GeoEco.DataProducts.NASA.PODAAC.GHRSSTLevel4Granules

class GeoEco.DataProducts.NASA.PODAAC.GHRSSTLevel4Granules(username, password, shortName, datasetType='netcdf', timeout=60, maxRetryTime=300, cacheDirectory=None, metadataCacheLifetime=86400.0)

Bases: CMRGranuleSearcher

A CMRGranuleSearcher for NASA JPL PO.DAAC GHRSST L4 datasets hosted by NASA Earthdata.

The Group for High-Resolution Sea Surface Temperature (GHRSST) provides a new generation of global high-resolution (<10km) SST products to the operational oceanographic, meteorological, climate and general scientific community. The overall aim of the GHRSST is to provide the best quality sea surface temperature data for applications in short, medium and decadal/climate time scales in the most cost effective and efficient manner through international collaboration and scientific innovation.

This class accesses Level 4 (L4) gap-free gridded SST products published in near real-time by the GHRSST Global Data Assembly Center (GDAC) at the NASA JPL Physical Oceanography Distributed Active Archive Center (PO.DAAC) and subsequently hosted and distributed by NASA Earthdata. These products provide regional and global daily cloud-free estimates of SST at spatial resolutions ranging from 0.25 degrees to down 1 km. To fill in cloudy areas, data from multiple satellite and in-situ sensors are combined and regions without any data are filled in various interpolation and modeling techniques.

All products accessed by this class are published at a daily timestep. Some products are updated on a continual basis and available in near real time; others are updated infrequently and are intended mainly for historical analysis. The temporal extent, spatial resolution and extent, and sensors and interpolation technique used vary by product. All products use the WGS 1984 geographic coordinate system. GHRSST temperatures are published in kelvin. By default, this class converts them to degrees Celsius but provides an option to obtain the original kelvin values.

This class supports many but not all of the GHRSST L4 published by PO.DAAC. If you see a GHRSST L4 product on PO.DAAC that is not available with this tool, please contact the MGET development team for assistance.

Please see these instructions on how to acknowledge your use of PO.DAAC products.

Requires: Python requests module, Python netCDF4 module.

Parameters:

username (str) – NASA Earthdata account user name. Minimum length꞉ 1.
password (str) – NASA Earthdata account password. Minimum length꞉ 1.
shortName (str) –
PO.DAAC Short Name of the GHRSST L4 product to access. Currently, the following products are supported:
All products use the WGS 1984 geographic coordinate system and are published at a daily time-step. Some products are updated on a continual basis and available in near real time; others are updated infrequently and are intended mainly for historical analysis. The temporal extent, spatial resolution and extent, sensors and, interpolation technique used vary by product. Please see the products’ documentation for details.

This tool supports many but not all of the GHRSST L4 products published by PO.DAAC. If you see a product on PO.DAAC that is not available with this tool, please contact the MGET development team for assistance.

Allowed values꞉ 'AVHRR_OI-NCEI-L4-GLOB-v2.0', 'AVHRR_OI-NCEI-L4-GLOB-v2.1', 'CMC0.1deg-CMC-L4-GLOB-v3.0', 'CMC0.2deg-CMC-L4-GLOB-v2.0', 'DMI_OI-DMI-L4-GLOB-v1.0', 'GAMSSA_28km-ABOM-L4-GLOB-v01', 'Geo_Polar_Blended-OSPO-L4-GLOB-v1.0', 'Geo_Polar_Blended_Night-OSPO-L4-GLOB-v1.0', 'K10_SST-NAVO-L4-GLOB-v01', 'MUR-JPL-L4-GLOB-v4.1', 'MUR25-JPL-L4-GLOB-v04.2', 'MW_IR_OI-REMSS-L4-GLOB-v5.0', 'MW_IR_OI-REMSS-L4-GLOB-v5.1', 'MW_OI-REMSS-L4-GLOB-v5.0', 'MW_OI-REMSS-L4-GLOB-v5.1', 'OISST_HR_NRT-GOS-L4-BLK-v2.0', 'OISST_HR_NRT-GOS-L4-MED-v2.0', 'OISST_UHR_NRT-GOS-L4-BLK-v2.0', 'OISST_UHR_NRT-GOS-L4-MED-v2.0', 'OSTIA-UKMO-L4-GLOB-REP-v2.0', 'OSTIA-UKMO-L4-GLOB-v2.0', 'RAMSSA_09km-ABOM-L4-AUS-v01'. Case sensitive.
datasetType (str, optional) –
Dataset type to access. Currently only netCDF is supported. netCDF files will be downloaded and cached locally. If you specify a Cache Directory, they will be stored there and not deleted. Otherwise a temporary directory will be created to hold the files while the download is in progress and deleted when the relevent data are extracted and execution is complete.

The disadvantage with this approach is that when your study area is small and you’re accessing a global product, a lot of bandwidth and disk space is wasted. This problem can become acute if you’re accessing a global product with very high resolution, such as one of the 1 km resolution datasets. If this proves too problematic, contact the MGET development team for assistance. We may be able to implement an alternative access method that allows downloads to be limited to a geographic bounding box.

Allowed values꞉ 'netCDF'.
timeout (int, optional) –
Number of seconds to wait for the server to respond before failing with a timeout error.

If you also provide a Maximum Retry Time and it is larger than the timeout value, the failed request will be retried automatically (with the same timeout value) until it succeeds or the Maximum Retry Time has elapsed.

If you receive a timeout error you should investigate the server to determine if it is malfunctioning or just slow. Check the Earthdata website to see if NASA has posted a notice about the problem, or contact the NASA directly. If the server just slow, increase the timeout value to a larger number, to give the server more time to respond.

