AIRS/Aqua L3 Monthly CO2 in the free troposphere (AIRS-only) 2.5 degrees x 2 degrees V005 (AIRS3C2M) at GES DISC

The Atmospheric Infrared Sounder (AIRS) is a grating spectrometer (R = 1200) aboard the second Earth Observing System (EOS) polar-orbiting platform, EOS Aqua. In combination with the Advanced Microwave Sounding Unit (AMSU) and the Humidity Sounder for Brazil (HSB), AIRS constitutes an innovative atmospheric sounding group of visible, infrared, and microwave sensors. This product is the AIRS mid-tropospheric Carbon Dioxide (CO2) Level 3 Monthly Gridded Retrieval, from the AIRS instrument on board of Aqua satellite. It is a monthly gridded data, at 2.5x2 deg (lon)x(lat) grid cell size. The data is in mole fraction units (data x 10^6 =ppm in volume). This quantity is not a total column quantity because the sensitivity function of the AIRS mid-tropospheric CO2 retrieval system peaks over the altitude range 6-10 km. The quantity is what results when the true atmospheric CO2 profile is weighted, level-by-level, by the AIRS sensitivity function. The file format is HDF-EOS 2.12 corresponding to HDF4. This AIRS mid-tropospheric CO2 Level 3 Monthly Gridded Retrieval Product contains standard retrieval means, standard deviations and input counts as well as the latitude and longitude arrays giving the centers of the grid boxes. Each file covers a calendar month. The mean values are simply the arithmetic means of the individual CO2 retrievals which fall within that grid box over the month. The mid-tropospheric CO2 retrievals have been averaged and binned into 2.5 degree longitude x 2 degree latitude grid cells, from -180.0 to +180.0 deg longitude and from -60.0 to +90.0 deg latitude. For each grid map of 4-byte floating-point mean values there is a corresponding 4-byte floating-point map of standard deviation and a 2-byte integer grid map of counts. The counts map provides the user with the number of points per bin that were included in the mean.

大气红外探测仪（AIRS）搭载于地球观测系统（EOS）第二颗极地轨道平台EOS Aqua之上，为一台衍射光栅光谱仪（R = 1200）。与高级微波探测单元（AMSU）以及巴西湿度探测仪（HSB）相结合，AIRS构成了一个创新的可见光、红外和微波大气探测组。本产品为AIRS搭载于Aqua卫星上的中高层大气二氧化碳（CO2）三级月度网格检索产品。数据以月度网格形式呈现，网格单元尺寸为2.5度（经度）×2度（纬度）。数据单位为摩尔分数（数据乘以10^6等于体积浓度ppm）。该量值并非总柱量，因为AIRS中高层CO2检索系统的灵敏度函数在海拔6-10公里的范围内达到峰值。该量值是通过对真实大气CO2剖面进行逐层加权，并利用AIRS灵敏度函数进行加权所得。文件格式为HDF-EOS 2.12，对应于HDF4格式。本AIRS中高层CO2三级月度网格检索产品包含标准检索平均值、标准偏差以及输入计数，以及表示网格单元中心的经纬度数组。每个文件覆盖一个月的日历。平均值是该月内落入该网格单元的各个CO2检索值的算术平均值。中高层CO2检索值已平均并分组为2.5度经度×2度纬度网格单元，范围从-180.0度至+180.0度经度，从-60.0度至+90.0度纬度。对于每个由4字节浮点数表示的平均值网格图，对应有一个4字节浮点数表示的标准偏差网格图，以及一个2字节整数网格图表示计数。计数图提供了每个分组中包含的平均值的点数。