I was intrigued by the assertion that COVID-19 depressing commercial aviation has lead to lower quality weather forecasting
The aircraft observations are a key piece in the jigsaw of national and global weather data that is fed into computer models through a process called data assimilation. Multiple studies have found that aircraft are among the most important data sources for reducing the error in forecast models.
After some poking around, I found out the system is called AMDAR
The AMDAR system predominantly utilises existing aircraft onboard sensors, computers and communications systems to collect, process, format and transmit meteorological data to ground stations via satellite or radio links. Once on the ground, the data is relayed to National Meteorological and Hydrological Services (NMHS), where it is processed, quality controlled and transmitted on the WMO Global Telecommunications System (GTS).
Is this system required by aviation authorities anywhere? Or is there merely some incentive system to encourage participation?