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Posts Tagged ‘rainfall

The weekly intelligencer

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Indices, prices, data series, readings and jottings of note over the last week, fortnight and month, compiled for the week beginning 6 August 2017.

Quick Estimates of Index of Industrial Production (IIP) with base 2011-12 for the month of May 2017, released by the Ministry of Statistics and Programme Implementation, Central Statistics Office. The General Index for the month of May 2017 stands at 124.3, which is 1.7% higher as compared to the level in the month of May 2016.

India Meteorological Department, Hydromet Division. Until 2 August 2017, 67% of the districts have recorded cumulative rainfall of normal, excess or large excess and 33% of the districts have recorded cumulative rainfall of deficient or large deficient. This compares with 69% and 31% respectively at the same time last year.

Ministry Of Commerce and Industry, Office Of The Economic Adviser. The official Wholesale Price Index for All Commodities (Base: 2011-12=100) for the month of June 2017 declined by 0.1% to 112.7 (provisional) from 112.8 (provisional) for the previous month.

Ministry of Water Resources, Central Water Commission. As on 3 August 2017 the total live storage capacity of the 91 major reservoirs is 157.799 billion cubic metres (BCM) which is about 62% of the total estimated live storage capacity of 253.388 BCM. As per reservoir storage bulletin dated 03 August 2017, live storage available in these reservoirs is 67.683 BCM, which is 43% of total water storage capacity of these reservoirs. Last year the live storage in these reservoirs for the corresponding period was 65.109 BCM and the average of last 10 years was 69.510 BCM.

Reserve Bank Of India Bulletin, Weekly Statistical Supplement. 4 August 2017. Aggregate deposits Rs 106,254 billion. Bank credit Rs 76.888 billion. Money stock: Rs 14,689 billion currency with the public, Rs 101,600 billion time deposits with banks.

Ministry of Agriculture. The total sown area as on 4 August 2017 stands at 878.23 lakh hectare as compared to 855.85 lakh hectare at this time last year. Rice has been sown/transplanted in 280.03 lakh hectare, pulses in 121.28 lakh hectare, coarse cereals in 156.95 lakh hectare, oilseeds in 148.88 lakh hectare, sugarcane in 49.71 lakh hectare and cotton in 114.34 lakh hectare.

Ministry of Consumer Affairs, Food and Public Distribution, Price Monitoring Cell in the Department of Consumer Affairs. Maximum prices recorded (per kilo and per litre) amongst the set of 100 cities monitored during the week of 23-29 July: Rice 52, Wheat 45, Atta (Wheat) 50, Gram Dal 132, Tur/ Arhar Dal 132, Urad Dal 150, Moong Dal 140, Masoor Dal 110, Sugar 52, Milk 65, Groundnut Oil 180, Mustard Oil 170, Vanaspati 120, Soya Oil 110, Sunflower Oil 130, Palm Oil 110, Gur 68, Tea Loose 360, Salt Pack (Iodised) 22, Potato 35, Onion 45, Tomato 100.

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A method for a post-carbon monsoon

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RG_Goan_monsoon_2015

The uses to which we have put available climatic observations no longer suit an India which is learning to identify the impacts of climate change. Until 2002, the monsoon season was June to September, there was an assessment in May of how well (or not) the monsoon could turn out, and short-term forecasts of one to three days were available only for the major metros and occasionally a state that was in the path of a cyclone. But 2002 saw the first of the four El Niño spells that have occurred since 2000, and the effects on our Indian summer monsoon began to be felt and understood.

The India Meteorology Department (which has become an everyday abbreviation of IMD for farmers and traders alike) has added computational and analytical resources furiously over the last decade. The new research and observational depth is complemented by the efforts of a Ministry of Earth Sciences which has channelled the copious output from our weather satellites, under the Indian Space Research Organisation (ISRO), and which is interpreted by the National Remote Sensing Centre (NRSC), to serve meteorological needs.

