# Tag Info

12

I made some pictures on my tablet to explain everything a bit better. Sorry that they are not that nice. Shuffle If we do not us shuffle, we store on value (float, double, integer, short integer, ...) after another. Thus, each variable itself is stored contiguously in memory. The first bit of a second value follows the last bit of the first value. If we ...

11

I've done work with SEGY files, and the fixed length headers with ignored fields were an issue. Also, endian issues. You have to remember SEGY is the present exchange and archiving standard. That's a good thing. The issue is that SEGY was designed for tape, so it's a single file. In this day and age, that may not be a good thing. It might be better to ...

10

A CDL file is basically a text output from a netcdf file. If you want to know the contents of a netcdf file but don't have the time (or ability) to use programs built to read/write netcdf, you can use the simple text output of "ncdump" and then read/write it with a basic text editor. You can also use "ncgen" to regenerate a netcdf file based on the new CDL ...

8

Here is how I would do this. ECMWF's ECCODES has a tool called bufr_ls and you can use that to write the contents of that output to a text file. Then I would read that file into a scripting language such as Python and write out the contents as a GRIB file using PyGrib. You can also explore the output of bufr_dump and convert that also to GRIB if you wish. ...

6

X-coordinate Y-coordinate Segment number Symbol code Two-way time (ms) Shot-point number CDP number Trace number Line type (2=2D, I=inline, X=crossline) 2D line name or 3D survey name The format allows for a column between 8 and 9, for amplitude value — not present in this example. This is a formatted layout to specific columns. So there is ...

5

Go to the user preferences. From there you will be able to choose different formats and data options. If you choose netCDF, you will be able to read these filetypes with most map readers. For Python, you can use netCDF4-python.

5

Grid Resolution of the NCEP/NCAR reanalysis data The data is available on different grids depending on the variables of interest: The original grid is a T62 Gaussian grid, which grid cells do not have a constant lon-lat spacing over the whole globe (see e.g. Gaussian grid at Wikipedia), with 28 sigma levels. The sigma levels are listed on this page, where ...

5

It's a mistake. You probably know this, but for anyone who's interested, these wireline logs are: DRHO — density ('RHO') correction (delta, or 'D') in g/cc. DPHI — porosity ('PHI') from density ('D'), as a fractional proportion. NPHI — porosity from the neutron log ('N'), as a fractional proportion. All of these logs are usually displayed on a linear ...

4

Because the surface or top-of-the-atmosphere products are not raw data. Atmospheric corrections have been applied to the raw data and those corrections have been done with a precision that can't be properly captured in 8-bit numbers. You can round data outputs to 8-bits, but there would be information loss. Some bands, like atmospheric opacity can be ...

4

SEG-Y files are a general purpose archival format. So they can be "anything". 2D seismic, 3D seismic, raw, processed, unstacked or even derivatives (seismic attributes). How to get information about your data in the SEG-Y file: SEG-Y contain 3 types of headers that describe the data. The EBCDIC header is a 40 by 80 character sheet that is a remnant from ...

4

SEG-D is a specialized format, while SEG-Y is a general-purpose format. In general, SEG-D is intended for field recordings of seismic data, and SEG-Y is intended for 'seismic data exchange'. Having said this, SEG-Y is so general-purpose, and so ubiquitous, that I'm not surprised to hear (anecdotally) that people are using it for data acquisition. Certainly, ...

4

Your understanding is inaccurate. The shifts by $\frac{1^\circ}{24}$ are only relevant for figuring out, where the pixel centers are located and where to start when you are looking to find the right grid index for a certain point. As for the resolution, it is much simpler. We have $4320$ pixels covering $360^\circ$ in longitude direction, i.e. a resolution ...

4

The same as scottlittle, but you can use also McIdas V. It also can read nedcdf files and also is a free software. http://www.ssec.wisc.edu/mcidas/software/v/documentation.html

4

The advantage of SEGY is also it's main problem; It's been around for very long. I've been struggling to open a decade old word document correctly, whiles one can actually still access a SEGY from the 70's or 80's. It's also an advantage that all program packages can, somehow, import and export the files. I agree with David, that the headers doesn't need ...

3

One thing that already exists is the ph5 format from the PASSCAL group: https://www.passcal.nmt.edu/content/ph5-what-it It is essentially a port of the SEG Y format that removes some restrictions and adds a bunch of new meta information. It is based on HDF5 and is currently mainly intended as an archival format although I don't see why it could not also be ...

3

There are no bytes in an IBG. SEGDrev1 is a tape format, and the schematic you are referencing in the standards document is a map of how the data is physically stored on a tape. Tape gaps are actual physical spaces on the tape between blocks of data. An IBG is, quite literally, a gap between blocks of actual data. If you are reading a tape, you should be ...

3

Date/timestamps are tricky to convert without further information; are the values you show days (unlikely, if 990555 is your date/time value), hours, seconds? See if you can figure out the system used (either by knowing which date your timestamp is supposed to represent, or looking at the step sizes for the data); this will generally give you an idea of what ...

3

My professor gives the solution, as we can see at the site were the climatic variables came from http://www.worldclim.org/formats1: Please note that the temperature data are in °C * 10. This means that a value of 231 represents 23.1 °C. This does lead to some confusion, but it allows for much reduced file sizes which is important as for many downloading ...

2

Unfortunately, the older weather satellite data is, the harder it is to read. Perhaps NOAA's Weather and Climate Toolkit can open it. The old stuff usually comes in tightly packed binary formats that may or may not be well documented (these satellites were designed to take pictures of clouds for weather forecasters to use, us future generations were more ...

2

There are some problems with your request, and maybe some misunderstandings. Misunderstanding: You actually need more than pressure to get wind vectors. Wind speed is nonlinear, and is dependent on more than just wind. Even if you had observations of pressure, that will only tell you how the wind is changing due to the pressure gradient force, and not due ...

2

The SEG has a sitting committee for SEG-Y revision 2, which has debated the need to adopt changes to SEG-Y since the last revision that are needed (such as removing trace length limits for continuous data, formats for passive data, etc.). If you want to do something about what SEG-Y for the future should look like, You should join the SEG and volunteer for ...

2

The Basic ENVISAT Atmospheric Toolbox (BEAT) contains a component called the Common Data Access toolbox (CODA; also available on github). BEAT and CODA are written in C and have bindings for Python (as well as Matlab, IDL, and a few other languages). Among the long list of supported products is IASI L1C. Apparently, BEAT is going to be replaced by HARP (...

1

It seems you have downloaded a native format file. This is not an HDF readable format. If you see the first link you've given, under distribution it notes there are several formats you can download: Native, Image (J2KBW, JPEGBW, PNGBW, TIFFBW), BUFR, or netCDF. If you want to use HDF libraries to read the file, you will need to download the netCDF ...

1

It should be easy to spot the lat and lon coordinates. Have you found the spec? http://www.seg.org/documents/10161/77915/ukooa_p1_90.pdf

1

The easiest way to look at earthquake data that you would like in a data set you can work on (filter,plot,process,etc.) is three steps. Get yourself a copy of Matlab Go to the iris website and download a program called IrisFetch.m (see http://ds.iris.edu/ds/nodes/dmc/manuals/) . Next you need a list of events and a list of stations from which to download ...

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