IMD develops technology to assess rise of water level in rivers, reservoirs by rain

New technology has been developed to assess the rise of water level in rivers and reservoirs by rain and can help state governments to minutely monitor the impact of rainfall.

The technology called the ‘Impact Based Forecasting Approach’ which shows “pre-event scenario” can help authorities in taking real-time decisions, he said.

The heavy downpour that ravaged Kerala for a fortnight ending August 21 caused the death of around 500 people and economic damages worth over Rs 40,000 crore.

The IMD director general admitted that excessive rainfall that led to floods in Kerala was a result of climate change and in terms of rainfall it was very heavy.

“The number of cyclones has increased from 10 to 18 every year as reported in Nature magazine and, secondly, the quantum of precipitation which was 13 days has come down to 10 days.

There is another technology that would help in identifying warm ocean segments that are contributing to the rapid intensification of the systems. Cyclone Ockhi’s unpredictability was due to such warm ocean segments, following which the technology was developed in October, Ramesh said.

Ockhi is the first severe cyclonic storm in almost 40 years to have traveled about 2,400 kilometers from the Bay of Bengal to as far as the Gujarat coast, a senior Met Department official said. Ockhi, which formed as a depression over southwest Bay of Bengal on November 29 last year, intensified into a cyclone off the Kanyakumari coast in Tamil Nadu on November 30 and traveled up to the Gujarat coast before it dissipated on December 6 after weakening into a low-pressure area.

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How the Antarctic Circumpolar Current helps keep Antarctica frozen

The Antarctic Circumpolar Current, or ACC, is the strongest ocean current on our planet. It extends from the sea surface to the bottom of the ocean and encircles Antarctica.

It is vital for Earth’s health because it keeps Antarctica cool and frozen. It is also changing as the world’s climate warms. Scientists like us are studying the current to find out how it might affect the future of Antarctica’s ice sheets, and the world’s sea levels.

The Antarctic Circumpolar Current, or ACC, is the strongest ocean current on our planet. It extends from the sea surface to the bottom of the ocean and encircles Antarctica. It is vital for Earth’s health because it keeps Antarctica cool and frozen.

The ACC carries an estimated 165 million to 182 million cubic meters of water every second (a unit also called a “Sverdrup”) from west to east, more than 100 times the flow of all the rivers on Earth. It provides the main connection between the Indian, Pacific and Atlantic Oceans.

The tightest geographical constriction through which the current flows is the Drake Passage, where only 800 km separates South America from Antarctica. While elsewhere the ACC appears to have a broad domain, it must also navigate steep undersea mountains that constrain its path and steer it north and south across the Southern Ocean.

Antarctica is a frozen continent surrounded by icy waters. Moving northward, away from Antarctica, the water temperatures rise slowly at first and then rapidly across a sharp gradient. It is the ACC that maintains this boundary.

The ACC is created by the combined effects of strong westerly winds across the Southern Ocean, and the big change in surface temperatures between the Equator and the poles.

Ocean density increases as water get colder and as it gets saltier. The warm, salty surface waters of the subtropics are much lighter than the cold, fresher waters close to Antarctica. The depth of constant density levels slopes up towards Antarctica. The westerly winds make this slope steeper, and the ACC rides eastward along it, faster where the slope is steeper, and weaker where it’s flatter.

Fronts and bottom water:

In the ACC there are sharp changes in water density known as fronts. The Subantarctic Front to the north and Polar Front further south are the two main fronts of the ACC (the black lines in the images). Both are known to split into two or three branches in some parts of the Southern Ocean and merge together in other parts. Scientists can figure out the density and speed of the current by measuring the ocean’s height, using altimeters.

The path of the ACC is a meandering one, because of the steering effect of the sea floor, and also because of instabilities in the current. The ACC also plays a part in the meridional (or global) overturning circulation, which brings deep waters formed in the North Atlantic southward into the Southern Ocean. Once there it becomes known as Circumpolar Deep Water and is carried around Antarctica by the ACC. It slowly rises toward the surface south of the Polar Front.

Once it surfaces, some of the water flows northward again and sinks north of the Subarctic Front. The remaining part flows toward Antarctica where it is transformed into the densest water in the ocean, sinking to the sea floor and flowing northward in the abyss as Antarctic Bottom Water. These pathways are the main way that the oceans absorb heat and carbon dioxide and sequester it in the deep ocean.

