This class stores data from the AMSR-2 satellite.
Details
The Advanced Microwave Scanning Radiometer (AMSR-2) is in current operation on
the Japan Aerospace Exploration Agency (JAXA) GCOM-W1 space craft, launched in
May 2012. Data are processed by Remote Sensing Systems. The satellite
completes an ascending and descending pass during local daytime and nighttime
hours respectively. Each daily file contains 7 daytime and 7 nighttime
maps of variables named as follows within the data
slot of amsr objects: timeDay,
SSTDay, LFwindDay (wind at 10m sensed in
the 10.7GHz band), MFwindDay (wind at 10m sensed at 18.7GHz),
vaporDay, cloudDay, and rainDay, along with
similarly-named items that end in Night.
See reference 1 for additional information on the instrument, how
to cite the data source in a paper, etc.
The bands are stored in raw() form, to save storage. The accessor
function [[,amsr-method can provide these values in raw
form or in physical units; plot,amsr-method(), and
summary,amsr-method() work with physical units.
Slots
dataAs with all
oceobjects, thedataslot foramsrobjects is a list containing the main data for the object.metadataAs with all
oceobjects, themetadataslot foramsrobjects is a list containing information about thedataor about the object itself. Examples that are of common interest includelongitudeandlatitude, which define the grid.processingLogAs with all
oceobjects, theprocessingLogslot foramsrobjects is a list with entries describing the creation and evolution of the object. The contents are updated by variousocefunctions to keep a record of processing steps. Object summaries andprocessingLogShow()both display the log.
Modifying slot contents
Although the [[<- operator may permit modification of the contents
of amsr objects (see [[<-,amsr-method),
it is better to use oceSetData() and oceSetMetadata(),
because those functions save an entry in the processingLog
that describes the change.
Retrieving slot contents
The full contents of the data and metadata slots of a amsr
object may be retrieved in the standard R way using slot(). For
example slot(o,"data") returns the data slot of an object named o,
and similarly slot(o,"metadata") returns
the metadata slot.
The slots may also be obtained with the [[,amsr-method
operator, as e.g. o[["data"]] and o[["metadata"]], respectively.
The [[,amsr-method operator can also
be used to retrieve items from within the data and metadata slots.
For example, o[["temperature"]] can be used to retrieve temperature
from an object containing that quantity. The rule is that a named
quantity is sought first within the object's metadata slot,
with the data slot being checked only if metadata does not
contain the item. This [[ method can also be used to get
certain derived quantities, if the object contains sufficient
information to calculate them. For example, an object that holds
(practical) salinity, temperature and pressure, along with
longitude and latitude, has sufficient information to compute
Absolute Salinity, and so o[["SA"]] will yield the
calculated Absolute Salinity.
It is also possible to find items more directly, using oceGetData() and
oceGetMetadata(), but neither of these functions can
retrieve derived items.
References
Information on the satellite, how to cite the data, etc. is provided at
http://www.remss.com/missions/amsr/.A simple interface for viewing and downloading data is at
http://images.remss.com/amsr/amsr2_data_daily.html.
See also
Other classes holding satellite data:
g1sst-class,
landsat-class,
satellite-class
Other things related to amsr data:
[[,amsr-method,
[[<-,amsr-method,
amsr,
composite,amsr-method,
download.amsr(),
plot,amsr-method,
read.amsr(),
subset,amsr-method,
summary,amsr-method