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Adding ET/PET/LE/PLE variables of MODIS dataset (#46)
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4 extra evapotranspiration (and its potential values) and latent heat
(and its potential values) are added from both Aqua and Terra products.
These variables are both available at 8-day or yearly time steps.
Necessary documentations on how to use the tools are added as well.

Signed-off-by: Kasra Keshavarz <kasra.keshavarz1@ucalgary.ca>
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Expand Up @@ -51,47 +51,77 @@ And the structure of the files is as following:
├── .
└── .
```
"The MCD12Q1 V6 product provides global land cover types at yearly intervals (2001-[2020]) derived from six different classification schemes. It is derived using supervised classifications of `MODIS` Terra and Aqua reflectance data. The supervised classifications then undergo additional post-processing that incorporate prior knowledge and ancillary information to further refine specific classes" [^reference]. The newest land cover dataset, `MCD12Q1.061`, is available annually for the 2001-2022 period [^reference2]

[^reference]: Google. (n.d.). MCD12Q1.006 MODIS land cover type yearly global 500M | Earth Engine Data catalog | Google developers. Google. Retrieved July 7, 2022, from https://developers.google.com/earth-engine/datasets/catalog/MODIS_006_MCD12Q1.
[^reference2]: USGS (n.d.). MODIS/Terra+Aqua Land Cover Type Yearly L3 Global 500m SIN Grid. Retrieved September 28, 2023, from https://lpdaac.usgs.gov/products/mcd12q1v061/.
## Dataset Variables
This dataset has 1 main variable that is described in the following table:

## Spatial and Temporal Extents
|# |Variable Name (keyword for `--variable`)|Description |Comments |
|---|----------------------------------------|--------------------------------------|---------------|
|1 |`MCD12Q1.006` |Global land cover classes |This dataset is retired, though available [Link](https://modis.gsfc.nasa.gov/data/dataprod/mod12.php)|
|2 |`MCD12Q1.061` |Global land cover classes |The most up-to-date MODIS Landcover dataset [Link](https://lpdaac.usgs.gov/products/mcd12q1v061/)|
|3 |`MOD16A2.061` |Global ET/PET/LE/PLE Land |8-day time-series of evapotranspiration (ET) and its potential value (PET), Latent Heat flux (LE) and its potential value (PLE) [link](https://modis.gsfc.nasa.gov/data/dataprod/mod16.php)|
|4 |`MOD16A2GF.061` |Global gap-filled ET/PET/LE/PLE Land |8-day time-series of evapotranspiration (ET) and its potential value (PET), Latent Heat flux (LE) and its potential value (PLE) [link](https://modis.gsfc.nasa.gov/data/dataprod/mod16.php)|
|5 |`MYD16A2.061` |Global ET/PET/LE/PLE Aqua |8-day time-series of evapotranspiration (ET) and its potential value (PET), Latent Heat flux (LE) and its potential value (PLE) [link](https://modis.gsfc.nasa.gov/data/dataprod/mod16.php)|
|6 |`MOD16A3GF.061` |Global gap-filled ET/PET/LE/PLE Aqua |Annual time-series of evapotranspiration (ET) and its potential value (PET), Latent Heat flux (LE) and its potential value (PLE) [link](https://modis.gsfc.nasa.gov/data/dataprod/mod16.php)|

The spatial extent of this dataset covers longitudes from `-180` to `+180` degress and latitudes from `-90` to `+90` degress. The `MCD12Q1.006` variable includes yearly land cover types from 2001 to 2020, while `MCD12Q1.061` provides from 2001 to 2022.
> [!WARNING]
> Currently, `gistool` **only** extracts `ET` values from `MOD16A2.061`,
> `MOD16A2GF.061`, `MYD16A2.061`, `MOD16A3GF.061` variables. This is a
> shortcoming of `gistool` and will be resolved in the future versions.
## Dataset Variables
This dataset has 1 main variable that is described in the following table:

|# |Variable Name (used in `gistool`) |Description |Comments |
|-------|---------------------------------------|---------------------------------------|---------------|
|1 |`MCD12Q1.006` |Global land cover classes |This dataset is retired, though available [Link](https://modis.gsfc.nasa.gov/data/dataprod/mod12.php)|
|2 |`MCD12Q1.061` |Global land cover classes |The most up-to-date MODIS Landcover dataset[Link](https://lpdaac.usgs.gov/products/mcd12q1v061/)|
## Spatial and Temporal Extents
|# |Variable Name (keyword for `--variable`)|Longitude Extents |Latitude Extents |Temporal Extents |
|---|----------------------------------------|-------------------|------------------|----------------------------|
|1 |`MCD12Q1.006` |`-180`° to `+180`° |`-90`° to `+90`° |`2001-01-01` to `2020-01-01`|
|2 |`MCD12Q1.061` |`-180`° to `+180`° |`-90`° to `+90`° |`2001-01-01` to `2022-01-01`|
|3 |`MOD16A2.061` |`-180`° to `+180`° |`-90`° to `+90`° |`2021-01-01` to `2024-02-10`|
|4 |`MOD16A2GF.061` |`-180`° to `+180`° |`-90`° to `+90`° |`2000-01-01` to `2023-12-27`|
|5 |`MYD16A2.061` |`-180`° to `+180`° |`-90`° to `+90`° |`2021-01-01` to `2024-02-18`|
|6 |`MOD16A3GF.061` |`-180`° to `+180`° |`-90`° to `+90`° |`2000-02-18` to `2023-01-01`|

> [!NOTE]
> The spatial resolution of MODIS datasets is 500m globally.