The IMD, with 559 surface observatories, 100 Insat satellite-based data collection platforms, an ‘integrated agro-advisory service of India’ which has provided district-level forecasts since 2008, a High Performance  Computing  System commissioned in 2010 (whose servers run at Pune, Kolkata, Chennai, Mumbai, Guwahati, Nagpur, Ahmedabad, Bengaluru, Chandigarh, Bhubaneswar, Hyderabad and New Delhi) ploughs through an astonishing amount of numerical data every hour. Over the last four years, more ‘products’ (as the IMD system calls them) based on this data and its interpretation have been released via the internet into the public domain. These are reliable, timely (some observation series have three-hour intervals), and valuable for citizen and administrator alike.

The new 11-grade indicator for assessing weekly rainfall departures in districts. Same data, but dramatically more useful guidance.

The new 11-grade indicator for assessing weekly rainfall departures in districts. Same data, but dramatically more useful guidance.

Even so, the IMD’s framing of how its most popular measures are categorised is no longer capable of describing what rain – or the absence of rain – affects our districts. These popular measures are distributed every day, weekly and monthly in the form of ‘departures from normal’ tables, charts and maps. The rain adequacy categories are meant to guide alerts and advisories. There are four: ‘normal’ is rainfall up to +19% above a given period’s average and also down to -19% from that same average, ‘excess’ is +20% rain and more, ‘deficient’ is -20% to -59% and ‘scanty’ is -60% to -99%. These categories can mislead a great deal more than they inform, for the difference between an excess of +21% and an excess of +41% can be the difference between water enough to puddle rice fields and a river breaking its banks to ruin those fields.

In today’s concerns that have to do with the impacts of climate change, with the increasing variability of the monsoon season, and especially with the production of food crops, the IMD’s stock measurement ‘product’ is no longer viable. It ought to have been replaced at least a decade ago, for the IMD’s Hydromet Division maintains weekly data by meteorological sub-division and by district. This series of running records compares any given monsoon week’s rainfall, in a district, with the long period average (a 50-year period). Such fineness of detail must be matched by a measuring range-finder with appropriate  interpretive indicators. That is why the ‘no rain’, ‘scanty’, ‘deficient’, ‘normal’ or ‘excess’ group of legacy measures must now be discarded.

In its place an indicator of eleven grades translates the numeric density of IMD’s district-level rainfall data into a much more meaningful code. Using this code we can immediately see the following from the chart ‘Gauging ten weeks of rain in the districts’:

1. That districts which have experienced weeks of ‘-81% and less’ and ‘-61% to -80%’ rain – that is, very much less rain than they should have had – form the largest set of segments in the indicator bars.

2. That districts which have experienced weeks of ‘+81% and over’ rain – that is, very much more rain than they should have had – form the next largest set of segments in the indicator bars.

3. That the indicator bars for ‘+10% to -10%’, ‘-11% to -20%’ and ‘+11% to +20%’ are, even together, considerably smaller than the segments that show degrees of excess rain and degrees of deficient rain.

Far too many districts registering rainfall departures in the categories that collect extremes of readings. This is the detailed reading required to alert state administrations to drought, drought-like and potential flood conditions.

Far too many districts registering rainfall departures in the categories that collect extremes of readings. This is the detailed reading required to alert state administrations to drought, drought-like and potential flood conditions.

Each bar corresponds to a week of district rainfall readings, and that week of readings is split into eleven grades. In this way, the tendency for administrations, citizens, the media and all those who must manage natural resources (particularly our farmers), to think in terms of an overall ‘deficit’ or an overall ‘surplus’ is nullified. Demands for water are not cumulative – they are made several times a day, and become more or less intense according to a cropping calendar, which in turn is influenced by the characteristics of a river basin and of an agro-ecological zone.

The advantages of the modified approach (which adapts the Food and Agriculture Organisation’s ‘Global Information and Early Warning System’ categorisation, designed to alert country food and agriculture administrators to impending food insecurity conditions) can be seen by comparing the single-most significant finding of the IMD’s normal method, with the finding of the new method, for the same point during the monsoon season.

