Formulasi inti model PT-JPL dalam framework OpenET tidak berubah dari formulasi asli yang dijelaskan dalam Fisher et al. (2008).
Namun, peningkatan dan pembaruan pada input model dan integrasi waktu untuk
PT-JPL dilakukan untuk memanfaatkan set data cuaca bergrid kontemporer,
memberikan konsistensi dengan model lain, meningkatkan perkiraan penguapan air terbuka, dan memperhitungkan adveksi di atas area tanaman dan lahan basah di lingkungan semi-gersang dan gersang. Perubahan ini mencakup penggunaan pantulan permukaan Landsat dan radiasi termal untuk menghitung radiasi bersih, radiasi aktif fotosintetik, variabel kelembapan dan kanopi tanaman, serta penggunaan data cuaca NLDAS, Spatial CIMIS, dan gridMET untuk memperkirakan insolasi dan ET referensi ASCE. Mirip dengan penerapan
model OpenET lainnya, estimasi ET terintegrasi waktu harian dan bulanan
didasarkan pada fraksi ET referensi ASCE. Penguapan air terbuka
diperkirakan mengikuti pendekatan keseimbangan energi permukaan Abdelrady
et al. (2016) yang khusus untuk badan air dengan memperhitungkan fluks panas air, bukan fluks panas tanah.
Fisher, J.B., Tu, K.P. dan Baldocchi, D.D., 2008. Estimasi global fluks air darat–atmosfer berdasarkan data bulanan AVHRR dan ISLSCP-II, divalidasi di 16 situs FLUXNET. Remote Sensing of Environment, 112(3),
pp.901-919.
doi:10.1016/j.rse.2007.06.025
Abdelrady, A., Timmermans, J., Vekerdy, Z. dan Salama, M., 2016.
Keseimbangan energi permukaan air tawar dan air asin: AquaSEBS. Remote
sensing, 8(7), hlm.583.
doi:10.3390/rs8070583
Priestley-Taylor Jet Propulsion Laboratory (PT-JPL) Formulasi inti model PT-JPL dalam framework OpenET tidak berubah dari formulasi asli yang dijelaskan dalam Fisher et al. (2008). Namun, peningkatan dan pembaruan pada input model dan integrasi waktu untuk PT-JPL dilakukan untuk memanfaatkan data cuaca terpetakan kontemporer …
[null,null,[],[[["\u003cp\u003eThe OpenET PT-JPL dataset provides monthly evapotranspiration estimates for the contiguous United States (CONUS) from 2008 to 2023.\u003c/p\u003e\n"],["\u003cp\u003eIt is based on the Priestley-Taylor Jet Propulsion Laboratory (PT-JPL) model, utilizing Landsat and gridMET data for improved accuracy.\u003c/p\u003e\n"],["\u003cp\u003eThe dataset is available at a 30-meter resolution and includes bands for evapotranspiration and the number of cloud-free observations used in the estimation.\u003c/p\u003e\n"],["\u003cp\u003eOpenET data is made available under the Creative Commons Attribution 4.0 International (CC BY 4.0) license.\u003c/p\u003e\n"],["\u003cp\u003eThis dataset can be accessed and analyzed using Google Earth Engine.\u003c/p\u003e\n"]]],["The dataset, provided by OpenET, Inc., offers monthly evapotranspiration (ET) data from 1999-10-01 to 2023-12-01, calculated using the Priestley-Taylor Jet Propulsion Laboratory (PT-JPL) model. This model uses Landsat data for variables and weather data to estimate ET, including adjustments for open water and advection. It outputs `et` values (mm) and a cloud-free `count`, with a 30-meter pixel size. The dataset is accessible through Google Earth Engine, which also provides an example code for annual evapotranspiration calculations.\n"],null,["# OpenET PT-JPL Monthly Evapotranspiration v2.0\n\nDataset Availability\n: 1999-10-01T00:00:00Z--2024-12-01T00:00:00Z\n\nDataset Provider\n:\n\n\n [OpenET, Inc.](https://openetdata.org/)\n\nCadence\n: 1 Month\n\nTags\n:\n[evapotranspiration](/earth-engine/datasets/tags/evapotranspiration) [gridmet-derived](/earth-engine/datasets/tags/gridmet-derived) [landsat-derived](/earth-engine/datasets/tags/landsat-derived) [monthly](/earth-engine/datasets/tags/monthly) [openet](/earth-engine/datasets/tags/openet) [water](/earth-engine/datasets/tags/water) [water-vapor](/earth-engine/datasets/tags/water-vapor) \n\n#### Description\n\nPriestley-Taylor Jet Propulsion Laboratory (PT-JPL)\n\nThe core formulation of the PT-JPL model within the OpenET framework has\nnot changed from the original formulation detailed in Fisher et al. (2008).\nHowever, enhancements and updates to model inputs and time integration for\nPT-JPL were made to take advantage of contemporary gridded weather datasets,\nprovide consistency with other models, improve open water evaporation\nestimates, and account for advection over crop and wetland areas in\nsemiarid and arid environments. These changes include the use of\nLandsat surface reflectance and thermal radiation for calculating net\nradiation, photosynthetically active radiation, plant canopy and moisture\nvariables, and use of NLDAS, Spatial CIMIS, and gridMET weather data for\nestimating insolation and ASCE reference ET. Similar to the implementation\nof other OpenET models, estimation of daily and monthly time integrated\nET is based on the fraction of ASCE reference ET. Open water evaporation\nis estimated following a surface energy balance approach of Abdelrady\net al. (2016) that is specific for water bodies by accounting for water\nheat flux as opposed to soil heat flux.