中国地区被动微波SSM/I亮度温度数据集（1987-2007）

本数据集中包括:使用美国国防气象卫星计划(DMSP)卫星所携带的星载微波辐射计SSM/I的微波亮度温度。包含1987年-2007年的19H，19V，22V，37H，37V，85H，85V七个通道的每日两次（升轨&降轨）亮度温度。
专用微波成像仪（Special Sensor Microwave/Image，SSM/I）由美国休斯公司研制，于1987年首次由美国国防气象卫星计划（DMSP）中的Block 5D-/F8卫星载入空间执行探测使命。从1987年DMSP升空到1997年TRMM升空的10年时间内，SSM/I一直是世界上最先进、空间分辨率最高的星载被动微波遥感探测仪器。DMSP卫星为近极地圆形太阳同步轨道，卫星高度约833 km，轨道面倾角98.8°，轨道周期102.2 min，地方时6时左右通过赤道，24h覆盖一次全球。SSM/I由设置在4个频率处的7个通道组成，中心频率分别为19.35、22.24、37.05和85.50 GHz。其仪器实际上是由7个相互独立的全功率型、平衡混频、超外差式接收的被动微波辐射计系统构成，可以同时测量来自地球和大气系统的微波辐射。除22.24 GHz频率外，其它频率均同时具有水平和垂直两种极化状态。
SSM/I若干特征值
通道 频率
（GHz） 极化方式（V/H） 空间分辨率
（km×km） 足迹大小
（km）
19V 19.35 V 25×25 56
19H 19.35 H 25×25 56
22V 22.24 V 25×25 45
37V 37.05 V 25×25 33
37H 37.05 H 25×25 33
85V 85.50 V 12.5×12.5 14
85H 85.50 H 12.5×12.5 14
1、文件格式和命名：
每组数据均由遥感数据文件，.JPG图像文件和.met辅助信息文件，以及.TIM时间信息文件和相应的.met时间信息辅助文件构成。
SSMI_Grid_China目录下的每组数据文件名及命名规则如下：

China-EASE-Fnn-ML/HaaaabbbA/D.ccH/V（遥感数据）
China-EASE-Fnn -ML/HaaaabbbA/D.ccH/V.jpg （图像文件）
China-EASE-Fnn-ML/HaaaabbbA/D.ccH/V.met（辅助信息文件）
China-EASE-Fnn-ML/HaaaabbbA/D.TIM （时间信息文件）
China-EASE- Fnn -ML/HaaaabbbA/D.TIM.met （时间信息辅助文件）
其中：EASE代表EASE-Grid投影方式；Fnn代表搭载卫星编号（F08，F11，F13）；ML/H分别代表多通道低分辨率和多通道高分辨率；A/D分别代表升轨（A）和降轨（D）；aaaa代表年份；bbb代表该年的儒略日；cc代表通道号（19H，19V，22V，37H，37V，85H，85V）；H/V分别代表水平极化（H）和垂直极化（V）。
2、坐标系及投影：
投影方式为等积割圆柱投影，双标准纬线为南北纬30度。有关EASE-GRID的相关详细信息，请参考http://www.ncgia.ucsb.edu/globalgrids-book/ease_grid/。如果需要将EASE-Grid投影方式转换成Geographic投影方式，请参照ease2geo.prj文件，内容如下：
Input
projection cylindrical
units meters
parameters 6371228 6371228

1 /* Enter projection type (1, 2, or 3)
0 00 00 /* Longitude of central meridian
30 00 00 /* Latitude of standard parallel
Output
Projection GEOGRAPHIC
Spheroid KRASovsky
Units dd
parameters
end
3、数据格式：
以整数形二进制存储，行列号：308*166，每个数据占2个字节。本数据集中实际存储的数据为亮温*10，读出数据后需除以10得到真实亮温。
4、数据分辨率：
空间分辨率：25km，12.5km (SSM/I 85GHz)；
时间分辨率：逐日，从1978年至2007年。
5、空间范围：
经度：60°-140°东经；
纬度：15°-55°北纬。
6、数据读取：
每一组数据包括遥感影像数据文件，.JPG图像文件和.met辅助信息文件，其中JPG文件可以用Windows图片和传真查看器打开，.met辅助信息文件可以用记事本打开，遥感影像数据文件可以在ENVI和ERDAS软件中打开。

This dataset contains microwave brightness temperature data acquired by the Special Sensor Microwave/Imager (SSM/I) onboard satellites of the U.S. Defense Meteorological Satellite Program (DMSP). It includes brightness temperature data from seven channels (19H, 19V, 22V, 37H, 37V, 85H, 85V) at two overpasses (ascending and descending orbits) per day during 1987 to 2007.

