MODTRAN 官方帮助学习
以下内容来自MODTRAN Web APP！
1.选择模式
选择计算透过率还是辐亮度（还是强度？先mark一下，回头查一下ppt）
2.大气参数选项
大气模型、水柱（？）、臭氧（？）、二氧化碳、一氧化碳、甲烷
ps一下，自己不做大气部分的遥感，这些参数对我都很陌生啊，一个一个来看
2.1 大气模型
MODTRAN里提供了6种差异显著且有代表性的大气模型，这些模型的温度、水汽、臭氧廓线都有明显差异。近北极冬季模型（Sub-Arctic Winter）具有最低陆表温度，中纬度冬季模型（Mid-Latitude Winter）次之；热带模型（Tropical）和中纬度夏季模型（Mid-Latitude Summer）具有最高的陆表温度。对流层顶，热带模型的温度反而是最低的，而近北极夏季模型（Sub-Arctic Summer）具有最高的温度。在这6种模型中，除陆表外的第二温度峰值高度出现在海拔50km左右，这里近北极夏季模型具有最高温度，中纬度夏季模型与之近乎相等，在这个海拔上近北极冬季模型的温度是最低的。1976美国标准模型（1976U.S. Standard）在这一系列模型中提供了一个近乎与中位数值的选择。
图2中包含了水汽和臭氧的密度廓线。表1中展示了12中不同波段模型种类的垂直柱数量（？？）。此表中使用的二氧化碳混合密度值为380ppmV。这6中模型为边界层和低对流层的水密度提供了很好的分布（？？）。
Atmosphere Model
The 6 model atmospheres in MODTRAN® differ most significantly in their temperature profiles, and in their H2O and O3 profiles. The temperature profiles are illustrated in Figure 1. Not surprisingly, the Sub-Arctic Winter Atmosphere has the coolest surface temperature; the Mid-Latitude Winter Atmosphere has the next coolest surface temperature. The Tropical and Mid-Latitude Summer Atmospheres have the warmest surface temperatures. At the tropopause, the temperature of the Tropical Atmosphere is the coolest and the temperature of the Sub-Arctic Summer Atmosphere is the warmest. For all 6 atmospheres, a secondary temperature peak occurs near 50 km; here the Sub-Arctic Summer temperature is the warmest, essentially equal to that of the Mid-Latitude Summer. The Sub-Arctic Winter temperature is the coolest at this altitude. The 1976 U.S. Standard Atmosphere temperature profile provides an effective median for the set of profiles.
Figure 2 contains the density profiles for H2O and O3. Total vertical column amounts for the 12 ambient band model species are listed in Table 1; the CO2 mixing ratio used in creating this table was 380 ppmV. The 6 model atmospheres provide a nice spread of boundary layer and lower tropospheric water densities.
2.2 水汽柱
水汽柱的值是以atm-cm（？？）计量的绝对垂直水汽值。图3（上文图2左图）包含了各种模型下的水汽密度廓线。
当发生改变时，模型水数密度值从模型大气中缩放以匹配指定的积分路径内容。 需要注意的是，在每个轮廓高度的水数密度不会增加超过100％相对湿度或超过原始模型大气值的5倍。 当达到相对湿度极限时，过量的水被分配到尽可能达到输入水柱的其他水平。（GOOGLE翻译）
Water Column
This value is the absolute vertical water vapor column in atm-cm. Figure 1 contains the density profiles for H2O for each model atmosphere.
When changed, the model water number density values are scaled from the model atmosphere to match the specified integrated path content. Note, the water number density at each profile altitude is not increased above 100% relative humidity or by more than 5 times the original model atmosphere value. When the relative humidity limit is reached, the excess water is distributed to other levels to the extent possible to achieve the input water column.
2.3 臭氧柱（？）
这是以atm-cm（？？）计量的绝对垂直臭氧值。图4（图2右图）包含了各种模型下的臭氧密度廓线。当发生改变时，模型臭氧密度值从模型大气中缩放以匹配指定的积分路径内容。
Ozone Column
This is the absolute vertical Ozone (O3) in atm-cm. Figure 1 contains the density profiles for O3 for each model atmosphere. When changed, the model ozone number density values are scaled from the model atmosphere to match the specified integrated path content.
