Climatologist: hurricanes can not be predicted exactly

© Big Nakayosi Mokhov, Director of the Institute of atmospheric physics. A. M. Obukhov RASClimatologist: hurricanes can not be predicted exactly© Big Science

. Academician Igor Mokhov, Director of the Institute of atmospheric physics of Russian Academy of Sciences and Professor at MIPT and MSU, explained why a series of powerful hurricanes are difficult to predict, and told about the possible causes of increased intense tropical hurricanes.

In the last two years the coast of North America is constantly «bombard» the most powerful hurricanes causing huge economic damage to coastal cities and villages of America and causing great problems for the populations of some rare animals such as monarch butterflies.

Only in August and September of this year in the Atlantic occurred just four of the most powerful hurricane of the fourth and fifth category of danger, Harvey, Irma, Jose, and Maria, who left the island of Puerto Rico without power and created a potentially disastrous situation on the Atlantic coast of the United States and Mexico.

Even in winter, the specialists of the administration of oceanic and atmospheric research USA (NOAA) talked about the fact that the number of powerful hurricanes this year will be higher than usual, but they are unable to predict when and where they occur. Academician Mokhov explains why today such predictions remain beyond the capabilities of scientists.

— The General pattern of seasonal activity of tropical cyclones, storms and hurricanes are known, although variations from year to year are great. On Earth, tropical cyclones, storms and hurricanes formed typhoons all year round. In the Northern hemisphere in General maximum activity is achieved by the end of summer or beginning of autumn, and in the South when in the Northern hemisphere winter.

Tropical cyclones in the Northwest Pacific, most of which transformirovalsya in the extratropical and penetrates to the Russian far East, are formed throughout the year with peak activity in late summer. And in the Northern tropics of the Atlantic season, tropical cyclone activity begins in may-June to winter with a maximum in early autumn.

But the uncertainty of the prediction of the timing of the formation of the first tropical storms, their number, intensity and trajectories of the oceanic basins in specific years is very large. This is due to substantial interannual variability of regional atmospheric and ocean processes, and the formation of tropical cyclones depends on a number of factors.

However, there are certain regularities, which allows to make a predictive assessment. For example, the frequency of occurrence and capacity of Pacific hurricanes-typhoons, depends on in what phase is the climatic phenomenon El niño. During the development of El niño in General, the lower the probability of formation of typhoons in the Northwest Pacific, which can reach the shores of Japan and the Russian Far East.

The formation of hurricanes depends on the temperature of water in the ocean – the more it warmed the upper layers, the more favorable the conditions for the formation of hurricanes. When in the tropics abnormally warm ocean temperatures around 26-27 degrees Celsius and more, high risk of hurricanes.

Also needed a special regime of the atmosphere for the development of convective processes, evaporation and transport in the atmosphere energy stored in the heated upper layer of the ocean. These processes are accompanied by cooling of the upper ocean and release tremendous energy in the atmosphere by condensation.

— What are the characteristics of tropical cyclone activity in 2017?

— This year, the first cyclone-a storm has formed in the tropics of the North Atlantic in April, followed a two-month break in the storm activity in the basin. In the second half of June was formed by two tropical storms, during the second half of July — a couple. And in August-September — explosion hurricane activity, including two powerful hurricane, Irma and Maria. The surface temperature of the ocean in the tropics of the Atlantic ocean in August of this year was higher than in previous years, while over much of the temperature anomalies exceeded one degree Celsius.

I must say that at the end of last year was projected from 3 to 9 tropical storms in the North Atlantic this year, including from one to five severe hurricanes, as well as from 10 to 18 tropical storms. On average in the Atlantic formed significantly fewer tropical cyclones than the Pacific ocean.

Most hurricanes and typhoons are born in the North-West Pacific ocean, where they affect East Asia, Japan and the Russian far East. In recent years, as shown by our analysis of the data, increasing the likelihood of penetration of tropical cyclones in middle latitudes.

Of course, in the Pacific typhoons and Atlantic hurricanes are affected by climatic fluctuations such as El niño or the North Atlantic oscillation. It should be understood that all these changes occur against the background of trends in the overall growth of the surface temperature of the water. For example, in the South Atlantic tropical cyclones are very rare – began to appear only in this century, the surface temperature of the ocean there is relatively low. Organoborane vortices began to appear in the Mediterranean and the Black sea.

