R: Class to Store AMSR-2 Satellite Data

amsr-class {oce} | R Documentation

## Class to Store AMSR-2 Satellite Data

### Description

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

`data`

  As with all `oce` objects, the `data` slot for `amsr` objects is a list containing the main data for the object.

`metadata`

  As with all `oce` objects, the `metadata` slot for `amsr` objects is a list containing information about the `data` or about the object itself. Examples that are of common interest include `longitude` and `latitude`, which define the grid.

`processingLog`

  As with all `oce` objects, the `processingLog` slot for `amsr` objects is a list with entries describing the creation and evolution of the object. The contents are updated by various `oce` functions to keep a record of processing steps. Object summaries and `processingLogShow()` 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.

### Author(s)

Dan Kelley and Chantelle Layton

### References

1. Information on the satellite, how to cite the data, etc. is provided at `http://www.remss.com/missions/amsr/`.

2. 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`

[Package oce version 1.7-2 Index]