The Meteorological Law of the People’s Republic came into force on 1 January 2000. This law directs that all governments at or above county level are to enhance their leadership over weather modification and actively carry out work in this field. Weather modification includes efforts at “rain or snow enhancement, hail suppression, rain suppression, fog dispersal, and frost prevention by exerting, under appropriate conditions, artificial influence on local atmospheric physical and chemical processes through scientific and technological means, in order to avert or mitigate meteorological disasters and rationally exploit climatic resources.” Additional regulatory instruments have also been enacted, including specific Regulations for Weather Modification Management, Rules for Protection of Meteorological Observation Conditions and Facilities, Rules for Lightning Disaster Prevention and Reduction Management, and Rules for Balloon-release Management.
Significant and rapid advances in issues relevant to weather modification have been made in the years since these laws came into effect. There has been measurable progress in aspects of theoretical atmospheric modeling, field experimentation, and cloud seeding technologies. More advanced cloud models with bin-microphysics and glaciogenic and hygroscopic seeding processes and mesoscale cloud resolving models with AgI-seeding processes have been developed to study seeding-induced changes of cloud structure and precipitation. More advanced cloud seeding tools such as mobile ground-based launching system of AgI-rockets and aircraft-based AgI-flares have been developed and used in operation around Beijing and across the country. Several important projects aimed at exploring weather modification techniques and their applications have been conducted.
Almost all weather modification operations in the country are funded by local governments through various agencies and institutions. However, national research projects funded by relevant departments of Central Government have increased in recent years. From 2000 to 2005, the Ministry of Science and Technology (MOST) sponsored a key project involving research and demonstration of rain enhancement techniques. Since 2006, this ministry has also supported several key projects on theoretical and experimental research. The projects aim to improve equipment engineering and are oriented to introduce more advanced radar, microwave radiometers, and aircraft probes in weather modification operations. In an attempt to address doubts of foreign scientists regarding whether or not cloud seeding can produce scientifically measurable positive results, Guo Xueliang, director of the Center for Weather Modification says, “We recognize the importance of basic research in guiding cloud seeding operations and will apply scientific rigor in testing their effectiveness in controlled, cross-province field experiments.”
According to Wang Guanghe at the Academy of Meteorological Sciences, more than 30 provinces and province-level municipalities currently boast weather-modification bases capable of conducting operational services by using artillery and rockets containing mixed AgI agents, 24 of which are presently using aircraft with AgI flares to do rain enhancement operations. This infrastructure cumulatively employs 32,998 people, 7,100 anti-aircraft guns, 4,991 special rocket launchers, and 36 aircraft (more than 500 PE flights per year, on average).
Beijing’s WMO has sixteen full-time employees who direct the activities of 135 part-time weather modifiers, mostly local farmers. The farmers maintain 31 emplacements of anti-aircraft guns and 46 rocket launchers, some of which are stationed in Fragrant Hills Park to the west of the city. These launchers are aimed to fire munitions loaded with AgI into appropriate clouds. In the winter, when clouds are lower, the modifiers burn chemical charges in land-based apparatuses. A small squadron of planes, flown from a military airfield, delivers AgI or dry ice into the clouds from above. Result estimates can be reported from control stations to the headquarters within 10 minutes.
Wang says training programs and licenses have sharply curbed accidents in recent years. The farmers who comprise the on-call rainmaking force in Beijing go through intensive training, lasting several weeks. The modifiers are paid 50 yuan for every shell fired, which would typically top out at six. They perform their duties about 40 times a year.
The nationwide annual budget for weather modification approaches 615 million yuan. As a result of this systemic effort, more than 250 billion tons of rain has been artificially induced since 2000. This is enough to fill the Yellow River several times over, meeting the needs of 400 million people.
“I believe that nearly every time it has rained in Beijing this year, cloud seeding technologies have been used,” said Hu Zhijin, an expert with CMA’s Institute of Artificial Rain.
This investment is significant because the annual per capita water supply is only 2,200 cubic meters – one quarter of the global average, and, due to drought, northern river levels are reduced by no less than 20%. In order to address these severe climatic demands, the capital hosted the “Second National Co-ordination Meeting on Weather Modification” on 27 Feb 2004. Moreover, the 11th Five Year Plan (2006-2010) calls for the creation of 48-60 billion cubic meters of artificial rain annually.