By 12 August 2015 the Hydromet Division’s weekly report card found that 15% of the districts had recorded cumulative rainfall of ‘normal’ and 16% has recorded cumulative rainfall of ‘deficient’. There are similar tallies concerning rainfall distribution – by region and temporally – for the meteorological sub-divisions and for states. In contrast the new eleven-grade measure showed that in seven out of 10 weeks, the ‘+81% and over’ category was the most frequent or next-most frequent, and that likewise, the ‘-81% and less’ category was also the most frequent or next-most frequent in seven out of 10 weeks. This finding alone demonstrates the ability of the new methodology to provide early warnings of climatic trauma in districts, which state administrations can respond to in a targeted manner.

Mapping climate behaviour, ten days at a time

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RG_GIEWS_2015_may_jun

This year, the Global Information and Early Warning System (GIEWS, a project of the FAO) has brought into public domain a new rainfall and vegetation assessment indicator. The indicator takes the form of maps which describe conditions over blocks of ten days each, with each such block termed a dekad (from the Greek for ‘ten’). Thus we have visual views of divisions of thirds of a month which from a crop cultivation point of view, now lies between the weekly and fortnightly assessments regularly provided by agri-meteorological services.

How to read the colours used in the rainfall anomaly maps.

How to read the colours used in the rainfall anomaly maps.

In 2015, what was quickly called “out of season” rainfall was experienced in most of India during March and April. These conditions carried over into May and that is why the typical contrast between a hot and rainless May and a wet June is not seen.

The panel of maps shows the incidence of normal, below normal and above normal rain during six dekads of May and June. Greens signal above normal, yellows are normal and reds are below normal. The first dekad of May looks like what the second week of June normally does, but for the large above normal zone in the north-central Deccan. The second dekad of May has in this set had the largest number of above normal points, with more rain than usual over the southern peninsula, and over Chhattisgarh, Odisha, West Bengal. Rajasthan and Punjab.

The third dekad of May shows most of India as far below normal. This changes in the first dekad of June, with rain over the eastern coast registering much above normal for the period – Tamil Nadu, Rayalaseema, Andhra Pradesh and Odisha. During the second dekad of June, the divide north and south of the Vindhyas is visible, when northern India and the Gangetic belt continued to experience very hot days whereas over Telengana, Karnataka, Vidarbha and Madhya Maharashtra there was above normal rainfall. During the third dekad of June the picture was almost reversed as the southern states fell below their running rainfall averages.

This panel describes not rainfall but the anomalies (above and below) recorded in received rainfall. At the level of a meteorological sub-division or a river basin, the anomaly maps are a quick and reliable guide for judging the impacts of climate variability on crop phases (preparation, sowing, harvest) and on water stocks.

Why IMD’s rain math doesn’t add up

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Each blue bar represents the actual rainfall recorded by a district as a percentage of its normal. There are 614 district recordings in this chart.. The red dotted line is the 100% mark, and many of the bars end below, or way below, this mark. This is the district-level view of cumulative rainfall over eight rain weeks using the IMD's own data.

Each blue bar represents the actual rainfall recorded by a district as a percentage of its normal. There are 614 district recordings in this chart.. The red dotted line is the 100% mark, and many of the bars end below, or way below, this mark. This is the district-level view of cumulative rainfall over eight rain weeks using the IMD’s own data.

Over eight weeks of recorded monsoon rain, the district-level data available with the India Meteorological Department (IMD) portrays a picture that is very different from its ‘national’ and ‘regional’ advice about the strength and consistency of rainfall.

In its first weekly briefing on the monsoon of August 2014, IMD said: “For the country as a whole, cumulative rainfall during this year’s monsoon (01 June to 30 July 2014) has so far upto 30 July been 23% below the Long Period Average.” Out of 36 meteorological sub-divisions, said the IMD, the rainfall has been normal over 15 and deficient over 21 sub-divisions.

