Resources Research

Culture and systems of knowledge, cultivation and food, population and consumption

Posts Tagged ‘IMD

Misreading monsoon

with one comment

Satellite image of evening cloud cover on 15 May 2019

As usual in May, there is a welter of forecasts and opinions about the monsoon, the great majority of which are short on understanding and shorter on elementary science. The media – newspapers, television news channels, their websites – are to blame for spreading half-baked forecasts and wild prognoses. Not one of the numerous newspapers and TV channels, whatever the language they employ, bother to provide their reporters a basic grounding in the climatological system that gives us our monsoon.

In the first place, the India Meteorological Department (IMD) issues an operational forecast for the south-west monsoon season (June to September) rainfall for the country as a whole in two stages. The first stage forecast is issued in April and the second stage forecast is issued in June. These forecasts are prepared using state-of-the-art Statistical Ensemble Forecasting system (SEFS) and using the dynamical coupled Ocean-Atmosphere global Climate Forecasting System (CFS) model developed under Monsoon Mission of the Ministry of Earth Sciences.

On 15 April 2019 the IMD issued its first stage forecast. Based on our own in-field observations from the west coast, from the patterns of maximum termperature bands and variations in the lower and central peninsular region, from the sea surface temperatures in the Arabian Sea particular its southerly reaches and ditto for the Bay of Bengal, and from the wind patterns that can be experienced at various places in the peninsula and on the west coast, we find the IMD first stage forecast to be reliable.

It is the chronically ignorant media – which over the last few years has displayed a tendency to prefer some so-called private sector weather forecasters instead of what the Ministry of Earth Sciences provides – found irresponsibly claiming that the monsoon of 2019 will be ‘deficient’ and will also begin ‘late’. Neither of these terms is sensible in any way, and we take no satisfaction in noting that only a media that is insensible to planetary and mesoscale events like climate, will employ such insensible terms in reporting that is meant to educate and benefit the public.

IMD’s April forecast used the following five predictors: 1. the Sea Surface Temperature (SST) Gradient between North Atlantic and North Pacific (in December and January), 2. the Equatorial South Indian Ocean SST (in February), 3. the East Asia Mean Sea Level Pressure (in February and March), 4. North-west Europe Land Surface Air Temperature (in January), and 5. Equatorial Pacific Warm Water Volume (in February and March).

There are two forecasts the IMD makes. One is based on the Monsoon Mission CFS Model, which considers global atmospheric and oceanic initial conditions up to March 2019 and use 47 ensemble members (or kinds of data). The forecast based on the CFS model suggests that the monsoon rainfall during the 2019 monsoon season (June to September) averaged over the country as a whole is likely to be 94% ± 5% of the Long Period Average (LPA).

The second is the forecast based on the operational Statistical Ensemble Forecasting system (SEFS). This shows that quantitatively, the monsoon seasonal rainfall is likely to be 96% of the Long Period Average (LPA) with a model error of ± 5%. The SEFS comprises five category probability forecasts for the June to September rainfall over the country as a whole:

Overall therefore the IMD forecast is for the 2019 monsoon rainfall to be near normal. The IMD has already pointed out (which can be seen from the probabilities of the categories given in the table) that there is only a small chance for the monsoon rainfall to be above normal or excess. In view of the weather events and the climatological changes that we are seeing from day to day in May, ascribing a ‘lateness’ to the monsoon is absurd. Monsoon conditions already exist in and over the Indian land mass and in and over the great watery zones extending southwards from latitude 8 degrees North – and that is why we will find rain-bearing clouds crossing the south-western coastline in the first week of June 2019.

(Reposted from India Climate Portal.)

Advertisements

Written by makanaka

May 16, 2019 at 18:14

Three views of monsoon 2018

leave a comment »

The India Meteorological Department (IMD) on 16 April had issued its first long range forecast for the 2018 South-West Monsoon season, which the IMD has historically taken to be 1 June to 30 September. The IMD had said that the “monsoon seasonal rainfall is likely to be 97% of the Long Period Average with a model error of ± 5%”. The IMD had also said that its forecast “suggests maximum probability for normal monsoon rainfall (96%-104% of the long period average) and low probability for deficient rainfall during the season”.

In early June, the IMD will issue its second long range forecast for the 2018 monsoon. Until then, I have studied three of the more reliable (in my view) international multi-model ensemble forecasts for the monsoon. What are ensemble forecasts? Each consists of several separate forecasts (some ensembles use 50) forecasts made by the same computer model – these are run on super-computers such as the High Performance Computer System of the Ministry of Earth Sciences (one is at the Indian Institute of Tropical Meteorology in Pune with 4.0 petaflops capacity and the other at the National Centre for Medium Range Weather Forecasting in Noida with 2.8 petaflops capacity).

The monsoon 2018 forecast for three-month blocks of the Multi-Model Ensemble (MME), USA National Centers for Environmental Prediction

The separate forecasts that make up one ensemble are all activated from the same starting time. The starting conditions for each differ from each other to account as far as possible for the staggering number of climatological, atmospheric, terrestrial and oceanographic variables that affect and influence our monsoon. The differences between these ensemble members tend to grow as the forecast travels two, three, four and more months ahead of the present.