The ACC is not immune to climate change. The Southern Ocean has warmed and freshened in the upper 2,000 m. Rapid warming and freshening have also been found in the Antarctic Bottom Water, the deepest layer of the ocean.

Waters south of the Polar Front are becoming fresher due to increased rainfall there, and waters to the north of the Polar Front are becoming saltier due to increased evaporation. These changes are caused by human activity, primarily through adding greenhouse gases to the atmosphere, and depletion of the ozone layer. The ozone hole is now recovering but greenhouse gases continue to rise globally.

Winds have strengthened by about 40% over the Southern Ocean over the past 40 years. Surprisingly, this has not translated into an increase in the strength of the ACC. Instead, there has been an increase in eddies that move heat towards the pole, particularly in hotspots such as Drake Passage, Kerguelen Plateau, and between Tasmania and New Zealand.

Scientists have observed much change already. The question now is how this increased transfer of heat across the ACC will impact the stability of the Antarctic ice sheet, and consequently the rate of global sea-level rise.

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Earth’s inner core is softer: How is the planet formed?

Contrary to the fact the Earth’s inner core is solid, researchers from Australian National University (ANU) have found that it is comparatively softer.

Facts about the inner core of the Earth:

  • Radius: 1,220 kilometers (760 miles) i.e. 70 percent of the Moon’s radius.
  • Composed of: Nickel-iron alloy.
  • Temperature: 5,700 K (5,430 °C) or 9806 °F, which is almost the temperature of the Sun.
  • The inner core is made up of two layers outer and inner.
  • Outer core is 1,355 miles (2,180 km) thick.
  • There is no estimated radius of the inner core; however, it plays a distinct role in making Earth’s magnetic field.
  • The inner core is measured by shear waves, a seismology term, which so tiny and feeble that it can’t be observed directly.
  • In fact, detecting them has been considered the ‘Holy Grail’ of global seismology since scientists first predicted the inner core was solid in the 1930s and 40s.

Purpose of the Earth’s inner core:

When charged particles from the solar wind collide with air molecules above Earth’s magnetic poles, it causes the air molecules to glow, causing the auroras – the northern and southern lights.

Researchers came up with a way to detect shear waves, or “J waves” in the inner core – a type of wave which can only travel through solid objects.

According to the research published by the university, the wavefield method looks at the similarities between the signals at two receivers after a major earthquake, rather than the direct wave arrivals. The study shows these results can then be used to demonstrate the existence of J waves and infer the shear wave speed in the inner core.

It has been found that the inner core shares some similar elastic properties with gold and platinum.

The understanding of the Earth’s inner core has direct consequences for the generation and maintenance of the geomagnetic field, and without that geomagnetic field, there would be no life on the Earth’s surface.

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Should India have two time zones? National timekeeper adds new arguments

Over the years, various citizens and political leaders have debated whether India should have two separate time zones. The demand is based on the huge difference in daylight times between the country’s longitudinal extremes, and the costs associated with following the same time zone. Those arguing against the idea, on the other hand, cite impracticability — particularly the risk of railway accidents, given the need to reset times at every crossing from the one-time zone into another.

Now, a proposal for two time zones has come from India’s national timekeeper itself. Scientists at the Council of Scientific & Industrial Research’s National Physical Laboratory (CSIR-NPL), which maintains Indian Standard Time, have published a research article describing the necessity of two time zones, with the new one an hour ahead of the existing time zone.

Need for two time zones:

India extends from 68°7’E to 97°25’E, with the spread of 29° representing almost two hours from the geographic perspective.

Legislators, activists, industrialists and ordinary citizens from the Northeast have often complained about the effect of IST on their lives and pursued the issue of having a separate time zone with the Central government, without much success.

In the Northeast, the sun rises as early as four in the morning and in winter it sets by four in the evening. By the time government offices or educational institutions open, many daylight hours are already lost. In winter this problem gets even more accentuated and the ecological costs are a disaster with much more electricity has to be consumed.

The research paper proposes to call the two time zones IST-I (UTC + 5.30 h) and IST-II (UTC + 6.30 h). The proposed line of demarcation is at 89°52’E, the narrow border between Assam and West Bengal.