# Other relevant information
## Land Cover Types
Below the land cover types for each values of the `.tif` files is detailed based on [1].
Below the land cover types for each values of the generated
`.tif` files by `gistool` is detailed based on [^1]. These
classes apply to the following variables of the MODIS datasets:
1. `MCD12Q1.006` and
2. `MCD12Q1.061`.

|Class Value (used in `gistool`) |Name |Land Cover Description |
|---------------------------------------|---------------------------------------|---------------------------------------------------------------|
|1 |Evergreen Needleleaf Forests |Dominated by evergreen conifer trees (canopy>2m). Tree cover>60%.|
|2 |Evergreen Broadleaf Forests |Dominated by evergreen broadleaf and palmate trees (canopy >2m). Tree cover >60%.|
|3 |Deciduous Needleleaf Forests |Dominated by deciduous needleleaf (larch) trees (canopy >2m). Tree cover >60%.|
|4 |Deciduous Broadleaf Forests |Dominated by deciduous broadleaf trees (canopy >2m). Tree cover >60%.|
|5 |Mixed Forests |Dominated by neither deciduous nor evergreen (40-60% of each) tree type (canopy >2m). Tree cover >60%.|
|6 |Closed Shrublands |Dominated by woody perennials (1-2m height) >60% cover. |
|7 |Open Shrublands |Dominated by woody perennials (1-2m height) 10-60% cover. |
|8 |Woody Savannas |Tree cover 30-60% (canopy >2m). |
|9 |Savannas |Tree cover 10-30% (canopy >2m). |
|10 |Grasslands |Dominated by herbaceous annuals (<2m). |
|11 |Permanent Wetlands |Permanently inundated lands with 30-60% water cover and >10% vegetated cover.|
|12 |Croplands |At least 60% of area is cultivated cropland. |
|13 |Urban and Built-up Lands |At least 30% impervious surface area including building materials, asphalt, and vehicles.|
|14 |Cropland/Natural Vegetation Mosaics |Mosaics of small-scale cultivation 40-60% with natural tree, shrub, or herbaceous vegetation.|
|15 |Permanent Snow and Ice |At least 60% of area is covered by snow and ice for at least 10 months of the year.|
|16 |Barren |At least 60% of area is non-vegetated barren (sand, rock, soil) areas with less than 10% veg- etation.|
|17 |Water Bodies |At least 60% of area is covered by permanent wa- ter bodies. |
|255 |Unclassified |Has not received a map label because of missing inputs. |
|Class Value|Name |Land Cover Description|
|-----------|-----------------------------------|----------------------|
|1 |Evergreen Needleleaf Forests |Dominated by evergreen conifer trees (canopy>2m). Tree cover>60%.|
|2 |Evergreen Broadleaf Forests |Dominated by evergreen broadleaf and palmate trees (canopy >2m). Tree cover >60%.|
|3 |Deciduous Needleleaf Forests |Dominated by deciduous needleleaf (larch) trees (canopy >2m). Tree cover >60%.|
|4 |Deciduous Broadleaf Forests |Dominated by deciduous broadleaf trees (canopy >2m). Tree cover >60%.|
|5 |Mixed Forests |Dominated by neither deciduous nor evergreen (40-60% of each) tree type (canopy >2m). Tree cover >60%.|
|6 |Closed Shrublands |Dominated by woody perennials (1-2m height) >60% cover.|
|7 |Open Shrublands |Dominated by woody perennials (1-2m height) 10-60% cover.|
|8 |Woody Savannas |Tree cover 30-60% (canopy >2m).|
|9 |Savannas |Tree cover 10-30% (canopy >2m).|
|10 |Grasslands |Dominated by herbaceous annuals (<2m).|
|11 |Permanent Wetlands |Permanently inundated lands with 30-60% water cover and >10% vegetated cover.|
|12 |Croplands |At least 60% of area is cultivated cropland.|
|13 |Urban and Built-up Lands |At least 30% impervious surface area including building materials, asphalt, and vehicles.|
|14 |Cropland/Natural Vegetation Mosaics|Mosaics of small-scale cultivation 40-60% with natural tree, shrub, or herbaceous vegetation.|
|15 |Permanent Snow and Ice |At least 60% of area is covered by snow and ice for at least 10 months of the year.|
|16 |Barren |At least 60% of area is non-vegetated barren (sand, rock, soil) areas with less than 10% veg- etation.|
|17 |Water Bodies |At least 60% of area is covered by permanent wa- ter bodies.|
|255 |Unclassified |Has not received a map label because of missing inputs.|

Also, the details of the above table has been included in the following files: [modis_classes.csv](./modis_classes.csv).

## ET Values
Based on [^2], the ET values calculated from the following variables
of the MODIS dataset come with a scale factor of `0.1`. In other words,
`final_values = gistool_outputs * 0.1`:
1. `MOD16A2.061`,
2. `MOD16A2GF.061`,
3. `MYD16A2.061`,
4. `MOD16A3GF.061`,

[^1]: [https://lpdaac.usgs.gov/products/mcd12q1v061/](https://lpdaac.usgs.gov/products/mcd12q1v061/)
[^2]: [https://lpdaac.usgs.gov/products/mod16a3gfv061/](https://lpdaac.usgs.gov/products/mod16a3gfv061/)

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