**6. Conclusion**

Optical properties of aerosols and clouds play an important role in the consideration of the Earth's radiation budget. In this chapter, we have described multi-wavelength and multidirectional remote sensing of the troposphere, putting emphasis on the visible part of the spectrum. The DOAS approach enables the direct observation of air pollutants by employing a nearly horizontal light path in the lowest part of troposphere, where the highest concentrations of pollutants such as NO2 and aerosol (SPM) are found. The observation of direct solar radiation and scattered solar radiation (sky light), on the other hand, is useful for retrieving detailed aerosol optical properties under clear-sky conditions. Thus, the data can be quite useful for implementing precise atmospheric correction on satellite-observed imagery that includes the ground observation point. The multiwavelength lidar observation provides an efficient tool to elucidate the vertical profiles of aerosol particles. By combining the lidar data with some appropriate ancillary data such as the ground-level characterization of aerosol properties, it becomes possible to derive useful information on temporal as well as spatial information on aerosol and cloud characteristics in the atmosphere.

### **7. Acknowledgment**

We acknowledge the financial support of the Grant-in-Aid from the Ministry of Education, Culture, Sports, Science & Technology in Japan (#21510006). Also, contributions of a number of graduate students who participated in various researches presented in this chapter are gratefully acknowledged.

#### **8. References**

292 Remote Sensing – Applications

Fig. 12. Analysis of MODIS data in November 2007: (a) surface reflectance map (540 - 570

Optical properties of aerosols and clouds play an important role in the consideration of the Earth's radiation budget. In this chapter, we have described multi-wavelength and multidirectional remote sensing of the troposphere, putting emphasis on the visible part of the spectrum. The DOAS approach enables the direct observation of air pollutants by employing a nearly horizontal light path in the lowest part of troposphere, where the highest concentrations of pollutants such as NO2 and aerosol (SPM) are found. The observation of direct solar radiation and scattered solar radiation (sky light), on the other hand, is useful for retrieving detailed aerosol optical properties under clear-sky conditions. Thus, the data can be quite useful for implementing precise atmospheric correction on satellite-observed imagery that includes the ground observation point. The multiwavelength lidar observation provides an efficient tool to elucidate the vertical profiles of aerosol particles. By combining the lidar data with some appropriate ancillary data such as the ground-level characterization of aerosol properties, it becomes possible to derive useful information on temporal as well as spatial information on aerosol and cloud characteristics

We acknowledge the financial support of the Grant-in-Aid from the Ministry of Education, Culture, Sports, Science & Technology in Japan (#21510006). Also, contributions of a number of graduate students who participated in various researches presented in this chapter are

nm), and (b) aerosol optical thickness at 550 nm on 24 November 2007.

**6. Conclusion** 

in the atmosphere.

**7. Acknowledgment** 

gratefully acknowledged.


**Section 3** 

**Oceans and Cryosphere** 