States west of the line would continue to follow IST (to be called IST-I). States east of the line — Assam, Meghalaya, Nagaland, Arunachal Pradesh, Manipur, Mizoram, Tripura, Andaman & Nicobar Islands —would follow IST-II.

India has a huge population; if the country were divided into two time zones, there would be chaos at the border between the two zones. It would mean resetting clocks with each crossing of the time zone. There is scope for more dangerous kinds of confusion. Railway signals are not fully automated and many routes have single tracks. Trains may meet with major accidents owing to human errors. Just one such accident would wipe out any benefits resulting from different time zones in the country.

Partitioning the already divided country further into time zones may also have undesirable political consequences. Moreover, our research shows that energy saving from creating two time zones is not particularly large.

While there is merit in the argument, the potentially adverse consequences of introducing a new time zone within the country are many. Not forgetting the fact that a country like Russia has as many as nine time zones across the contiguous territory, having to cope with the zones and to be forced to reset the watch each time you need to cross a domestic line could be complicated.

With a time difference of one hour in the mornings and in the evenings, there would be nearly 25% less overlap between office timings in the two zones. This could be important for banks, offices, industries and multinational companies which need to be constantly interconnected. This will be further detrimental to productivity and to the interests of the eastern region.

There is already a sense of alienation between the relatively prosperous and industrialized western zone and the less developed eastern zone. The people in the Northeast sense a distance from the mainland and a separateness in clock time may accentuate it.

Having a separate time zone for the eastern region will provide no energy or other benefits to the rest of the country. Moreover, India will continue to be in off-set time zones, five and a half hours in the west and six and a half in the eastern region ahead of.

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Centre sets ‘minimum river flows’ for the Ganga

In a first, the Union government has mandated the minimum quantity of water — or ecological flow as it’s called in scientific circles — that various stretches of the Ganga must necessarily have all through the year. The new norms would require hydropower projects located along the river to modify their operations so as to ensure they are in compliance.

In a gazette notification made public, the National Mission for Clean Ganga has laid down the flow specifications. The upper stretches of the Ganga — from its origins in the glaciers and until Haridwar — would have to maintain: 20% of the monthly average flow of the preceding 10-days between November and March, which is the dry season; 25% of the average during the ‘lean season’ of October, April and May; and 30% of monthly average during the monsoon months of June-September.

The new norms would require hydropower projects located along the river to modify their operations so as to ensure they are in compliance. Power projects that don’t meet these norms as yet would be given three years to comply and “mini and micro-projects” would be exempt from these requirements.

For the main stem of the Ganga — from Haridwar in Uttarakhand to Unnao, Uttar Pradesh — the notification specifies minimum flow at various barrages: Bhimgoda (Haridwar) must ensure a minimum of 36 cubic meters per second (cumecs) between October-May, and 57 cumecs in the monsoon; and the barrages at Bijnor, Narora and Kanpur must maintain a minimum of 24 cumecs in the non-monsoon months of October-May, and 48 cumecs during the monsoon months of June-September.

Designated Authority:

The Central Water Commission would be the designated authority to collect relevant data and submit flow monitoring-cum-compliance reports on a quarterly basis to the NMCG, according to the notification.

The notification is issued in the backdrop of ongoing ‘fast unto death’ by environmentalist and former IIT Kanpur faculty member GD Agarwal at Haridwar on the issue of Ganga conservation. The 87-year-old Agrawal has been observing hunger strike since June 22 for pollution free and uninterrupted flow in the Ganga.

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Very severe cyclone ‘Titli’ crosses Odisha coast in hour-long act

The destructive very severe cyclone ‘Titli’ has crossed the North Andhra Pradesh and South Odisha coast early this morning, near Palasa in Srikakulam district of Andhra Pradesh, exactly as India Met Department (IMD) had predicted.

In September 2004, an international panel on tropical cyclones decided that countries from the region would each put in names, which would be assigned to storms in the Bay of Bengal and the Arabian Sea.

Eight countries — India, Pakistan, Bangladesh, Maldives, Myanmar, Oman, Sri Lanka, and Thailand – participated and came up with a list of 64 names.

In the event of a storm, the Regional Specialized Meteorological Centre, New Delhi, selects a name from the list.

The late origin of this naming system — unlike storms in the Atlantic, which have been getting named since 1953 — was ostensibly to protect sensitivities in the ethnically diverse region.