The formation of hurricanes depends on a number of factors, not only on the temperature, and the variation in their number in different years big. For example, in 2010, when the heat prevailed in European Russia, in the Pacific ocean occurred a total of 14 cyclones, and in 1971 there were about 36. And in the Atlantic in 1984 there were only four cyclones in 2005 were 7 times more.

— What can you expect in the future?

— Now there is a General significant upward trend in the frequency of penetration of strong cyclones from tropical latitudes in the middle. A predictive model estimates indicate that global warming will increase the intensity of hurricanes, although the overall frequency of tropical cyclones may decrease. In other words, the total number of tropical cyclones may decrease, and super-hurricanes to occur more often.

These trends are already evident, and powerful tropical storms this year are proof. Similar trends are evident for extratropical cyclones. There is a significant risk that further warming of the waters of the Atlantic, the frequency of hurricanes will increase. On the other hand, as I said, there is a very large variation in empirical estimates and the results of the model calculations that do not allow a reliable prognostic assessment.

In a report prepared in 2013 by the intergovernmental panel on climate change (IPCC) — I participated in its preparation as the lead author noted that uncertainty in the predictive estimates is still very large. You need to understand that the confidence level of possible risks yet remains low, but these risks should not be underestimated. Are already implementing many model estimates of possible climate changes that a few decades it seemed incredible.

For more reliable estimates of the need for more statistics for hurricanes. The large scatter associated with natural variability, makes it difficult to obtain reliable estimates of General trends. More reliable can be the evaluation at the global level or at the level of individual hemispheres, with large uncertainties for individual basins.

— Is it possible to explain this idea, policies that require accurate forecasts?

— Absolutely accurate climate forecasts are fundamentally impossible. It should be understood, not to get into a stupid situation, asking the impossible. The formation and development of hurricanes as an important component of the climate system is a very complex process.

The Earth’s climate system — a complex system for calculating the modes which need not only supercomputers, but also a deep understanding of interaction between its various components how the interaction of atmosphere and ocean. Even a very simplified model, known as the Lorentz model describing the processes of atmospheric convection, which are associated with the processes of formation and tropical cyclones, shows a complex dynamics, think of the «butterfly effect» — highlights the complexity and predictability of climatic processes. Climatologist: hurricanes can not be predicted exactly© Big Naukuchiyatal explained why the March in Russia was warm, and may – cool

However, progress in the modeling, combined with the development of the global observing systems contributes to the fact that in the coming decades we will significantly advance the search for more reliable prognostic assessments of climate change. However, you should realize that climate projections cannot be completely accurate, it is necessary to assess the probabilities and risks of possible changes and their consequences.

For more reliable estimates of modern trends on the background of natural climate variability on different time scales requires a reliable Foundation of data from continuous and prolonged measurements. But satellite measurements of only a few tens of years.

— How hurricanes can affect the ecosystems and animal life?

— It is obvious that the strongest hurricanes are associated negative environmental impacts, including long-term. On the other hand, tropical cyclones bring a lot of moisture and can contribute to ending regional droughts.

From a global perspective of tropical cyclones, storms and hurricanes are the stabilizing response of the climate system for it to overheat, taking the ocean heat and lowering its temperature in the tropics.

— Can such tropical storms to threaten Russia?

— Our country, because of its geographical situation, is exposed to strong cyclones that reach the coast of the Far East in a modified form of the tropical latitudes. On average, for the year in the extratropical latitudes in the Northwest Pacific breaks over 10 tropical cyclones. Climatologist: hurricanes can not be predicted exactly© NASA / JAXA, Hal Resembalnce NASA took video of the flood caused by hurricane «Maria»

In the future, despite the variability, which I have already said, it can be expected that the frequency of hurricanes in the basin, can grow. The analysis shows the IPCC, if global warming continues, the frequency of the strongest tropical storms in the Northwest Pacific ocean and in the North Atlantic will grow rather than will not change.

Climate models show what is possible and shift to the East region of active generation of cyclones in tropical latitudes in the Northwest Pacific ocean. Complicate more reliable prognostic assessments and regional characteristics of possible changes in atmospheric circulation and monsoon regimes.

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