Mosaik PALSAR/PALSAR-2 25 m global adalah gambar SAR global yang mulus yang dibuat dengan menggabungkan strip gambar SAR dari PALSAR/PALSAR-2. Untuk setiap tahun dan lokasi, data strip dipilih melalui pemeriksaan visual pada mozaik penjelajahan yang tersedia selama periode tersebut, dengan mozaik yang menunjukkan respons minimum terhadap kelembapan permukaan yang lebih disukai. Dalam kasus
ketika ketersediaan terbatas (misalnya, karena persyaratan
untuk pengamatan selama keadaan darurat tertentu), data harus
dipilih dari tahun sebelumnya atau sesudahnya, termasuk dari tahun 2006.
Shimada et al. 2014
Tidak ada data untuk tahun 2011-2014 karena kesenjangan antara cakupan temporal ALOS dan ALOS-2.
Gambar SAR diortorektifikasi dan dikoreksi kemiringannya
menggunakan Model Ketinggian Digital SRTM 90 m.
Proses penghilangan garis (Shimada & Isoguchi, 2002, 2010) diterapkan untuk menyamakan perbedaan intensitas antara garis yang berdekatan, yang sebagian besar terjadi karena perbedaan musiman dan harian dalam kondisi kelembapan permukaan.
Data polarisasi disimpan sebagai angka digital (DN) 16-bit.
Nilai DN dapat dikonversi menjadi nilai gamma nol dalam satuan desibel (dB) menggunakan persamaan berikut:
γ₀ = 10log₁₀(DN²) - 83,0 dB
Perhatian:
Nilai hamburan balik dapat sangat bervariasi dari jalur ke jalur di area hutan lintang tinggi. Hal ini disebabkan oleh perubahan intensitas hamburan balik yang disebabkan oleh pohon yang membeku di musim dingin.
Koefisien hamburan balik polarisasi HH, DN 16-bit.
HV
meter
Koefisien hamburan balik polarisasi HV, DN 16-bit.
angle
deg
meter
Sudut datang lokal.
date
meter
Tanggal observasi (hari sejak 1 Januari 1970).
qa
meter
Memproses informasi.
qa Class Table
Nilai
Warna
Deskripsi
0
#000000
Tidak ada data
50
#0000ff
Lautan dan air
100
#aaaa00
Transit radar
150
#005555
Bayangan radar
255
#aa9988
Daratan
Persyaratan Penggunaan
Persyaratan Penggunaan
JAXA mempertahankan kepemilikan set data dan tidak dapat menjamin masalah apa pun yang disebabkan oleh atau mungkin disebabkan oleh penggunaan set data.
Siapa pun yang ingin memublikasikan hasil apa pun menggunakan set data harus
dengan jelas mengakui kepemilikan data dalam publikasi tersebut.
Kutipan
Kutipan:
Masanobu Shimada, Takuya Itoh, Takeshi Motooka, Manabu Watanabe,
Shiraishi Tomohiro, Rajesh Thapa, dan Richard Lucas, "New Global
Forest/Non-forest Maps from ALOS PALSAR Data (2007-2010)", Remote Sensing
of Environment, 155, hlm. 13-31, Desember 2014.
doi:10.1016/j.rse.2014.04.014.
Versi terbaru set data ini dengan data untuk tahun 2015-2021 dapat ditemukan di JAXA/ALOS/PALSAR/YEARLY/SAR_EPOCH Mosaik PALSAR/PALSAR-2 25 m global adalah gambar SAR global yang lancar dan dibuat dengan menggabungkan strip gambar SAR dari PALSAR/PALSAR-2. Untuk setiap tahun dan lokasi, data strip dipilih melalui pemeriksaan visual terhadap …
[null,null,[],[[["\u003cp\u003eThe JAXA/ALOS/PALSAR/YEARLY/SAR dataset provides a global 25m resolution mosaic of PALSAR/PALSAR-2 SAR imagery from 2007-2020, excluding 2011-2014.\u003c/p\u003e\n"],["\u003cp\u003eThe dataset includes HH and HV polarization backscattering coefficients, local incidence angle, observation date, and processing information bands.\u003c/p\u003e\n"],["\u003cp\u003eImagery was orthorectified, slope corrected, and destriped to minimize intensity differences between neighboring strips.\u003c/p\u003e\n"],["\u003cp\u003eDN values can be converted to gamma naught values (dB) using the equation: γ₀ = 10log₁₀(DN²) - 83.0 dB.\u003c/p\u003e\n"],["\u003cp\u003eBackscatter values may vary over high latitude forests due to seasonal changes in tree freezing.\u003c/p\u003e\n"]]],[],null,["# Global PALSAR-2/PALSAR Yearly Mosaic, version 1\n\nDataset Availability\n: 2007-01-01T00:00:00Z--2020-01-01T00:00:00Z\n\nDataset Provider\n:\n\n\n [JAXA EORC](https://www.eorc.jaxa.jp/ALOS/en/dataset/fnf_e.htm)\n\nTags\n:\n[alos](/earth-engine/datasets/tags/alos) [alos2](/earth-engine/datasets/tags/alos2) [eroc](/earth-engine/datasets/tags/eroc) [jaxa](/earth-engine/datasets/tags/jaxa) [palsar](/earth-engine/datasets/tags/palsar) [palsar2](/earth-engine/datasets/tags/palsar2) [sar](/earth-engine/datasets/tags/sar) [satellite-imagery](/earth-engine/datasets/tags/satellite-imagery) \n\n#### Description\n\nA newer version of this dataset with data for 2015-2021 can be found in\n[JAXA/ALOS/PALSAR/YEARLY/SAR_EPOCH](/earth-engine/datasets/catalog/JAXA_ALOS_PALSAR_YEARLY_SAR_EPOCH)\n\nThe global 25m PALSAR/PALSAR-2 mosaic is a seamless global\nSAR image created by mosaicking strips of SAR imagery\nfrom PALSAR/PALSAR-2. For each year and location,\nthe strip data were selected through visual inspection of the\nbrowse mosaics available over the period, with those showing minimum\nresponse to surface moisture preferentially used. In cases\nwhere the availability was limited (e.g., because of the requirement\nfor observations during specific emergencies), data were necessarily\nselected from the year before or after, including from 2006.