2.4 其他
二氧化碳、一氧化碳、甲烷，以ppmv计，在大气中被认为为常量
3.陆地表面参数（？不知道这么分类对不对）
3.1 陆表温度
重点就这句话
The calculation of the ground surface emission depends on this value.
如果要计算陆表发射能量的话，这个值很重要
目前做的火点都是反演设备上的MIR/TIR/SWIR亮温值，没看到有人拿LST做的，为什么呢？需要查下资料。
3.2 陆表反照率
It can vary between zero and unity depending on the surface material. The calculation of the ground surface emission is also dependent on this parameter.
这部分的介绍也是很简洁，反射率的信息。同样，计算陆表发射能量也很重要。这两个值对于中分辨率以上的数据应该很关键，现在的VIRR1km分辨率怕是用不上了，不过一些高反射率陆表的影响还是可以具体研究一下。
4.气溶胶模型相关
4.1 气溶胶模型
气溶胶模型描述了陆地边界层（海拔0-2km）的气象范围。每个模型的默认的可视参数都可以增加或减少。
乡村模型
用于没有显著工业进程的地区，水溶性物质组成了气溶胶中的70%，剩余的成分多为灰尘。
城市模型
城市模型中加入了工业进程的考虑，乡村模型的气溶胶构成80%的成分，剩余的20%为含碳气溶胶。
海上气溶胶模型
该模型适用于海洋气溶胶，并且包括由多个来源采集的气溶胶尺寸分布。（GOOGLE）模型依赖于风速，风速的不同又取决于大气模型，总结如表2
沙漠模型
沙漠模型使用了三种主要成分（含碳颗粒、水溶性颗粒和沙粒）来描述其效果。
每个分量具有不同的对数正态尺寸分布和折射率集合。（GOOGLE）
Aerosol Model
The aerosol model describes the meteorological range for the ground boundary layer (0 to 2 km altitude). The default visibility parameter can be increased or decreased for each model.
Rural Model
This model is best used in regions where there are no appreciable industrial processes. Water soluble materials make up 70% of the aerosols, with the remaining made up of dust like aerosols. The rural and urban models were developed by Shettle and Fenn.
Urban Model
The urban aerosol adds effects from industrial processes. The rural aerosol mixture makes up 80%, while the remaining 20% is carbonaceous aerosols. The rural and urban models were developed by Shettle and Fenn.
Navy Aerosol Model
This model is adapted for marine aerosol and includes aerosol size distributions taken by a number of sources. The model depends on a wind speed. The wind speed varies based on the atmospheric model, which is summarized in Table 1. The Navy Aerosol Model was developed by Gathman.
Desert Model
The desert aerosol model was first proposed by Longtin et al. and uses three major components (carbonaceous particles, water soluble particles, and sand) to describe the effect. Each component has a different log normal size distribution and set of indices of refraction.
4.2 能见度
气溶胶浓度的变化可以基于表面气象范围或可见度而改变。 对于混浊条件（2 <VIS <10km），气溶胶消光系数在最高1km以内的高度是恒定的。 对于清晰条件（23 <VIS <50km），气溶胶的垂直分布呈指数分布。（参考GOOGLE）
Visibility
The variation in the concentration of aerosols can change based on the surface meterological range, or visibility. For hazy conditions (2<VIS<10 km), the aerosol extinction coefficient is assumed to be constant for altitudes up to 1 km. For clear conditions (23<VIS<50 km) the vertical distribution of aerosols is exponential.
5.传感器参数
图5解释了传感器高度和传感器天顶角。需要注意的是在这个免费版本里天顶角被固定为0。
(〃＞目＜)
Sensor Altitude
Figure 1 shows a schematic that includes the definition of the sensor zenith and altitude. Note that the solar zenith angle is fixed at 0 deg (directly over the sensor) in the free version of the MODTRAN® web app.
以上就是全部内容了，感觉跟自己相关的有一部分，具体怎么用这个工具还得找找文献参考一下。
