Water States - Corrected Reflectance (MODIS / Terra)

Overview and Intended Use This visualization represents a "false color" band combination (Red = 3, Green = 6, Blue = 7) of data collected by the MODIS instrument on the NASA Terra satellite. The imagery is most useful for distinguishing water in its various states (e.g. liquid, ice, and snow). For example, clouds over snow, ice cloud versus water cloud; or floods from dense vegetation. At its highest resolution, this visualization represents the underlying data scaled to a resolution of 250m per pixel at the equator. The MODIS Corrected Reflectance product retains visible aerosols for a natural-looking visualization, though gross atmospheric effects (e.g. Rayleigh scattering) have been removed. The following guidelines will aid in understanding this visualization. See here for additional information on how this "false color" band combination highlights these physical characteristics of the Earth. Thick ice and snow appear a vivid red (or dark pink), while ice crystals in clouds will appear pinkish. Vegetation will appear green. Naturally bare soil, like a desert, will appear bright cyan. Liquid water on the ground will appear very dark, while water droplets in clouds will appear white. Sediments in water will appear dark red. Multi-Spectral Bands The following table lists the MODIS bands that are utilized to create this visualization. See here for a full description of all MODIS bands. Band Description Wavelength (µm) Resolution (m) 3 Visible (Blue) 0.459 - 0.479 500 6 Shortwave IR 1.628 - 1.652 500 7 Shortwave IR 2.105 - 2.155 500 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 the start of the mission (February 24th, 2000). 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 本可视化成果采用假彩色（false color）波段组合，其中红通道对应波段3、绿通道对应波段6、蓝通道对应波段7，数据源自NASA Terra卫星搭载的中分辨率成像光谱仪（Moderate Resolution Imaging Spectroradiometer，MODIS）。该影像在区分水的多种存在状态（如液态水、冰与积雪）方面具备优异应用价值，例如可识别积雪上空的云系、区分冰云与水云，或是区分茂密植被覆盖区与洪水区域。在最高分辨率下，本可视化成果对应的原始数据经缩放后，在赤道区域的像素分辨率可达250米。 本成果采用MODIS校正反射率产品（MODIS Corrected Reflectance）生成，该产品保留了可见气溶胶以呈现自然的可视化效果，同时已去除显著的大气影响（如瑞利散射（Rayleigh scattering））。以下说明将帮助您理解本可视化成果，点击此处可获取更多关于该假彩色波段组合如何凸显地球物理特征的详细信息： 厚层冰与积雪呈鲜艳红色（或深粉色），云层中的冰晶则呈偏粉色；植被呈现绿色；自然裸露的土壤（如沙漠）呈亮青色；地面液态水颜色极深，而云层中的水滴呈白色；水体中的沉积物呈暗红色。 多光谱波段 下表列出了用于生成本可视化成果的MODIS波段，点击此处可查看所有MODIS波段的完整说明： | 波段 | 描述 | 波长（μm） | 分辨率（m） | | ---- | ---- | ---------- | ---------- | | 3 | 可见光（蓝光波段） | 0.459 - 0.479 | 500 | | 6 | 短波红外 | 1.628 - 1.652 | 500 | | 7 | 短波红外 | 2.105 - 2.155 | 500 | 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用的最新影像。影像的更新频率为每日合成产品（daily composite），由数百份独立数据文件拼接而成。当查看“今日”影像时，您可能会发现地图仅部分区域有影像，这是因为可视化成果会随着卫星收集到更多数据而持续更新。若要查看随时间变化的影像，您可以更新图层属性以启用时间动画功能，并配置时间相关设置。本图层的可获取时间范围为自任务启动之日（2000年2月24日）起至今。 数据来源：NASA全球影像浏览服务（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，可为数百项NASA地球科学数据集与科学参数提供全球全分辨率卫星影像。通过其服务与NASA Worldview客户端，GIBS可为广大用户提供NASA地球影像的交互式探索功能。依托NASA LANCE技术，数据与影像可在采集后的3小时内完成生成。 Esri与NASA联合服务 本可视化成果通过部署在Esri服务器上的ArcGIS影像服务提供，可帮助用户便捷访问NASA GIBS服务端点。针对每一次影像服务请求，Esri服务器会向GIBS服务发起多次请求，对响应结果进行处理与拼接后，向用户返回完整的镶嵌影像。每一次请求都会实时进行处理，以确保GIBS影像的任何更新都能立即向用户开放。因此，本可视化成果的可用性同时取决于Esri与NASA GIBS两项服务的运行状态。