Zhang Qiang, deputy director of The Beijing Weather Modification Command Center explains. “We’re not that far ahead of other countries. It’s only that we’re still working at it continuously, trying to tackle these problems, that we have results.”
The country conducted its first independent cloud seeding experiments, in both northern and western regions, in 1958, and has since become a world-leader in the field.
“Man-made efforts to influence the weather are an important method by mankind to use modern science and technology to prevent and reduce disasters, and are receiving a high level of importance in our country,” Qin Dahe, minister of the State Meteorological Bureau said in August of 2008 during a celebration of 50 years of weather modification by the People’s Republic. “At first, the focus of this research was to ease drought and improve harvests for farmers, but it has expanded to include firefighting, prevention of hailstorms, replenishment of river heads and reservoirs, and combatting drought and sandstorms. Artificial rain-making, hail prevention, and fog-dispersal techniques are used to help improve ecosystems and to secure freeway transportation and the success of key social events.”
With the pioneering experiments on dry ice seeding by Schaefer (1946) and the discovery of the ice nucleating ability of AgI by Vonnegut (1947), the modern era of weather modification activities began immediately through field experiments on glaciogenic seeding (dry ice and AgI). Weather modification operational programs have been increasing in number and scale across the world. This is mainly due to two facts. First, weather modification and precipitation enhancement could potentially contribute to alleviating water resource stresses and severe weather hazards, demands that have been increasing rapidly alongside 21st century development. Second, atmospheric changes such as the emission of industrial air particulate can alter atmospheric processes on scales ranging from local precipitation patterns to global climate systems. Over 70% of natural damages are caused by meteorological disasters in which severe drought, flood, hailstorms, and fog are more common, and the extreme weather events show an increased trend in intensity and frequency in the continental country in recent years.
These facts motivate a sustained effort to mitigate and enhance weather by synthetic methods and developed technology.
Materials used for cloud seeding include AgI (in the form of pyrotechnic), azotic cooling liquid, dry ice (CO2) and propane. Aircraft, rockets, artillery shells, meteorological balloons and mountain-top-based devices have been employed. Most attempts have been aimed at initiating the onset or accelerating or suppressing the rate of the cloud physical processes involved in precipitation formation. Because AgI is very effective, one gram of it can produce 100,000 billion ice crystals over a very wide area, so the quantity used is relatively small. Nitrogen and calcium chloride, contained in cloud seeding materials, exist naturally in the air. “There’s no chance of negatively affecting the environment,” said Zhang.
Contemporary circumstances in Beijing and surrounding provinces create both the need and the opportunity to aggressively explore this dynamic field. Specific geographic, global, industrial, and economic factors in the capital city make it a natural center for the advancement of weather modification. The city is located on an inland offshoot of the Huabei coastal plain, resulting in the topography being very flat. Overlapping mountain ranges surround the city – the Taihang to the west and the Yan to the north and northwest – making it a natural basin for the settling of atmospheric particulate. Due to its proximity to the Gobi desert (currently 100km), Beijing is naturally very arid and suffers frequent sand and dust storms that increase the concentration of drying airborne micro-matter to unusual levels. Land-based efforts to stay the steady encroach of the desert environment have been as yet unsuccessful. Weather modification technology, however, has shown promise as an efficient means for addressing the challenge.
In late April of 2006, Beijing was barraged by a severe sandstorm dumping 330,000 tons of sand and dust on the city. After some days of dust settling, a heavy rainfall was induced to wash off the deposited layer of grit. Seven rocket shells containing 163 sticks of AgI were used. Just over 102mm of precipitation was created making it the heaviest rainfall of the year at that time.
In addition to challenges of natural geography, Beijing is a center of global industry. Beijing has sought to improve air quality by transferring heavy industry to Hebei Province and the port of Tianjin. The wind that blows off the ocean, from the south and the east, however, carries the Hebei air up the plain until it is stalled by the mountains and hangs over the capital. Induced rain or snowfall has been used to drastically reduce aerosol particulate. In July of 2005, 343 AgI shells (37mm) were used to reduce haze. Visibility before induction was recorded at 50 meters in Beijing. The following morning, following 30 minutes of artillery fire, visibility had been increased to 1km. Increased afternoon firings resulted in very mild flooding and blue skies by 3 pm – the first instance of clarity in 13 days.
