MODIS Land Cover Product Algorithm Theoretical Basis Document (ATBD) Version 5.0
MODIS Land Cover Product Algorithm Theoretical Basis Document (ATBD) Version 5.0
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发表时间：
1994
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通讯作者：
A. Strahler
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作者：
A. Strahler
本文详细介绍了MODIS土地覆盖产品的结构定义、开发流程和功能流程。土地覆盖和土地覆盖变化参数是由MODIS土地小组提出的，小组成员艾伦·斯特拉勒领导这项工作。土地覆盖参数是在1999年7月EOS-A平台(TERRA)上的MODIS仪器获取全球数据集后大约一年开始按季度提供的1公里产品。土地覆盖变化参数是发射后的近期参数，也计划按季度交付。这两个参数都依赖于由MODIS 2级和3级产品组成的1公里网格数据库。输入内容包括：(1)EOS陆地/水域掩模，将分类限于陆地区域和浅水区域；(2)MODIS陆地波段(1-7)中MODIS BRDF/Albedo产品(MOD43B4)的Nadir BRDF调整反射率(NBAR)，在每16天周期的中值太阳角度调整为最低视角；(3)从1000米分辨率的波段1(红色，250米)获得的空间纹理(MODAGTEX)；(4)16天周期1k的定向反射率信息(MOD43B1)；(5)MODIS增强植被指数(EVI)16天(MOD13)；(6)海拔500米积雪8天(MOD10)；(7)陆地表面温度1公里(MOD11)；以及(8)地形高度信息(MOD03)。这些数据在一个月的时间内被合成，以在1公里网格上产生一个全球一致的多时态数据库，作为分类和变化表征算法的输入。土地覆盖参数识别遵循国际地圈-生物圈计划(IGBP)的17类土地覆盖。这套覆盖类型包括按生命形式划分的11类自然植被覆盖，3类开发和镶嵌土地，3类非植被土地。利用决策树和人工神经网络分类算法对32天的数据库进行处理，根据训练数据分配土地覆盖类别，从而生成土地覆盖类别。为了减少计算开销并增加灵活性，分类按大洲进行。土地覆盖变化1公里参数旨在量化微妙和渐进的地表变化，即土地覆盖的变化，以及明显和瞬时的变化，如土地覆盖的转换。因此，它不是一个传统的变化产品，简单地比较两个不同时间的土地覆盖数据库，并确定分类土地覆盖的变化。土地覆盖变化参数的算法将多光谱-多时相数据向量的变化分析与植被变化机制模型相结合，以识别变化的类型和强度。土地覆盖产品的算法开发和验证工作基于为代表主要的全球生物群落和覆盖类型而开发的测试地点网络。发射前的工作侧重于可获得专题测绘仪(TM)和高级甚高分辨率辐射计(AVHRR)数据的时间序列以及高分辨率土地覆盖和植被数据的地点，特别是在北美和南美洲。在启动后期间，将使用一套全球站点来培训分类器并验证其输出。LANDSAT-7和ASTER图像将对MOD12 ATBD版本5.0-5/1/99特别有用，用于更新有关试验场的信息和确定本地变化过程。验证程序将确定产品的准确性，并提供可用于空间聚合的信息，以便以较粗的分辨率提供土地复盖和土地复盖变化数据。土地覆盖参数产品将在购买特定地区一年的32天合成数据后大约三个月发布。随着投入产品的全球生产，将实现全球土地复盖的全面生产。在此期间，将生产一批土地覆盖产品的原型。土地覆盖变化参数需要两年的数据，将同样分阶段实施，临时原型将在发射后的早期阶段提供。
This document details the structural definition, development process, and functional flow of the MODIS Land-Cover Product. The Land Cover and Land-Cover Change Parameters were proposed by the MODIS Land Team, with Team Member Alan Strahler leading the effort. The Land Cover Parameter is a 1-km product provided on a quarterly basis beginning about one year following the acquisition of a global dataset by the MODIS instrument aboard the EOS-A platform (Terra) in July, 1999. The Land-Cover Change Parameter is a post-launch, near-term parameter also planned for quarterly delivery. Both parameters rely on a 1-km gridded database composited from MODIS Level 2 and 3 products. Inputs include: (1) EOS land/water mask that restricts classification to land regions and shallow water regions; (2) Nadir BRDF-adjusted Reflectances (NBARs) derived from the MODIS BRDF/Albedo product (MOD43B4) in the MODIS Land Bands (1-7), adjusted to nadir view at the median sun angle of each 16-day period; (3) spatial texture derived from Band 1 (red, 250-meter) at 1000-m resolution MODAGTEX); (4) directional reflectance information at 1k for 16-day periods (MOD43B1); (5) MODIS Enhanced Vegetation Index (EVI) at 1km for 16-day periods (MOD13); (6) snow cover at 500m for 8-day periods (MOD10); (7) land surface temperature at 1 km for 8-day periods (MOD11); and (8) terrain elevation information (MOD03). These data are composited over a one-month time period to produce a globally-consistent, multitemporal database on a 1-km grid as input to classification and change characterization algorithms. The Land Cover Parameter recognizes 17 categories of land cover following the International Geosphere-Biosphere Program (IGBP) scheme. This set of cover types includes eleven categories of natural vegetation covers broken down by life form, three classes of developed and mosaic lands, and three classes of non-vegetated lands. Land cover classes are produced by processing the 32-day database using decision tree and artificial neural network classification algorithms to assign land cover classes based on training data. To reduce computational overhead and increase flexibility, classification proceeds by continents. The Land-Cover Change 1-km Parameter is designed to quantify subtle and progressive land-surface transformations, i.e., land cover modifications, as well as obvious and instantaneous changes, such as land cover conversions. As such, it is not a conventional change product that simply compares land cover databases at two different times and identifies changes in categorical land cover. The algorithm for the Land-Cover Change Parameter combines analyses of change in multispectral-multitemporal data vectors with models of vegetation change mechanisms to recognize both the type of change as well as its intensity. The algorithm development and validation efforts for the Land Cover Product are based on a network of test sites developed to represent major global biomes and cover types. Prelaunch efforts have focused on sites for which temporal sequences of Thematic Mapper (TM) and Advanced Very High Resolution Radiometer (AVHRR) data, coupled with fine-resolution land cover and vegetation data, are available, especially in North and South America. In the postlaunch period, a global suite of sites will be used to train the classifier and validate its output. Landsat-7 and ASTER images will be particularly useful MOD12 ATBD Version 5.0—5/1/99 for updating information about test sites and identifying local change processes. The validation procedure will characterize the accuracy of the product as well as provide information that can be used in spatial aggregation to provide land cover and land-cover change data at coarser resolutions. Land Cover Parameter products will be released about three months after the acquisition of a year of 32-day composites for a given region. Full global production of land cover will be reached as global production of input products is achieved. In the interim, a number of prototype land cover products will be produced. The Land-Cover Change Parameter, which requires two years of data, will be similarly phased in, with interim prototypes made available in the early-postlaunch period.