يوفّر المنتج MYD13Q1 V6.1 قيمة مؤشر الغطاء النباتي (VI) لكل بكسل. هناك طبقتان أساسيتان من الغطاء النباتي.
أولاً، مؤشر الاختلاف النباتي القياسي (NDVI)
الذي يُشار إليه كمؤشر استمرارية لمؤشر الاختلاف النباتي القياسي (NDVI) الحالي المستمد من جهاز قياس الإشعاع المتقدّم ذي الدقة العالية جدًا (AVHRR) التابع للإدارة الوطنية للمحيطات والغلاف الجوي (NOAA). طبقة الغطاء النباتي الثانية هي "مؤشر الغطاء النباتي المحسّن" (EVI) الذي يقلّل من الاختلافات في خلفية الغطاء النباتي ويحافظ على حساسيته في ظروف الغطاء النباتي الكثيف.
يستخدم مؤشر EVI أيضًا النطاق الأزرق لإزالة التلوّث المتبقّي في الغلاف الجوي
الناجم عن الدخان والسحب الرقيقة التي تقلّ عن البكسل. يتم احتساب منتجات MODIS NDVI وEVI من الانعكاسات ثنائية الاتجاه على السطح التي تم تصحيحها جويًا وتم إخفاء المياه والسحب والهباء الجوي الكثيف وظلال السحب فيها.
يوفر المنتج MYD13Q1 V6.1 قيمة مؤشر الغطاء النباتي (VI) على أساس كل بكسل. هناك طبقتان أساسيتان من الغطاء النباتي. أولاً، مؤشر الاختلاف النباتي القياسي (NDVI) الذي يُشار إليه باسم مؤشر الاستمرارية في "الإدارة الوطنية للمحيطات والغلاف الجوي" (NOAA) و"مقياس الإشعاع المتقدّم ذو الدقة العالية جدًا" (AVHRR) الحاليين…
[null,null,[],[[["\u003cp\u003eThe MYD13Q1 V6.1 product provides Vegetation Index (VI) values, including NDVI and EVI, at a 250-meter resolution.\u003c/p\u003e\n"],["\u003cp\u003eThis dataset, derived from the MODIS sensor on the Aqua satellite, offers global coverage with 16-day intervals.\u003c/p\u003e\n"],["\u003cp\u003eIt includes quality assessment bands and surface reflectance bands for red, near-infrared, blue, and middle-infrared wavelengths.\u003c/p\u003e\n"],["\u003cp\u003eData is freely available from 2002-07-04 to 2024-11-08 with no restrictions on use, sale, or redistribution.\u003c/p\u003e\n"],["\u003cp\u003eUsers can access and analyze this dataset using Google Earth Engine.\u003c/p\u003e\n"]]],["The MYD13Q1 V6.1 dataset, provided by NASA LP DAAC, offers 16-day global vegetation index values from 2002-07-04 to 2025-01-25. It includes the Normalized Difference Vegetation Index (NDVI) and the Enhanced Vegetation Index (EVI), calculated from atmospherically corrected surface reflectance. Data is available at a 250-meter pixel size and includes quality assessment layers and surface reflectance bands. The data can be accessed through Google Earth Engine. There are no use restrictions.\n"],null,["# MYD13Q1.061 Aqua Vegetation Indices 16-Day Global 250m\n\nDataset Availability\n: 2002-07-04T00:00:00Z--2025-08-05T00:00:00Z\n\nDataset Provider\n:\n\n\n [NASA LP DAAC at the USGS EROS Center](https://doi.org/10.5067/MODIS/MYD13Q1.061)\n\nCadence\n: 16 Days\n\nTags\n:\n [16-day](/earth-engine/datasets/tags/16-day) [aqua](/earth-engine/datasets/tags/aqua) [evi](/earth-engine/datasets/tags/evi) [global](/earth-engine/datasets/tags/global) [modis](/earth-engine/datasets/tags/modis) [nasa](/earth-engine/datasets/tags/nasa) [ndvi](/earth-engine/datasets/tags/ndvi) [usgs](/earth-engine/datasets/tags/usgs) [vegetation](/earth-engine/datasets/tags/vegetation) [vegetation-indices](/earth-engine/datasets/tags/vegetation-indices) \nmyd13q1 \n\n#### Description\n\nThe MYD13Q1 V6.1 product provides a Vegetation Index (VI)\nvalue at a per pixel basis. There are two primary vegetation layers.\nThe first is the Normalized Difference Vegetation Index (NDVI)\nwhich is referred to as the continuity index to the existing National\nOceanic and Atmospheric Administration-Advanced Very High Resolution\nRadiometer (NOAA-AVHRR) derived NDVI. The second vegetation layer\nis the Enhanced Vegetation Index (EVI) that minimizes canopy background\nvariations and maintains sensitivity over dense vegetation conditions.\nThe EVI also uses the blue band to remove residual atmosphere contamination\ncaused by smoke and sub-pixel thin cloud clouds. The MODIS NDVI\nand EVI products are computed from atmospherically corrected bi-directional\nsurface reflectances that have been masked for water, clouds, heavy\naerosols, and cloud shadows.