The quantity of winter rain and snow in the western Himalayas may fluctuate by about 50% depending on the air pressure gradient across the Atlantic Ocean between the Azores and Iceland, according to a study headed by the University of Reading.
Atlantic air alters India's supply
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Scientists have spent decades attempting to determine the origins of the relationship between the two locations, as per ScienceDaily.
This new study adds to the body of knowledge that might lead to more accurate forecasting of winter precipitation levels in India months in advance.
The findings might be used to boost agricultural yields of critical commodities like wheat and barley, as well as to assist manage the country's vital water supply.
Dr. Kieran Hunt, principal author of the study and research scientist in tropical meteorology at the University of Reading, stated, "Despite being thousands of kilometers distant, we have known that pressure patterns over the North Atlantic had some impact over winter weather in the western Himalayas."
However, scientists have spent years trying to figure out what that relationship is and how strong it is.
The correlation we discovered might be extremely beneficial for states and rural people in northwestern India who rely on winter rain and snow for food and water supplies.
Observing the North Atlantic for any movement towards wetter or drier weather might be a lifeline in preparing for water shortages or flooding.
The new study, published in Climate Dynamics, looked at the relationship between the North Atlantic Oscillation (NAO) and winter rain and snow in the western Himalayas.
The large difference between high pressure in the Azores and low pressure around Iceland pulls the North Atlantic jet stream northward during a positive NAO phase.
Storms are brought to northwest India by extra disturbances in the subtropical jet.
According to the study, winter storms in the region were 20% more common and 7% more powerful during a positive NAO phase than during a negative phase.
This climbed to 31% more frequent winter storms in locations where they already occur often.
This resulted in 40% more moisture being carried by the subtropical jet on average, resulting in 45% more rain and snow in the western Himalayas during the winter months when the NAO was positive.
Storms in northwestern India are expected to strike regions such as Jammu and Kashmir, Punjab, Gujarat, and southern Pakistan.
The study drew on data from the European Centre for Medium-Range Weather Forecasts and other organizations, as well as rainfall gauge data from the western Himalayan area given by the Indian Meteorological Department, which spanned 70 years.
The authors discovered the highest link in NAO change during the 2-3 and 12-16 year cycles. The NAO's gradual changes allow for better forecasting of wetter or drier-than-average north-west Indian winter weather up to three months in advance.
In addition to assisting crops cultivated during the winter, snow that falls on the Himalayas melts and feeds rivers throughout the spring, making this critical to India's water security.
Rao Bahadur N. S. Joshi explores strategies to satisfy the predicted requirements of 1971 in a booklet titled "Food and Irrigation Problems Affecting India in General and Bombay in Particular," as per Nature.
He is primarily concerned with the engineering elements of the irrigation that is assumed to be required; and, while the nutritional discussion is mostly in terms of crop area and tonnages, the necessity for improved diet is not overlooked.
A universal movement of food from surplus to 'deficit' regions is impractical due to the large distances. According to the author, the solution is a significant expansion of irrigation; but, in Bombay, the type of barrage-and-canal irrigation that has been a spectacular success in the river-plains areas is not feasible.
The paper can be viewed as a well-reasoned criticism of canal irrigation. Contour cultivation (bunding) may boost yields in steep locations, however, crops ideal for upland agriculture are grains of poor nutritional value, which Bombay usually has in abundance; and contouring is incompatible with catchment storage.
As a result, the final answer for Bombay Province is a massive increase in the number of tiny wells. The author recommends how these should be planned and funded, as well as how barrage and water-storage structures could be supplied to make the most use of all available water resources.