The Special Sensor Microwave/Imager (SSM/I) was developed by Hughes Company of the U.S., and was first launched into space for detection missions aboard the Block 5D-/F8 satellite of the DMSP program in 1987. During the 10-year period from the launch of DMSP in 1987 to the launch of the Tropical Rainfall Measuring Mission (TRMM) in 1997, SSM/I was the world's most advanced and highest spatial resolution space-borne passive microwave remote sensing instrument. DMSP satellites operate in near-polar circular Sun-synchronous orbits, with an altitude of approximately 833 km, an orbital inclination of 98.8°, an orbital period of 102.2 minutes, pass over the equator at around 6 o'clock local solar time, and provide global coverage every 24 hours. SSM/I consists of 7 channels at 4 frequency bands, with central frequencies of 19.35, 22.24, 37.05 and 85.50 GHz respectively. The instrument is actually composed of 7 independent full-power, balanced mixer, superheterodyne reception passive microwave radiometer systems, which can simultaneously measure microwave radiation from the Earth and atmospheric systems. Except for the 22.24 GHz frequency band, all other frequencies have both horizontal and vertical polarization states.

### SSM/I Characteristic Parameters
| Channel | Frequency (GHz) | Polarization (V/H) | Spatial Resolution (km×km) | Footprint Size (km) |
|---------|-----------------|--------------------|----------------------------|---------------------|
| 19V | 19.35 | V | 25×25 | 56 |
| 19H | 19.35 | H | 25×25 | 56 |
| 22V | 22.24 | V | 25×25 | 45 |
| 37V | 37.05 | V | 25×25 | 33 |
| 37H | 37.05 | H | 25×25 | 33 |
| 85V | 85.50 | V | 12.5×12.5 | 14 |
| 85H | 85.50 | H | 12.5×12.5 | 14 |

1. File Format and Naming
Each dataset consists of a remote sensing data file, a .JPG image file, a .met auxiliary information file, a .TIM time information file and a corresponding .TIM.met time auxiliary information file.
The naming rules for datasets under the SSMI_Grid_China directory are as follows:

Remote sensing data file: China-EASE-Fnn-ML/HaaaabbbA/D.ccH/V
Image file: China-EASE-Fnn-ML/HaaaabbbA/D.ccH/V.jpg
Auxiliary information file: China-EASE-Fnn-ML/HaaaabbbA/D.ccH/V.met
Time information file: China-EASE-Fnn-ML/HaaaabbbA/D.TIM
Time auxiliary information file: China-EASE-Fnn-ML/HaaaabbbA/D.TIM.met

Wherein: EASE represents the EASE-Grid projection method; Fnn represents the satellite number (e.g., F08, F11, F13); ML/H represent multi-channel low resolution and multi-channel high resolution respectively; A/D represent ascending orbit (A) and descending orbit (D) respectively; aaaa represents the 4-digit year; bbb represents the Julian day of the year; cc represents the channel number (19H, 19V, 22V, 37H, 37V, 85H, 85V); H/V represent horizontal polarization (H) and vertical polarization (V) respectively.

2. Coordinate System and Projection
The projection method is equal-area secant cylindrical projection, with two standard parallels at 30° north and south latitudes. For detailed information about EASE-GRID, please refer to http://www.ncgia.ucsb.edu/globalgrids-book/ease_grid/. If you need to convert the EASE-Grid projection to Geographic projection, please refer to the ease2geo.prj file with the following content:

Input
projection cylindrical
units meters
parameters 6371228 6371228

1 /* Enter projection type (1, 2, or 3)
0 00 00 /* Longitude of central meridian
30 00 00 /* Latitude of standard parallel
Output
Projection GEOGRAPHIC
Spheroid KRASovsky
Units dd
parameters
end

3. Data Format
The data is stored as integer binary format, with a dimension of 308×166 rows and columns, and each data point occupies 2 bytes. The actual stored values are the brightness temperature multiplied by 10; divide the read values by 10 to obtain the true brightness temperature.

4. Data Resolution
Spatial resolution: 25 km (except for 85 GHz channels of SSM/I, which is 12.5 km); Temporal resolution: daily, covering the period from 1978 to 2007.

5. Spatial Extent
Longitude: 60°E to 140°E; Latitude: 15°N to 55°N.

6. Data Reading
Each dataset includes a remote sensing image data file, a .JPG image file and a .met auxiliary information file. The .JPG files can be opened with Windows Photos and Fax Viewer, the .met auxiliary files can be opened with Notepad, and the remote sensing image data files can be opened with ENVI and ERDAS software.

搜集汇总

背景与挑战

背景概述

该数据集提供了1987-2007年中国地区的被动微波SSM/I亮度温度数据，包含7个通道的每日两次观测，数据覆盖范围广，适用于冰冻圈和微波遥感研究。