In preparation for the “Man and Nature, marching into the 21st century” World Horticultural Exposition in Kunming, rain enhancement techniques were used to improve air quality. Five rocket launchers and 94 AgI sticks were used, followed by 68 additional sticks. In November of 2006, 383 AgI shells were fired into clouds to beautify Beijing for the Pan-African Summit. Aircraft equipped with wing-mounted AgI flare racks were also used. Weather modification operations as a technique for improving A.Q.I. levels have also been extensively employed by officials in anticipation of the Six-Party Talks on North Korea since 2003.
According to Zhang Qiang, significant precipitation enhancement operations will help Beijing reach the ambitious 2008 quota of 256 “blue-sky” days (designated A.Q.I. grade 1 or 2/index of less than 100). “Normally, if conditions permit, yes, we modify,” she explains.
High levels of airborne particles from natural and industrial sources have been shown to be a contributing factor to lower overall levels of rainfall, creating an additional challenge for modifiers. Yao Zhanyu, weather modification professor at the Academy of Meteorological Sciences, has demonstrated in recent research that high aerosol particulate matter increases cloud lifetime and reduces precipitatory efficacy by 30 to 50 percent. According to the 2005 study, the 3 km thick particulate layer above Beijing absorbs solar energy (10-25% dimming effect) causing the evaporation instead of perspiration of cloud masses. Weather modification operations can reverse this effect by saturating clouds with glaciogenic or hygroscopic chemicals, creating appropriate condensation nuclei within cumulus clouds, resulting in either rain or snow. Hail suppression is also a result of seeding in this manner, transforming crop-damaging hail potential into productive moisture production.
In March of 2006, severe hailstorms were successfully averted by modification operations (overseeding), saving apricot orchards in the hills west of Beijing. In February of 2008, more than one hundred days without precipitation led to precipitation enhancement technologies being employed. 500 AgI sticks were used to induce a rare snowfall, followed by 313 additional sticks to make the snowfall heavier. Many roads were closed and the snow created picturesque scenes for tourism. In July of 2004, during a prolonged heat wave, rain was induced to lower temperatures, ease pressure on power grids, and improve the morale of citizens. This marked the first documented case of temperature control through known precipitation modification techniques.
Data collected in relevant orographic climate regions has demonstrated that properly conducted seeding efforts do not simply direct where and when rainfall occurs. They measurably increase overall precipitation efficiency resulting in more total rainfall that falls over a broader area compared with the unseeded case. Dr. Deon Terblanche of the United Nations Meteorological Organization estimates that an average rain cloud contains about eight million tons of rainwater. “Therefore, there is a vast quantity of untapped fresh water in the sky and this is where cloud-seeding comes in. It is not a case of robbing Peter to pay Paul.”
According to American National Center for Atmospheric Research scientist Roelof Bruintjes, when unmodified clouds do produce rain or snow, they usually effuse less than 30 percent of their moisture. Fewer than 5 percent of cumulus-type clouds last long enough to manifest their potential. Weather modification studies using radar measurements in Beijing, as well as studies in Israel and Russia, have shown that seeding operations can create increased cloud success by a factor of 6-30%, recovering reservoir holdings, supplementing dry river basins, and restoring soil moisture to support agriculture.
Atmospheric management has been shown to provide a cost-effective means for augmenting available water compared to other methods of addressing the persistent severe drought, which has affected more than 140 million mu (9.3 million hectares) of wheat this winter. The South-North Water Diversion Project will cost 136 billion yuan to transfer water via pipeline from the Yangtze basin to the Yellow and Hai rivers. Beijing has endured a water price hike of more than 20% to account for this expense. Contrarily, “In one dry season only 2-3 million yuan was needed to carry out the cloud seeding programs,” Hu Zhijin said. According to statistics provided by Zhang Qiang, one cubic meter of man-made rain costs 0.2 yuan. One AgI shell costs up to 88 yuan. One pyrotechnic rocket costs 2000 yuan. One aircraft trip spends 100 shells or 4 rockets in each single action.
