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MOD11A2地表温度产品的质量评价图层分析
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MOD11A2地表温度产品的质量评价图层
质量评价的标识代码如下
bits | Long Name | Key |
1 & 0 | Mandatory QA flags | 00=LST produced, good quality, not necessary to examine more detailed QA 01=LST produced, other quality, recommend examination of more detailed QA 10=LST not produced due to cloud effects 11=LST not produced primarily due to reasons other than cloud |
3 & 2 | Data quality flag | 00=good data quality 01=other quality data 10=TBD 11=TBD |
5 & 4 | Emis Error flag | 00=average emissivity error <= 0.01 01=average emissivity error <= 0.02 10=average emissivity error <= 0.04 11=average emissivity error > 0.04 |
7 & 6 | LST LST Error flag | 00=average LST error <= 1K 01=average LST error <= 2K 10=average LST error <= 3K 11=average |
以MOD11A2_2001145数据进行分析：
以MOD11A2_2001145_V5_QC_Sta产品的DN值统计情况如下
0 | 13079028 | 48.0847 | 48.0847 | Good |
2 | 3183662 | 11.7046 | 59.7893 | 云污染 |
3 | 4875711 | 17.9254 | 77.7147 | 其他原因 |
17 | 575936 | 2.1174 | 79.8321 |
|
33 | 178 | 0.0007 | 79.8328 |
|
65 | 4555826 | 16.7494 | 96.5821 |
|
81 | 886276 | 3.2584 | 99.8405 |
|
97 | 1384 | 0.0051 | 99.8456 |
|
129 | 15369 | 0.0565 | 99.9021 |
|
145 | 25252 | 0.0928 | 99.9949 |
|
161 | 1249 | 0.0046 | 99.9995 |
|
193 | 128 | 0.0005 | 100 |
|
209 | 1 | 0 | 100 |
|
偶数0标识8bit全部为0，
偶数2标识为云污染，未生产
奇数3表示未生产，原因不明，大概超出查抄表范围了
所有大于3的奇数标识为生产了，但发射率或者是反演温度误差过大，程度进行了分别标识
以Good quality即首两位00图层进行掩模，统计值全部为0，如下表印证上述推测
Histogram | DN | Npts | Total | Percent | Acc |
Band1 | 0 | 13079028 | 13079028 | 100 | 100 |
总结：
首两位00-good quality的意思就是
00=LST produced,good quality, not necessary to examine more detailed QA
00=good dataquality，
00=averageemissivity error <= 0.01，
00=average LSTerror <= 1K
https://blog.sciencenet.cn/blog-219445-772995.html
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