The four regional readings that make IMD's data look less worrisome than it actually is.

The four regional readings that make IMD’s data look less worrisome than it actually is.

However, here is a far more realistic reading of the monsoon season so far, from the IMD’s own data. For the 614 individual readings from districts that have regular rainfall readings, we have the following: 86 districts have registered scanty rainfall (-99% to -60%); 281 districts have registered deficient rainfall (-59% to -20%); 200 districts have registered normal rainfall (-19% to +19%); and 47 districts have registered excess rainfall (+20% and more).

What this means, and the chart I have provided to illustrate the 614 individual values leaves us in no doubt, is that 367 out of 614 districts have had meagre rain for eight weeks. This also means that over eight weeks where there should have been rainfall that – as the IMD predicted in early June – would be around 95% of the ‘long period average’, instead three out of five districts have had less than 80% of their usual quota.

Quiet preparations for scarce water, smaller harvests

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State and district officials will have to turn forms like this (the drought management information system) into preparation on the ground and in each panchayat.

State and district officials will have to turn forms like this (the drought management information system) into preparation on the ground and in each panchayat.

The Ministry of Agriculture through the Department of Agriculture and Cooperation has released its national drought crisis management plan. This is not taken as the signal for India that drought conditions will set in, but to prepare for drought where it is identified. In the fifth week of the South-West monsoon, the trend continues to be that week by week, the number of districts which have recorded less rainfall than they normally receive outnumber those districts with normal rainfall. When this happens over a prolonged period, such as four to six weeks, drought-like conditions set in and the administration prepares for these conditions.

There are a group of ‘early warning indicators’ for the kharif crop (sowing June to August) which are looked for at this time of the year. They are: (1) delay in the onset of South-West monsoon, (2) long ‘break’ activity of the monsoon, (3) insufficient rains during June and July, (4) rise in the price of fodder, (5) absence of rising trend in the water levels of the major reservoirs, (6) drying up of sources of rural drinking water, (7) declining trend in the progress of sowing over successive weeks compared to corresponding figures for ‘normal years’.

On this list, points 1 and 2 are true, 3 is true for June and July until now, 4 and 5 are true, we have insufficient information for 6 and 7 but from mid-May there have been a number of media reports on water scarcity in the districts of peninsular, central and northern India. Thus the state of the ‘early warning’ indicators taken together have triggered the issuing of the government’s drought crisis management plan. Please read the rest at the India Climate Portal.

Written by makanaka

July 18, 2014 at 12:00

A month of truant rain

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RG_four_weeks_rain_graphic_20140709

We now have rain data for four complete weeks from the India Meteorological Department (IMD) and for all the districts that have reported the progress of the monsoon. The overall picture is even more serious than reported earlier because of the falling levels of water in the country’s major reservoirs. [05 to 11 June is the first week. 12 to 18 June is the second week. 19 to 25 June is the third week. 26 June to 02 July is the fourth week.]

Using the new measure of assessing the adequacy of district rainfall (and not the meteorological cgradations that is the IMD standard), in the fourth week of the monsoon the number of districts that reported normal rains in that week (+5% to -5%) is 18; deficient 1 (-6% to -20%) is 31; deficient 2 (-21% and more) is 437; excess 1 (+6% to +20%) is 17; excess 2 (+21% and more) is 113; no data was reported from 25.

Monsoon 2014 and a third dry week

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05 to 11 June is the first week. 12 to 18 June is the second week. 19 to 25 June is the third week. The bars represent the weeks and are divided by IMD's rainfall categories, with the length of each category in a bar showing the proportion of that category's number of districts. The colours used here match those used in IMD's weekly rainfall map (below) which displays the category-wise rainfall in the 36 meteorological sub-divisions (but not by district).

