and Cartopy for plotting.
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  • 379
1 vote
Accepted

How can I account for rainfall effects on air pollution?

Thank you all for your suggestions, I greatly appreciate it. I was able to get a solution to this problem which essentially obtains correlated errors (using ARMA correlation) in a linear (or non-...
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1 vote

ERA Interim problem with Waves

This doesn't answer your question but I can't comment; It is worth noting that there are several changes in SST packages which drive the models. The most significant is the difference from before ...
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1 vote

CFSR hourly surface wind time series

If you check the 6-hourly products in the links you shared, you can see that CFSR includes 50 variables in the "complete" dataset. The hourly dataset has a limited number of variables (25 in total). ...
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  • 11
1 vote

What is the meaning of step in ERA reanalysis data?

Some confusion comes from the mixture of analysis data (such as 2m-air temperature) and reanalysis products (such as downward radiation) in the final reanalysis product. The following text directly ...
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