Landsat 8 Landsat8 Collection2大气层顶反射率数据-编程知识

Landsat 8 Landsat8 Collection2大气层顶反射率数据

简介

Landsat8 TOA数据集是将数据每个波段的辐射亮度值转换为大气层顶表观反射率TOA，是飞行在大气层之外的航天传感器量测的反射率，包括了云层、气溶胶和气体的贡献，可通过辐射亮度定标参数、太阳辐照度、太阳高度角和成像时间等几个参数计算得到。为了便于在线分析存储，平台将影像像素值扩大了10000倍。前言 – 人工智能教程
Landsat-8卫星包含OLI（Operational Land Imager 陆地成像仪）和TIRS（Thermal Infrared Sensor 热红外传感器）两种传感器，每16天可以实现一次全球覆盖。
OLI包括9个波段，空间分辨率为30米，其中包括一个15米的全色波段，成像宽幅为185x185km。TIRS用于收集地球两个热区地带的热量流失，能够了解所观测地带水分消耗。

数据集ID:

LC08/02/T1

时间范围: 2022年01月-现在

范围: 全国

来源: USGS

复制代码段:

var images = pie.ImageCollection("LC08/02/T1")

名称	比例因子	分辨率	波段范围(μm)	描述信息
B1	0.0001	30m	0.43-0.45μm	Coastal
B2	0.0001	30m	0.45-0.51μm	Blue
B3	0.0001	30m	0.53-0.59μm	Green
B4	0.0001	30m	0.64-0.67μm	Red
B5	0.0001	30m	0.85-0.88μm	NIR
B6	0.0001	30m	1.57-1.65μm	SWIR 1
B7	0.0001	30m	2.11-2.29μm	SWIR 2
B8	0.0001	15m	0.50-0.68μm	Pan
B9	0.0001	30m	1.36-1.38μm	Cirrus
B10	0.0001	100m	10.6-11.19μm	TIRS 1
B11	0.0001	100m	11.5-12.51μm	TIRS 2
QA_PIXEL	--	--	--	QA Bitmask

Bitmask for BQA
Bit 0: Designated Fill 0: No 1: Yes Bit 1: Terrain Occlusion 0: No 1: Yes Bits 2-3: Radiometric Saturation 0: No bands contain saturation 1: 1-2 bands contain saturation 2: 3-4 bands contain saturation 3: 5 or more bands contain saturation Bit 4: Cloud 0: No 1: Yes Bits 5-6: Cloud Confidence 0: Not Determined / Condition does not exist. 1: Low, (0-33 percent confidence) 2: Medium, (34-66 percent confidence) 3: High, (67-100 percent confidence) Bits 7-8: Cloud Shadow Confidence 0: Not Determined / Condition does not exist. 1: Low, (0-33 percent confidence) 2: Medium, (34-66 percent confidence) 3: High, (67-100 percent confidence) Bits 9-10: Snow / Ice Confidence 0: Not Determined / Condition does not exist. 1: Low, (0-33 percent confidence) 2: Medium, (34-66 percent confidence) 3: High, (67-100 percent confidence) Bits 11-12: Cirrus Confidence 0: Not Determined / Condition does not exist. 1: Low, (0-33 percent confidence) 2: Medium, (34-66 percent confidence) 3: High, (67-100 percent confidence)

Bitmask for BQA

Bit 0: Designated Fill
- 0: No
- 1: Yes
Bit 1: Terrain Occlusion
- 0: No
- 1: Yes
Bits 2-3: Radiometric Saturation
- 0: No bands contain saturation
- 1: 1-2 bands contain saturation
- 2: 3-4 bands contain saturation
- 3: 5 or more bands contain saturation
Bit 4: Cloud
- 0: No
- 1: Yes
Bits 5-6: Cloud Confidence
- 0: Not Determined / Condition does not exist.
- 1: Low, (0-33 percent confidence)
- 2: Medium, (34-66 percent confidence)
- 3: High, (67-100 percent confidence)
Bits 7-8: Cloud Shadow Confidence
- 0: Not Determined / Condition does not exist.
- 1: Low, (0-33 percent confidence)
- 2: Medium, (34-66 percent confidence)
- 3: High, (67-100 percent confidence)
Bits 9-10: Snow / Ice Confidence
- 0: Not Determined / Condition does not exist.
- 1: Low, (0-33 percent confidence)
- 2: Medium, (34-66 percent confidence)
- 3: High, (67-100 percent confidence)
Bits 11-12: Cirrus Confidence
- 0: Not Determined / Condition does not exist.
- 1: Low, (0-33 percent confidence)
- 2: Medium, (34-66 percent confidence)
- 3: High, (67-100 percent confidence)

代码：

/*** @File    :   PIELandsat8_c2_TOA* @Time    :   2022/5/19* @Author  :   piesat* @Version :   1.0* @Contact :   400-890-0662* @License :   (C)Copyright 航天宏图信息技术股份有限公司* @Desc    :   加载Landsat 8 collection2 TOA影像*/// 加载Landsat 8 TOA影像
var landsat8 = pie.ImageCollection("LC08/02/T1").filterDate("2022-01-01","2022-06-01").filter(pie.Filter.lte('cloud_cover',30)).first().select(["B2","B3","B4"]).multiply(0.0001)
print(landsat8)
Map.addLayer(landsat8,{min:0.05,max:0.3,bands:["B4","B3","B2"]},"Landsat8-TOA");
Map.centerObject(landsat8,7);

属性

landsat_product_id	string	影像名称
scene_id	string	影像id
correction	string	产品级别
collection_number	string	数据集编号
date	string	影像日期
collection_category	string	影像质量级别属性,如T2，T1等
cloud_cover	float	云量覆盖百分比，-1表示未计算
cloud_cover_land	float	陆地云量覆盖百分比，-1表示未计算
sun_azimuth	double	太阳方位角
sun_elevation	double	太阳高度角
off_nadir	double	天底偏角
sensor_id	string	传感器类型
wrs_path	int	条带号
wrs_row	int	行编号