R: Class to Store G1SST Satellite-model Data

g1sst-class {oce} | R Documentation

## Class to Store G1SST Satellite-model Data

### Description

This class stores G1SST model-satellite products.

### Details

G1SST is an acronym for global 1-km sea surface temperature, a product that combines satellite data with the model output. It is provided by the JPO ROMS (Regional Ocean Modelling System) modelling group. See the JPL website (reference 1) to learn more about the data, and see the `read.g1sst()` documentation for an example of downloading and plotting.

It is important not to regard G1SST data in the same category as, say, amsr data, because the two products differ greatly with respect to cloud cover. The satellite used by amsr has the ability to sense water temperature even if there is cloud cover, whereas `g1sst` fills in cloud gaps with model simulations. It can be helpful to consult reference 1 for a given time, clicking and then unclicking the radio button that turns off the model-based filling of cloud gaps.

### Slots

`data`

  As with all `oce` objects, the `data` slot for `g1sst` objects is a list containing the main data for the object.

`metadata`

  As with all `oce` objects, the `metadata` slot for `g1sst` objects is a list containing information about the `data` or about the object itself.

`processingLog`

  As with all `oce` objects, the `processingLog` slot for `g1sst` 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 g1sst objects (see `[[<-,g1sst-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 g1sst 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 `[[,g1sst-method` operator, as e.g. `o[["data"]]` and `o[["metadata"]]`, respectively.

The `[[,g1sst-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

### References

1. JPO OurOcean Portal `https://ourocean.jpl.nasa.gov/SST/` (link worked in 2016 but was seen to fail 2017 Feb 2).

### See Also

Other classes holding satellite data: `amsr-class`, `landsat-class`, `satellite-class`

Other things related to g1sst data: `[[,g1sst-method`, `[[<-,g1sst-method`, `read.g1sst()`

[Package oce version 1.7-2 Index]