The purpose of the move was also to make it easier for “people easy to understand and remember the tropical cyclone/hurricane in a region, thus to facilitate disaster risk awareness, preparedness, management, and reduction.

Guidelines for naming cyclones:

Citizens can submit names to the Director General of Meteorology, IMD, for consideration, but the weather agency has strict rules for the selection process.

A name, for instance, ‘should be short and readily understood when broadcast’.

The names must also be neutral, ‘not culturally sensitive and not convey some unintended and potentially inflammatory meaning’.

Furthermore, on the account of the ‘death and destruction,’ a storm in the Indian Ocean causes, their names are retired after use, unlike those in the Atlantic and Eastern Pacific lists, which are reused every few years.

Category 1: Wind and gales of 90-125 kph, negligible house damage, some damage to trees and crops.

Category 2: Destructive winds of 125-164 kph. Minor house damage, significant damage to trees, crops and caravans, the risk of power failure.

Category 3: Very destructive winds of 165-224 kph. Some roof and structural damage, some caravans destroyed, power failure likely.

Category 4: Very destructive winds of 225-279 kph. Significant roofing loss and structural damage, caravans destroyed, blown away, widespread power failures.

Category 5: Very destructive winds gusts of more than 280 kph. Extremely dangerous with widespread destruction.

Atlantic and Pacific storm names are reused every six years but are retired “if a storm is so deadly or costly that the future use of the name would be insensitive or confusing,” according to forecasters at the US National Hurricane Center in Miami.

The country’s cyclone season runs from April to December, with severe storms often causing dozens of deaths, evacuations of tens of thousands of people from low-lying villages and widespread damage to crops and property.

What’s the difference between hurricanes, cyclones, and typhoons?

Hurricanes, cyclones, and typhoons are all tropical storms. They are all the same thing but are given different names depending on where they appear. When they reach populated areas they usually bring very strong wind and rain which can cause a lot of damage.

Hurricanes are tropical storms that form over the North Atlantic Ocean and Northeast Pacific. Cyclones are formed over the South Pacific and the Indian Ocean. Typhoons are formed over the Northwest Pacific Ocean.

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How wet is the ground after rain? For first time, India gets soil moisture map

Sugarcane farmers cutting last lot of crop in Bagpat District, Uttar Pradesh. Recently one Sugarcane farmer Udayveer Singh, who was on a dharna over non-payment of dues by sugar mills, died at the protest site. Sugarcane farmers who launched the protest on May 21, at Tehsil Baraut in Bagpat District, Uttar Pradesh. EXPRESS PHOTO BY PRAVEEN KHANNA 31 05 2018. *** Local Caption *** Sugarcane farmers cutting last lot of crop in Bagpat District, Uttar Pradesh. Recently one Sugarcane farmer Udayveer Singh, who was on a dharna over non-payment of dues by sugar mills, died at the protest site. Sugarcane farmers who launched the protest on May 21, at Tehsil Baraut in Bagpat District, Uttar Pradesh.

With the rabi season around the corner, a countrywide forecast prepared at the end of the monsoon season suggests deficit soil moisture conditions are likely in Gujarat, Bihar, Jharkhand, Tamil Nadu, and southern Andhra Pradesh.

This forecast, following a joint exercise by IIT Gandhinagar and the India Meteorological Department (IMD), for the first time, provides a country-wide soil moisture forecast at seven and 30-day lead times.

How was it developed?

The experts used the ‘Variable Infiltration Capacity’ model to provide the soil moisture prediction.

The product, termed ‘Experimental Forecasts Land Surface Products’, is available on the IMD website. It has been developed using the hydrological model that takes into consideration soil, vegetation, land use and land cover among other parameters.

In Bundelkhand, most farmers keep their land fallow or just grow some fodder crop during the kharif season since the rains are unpredictable and there could be extended dry spells after sowing. They then mainly cultivate the rabi crop using the soil moisture left behind by the monsoon rains.

It is a similar trend in Bihar, in low lying areas of Seemanchal and Kosi belt, where no crop is grown during Kharif because of inundated lands. This means that if there is not enough rainfall in one or two months, these are regions which will demand heavy irrigation whether that comes from groundwater or surface water storage (reservoirs).

Based on observed conditions at present, Gujarat, parts of Maharashtra, Chhattisgarh, Jharkhand, Tamil Nadu and parts of Andhra Pradesh are deficient in terms of soil moisture right now.

