Grand challenges in satellite remote sensing

The past five decades have witnessed satellite remote sensing become one of most efficient tools for surveying the Earth at local, regional, and global spatial scales. The satellite sensors launched in the 1970s were often highly target-specific: Landsat and AVHRR targeted land surfaces and clouds, TOMS focused on observing the total column ozone, and HIRS supported weather forecasting and climate monitoring. Those missions provided unique data and were extended for many years. The increasingly advanced instruments launched in ∼1990 - 2010, such as MOPITT, OCO and GOSAT, observed greenhouse gases, the TIR sounders AIRS, TES, IASI, IMG, and CRIS used for weather prediction and climate change. Other imagers such as MODIS, MERIS, SGLI, ATSR and AATSR, MISR radiometers and POLDER polarimeters were deployed for observing land and ocean. CloudSat radar and CALIPSO lidar were launched for monitoring the vertical structure of clouds and aerosols.

All of these and other satellite observations helped to build the understanding of the real value and potential of satellite remote sensing. The community has obtained sizable amounts of satellite data, accumulated experience in data analysis, as well as understanding of the necessary steps for improving the approaches in the future. Also, the progress in space technologies and a boom in informatics have created an unprecedented situation for deploying advanced satellite sensors. On the other hand, the community also realized that the fundamental challenges of remote observations never end. The technology advances but the data is never fully sufficient to uniquely characterize all of parameters of interest and the list of desired observables grows continuously. Thus, remote sensing remains a fundamentally ill-posed problem that needs to be appropriately defined and constrained by theoretical models, a priori knowledge, and ancillary observations (Dubovik et al., 2021). This presentation discusses several important challenges to be considered when designing new scientific objectives of satellite observation with focus on aerosol remote sensing.

Dubovik, O., G. Schuster, F. Xu, Y. Hu, H. Boesch, J. Landgraf and Z. Li, "Grand challenges in satellite remote sensing", Front. Remote Sens., 2:619818. doi: 10.3389/frsen.2021.619818, 2021.