\n\n[Additional information](https://openetdata.org/methodologies/)\n\n### Bands\n\n\n**Pixel Size**\n\n30 meters\n\n**Bands**\n\n| Name | Units | Pixel Size | Description |\n|---------|-------|------------|-----------------------------|\n| `et` | mm | meters | PT-JPL ET value |\n| `count` | count | meters | Number of cloud free values |\n\n### Image Properties\n\n**Image Properties**\n\n| Name | Type | Description |\n|-----------------------|--------|----------------------------------------------------------------------------------------------|\n| build_date | STRING | Date assets were built |\n| cloud_cover_max | DOUBLE | Maximum CLOUD_COVER_LAND percent value for Landsat images included in interpolation |\n| collections | STRING | List of Landsat collections for Landsat images included in the interpolation |\n| core_version | STRING | OpenET core library version |\n| end_date | STRING | End date of month |\n| et_reference_band | STRING | Band in et_reference_source that contains the daily reference ET data |\n| et_reference_resample | STRING | Spatial interpolation mode to resample daily reference ET data |\n| et_reference_source | STRING | Collection ID for the daily reference ET data |\n| interp_days | DOUBLE | Maximum number of days before and after each image date to include in interpolation |\n| interp_method | STRING | Method used to interpolate between Landsat model estimates |\n| interp_source_count | DOUBLE | Number of available images in the interpolation source image collection for the target month |\n| mgrs_tile | STRING | MGRS grid zone ID |\n| model_name | STRING | OpenET model name |\n| model_version | STRING | OpenET model version |\n| scale_factor_count | DOUBLE | Scaling factor that should be applied to the count band |\n| scale_factor_et | DOUBLE | Scaling factor that should be applied to the et band |\n| start_date | STRING | Start date of month |\n\n### Terms of Use\n\n**Terms of Use**\n\n[CC-BY-4.0](https://spdx.org/licenses/CC-BY-4.0.html)\n\n### Citations\n\nCitations:\n\n- Fisher, J.B., Tu, K.P. and Baldocchi, D.D., 2008. Global estimates of the\n land--atmosphere water flux based on monthly AVHRR and ISLSCP-II data,\n validated at 16 FLUXNET sites. Remote Sensing of Environment, 112(3),\n pp.901-919.\n [doi:10.1016/j.rse.2007.06.025](https://doi.org/10.1016/j.rse.2007.06.025)\n- Abdelrady, A., Timmermans, J., Vekerdy, Z. and Salama, M., 2016.\n Surface energy balance of fresh and saline waters: AquaSEBS. Remote\n sensing, 8(7), p.583.\n [doi:10.3390/rs8070583](https://doi.org/10.3390/rs8070583)\n\n### DOIs\n\n- \u003chttps://doi.org/10.1016/j.rse.2007.06.025\u003e\n\n### Explore with Earth Engine\n\n| **Important:** Earth Engine is a platform for petabyte-scale scientific analysis and visualization of geospatial datasets, both for public benefit and for business and government users. Earth Engine is free to use for research, education, and nonprofit use. To get started, please [register for Earth Engine access.](https://console.cloud.google.com/earth-engine)\n\n### Code Editor (JavaScript)\n\n```javascript\nvar dataset = ee.ImageCollection('OpenET/PTJPL/CONUS/GRIDMET/MONTHLY/v2_0')\n .filterDate('2020-01-01', '2021-01-01');\n\n// Compute the annual evapotranspiration (ET) as the sum of the monthly ET\n// images for the year.\nvar et = dataset.select('et').sum();\n\nvar visualization = {\n min: 0,\n max: 1400,\n palette: [\n '9e6212', 'ac7d1d', 'ba9829', 'c8b434', 'd6cf40', 'bed44b', '9fcb51',\n '80c256', '61b95c', '42b062', '45b677', '49bc8d', '4dc2a2', '51c8b8',\n '55cece', '4db4ba', '459aa7', '3d8094', '356681', '2d4c6e',\n ]\n};\n\nMap.setCenter(-100, 38, 5);\n\nMap.addLayer(et, visualization, 'OpenET PT-JPL Annual ET');\n```\n[Open in Code Editor](https://code.earthengine.google.com/?scriptPath=Examples:Datasets/OpenET/OpenET_PTJPL_CONUS_GRIDMET_MONTHLY_v2_0) \n[OpenET PT-JPL Monthly Evapotranspiration v2.0](/earth-engine/datasets/catalog/OpenET_PTJPL_CONUS_GRIDMET_MONTHLY_v2_0) \nPriestley-Taylor Jet Propulsion Laboratory (PT-JPL) The core formulation of the PT-JPL model within the OpenET framework has not changed from the original formulation detailed in Fisher et al. (2008). However, enhancements and updates to model inputs and time integration for PT-JPL were made to take advantage of contemporary gridded weather ... \nOpenET/PTJPL/CONUS/GRIDMET/MONTHLY/v2_0, evapotranspiration,gridmet-derived,landsat-derived,monthly,openet,water,water-vapor \n1999-10-01T00:00:00Z/2024-12-01T00:00:00Z \n25 -126 50 -66 \nGoogle Earth Engine \nhttps://developers.google.com/earth-engine/datasets\n\n- [https://doi.org/10.1016/j.rse.2007.06.025](https://doi.org/https://openetdata.org/)\n- [https://doi.org/10.1016/j.rse.2007.06.025](https://doi.org/https://developers.google.com/earth-engine/datasets/catalog/OpenET_PTJPL_CONUS_GRIDMET_MONTHLY_v2_0)"]]