Beijing’s drinking water comes from the Miyun, Guanting, and Chaobai reservoirs. In 2006, precipitation increased by 25%, contributing 23.77 million cubic meters to these sources. Between 2003 and 2006, the city’s 26 rainmaking stations boosted local reservoirs an average of 212 mm, or 12 - 15%. To continue to grow this yield, rainmaking workers are stationed 50 km upstream and are instructed when to fire artillery shells.
RYI-6300 is the cloud-seeding rocket currently in use. Beijing also uses specially modified Military Aviation Xia Yan IIIA and An-26 aircraft fitted with wing-borne catalystic AgI burners for cloud seeding operations. The Beijing bureau buys its equipment from State Owned Factory No. 556 in Wuhai City, a former military plant that now makes weather-control gear and industrial blasting fuses.
Beijing’s Weather Modification Office tracks weather via satellites, planes, radar, and an IBM p575 supercomputer that executes 9.8 trillion floating point operations per second. It models an area of 44,000 square kilometers (17,000 square miles) accurately enough to generate hourly forecasts for each kilometer.
In 2008, the special 2,295 kg Fenguyn-3 weather satellite was sent into space. It was launched from Taiyuan Satellite Launch Center by a Long March-4C carrier rocket. The ascent took 27 minutes from launch to orbital insertion. Fengyun-3 carries 3D sensors measuring atmospheric dynamics and climate, as well as monitoring polar regions and ocean conditions. Sensitivity is tuned to 0.1 degree F and has spatial resolution of 250 meters (0.15 miles). This is a vast improvement on the resolution of its predecessors of only 1 kilometer (0.62 miles). “The 250-m resolution images will be of vital significance for censoring global climate changes and possible subsequent natural disasters,” reports Gao Huoshan, general director of the FY-3 research team. The Fengyun-3 was an invaluable technology for analyzing weather conditions in August of 2008. In addition to its importance to the field of weather modification, the Fengyun-3 is a key contributor to acquiring geographical data for aviation, navigation, agriculture, forestry, and oceanography research.
Due to groundwater shortages, Beijing has been sinking into the ground at an annual rate of about 2.5 centimeters in the past 20 years, whereas Hebei province has subsided more than 70 centimeters. In April of 2004, dry conditions resulted in 2,392 rockets and 409 cannon shells being launched over the course of one weekend. Results were estimated at 17mm of precipitation. In August of 2007, similar weather modification operations were undertaken, and Boading City of Hebei province received a rainfall of 100 mm. Beijing’s Fangshan District received 25 mm. Municipal authorities in Beijing have announced that the city will receive 300 million cubic meters of water from Hebei Province until March 2009.
In accordance with the Meteorological Law, The Beijing Weather Modification Command Center utilizes weather modification technologies for purposes beyond climate manipulation. Since 1999 during the Tian’an men Square celebrations of the 50th anniversary of the People’s Republic, rain suppression techniques have become a significant aspect of Beijing’s statesmanship efforts, enhancing national diplomatic and economic interests, as well as ensuring the success of major cultural events and festivals. The 10th National games of 2005 were protected from rain by Beijing officials, as was the Great Panda Festival of 2001.
“We can say we have already mastered the available rain reduction technologies in the world,” said the director of the Meteorological Administration, Yu Xinwen. During the Games of August 2008, an arsenal of 84 rockets and cannons was arranged on three lines of defense between 15 and 120 kilometers from Beijing, to prevent rain from marring the ceremonies. Twenty-six control stations were deployed to fend off and delay movement of clouds. 1,104 missile launches were coordinated. The rain-prevention program involved four cities in Hebei Province, including Zhangjiakou, Baoding, Chengde, and Langfang, as well as parts of the neighboring Tianjin Municipality.
It has been well established in Beijing that successful implementation of cloud seeding resulting in precipitation enhancement has significant impact in managing the issue of global climate. The tools of satellite meteorology, Radar technology, cloud dynamics, environmental chemistry, flare technology, numerical modeling techniques, statistics, fluid dynamics and spatial information, and communication technologies have provided excellent scope for research and development and operational implementation of weather modification technologies.
More than 40 countries have similar projects underway to modify weather. Talks have been underway with officials in Spain and Egypt, who are said to be interested in the purchase of modification instruments. In 2005, a bilateral agreement was signed with Cuba to begin operations there.