Chinese Scientists Use Drones to Boost Rainfall in Arid Xinjiang Region

Chinese scientists have successfully increased rainfall in Xinjiang by over 4% using drone-based cloud seeding, covering 8,000 square kilometers in a single day. Using just one kilogram of silver iodide, the experiment added 70,000 cubic meters of rainfall. Drones dispersed the compound at 5,500 meters, with results validated through satellite imagery, spectrometers, and simulations. The project highlights the potential of weather modification to combat desertification and glacial retreat in Xinjiang, though researchers note further studies are needed to optimize and scale the technology.

In a groundbreaking weather modification experiment, Chinese government scientists have successfully increased rainfall in the arid western region of Xinjiang. Utilizing advanced cloud-seeding techniques, a fleet of drones managed to raise precipitation levels by over 4% across a vast area spanning more than 8,000 square kilometers (3,089 square miles) in just a single day. The project, led by senior engineer Li Bin from the China Meteorological Administration (CMA), resulted in an additional 70,000 cubic meters (18.5 million gallons) of rainfall—enough to fill 30 Olympic-sized swimming pools.

This ambitious operation relied on just one kilogram (2.2 pounds) of silver iodide, a commonly used cloud-seeding compound, to achieve its results. The silver iodide powder, with a density six times that of water, was dispersed into the atmosphere using flame bars attached to drones. These medium-sized drones, flying at altitudes of up to 5,500 meters (18,000 feet), performed four consecutive flights on July 9, 2023, over the Bayanbulak Grasslands in Xinjiang. The experiment was detailed in a peer-reviewed paper published on April 10 in the Chinese-language journal 'Desert and Oasis Meteorology'.

How the Experiment Worked

The drones deployed the silver iodide powder, wrapped in flame bars, into the atmosphere in smoke form. Each flight used two flame bars, with each bar containing 125 grams (0.2 pounds) of silver iodide. The particles were dispersed at a precise rate of 0.28 grams per second. The CMA’s key laboratory for cloud-precipitation physics and weather modification in Beijing spearheaded this innovative effort.

Since 2021, the research team has integrated 24 automated ground stations with satellites and drone fleets to support weather modification operations. According to the researchers, drone-based systems offer significant advantages, including lower safety risks, enhanced maneuverability, precise control, and extensive coverage. These attributes make it possible to conduct large-scale, year-round rain and snow enhancement activities in all weather conditions.

Validating the Results

The team collaborated with Xinjiang’s Weather Modification Office to validate the experiment’s outcomes through three independent methods. Raindrop spectrometers revealed that droplet diameters increased from 0.46mm to 3.22mm (0.02 inches to 0.12 inches) following the cloud seeding. Satellite imagery provided further evidence, showing cloud-top temperatures cooling by up to 10 degrees Celsius (50 degrees Fahrenheit) and vertical cloud growth of around 3 kilometers (1.8 miles). Additionally, a statistical analysis of 50 years of regional climate data estimated that the cloud seeding enhanced rainfall by approximately 78,200 cubic meters, representing a relative increase of 3.8%.

Supercomputer simulations aligned closely with these findings, predicting a 73,800 cubic meter increase, or a 4.3% boost in rainfall. The researchers emphasized that weather modification outcomes depend on various factors, such as timing, altitude, and dosage, which can vary significantly across different locations and time periods. To refine their understanding, the team plans to conduct further numerical simulations, systematically analyzing how each parameter contributes to precipitation yield.

Broader Implications and Challenges

The success of this experiment highlights the potential of drone-based weather modification systems to address challenges in regions like Xinjiang, which is grappling with severe environmental threats. The region, home to parts of the Gobi and Taklamakan deserts, faces accelerating glacial retreat and desertification. Official estimates indicate that the ice caps of the Tianshan Mountains—vital for the survival of 25 million residents—are shrinking by 2 to 3 square kilometers (0.8 to 1.15 square miles) annually.

However, Xinjiang is also experiencing a gradual increase in rainfall, with some climate studies reporting a rise of 6.44mm (0.25 inches) per decade due to global warming. Coupled with China’s ambitious geoengineering initiatives, such as artificial forests and solar energy projects, these weather modification efforts may further contribute to mitigating the region’s environmental challenges.

Unanswered Questions and Future Directions

Despite the promising results, the researchers acknowledge that critical questions remain unanswered. For instance, how can scientists definitively determine whether cloud seeding amplifies or suppresses precipitation? What are the precise metrics for quantifying the water volume gained or lost? And what are the long-term benefits when scaling such operations over an entire year? These questions are receiving increasing attention from both the government and the public.

The researchers aim to address these uncertainties through more extensive and iterative experiments. By systematically varying parameters such as timing, altitude, and dosage, they hope to gain deeper insights into the factors influencing precipitation yields.

China’s success in using drones for weather modification demonstrates the country’s commitment to leveraging cutting-edge technology to tackle environmental challenges. While questions remain about the scalability and long-term impact of such efforts, this experiment marks a significant step forward in the field of geoengineering. As climate change continues to reshape the planet, innovative solutions like this may play a pivotal role in safeguarding vulnerable regions like Xinjiang.

Source: Information taken from an article published in SCMP