Sufficiently large and cleverly designed solar parks could influence the weather in coastal desert areas in such a way that it rains. A similar effect could probably also be achieved by artificial dunes several hundred meters high. This is the assessment of a research team at the University of Hohenheim in Stuttgart. They now intend to confirm their hypothesis in the desert on the Arabian Peninsula. Intensive 3D weather observations and high-resolution computer simulations are planned. This is made possible by a highly endowed research prize from the United Arab Emirates: the UAEREP program awards US$5 million each year to fund cutting-edge international research on rain enhancement in deserts and semi-deserts. This year, a total of three research teams received the top funding out of 120 submissions worldwide. The University of Hohenheim is among them for the second time.
They have been researching the weather in the desert for over ten years, and are already familiar with the deserts of the Arabian Peninsula: Principle Investigator Dr. Oliver Branch and Prof. Volker Wulfmeyer from the University of Hohenheim. The two Earth system scientists now believe they have found a new approach to bringing rain to the arid region.
The research conducted by Dr. Branch and the team at the Institute of Physics and Meteorology (IPM) could radically change the landscape in coastal desert regions. Their vision is a landscape in which large solar parks glitter in the sun, and large plantations of oil crops such as jojoba or jatropha create new soil. Rising from this plain are pyramid-like dunes – man-made and several hundred meters high.
In this future landscape, a fraction of the solar power drives the pumps that irrigate the plantations with groundwater and cisterns. The plants cool the hot air, thereby increasing the efficiency of the solar modules. Winds blow in from the nearby sea. On favorable summer days, clouds form and discharge rain.
Hot solar panels cause moist winds to rise
The theory behind this is well-elaborated: the air above black solar modules and plantations heats up more than the surrounding air. Moist winds flow in from the sea. Under the influence of the sea breeze, this warm air rises and turbulence increases.
"Our calculation is that if future solar parks reach a certain size, the warm air would rise strong enough to reach higher atmospheric layers where clouds can form. There, the water would condense, resulting in rain and thunderstorms," explains Dr. Branch.
Large artificial dunes could have a similar effect. "We know from research that mountain tops, for example, divert wind currents in such a way that they collide, rise, and form clouds and rain," adds the institute's director, Prof. Dr. Volker Wulfmeyer.
Simple theory requires highly complex analyses
As simple as the theory seems, the research required is complex: "The basic principles are known, but for a project like this, the details are what matter. To do this, we need to study the processes on site very closely," says Dr. Branch.
To take these measurements, the team at the University of Hohenheim relies on high-performance laser systems, which they will set up next to existing solar parks: so-called LiDARs (light detection and ranging). "With these LiDARs, we can measure temperatures, humidity, and wind dynamics in three dimensions: from the solar park to the coast and vertically up into the layers of air where clouds form."
It helps that some of the world's largest solar plants are already located in the United Arab Emirates, including the largest single-site park in the world - the Mohammed bin Rashid Al Maktoum Solar Park near Dubai.
High-performance computers enable suitable weather modeling
Using this measurement data, the working group at the University of Hohenheim is developing a high-resolution computer model that accurately simulates these processes.
"In the first step, we compare and tweak the model using the measurement data until it accurately reflects the existing processes. In a second step, we can then make predictions: What effect will it have if we enlarge the solar park or change the shape and size of an artificial dune? In this way, we can then determine the optimal location, size, and design of solar parks and artificial dunes."
The computer model is designed to represent weather patterns with an resolution of up to 100 meters. This is only possible in conjunction with the high-performance computers "Hunter" and "HoreKa" at the University of Stuttgart and the Karlsruhe Institute of Technology (KIT).
Award ceremony at a festive gala evening in Abu Dhabi
With this approach, the scientist from the University of Hohenheim also convinced the international expert committee of the Research Program for Rain Enhancement Sciences. In this program, the government of the United Arab Emirates (UAE) annually allocates US$5 million worldwide for international cutting-edge research.
The goal is to develop scientifically sound methods to increase rainfall over deserts and semi-deserts. Each year, a maximum of five research projects are funded for three years each.
The research funding was awarded in the form of a prize at a gala evening on January 22 in Abu Dhabi (UAE). In addition to Dr. Branch's project, teams from Australia and the USA were also honored (
https://www.uaerep.ae/media/press/view?aID=772&locale=en).
Special challenges in desert research
This was the second time that Prof. Dr. Wulfmeyer had been among the guests at this event: in 2015, he himself was one of the first three winners of the program. At that time, Dr. Branch was a postdoctoral researcher in the team, and this time he was honored as Principle Investigator.
Dr. Branch can now draw on their work from back then and continue to develop it towards practical application. At that time, the meteorologists also broke new technical ground in the desert: "Even in Europe, we have to cool our lasers. The desert temperatures pose a particular challenge for these air conditioning systems, because without additional cooling, the electronics could easily have overheated or the optics could have warped," said Prof. Dr. Wulfmeyer.
Another challenge that the scientists have to keep an eye on is free-roaming camels. "We were warned that the animals like to chew through cables at night," reports Dr. Branch. But he and his team will find a solution for that too.
Further information
Research Program for Rain Enhancement Science:
http://www.uaerep.ae
Press release regarding the 2026 UAEREP Awards Ceremony:
https://www.uaerep.ae/media/press/view?aID=772&locale=en
To the University of Hohenheim’s press releases
http://www.uni-hohenheim.de/en/press
Text: Klebs