05 to 11 June is the first week. 12 to 18 June is the second week. 19 to 25 June is the third week. The bars represent the weeks and are divided by IMD’s rainfall categories, with the length of each category in a bar showing the proportion of that category’s number of districts. The colours used here match those used in IMD’s weekly rainfall map (below) which displays the category-wise rainfall in the 36 meteorological sub-divisions (but not by district).

IMD's weekly rainfall chart, 19 to 25 June

IMD’s weekly rainfall chart, 19 to 25 June

We now have rain data for three complete weeks from the India Meteorological Department (IMD) and for all the districts that have reported the progress of the monsoon.

The overall picture remains grim. In the third week of the monsoon the number of districts that reported normal rains in that week (-19% to +19% of the average) is only 74. No rain (-100%) was reported by 71 districts Scanty rain (-99% to -60%) was reported by 221 districts, deficient rain (-59% to -20%) was reported by 125 districts, excess rain (+20% and more) was reported by 129 districts, and there was no data from 21 districts.

IMD_districts_table_3_weeksThe Department of Agriculture and Cooperation, of the Ministry of Agriculture, has already issued its guidance to states on the contingency plans to be followed for a delayed monsoon. That is why it is important to make available the district-level normals and rainfall departures – the meteorological sub-divisions are too broad for such analysis and are irrelevant to any contingency plans and remedial work.

By end-June, when the IMD updates its outlook for the rest of monsoon 2014, we expect more detailed assessments of the districts to be publicly available – the agromet (agricultural meteorology section) already provides this to the states, with state agriculture departments given the responsibility of ensuring that the advice – which is especially important for farmers to plan the sowing of crop staples – reaches every panchayat.

Written by makanaka

June 28, 2014 at 09:09

The new measure of monsoon

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Districts reporting monsoon data, over two weeks, colour-coded under a revised categorisation (explained in the text) for weekly rainfall. The left bar in each pair is the second week, the right bar is the first. Most districts are coloured light red, signifying rainfall much below the weekly normal. Peach is for the lesser deficient category. Green is normal. The two blue hues - lighter and darker - are for the two excess categories. It is immediately apparent that 485 out of 618 reporting districts (78%) have experienced less rainfall than they should have at this stage of the monsoon.

Districts reporting monsoon data, over two weeks, colour-coded under a revised categorisation (explained in the text) for weekly rainfall. The left bar in each pair is the second week, the right bar is the first. Most districts are coloured light red, signifying rainfall much below the weekly normal. Peach is for the lesser deficient category. Green is normal. The two blue hues – lighter and darker – are for the two excess categories. It is immediately apparent that 485 out of 618 reporting districts (78%) have experienced less rainfall than they should have at this stage of the monsoon.

The changes that we find in the patterns, trends, intensity and quantity of India’s monsoon now require an overhaul in the way we assess what is satisfactory or not for environmental and human needs. India’s summer monsoon is already late, and where it is late but active it is weak. The indications from the central earth science agencies (including the India Meteorological Department), from the Indian Institute of Tropical Meteorology, from the National Centre for Medium Range Weather Forecasting are that it will be the end of June before the summer monsoon system settles over central India and the western Gangetic plains. Even so, it will be a relief from the searing temperatures but will not assure sowing conditions for farmers and cultivators, nor will it add to the stores of water in major and minor reservoirs.

In this commentary written for India Climate Portal, I have explained why IMD’s hoary top level categorisation of rainfall weekly quantities in the subdivisions must be replaced, both for what they describe and for how frequently they are described. These currently are: ‘normal’ in a subdivision is rainfall that is up to +19% above a given period’s average and down to -19% from that same average; likewise excess is +20% and more, deficient is -20% to -59% and scanty is -60% to -99%. The ‘normals’ are calculated based on the mean weekly rainfall for the period 1951-2000 with monitoring done in 641 districts distributed amongst the 36 meteorological subdivisions.