Minimum value꞉ 1.
maxRetryTime (int, optional) –
Number of seconds to retry requests to the server before giving up.

Use this parameter to cope with transient failures. For example, you may find that the server is rebooted nightly during a maintenance cycle. If you start a long running operation and want it to run overnight without failing, set the maximum retry time to a duration that is longer than the time that the server is offline during the maintenance cycle.

To maximize performance while minimizing load during failure situations, retries are scheduled with progressive delays:
- The first retry is issued immediately.
- Then, so long as fewer than 10 seconds have elapsed since the original request was issued, retries are issued every second.
- After that, retries are issued every 30 seconds until the maximum retry time is reached or the request succeeds.
Minimum value꞉ 1.
cacheDirectory (str, optional) –
Directory for caching local copies of downloaded data. A cache directory is optional but highly recommended if you plan to repeatedly access data for the same range of dates.

When data are requested, the cache directory will be checked for data that was downloaded and cached during prior requests. If cached data exists that can fulfill part of the current request, the request will be serviced by reading from cache files rather than downloading from the server. If the entire request can be serviced from the cache, the server will not be accessed at all and the request will be completed extremely quickly. Any parts of the request that cannot be serviced from the cache will be downloaded from the server and added to the cache, speeding up future requests for the same data.

If you use a cache directory, be aware of these common pitfalls:
- The caching algorithm permits the cache to grow to infinite size and never deletes any cached data. If you access a large amount of data (e.g. an entire 20 terabyte collection of satellite images) it will all be added to the cache. Be careful that you do not fill up your hard disk. To mitigate this, manually delete the entire cache or selected directories or files within it.
- The caching algorithm stores data in uncompressed files, so that subsets of those files may be quickly accessed. To save space on your hard disk, you can enable compression of the cache directory using the operating system. On Windows, right click on the directory in Windows Explorer, select Properties, click Advanced, and enable “Compress contents to save disk space”.
- The caching algorithm cannot detect when portions of a dataset have been replaced on the server, thereby making the cached data obsolete. Thus, if a data provider republishes a dataset with improved data values, the caching algorithm will continue to use the old, obsolete values. To mitigate this, you should monitor when data providers reprocess their datasets, and delete the cached files when they become obsolete.
Minimum length꞉ 1.
metadataCacheLifetime (float, optional) –
Maximum amount of time, in seconds, that granule metadata downloaded from the NASA Earthdata Common Metadata Repository (CMR) will be cached.

Downloading metadata from the NASA Earthdata CMR can be slow. If this parameter and a cache directory are both provided, when the CMR is queried for all granule metadata for a given collection_concept_id, the downloaded metadata will be cached in the directory for this amount of time. During this period, the cached metadata will be accessed instead of the server, which can greatly speed up processing involving NASA Earthdata granules. However, if new datasets are stored in the CMR, they will not be discovered until the cached metadata has expired.

If this parameter is not provided (the default), then granule metadata will not be cached.

Minimum value꞉ 1.0.

Returns:

GHRSSTLevel4Granules instance.

Return type:

GHRSSTLevel4Granules

Properties

property CacheDirectory

(str or None) Directory for caching local copies of remote datasets. Minimum length꞉ 1. If a cache directory is not provided, then after a remote dataset is downloaded it will be kept either only in memory or in a temporary directory on disk, depending on the type of data it is. The temporary directory will be automatically deleted when Close() is called.

If a cache directory is provided, remote datasets will be stored in it when they are downloaded. Before a download is attempted, the cache directory will be checked first for the relevant dataset, and if it is found, the download will be skipped, speeding up execution.

The datasets are organized in the cache directory in an undocumented format that is specific to the collection. Once a dataset is stored in the cache directory, it is never changed or deleted. If the original remote datasets are changed, these changes will not be detected and the cache will not be updated. If the disk fills up, cached datasets will not be automatically deleted to mitigate the problem.

If you determine that the cached datasets are obsolete or the disk is too full, delete the entire cache directory. You may also be able to delete a portion of it, if you can reverse engineer how datasets are stored within it, but the organizational structure is not documented.

property DisplayName: (str) Informal name of this object, suitable to be displayed to the user. Read only. Minimum length꞉ 1.

property ParentCollection: (DatasetCollection or None) Parent DatasetCollection that this object is part of (if any). Read only.

Methods

`Close`	Closes any open files or connections associated with this object and releases any other resources allocated to access it.
`DeleteLazyPropertyValue`	Deletes the lazy property with the specified name.
`GetAllQueryableAttributes`	Returns a list of all queryable attributes.
`GetLazyPropertyValue`	Returns the value of the lazy property with the specified name.
`GetNewestDataset`	Queries the collection and returns the newest `Dataset` that matches the search expression.
`GetOldestDataset`	Queries the collection and returns the oldest `Dataset` that matches the search expression.
`GetQueryableAttribute`	Returns the queryable attribute with the specified name.
`GetQueryableAttributeValue`	Returns the value of the queryable attribute with the specified name.
`GetQueryableAttributesWithDataType`	Returns a list queryable attributes having the specified data type.
`HasLazyPropertyValue`	Returns True if the specified lazy property has a value.
`ImportDatasets`	Copies each `Dataset` in a `list` into this `DatasetCollection`.
`QueryDatasets`	Queries the collection and returns a `list` of `Dataset`s that match a search expression.
`SetLazyPropertyValue`	Sets the lazy property with the specified name to the specified value.
`TestCapability`	Tests whether a capability is supported by this class or an instance of it.