I have considered the ensemble forecasts for the 2018 monsoon of the European Centre for Medium-Range Weather Forecast (ECMWF), the NOAA Climate Prediction Center and the Multi-Model Ensemble (MME) of the USA National Centers for Environmental Prediction. In this order, I find that the ECMWF forecast is somewhat pessimistic, the NOAA CPC is largely neutral and the MME is optimistic. The forecasting periods are in blocks of three months.

I have considered the ensemble forecasts for the 2018 monsoon of the Multi-Model Ensemble (MME) of the USA National Centers for Environmental Prediction, the NOAA Climate Prediction Center and the European Centre for Medium-Range Weather Forecast (ECMWF). In this order, I find that the MME is optimistic, the NOAA CPC is largely neutral and the ECMWF forecast is somewhat pessimistic.

Here are the details:

(1) The MME forecast, precipitation anomalies relative to the period 1993-2016, based on initial conditions calculated at the beginning of May 2018.
June July August (JJA) – west coast and Konkan, coastal Andhra Pradesh and Odisha, West Bengal, part of the North-East, the entire upper, middle and lower Gangetic region (Uttarakhand, Himachal, Uttar Pradesh, Bihar, Jharkhand), Madhya Pradesh, Chhattisgarh, Maharashtra and Telengana to have up to +1 mm/day. Rest of India other than Gujarat (-0.5 mm/day) normal.
July August September (JAS) – Gujarat to have up to -1 mm/day, Rajasthan up to -0.5 mm/day, Sikkim, Brahmaputra valley and Arunachal Pradesh up to -0.5 mm/day. Himachal Pradesh and Uttarakhand up to +0.5 mm/day, Madhya Pradesh, Odisha, Chhattisgarh, Jharkhand and West Bengal up to +0.5 mm/day. Andhra Pradesh and Tamil Nadu up to -0.5 mm/day.
August September October (ASO) – Gujarat up to -0.5 mm/day. Tamil Nadu up to -1 mm/day. Kerala and adjacent Karnataka up to -0.5 mm/day. Madhya Pradesh, Chhattisgarh, Odisha, West Bengal up to +1 mm/day. Tripura, Mizoram, Manipur, Nagaland, Uttarakhand, Himachal Pradesh up to +0.5 mm/day
September October November (SON) – Tamil Nadu, Kerala and adjacent Karnataka up to -1 mm/day. Maharashtra, Madhya Pradesh, Chhattisgarh, Odisha, West Bengal, Himachal Pradesh and Uttarakhand up to +0.5 mm/day.

(2) The NOAA CPC forecast, seasonal precipitation anomalies using initial conditions of 30 April 2018 to 9 May 2018.
May June July (MJJ) – for most of India a normal reading (+0.5 to -0.5 mm/day fluctuation) and for the west coastal, Konkan, Kerala, south Tamil Nadu and coastal Andhra Pradesh areas variation of up to +1.5 mm/day.
June July August (JJA) – for most of India a normal reading (+0.5 to -0.5 mm/day fluctuation).
July August September (JAS) – normal for most of India. Some areas in the central Deccan plateau, on the west coast and east coast variation of up to -1 mm/day.

(3) The ECMWF forecast, mean precipitation anomaly based on climate period data of 1993-2016 and initial conditions as on 1 May 2018.
June July August (JJA) – all of the southern peninsula and part of the Deccan region (Kerala, Tamil Nadu, Karnataka, Andhra Pradesh, part of Telengana) up to -100 mm for the period. West Bengal, Bihar, Jharkhand, Uttar Pradesh up to +100 mm for the period.
July August September (JAS) – all of the southern peninsula and the Deccan region – Kerala, Tamil Nadu, Karnataka, Andhra Pradesh, part of Telengana and Maharashtra up to -100 mm for the period.
August September October (ASO) – Maharashtra, Telegana, Andhra Pradesh and Karnataka up to -100 mm for the period.
September October November (SON) – Central and western India, eastern states and entire Gangetic region up to -50 mm for the period.

Written by makanaka

May 12, 2018 at 20:31

A method for a post-carbon monsoon

with one comment

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.

Monsoon 2015 could be 93% with ifs and buts

leave a comment »

RG_monsoon_forecast_20150422

The India Meteorological Department has just released it’s long-awaited forecast for the 2015 Indian monsoon. In terms of the quantity of rainfall over the duration of the monsoon season (June to September) the IMD has said it will be 93% of the ‘Long Period Average’. This average is based on the years 1951-2000.

What this means is the ‘national’ average rainfall over the monsoon season for India is considered to be 89 centimetres, or 890 millimetres. So, based on the conditions calculated till today, the ‘national’ average rainfall for the June to September monsoon season is likely to be 830 millimetres.