By categorising rainfall ‘normals’ and departures from  ‘normal’ to become more administratively impelling – these proposed corrections also simplify the interpretations possible for rainfall above and below ‘normals’ – greater awareness and preparedness of administrations, key agencies and citizens to the deficiencies of monsoon can be fostered. For the district tables below therefore, I have re-cast the categories as follows (all based on the long-term average provided by IMD): Normal in a district is +5% to -5%; Deficient 1 is -6% to -20%; Deficient 2 is -21% and more; Excess 1 is +6% to +20%; Excess 2 is +21% and more.

Whereas, for the same second rainfall week the IMD categories were ‘No Rain’ in 80 districts, ‘Scanty’ in 241 districts and ‘Deficient’ in 130 districts, under the proposed revision they will simply be ‘Deficient 2’ with 449 districts – thereby showing dramatically how widespread the conditions of the late and weak monsoon 2014 are – and ‘Deficient 1’ with 36 districts. Please read the rest at India Climate Portal.

India’s troubled 2011 monsoon continues

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India regional rainfall, monsoon 2011, from 01 June to 20 July 2011, week and total

The India Meteorological Department, Ministry of Earth Sciences, has issued a new forecast for the 2011 south-west monsoon and the overall number does not at all look like what the country needs. The IMD has said that by the end of the second half of the 2011 monsoon, it expects the national average to be 90% or thereabouts of the long period average (called LPA by the Met).

India’s central government has only recently announced the foodgrain estimates for the year, at a record 241 million tons. The question now is, what will this lower prognosis mean at district level, and for those districts which supply the country its cereals, vegetables and commercial crops. We’ll have to wait and watch for more indicators. The main paragraphs of the IMD statement follow, and I have put together picture panels based on the rainfall maps issued by the IMD every week. These show the regional variations of rainfall and how they have moved over time.

The IMD statement is titled “Long Range Forecast Outlook for the Rainfall During the Second Half (August–September) of 2011 Southwest Monsoon” and says:

“Summary of the Forecast outlook for the Rainfall During the Second Half of the 2011 Southwest Monsoon Rainfall – Rainfall over the country as a whole for the second half (August to September) of the 2011 southwest monsoon season is likely to be below normal (86 to 94% of long period average (LPA)). Quantitatively, rainfall for the country as a whole during the period August to September, 2011 is likely to be 90% of LPA with a model error of ±8%.”

“The outlook for the 2011 Southwest Monsoon Season Rainfall is that the monsoon season (June to September) rainfall for the country as a whole is likely to be below normal (90-96% of LPA) as forecasted by IMD in June. The season (June to September) rainfall over the 3 geographical regions (Northwest India, Central India and South Peninsula) is also likely to be within the limits of forecasts (i.e.97% of LPA, 95% of LPA and 94% of LPA respectively all with model errors of ±8% of LPA) issued by IMD in June. However, the season rainfall over Northeast India is likely to be less than the lower limit of the IMD forecast (95 ±8% of LPA) issued in June.”

[See my earlier post on the IMD updated forecast.]

This year, the IMD’s first stage forecast was issued on 19 April 2011 and its second stage forecast was issued on 21 June 2011. For climatoligists, the IMD has also said that there are ‘ENSO Neutral conditions over Equatorial Pacific’ after the dissipation of the moderate to strong La Nina event around mid-May 2011. “The latest forecasts from a majority of the dynamical and statistical models indicate high probability (about 80%) for the present ENSO-neutral conditions to continue during the remaining part of the 2011 southwest monsoon season. However, the probability for re-emergence of La Nina or that for development of El Nino (10% each) is relatively less.”

India regional rainfall, monsoon 2011, from 01 June to 27 July 2011, week and total

India regional rainfall, monsoon 2011, from 01 June to 13 July 2011, week and total

India regional rainfall, monsoon 2011, from 01 June to 06 July 2011, week and total

India regional rainfall, monsoon 2011, from 01 June to 29 June 2011, week and total

India regional rainfall, monsoon 2011, from 01 June to 15 June 2011, week and total

Written by makanaka

August 10, 2011 at 18:54