\n[Shimada et al. 2014](https://doi.org/10.1016/j.rse.2014.04.014)\n\nThere is no data for 2011-2014 due to the gap between ALOS and ALOS-2\ntemporal coverage.\n\nThe SAR imagery was ortho-rectificatied and slope corrected\nusing the 90m SRTM Digital Elevation Model.\nA destriping process (Shimada \\& Isoguchi, 2002, 2010) was applied\nto equalize the intensity differences between neighboring strips,\noccurring largely due to seasonal and daily differences\nin surface moisture conditions.\n\nPolarization data are stored as 16-bit digital numbers (DN).\nThe DN values can be converted to gamma naught values\nin decibel unit (dB) using the following equation:\n\n- γ₀ = 10log₁₀(DN²) - 83.0 dB\n\nAttention:\n\n- Backscatter values may vary significantly from path to path over high latitude forest areas. This is due to the change of backscattering intensity caused by freezing trees in winter.\n\nMore information is available in the provider's\n[Dataset Description](https://www.eorc.jaxa.jp/ALOS/en/palsar_fnf/DatasetDescription_PALSAR2_Mosaic_FNF_revH.pdf).\n\n### Bands\n\n\n**Pixel Size**\n\n25 meters\n\n**Bands**\n\n| Name | Units | Pixel Size | Description |\n|---------|-------|------------|--------------------------------------------------------|\n| `HH` | | meters | HH polarization backscattering coefficient, 16-bit DN. |\n| `HV` | | meters | HV polarization backscattering coefficient, 16-bit DN. |\n| `angle` | deg | meters | Local incidence angle. |\n| `date` | | meters | Observation date (days since Jan 1, 1970). |\n| `qa` | | meters | Processing information. |\n\n**qa Class Table**\n\n| Value | Color | Description |\n|-------|---------|-----------------|\n| 0 | #000000 | No data |\n| 50 | #0000ff | Ocean and water |\n| 100 | #aaaa00 | Radar layover |\n| 150 | #005555 | Radar shadowing |\n| 255 | #aa9988 | Land |\n\n### Terms of Use\n\n**Terms of Use**\n\nJAXA retains ownership of the dataset and cannot guarantee\nany problem caused by or possibly caused by using the datasets.\nAnyone wishing to publish any results using the datasets should\nclearly acknowledge the ownership of the data in the publication.\n\n### Citations\n\nCitations:\n\n- Masanobu Shimada, Takuya Itoh, Takeshi Motooka, Manabu Watanabe,\n Shiraishi Tomohiro, Rajesh Thapa, and Richard Lucas, \"New Global\n Forest/Non-forest Maps from ALOS PALSAR Data (2007-2010)\", Remote Sensing\n of Environment, 155, pp. 13-31, December 2014.\n [doi:10.1016/j.rse.2014.04.014.](https://doi.org/10.1016/j.rse.2014.04.014)\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('JAXA/ALOS/PALSAR/YEARLY/SAR')\n .filter(ee.Filter.date('2017-01-01', '2018-01-01'));\nvar sarHh = dataset.select('HH');\nvar sarHhVis = {\n min: 0.0,\n max: 10000.0,\n};\nMap.setCenter(136.85, 37.37, 4);\nMap.addLayer(sarHh, sarHhVis, 'SAR HH');\n```\n[Open in Code Editor](https://code.earthengine.google.com/?scriptPath=Examples:Datasets/JAXA/JAXA_ALOS_PALSAR_YEARLY_SAR) \n[Global PALSAR-2/PALSAR Yearly Mosaic, version 1](/earth-engine/datasets/catalog/JAXA_ALOS_PALSAR_YEARLY_SAR) \nA newer version of this dataset with data for 2015-2021 can be found in JAXA/ALOS/PALSAR/YEARLY/SAR_EPOCH The global 25m PALSAR/PALSAR-2 mosaic is a seamless global SAR image created by mosaicking strips of SAR imagery from PALSAR/PALSAR-2. For each year and location, the strip data were selected through visual inspection of the ... \nJAXA/ALOS/PALSAR/YEARLY/SAR, alos,alos2,eroc,jaxa,palsar,palsar2,sar,satellite-imagery \n2007-01-01T00:00:00Z/2020-01-01T00:00:00Z \n-90 -180 90 180 \nGoogle Earth Engine \nhttps://developers.google.com/earth-engine/datasets\n\n- [](https://doi.org/https://www.eorc.jaxa.jp/ALOS/en/dataset/fnf_e.htm)\n- [](https://doi.org/https://developers.google.com/earth-engine/datasets/catalog/JAXA_ALOS_PALSAR_YEARLY_SAR)"]]