Significance and the need for data on soil moisture:

Soil moisture is crucial for agriculture since it directly affects crop growth and how much irrigation is required for the area. It is because the crucial information needed for agriculture is not revealed only through rainfall data.

Soil moisture gives us more information on what is needed for crop growth in different parts of the country. Besides, timely soil moisture forecasts will help target interventions, in terms of seed varieties for better planning in agriculture.

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Tamil Nadu govt announces novel scheme for the protection of the exotic Neela Kurinji plants

Tamil Nadu government has announced a novel scheme for the protection of the exotic Neela kurinji (Strobilanthus kunthianus) plants that flower only once in 12 years. Following complaints that these rare and ecologically unique flowers are being packaged and sold on the commercial basis, the state department has warned that strict fines will be imposed in offenders.

Why Neelakurinji flowers only once in 12 years?

Among plants, there are annuals and perennials. Annual plants complete their life cycle in one year. They grow from the seed, bloom, produce seeds and die in one growing season. Perennials live for more than two years and usually flower every year and set seeds.

Some perennials flower only once in their lifetime, set seeds and die. The next generation of the plants are established from these seeds and the cycle is repeated. Such plants are known as monocarpic, opposed to polycarpic plants that flower and set seeds many times during its lifetime. Monocarpic plants flower only after attaining maturity. The time taken by different species may differ in this respect.

Bamboos are monocarpic plants taking more than 40 years to mature and flower. Another characteristic shown by such plants is that these will flower gregariously in a single season. This happens in the case of bamboos and Kurinjis. The term ‘plietesials’ is used to refer to such plants. The time taken to mature varies in different species of Kurinjis. So different species of Kurinjis have different intervals of flowering. Neelakurinji matures in 12 years time and flowers gregariously every 12 years.

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NITI Aayog for clear policy on ‘jhum’ cultivation

A recent NITI Aayog publication on shifting cultivation which is particularly practiced in the northeastern States has recommended that the Ministry of Agriculture should take up a “mission on shifting cultivation” to ensure inter-ministerial convergence.

Various authorities often have divergent approaches towards shifting cultivation. This creates confusion among grass-roots level workers and jhum farmers said the report.

Therefore, shifting cultivation fallows must be legally perceived and categorized as ‘regenerating fallows’ and credit facilities must be extended to those who practice shifting cultivation.

Land for shifting cultivation should be recognized as “agricultural land” where farmers practice agro-forestry for the production of food rather than as forestland.

Jhum cultivation, also known as the slash and burn agriculture, is the process of growing crops by first clearing the land of trees and vegetation and burning them thereafter. The burnt soil contains potash which increases the nutrient content of the soil.

This practice is considered as an important mainstay of food production for a considerable population in North-East India.

The report notes that between 2000 and 2010, the land under shifting cultivation dropped by 70 %. People are returning to fallow land left after shifting in a shorter span. Earlier the cultivators returned to fallows after 10-12 years, now they are returning in three to five years which has impacted on the quality of the soil.

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Erratic monsoon rainfall in India partly due to air pollution: Study

The Erratic behavior of monsoon rainfall, including the phenomenon of concentrated heavy rainfall on a small number of days, could, at least in part, be attributed to the rising air pollution, especially the increase in suspended particles in the atmosphere, a new study

The study, published in the prestigious journal, Nature Communications, has shown how excess aerosols, suspended solid particles like dust, smoke, and industrial effluents, in the atmosphere is changing cloud patterns, its shape, size and other properties like temperature, which in turn is resulting in variability in rainfall over the Indian sub-continent during the monsoon season.

The group analyzed satellite data and data from atmospheric computer models from the last 16 years to make an assessment of the likely impacts of changes in cloud behavior over the land area of about 16 lakh square kilometers.

The linkage of air pollution to rainfall activity is not new and has been established in many earlier studies as well. Tripathi’s team, however, has, for the first time, given details of the exact changes that take place in the clouds over India as a result of an increase in aerosols, and how this was leading to a reduction in the difference in day and night temperatures, and also impacting rainfall activity.

Since the Uttarakhand tragedy in 2013, India has had an unusually extreme rainfall event every year. Long-term rainfall data also shows that rainfall activity is getting increasingly concentrated to a few extremely wet days during the season, while most of the other days remain relatively dry.

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