True Color - Corrected Reflectance (VIIRS / Suomi-NPP)

Overview and Intended Use This visualization represents a "true color" band combination (Red = I1, Green = M4, Blue = M3) of data collected by the VIIRS instrument on the joint NASA/NOAA Suomi-NPP satellite. The imagery is most similar to how we see the Earth’s surface with our own eyes. It is a natural looking image that is useful at a global and regional scale. At its highest resolution, this visualization represents the underlying data scaled to a resolution of 250m per pixel at the equator. The VIIRS Corrected Reflectance product provides natural-looking images by removing gross atmospheric effects such as Rayleigh scattering from the visible bands. By contrast the VIIRS Surface Reflectance product, also available in the Living Atlas, provides a more complete atmospheric correction algorithm that includes aerosol correction and is designed to derive land surface properties. In clear atmospheric conditions the Corrected Reflectance product is similar to the Surface Reflectance product, but they depart from each other in the presence of aerosols. Multi-Spectral Bands The following table lists the VIIRS bands that are utilized to create this visualization. See here for a full description of all VIIRS bands. Band Description Wavelength (µm) Resolution (m) I3 Shortwave IR (Red) 1.58 - 1.64 375 M3 Visible / Reflective 0.478 - 0.488 750 M4 Visible / Reflective 0.545 - 0.565 750 Temporal Coverage and Limitations of Use By default, this layer will display the imagery currently available for today’s date. The update frequency of the imagery is a "daily composite" that is assembled from hundreds of individual data files. When viewing imagery for “today,” you may notice that only a portion of the map has imagery. This is because the visualization is continually updated as the satellite collects more data. To view imagery over time, you can update the layer properties to enable time animation and configure time settings. The current version of this layer is available from present back to November 24th, 2015. In the coming months, this will be extended to the start of the mission (October 28th, 2011). Source: NASA Global Imagery Browse Services (GIBS), NASA Worldview, & NASA LANCE This visualization is provided through the NASA Global Imagery Browse Services (GIBS), which are a set of standard services to deliver global, full-resolution satellite imagery for hundreds of NASA Earth science datasets and science parameters. Through its services, and the NASA Worldview client, GIBS enables interactive exploration of NASA's Earth imagery for a broad range of users. The data and imagery are generated within 3 hours of acquisition through the NASA LANCE capability. Esri and NASA Collaborative Services This visualization is made available through an ArcGIS image service hosted on Esri servers and facilitates access to a NASA GIBS service endpoint. For each image service request, the Esri server issues multiple requests to the GIBS service, processes and assembles the responses, and returns a proper mosaic image to the user. Processing occurs on-the-fly for each and every request to ensure that any update to the GIBS imagery is immediately available to the user. As such, availability of this visualization is dependent on both the Esri and the NASA GIBS services.### 概述与适用场景 本可视化成果展示了NASA与NOAA联合研制的Suomi-NPP卫星搭载的VIIRS（可见光红外成像辐射仪，Visible Infrared Imaging Radiometer Suite）仪器采集的多波段数据，采用“真彩色”波段组合方案（红通道对应I1波段，绿通道对应M4波段，蓝通道对应M3波段）。该影像高度还原人类肉眼所见的地球地表风貌，属于自然色彩影像，适用于全球及区域尺度的观测与分析。在最高分辨率模式下，该可视化成果的原始数据在赤道处的像素分辨率可达250米。 VIIRS校正反射率产品通过移除可见光波段中的瑞利散射等显著大气干扰，生成自然色彩的影像。与之相对，同样可在Living Atlas平台获取的VIIRS地表反射率产品则采用了更完整的大气校正算法，包含气溶胶校正环节，旨在精准反演陆地地表属性。在大气洁净的场景下，校正反射率产品与地表反射率产品效果相近，但在存在气溶胶的场景下二者会出现显著差异。 ### 多光谱波段 下表列出了用于生成本可视化成果的VIIRS波段，可点击此处查看所有VIIRS波段的完整技术说明。 | 波段编号 | 波段描述 | 波长范围（μm） | 空间分辨率（m） | |----------|----------|---------------|----------------| | I3 | 短波红外（红色通道） | 1.58–1.64 | 375 | | M3 | 可见光/反射波段 | 0.478–0.488 | 750 | | M4 | 可见光/反射波段 | 0.545–0.565 | 750 | ### 时间覆盖范围与使用限制 默认情况下，该图层将显示当前日期可获取的最新影像。该影像采用每日合成模式更新，由数百份独立数据文件拼接而成。当查看“今日”影像时，您可能仅能看到地图部分区域有影像，这是因为该可视化成果会随着卫星收集到更多数据而持续更新。若需查看不同时段的影像，可通过更新图层属性启用时间动画功能并配置时间参数。 当前版本的该图层可获取的影像回溯至2015年11月24日，未来数月内，可获取的影像将扩展至任务启动之日（2011年10月28日）。 ### 数据来源 NASA全球影像浏览服务（NASA Global Imagery Browse Services, GIBS）、NASA Worldview及NASA LANCE。 本可视化成果由NASA全球影像浏览服务（GIBS）提供，该服务是一套标准化服务体系，可为数百项NASA地球科学数据集及科学参数提供全球全分辨率卫星影像。通过该服务及NASA Worldview客户端，GIBS可为广大用户提供NASA地球影像的交互式浏览功能。依托NASA LANCE系统，卫星数据采集后3小时内即可生成相关数据与影像。 ### Esri与NASA合作服务 本可视化成果通过部署在Esri服务器上的ArcGIS影像服务提供，可便捷调用NASA GIBS服务端点。每一次影像服务请求中，Esri服务器都会向GIBS服务发起多项请求，对返回结果进行处理与拼接后，向用户返回完整的镶嵌影像。所有请求均实时处理，以确保GIBS影像的任何更新都能立即对用户可见。因此，本可视化成果的可用性同时依赖于Esri服务与NASA GIBS服务。