\n\nDocumentation:\n\n- [User's Guide](https://lpdaac.usgs.gov/documents/103/MOD13_User_Guide_V6.pdf)\n\n- [Algorithm Theoretical Basis Document (ATBD)](https://lpdaac.usgs.gov/documents/104/MOD13_ATBD.pdf)\n\n- [General Documentation](https://ladsweb.modaps.eosdis.nasa.gov/filespec/MODIS/61/MOD13A2)\n\n### Bands\n\n\n**Pixel Size**\n\n250 meters\n\n**Bands**\n\n| Name | Units | Min | Max | Scale | Pixel Size | Wavelength | Description |\n|-------------------|-------|--------|-------|--------|------------|----------------------|----------------------------------------|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|\n| `NDVI` | | -2000 | 10000 | 0.0001 | meters | None | Normalized Difference Vegetation Index |\n| `EVI` | | -2000 | 10000 | 0.0001 | meters | None | Enhanced Vegetation Index |\n| `DetailedQA` | | | | | meters | None | VI quality indicators |\n| Bitmask for DetailedQA - Bits 0-1: VI quality (MODLAND QA Bits) - 0: VI produced with good quality - 1: VI produced, but check other QA - 2: Pixel produced, but most probably cloudy - 3: Pixel not produced due to other reasons than clouds - Bits 2-5: VI usefulness - 0: Highest quality - 1: Lower quality - 2: Decreasing quality - 4: Decreasing quality - 8: Decreasing quality - 9: Decreasing quality - 10: Decreasing quality - 12: Lowest quality - 13: Quality so low that it is not useful - 14: L1B data faulty - 15: Not useful for any other reason/not processed - Bits 6-7: Aerosol Quantity - 0: Climatology - 1: Low - 2: Intermediate - 3: High - Bit 8: Adjacent cloud detected - 0: No - 1: Yes - Bit 9: Atmosphere BRDF correction - 0: No - 1: Yes - Bit 10: Mixed Clouds - 0: No - 1: Yes - Bits 11-13: Land/water mask - 0: Shallow ocean - 1: Land (nothing else but land) - 2: Ocean coastlines and lake shorelines - 3: Shallow inland water - 4: Ephemeral water - 5: Deep inland water - 6: Moderate or continental ocean - 7: Deep ocean - Bit 14: Possible snow/ice - 0: No - 1: Yes - Bit 15: Possible shadow - 0: No - 1: Yes ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||\n| `sur_refl_b01` | | 0 | 10000 | 0.0001 | meters | 645nm | Red surface reflectance |\n| `sur_refl_b02` | | 0 | 10000 | 0.0001 | meters | 858nm | NIR surface reflectance |\n| `sur_refl_b03` | | 0 | 10000 | 0.0001 | meters | 469nm | Blue surface reflectance |\n| `sur_refl_b07` | | 0 | 10000 | 0.0001 | meters | 2130nm/2105 - 2155nm | MIR surface reflectance |\n| `ViewZenith` | deg | 0 | 18000 | 0.01 | meters | None | View zenith angle |\n| `SolarZenith` | deg | 0 | 18000 | 0.01 | meters | None | Solar zenith angle |\n| `RelativeAzimuth` | deg | -18000 | 18000 | 0.01 | meters | None | Relative azimuth angle |\n| `DayOfYear` | | 1 | 366 | | meters | None | Julian day of year |\n| `SummaryQA` | | | | | meters | None | Quality reliability of VI pixel |\n| Bitmask for SummaryQA - Bits 0-1: VI quality (MODLAND QA Bits) - 0: Good data, use with confidence - 1: Marginal data, useful but look at detailed QA for more information - 2: Pixel covered with snow/ice - 3: Pixel is cloudy ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||\n\n### Terms of Use\n\n**Terms of Use**\n\nMODIS data and products acquired through the LP DAAC\nhave no restrictions on subsequent use, sale, or redistribution.\n\n### Citations\n\nCitations:\n\n- Please visit [LP DAAC 'Citing Our Data' page](https://lpdaac.usgs.gov/citing_our_data)\n for information on citing LP DAAC datasets.\n\n### DOIs\n\n- \u003chttps://doi.org/10.5067/MODIS/MYD13Q1.061\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('MODIS/061/MYD13Q1')\n .filter(ee.Filter.date('2018-01-01', '2018-05-01'));\nvar ndvi = dataset.select('NDVI');\nvar ndviVis = {\n min: 0,\n max: 8000,\n palette: [\n 'ffffff', 'ce7e45', 'df923d', 'f1b555', 'fcd163', '99b718', '74a901',\n '66a000', '529400', '3e8601', '207401', '056201', '004c00', '023b01',\n '012e01', '011d01', '011301'\n ],\n};\nMap.setCenter(6.746, 46.529, 2);\nMap.addLayer(ndvi, ndviVis, 'NDVI');\n```\n[Open in Code Editor](https://code.earthengine.google.com/?scriptPath=Examples:Datasets/MODIS/MODIS_061_MYD13Q1) \n[MYD13Q1.061 Aqua Vegetation Indices 16-Day Global 250m](/earth-engine/datasets/catalog/MODIS_061_MYD13Q1) \nThe MYD13Q1 V6.1 product provides a Vegetation Index (VI) value at a per pixel basis. There are two primary vegetation layers. The first is the Normalized Difference Vegetation Index (NDVI) which is referred to as the continuity index to the existing National Oceanic and Atmospheric Administration-Advanced Very High Resolution Radiometer ... \nMODIS/061/MYD13Q1, 16-day,aqua,evi,global,modis,nasa,ndvi,usgs,vegetation,vegetation-indices \n2002-07-04T00:00:00Z/2025-08-05T00:00:00Z \n-90 -180 90 180 \nGoogle Earth Engine \nhttps://developers.google.com/earth-engine/datasets\n\n- [https://doi.org/10.5067/MODIS/MYD13Q1.061](https://doi.org/https://doi.org/10.5067/MODIS/MYD13Q1.061)\n- [https://doi.org/10.5067/MODIS/MYD13Q1.061](https://doi.org/https://developers.google.com/earth-engine/datasets/catalog/MODIS_061_MYD13Q1)"]]
