MODIS数据介绍
Modis目前主要存在于两颗卫星上：TERRA和AQUA。
TERRA卫星每日地方时上午10:30时过境，因此也称作地球观测第一颗上午星（EOS-AM1）
AQUA每日地方时下午过境，因此称作地球观测第一颗下午星(EOS-PM1)。
获取36个波段的数据
MODIS获取数据的原始分辨率包括三类：波段1–2 – 250m、波段3–7 – 500m、波段8–36-1000m
其产品的分辨率包括四类: 250m, 500m, 1000m, 以及5600m (0.05度)。
大多数标准MODIS产品使用的时正弦投影，在赤道处是10° 10°的格网，行代号由左上角(0, 0)起始，到右下角(35, 17)
MOD13Q1官网数据说明
https://ladsweb.modaps.eosdis.nasa.gov/missions-and-measurements/products/MOD13Q1
MODIS NDVI和EVI产品是根据经过大气校正的双向表面反射率计算得出的，该反射率已针对水，云，重气溶胶和云影进行了屏蔽。
每16天以250米的空间分辨率提供正弦投影中的全球MOD13Q1数据，作为grid L3级产品。
通过用历史MODIS时间序列气候记录代替云，可以实现全球无云覆盖。 植被指数用于全球植被状况监测，并用于显示土地覆盖和土地覆盖变化的产品。
MOD09A1官网数据说明
https://ladsweb.modaps.eosdis.nasa.gov/missions-and-measurements/products/MOD09A1
MOD09A1在正弦投影的8天网格3级产品中以500米的分辨率提供1-7波段。 每个MOD09A1像素均包含8天的最佳L2G观测结果，这是根据高观测范围，低视角，不存在云或云影以及气溶胶负载选择的。 为此产品提供的科学数据集包括1-7波段的反射率值，质量保证评估以及像素的一年中的某天以及太阳角，视角和天顶角。
MOD09Q1 - MODIS/Terra Surface Reflectance 8-Day L3 Global 250m SIN Grid
https://ladsweb.modaps.eosdis.nasa.gov/missions-and-measurements/products/MOD09Q1
The MODIS Surface Reflectance products provide an estimate of the surface spectral reflectance as it would be measured at ground level in the absence of atmospheric scattering or absorption. Low-level data are corrected for atmospheric gases and aerosols, yielding a level-2 basis for several higher-order gridded level-2 (L2G) and level-3 products.
MOD09Q1 provides Bands 1 and 2 at 250-meter resolution in an 8-day gridded level-3 product in the Sinusoidal projection. Each MOD09Q1 pixel contains the best possible L2G observation during an 8-day period as selected on the basis of high observation coverage, low view angle, the absence of clouds or cloud shadow, and aerosol loading. Science Data Sets provided for this product include reflectance values for Bands 1 and 2, and a quality assurance rating.
Collection-5 MODIS/Terra Surface Reflectance products are Validated Stage 2, meaning that accuracy has been assessed over a widely distributed set of locations and time periods via several ground-truth and validation efforts. Although there may be later improved versions, these data are ready for use in scientific publications.
MOD09Q1在正弦投影的8天网格3级产品中以250米的分辨率提供波段1和波段2。每个MOD09Q1像素均包含8天的最佳L2G观测值，这是根据高观测覆盖率，低视角，不存在云或云影以及气溶胶负载选择的。为此产品提供的科学数据集包括波段1和波段2的反射率值以及质量保证等级。
MOD09A1 - MODIS/Terra Surface Reflectance 8-Day L3 Global 500m SIN Grid
https://ladsweb.modaps.eosdis.nasa.gov/missions-and-measurements/products/MOD09A1
The MODIS Surface Reflectance products provide an estimate of the surface spectral reflectance as it would be measured at ground level in the absence of atmospheric scattering or absorption. Low-level data are corrected for atmospheric gases and aerosols, yielding a level-2 basis for several higher-order gridded level-2 (L2G) and level-3 products.
MOD09A1 provides Bands 1-7 at 500-meter resolution in an 8-day gridded level-3 product in the Sinusoidal projection. Each MOD09A1 pixel contains the best possible L2G observation during an 8-day period as selected on the basis of high observation coverage, low view angle, the absence of clouds or cloud shadow, and aerosol loading. Science Data Sets provided for this product include reflectance values for Bands 1-7, quality assurance assessment, and the day of the year for the pixel along with solar, view, and zenith angles.
Collection-5 MODIS/Terra Surface Reflectance products are Validated Stage 2, meaning that accuracy has been assessed over a widely distributed set of locations and time periods via several ground-truth and validation efforts. Although there may be later improved versions, these data are ready for use in scientific publications.
MODIS表面反射率产品提供了表面光谱反射率的估计值，因为它将在没有大气散射或吸收的情况下在地面上进行测量。对大气气体和气溶胶的低水平数据进行了校正，从而为几种高阶网格2级（L2G）和3级产品提供了2级基础。
MOD09A1在正弦投影的8天网格3级产品中以500米的分辨率提供1-7波段。每个MOD09A1像素均包含8天的最佳L2G观测结果，这是根据高观测范围，低视角，不存在云或云影以及气溶胶负载选择的。为此产品提供的科学数据集包括1-7波段的反射率值，质量保证评估以及像素的一年中的某天以及太阳角，视角和天顶角。
Collection-5 MODIS / Terra表面反射率产品已通过验证阶段2，这意味着已通过数项真实的事实和验证工作在广泛分布的位置和时间段内评估了准确性。尽管以后可能会有改进的版本，但这些数据已准备好在科学出版物中使用。