There are caveats and conditions. The first is that the 93% forecast is to be applied to the long period average for each of the 36 meteorological sub-divisions, and a ‘national average’ does not in fact have much meaning without considerable localisation. The second is that the forecasting methodology itself comes with a plus-minus caution. There is “a model error of ± 5%” is the IMD’s caution.

IMD_categories_201504This first forecast and the model that the forecast percentage has emerged from are thanks to the efforts of the Earth System Science Organization (ESSO), under the Ministry of Earth Sciences (MoES), and the India Meteorological Department (IMD), which is the principal government agency in all matters relating to meteorology. This is what the IMD calls a first-stage forecast.

As with all complex models, this one comes with several considerations. The ESSO, through the Indian Institute of Tropical Meteorology (IITM, which is in Pune), also runs what it calls an ‘Experimental Coupled Dynamical Model Forecasting System’. According to this, the monsoon rainfall during the 2015 monsoon season (June to September) averaged over India “is likely to be 91% ±5% of long period model average”. (The IMD forecast is available here, and in Hindi here.)

This is a lower figure than the 93% headline issued by the IMD. This too should be read with care as there are five “category probability forecasts” that are calculated – deficient, below normal, normal, above normal and excess. Each is accompanied by a forecast probability and a climatological probability (see the table). The maximum forecast probability of 35% is for a below normal monsoon, while the maximum climatological probability is for a normal monsoon.

As before, time will tell and the IMD will issue its second long range forecast in June 2015. Our advice to the Ministry of Earth Sciences and to the IMD is to issue its second long range forecast a month from now, in May, and also to confirm these forecasts two months hence in June, when monsoon 2015 will hopefully be active all over the peninsula. [This is also posted on India Climate Portal.]

Why IMD’s rain math doesn’t add up

leave a comment »

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.

An India economical with monsoon truths

with one comment

Monsoon measures for six weeks. A few more districts reporting the revised normal, but the deficient-2 category still has too many districts, and so does excess-2. And why so many 'no data' (many from the north-east)?

Monsoon measures for six weeks. A few more districts reporting the revised normal, but the deficient-2 category still has too many districts, and so does excess-2. And why so many ‘no data’ (many from the north-east)?

When a politician and a bureaucrat get together to supply punditry on the monsoon, the outcome is directionless confusion. There is no reason for our shared knowledge on monsoon 2014 to be reduced to a few boilerplate paragraphs and a couple of amateurish maps and charts, not with the equipment and scientific personnel the Republic of India has invested in so that we read the rain better. But Jitendra Singh, the Minister of State who is in charge of Science, Technology and Earth Sciences, and Laxman Singh Rathore, the Director General of the India Meteorological Department, have not progressed beyond the era of cyclostyled obfuscation.

The Press Information Bureau reported Singh as saying that there has been “significant increase in the monsoon during the last one week beginning from 13th July, and the seven days between last Sunday and this Sunday have recorded 11 percent increase in the monsoon country-wide”. Following suit, Rathore said: “The monsoon deficit has come down by 12 per cent and the overall deficit stands at around 31 per cent. This will bring in much needed relief to the farmers and solve the water issues.”

Coming from senior administrators, such fuzzy distraction cannot be tolerated. The Ministry of Earth Sciences, the India Meteorology Department and the Ministry of Information and Broadcasting must cease (desist, stop, halt – do it now) the use of a ‘national’ rainfall average to describe the progress of monsoon 2014. This is a measure that has no meaning whatsoever for cultivators in any of our agro-ecological zones, and has no meaning for any individual taluka or tehsil in the 36 meteorological sub-divisions. What we need to see urgently adopted is a realistic overview that numerically and graphically explains the situation, at as granular a level as possible.

RG_rainfall_measure_six_weeks_20140723_sectionWhen that does not happen, news media and information sources struggle to make sense of monsoon and climate and their reporting becomes dangerously misleading – consider “Late monsoon starts Indian farmer’s ‘journey to hell’ “; “Why the monsoon numbers hide reality” (this report is an attempt to point out the problem); “Monsoon deficit has come down to 31 per cent, no need to be ‘alarmist’: Met office”; “Satisfactory rainfall may wash away monsoon deficit”.

Using a revised categorisation of rainfall sufficiency levels (my method and the reasoning for it use is available here) we find that for the fifth and sixth weeks of monsoon, there has been a small improvement which does not lower the high likelihood of drought conditions becoming prevalent in districts and scarcity of water for our settlements – Messers Singh and Rathore please note (or visit the Indian Climate Portal Monsoon 2014 page which is an active repository of reportage, views, commentary and original data analysis on our monsoon).

The fifth monsoon week is 03 to 09 July 2014 and the sixth monsoon week is 10 to 16 July 2014. There has been a small addition to the revised normal rainfall category (-5% to +5%), rising from 18 districts recording normal rainfall in the 4th week to 22 in the 5th and 28 in the 6th. There has also been an improvement in the number of districts recording deficit-2 levels of rainfall (-21% and more) with 437 in the 4th week, 411 in the 5th week and 385 in the 6th week. For the remainder of July the likelihood of more rainfall in the districts that have recorded normal or excess-1 (+6% to +20%) is small, according to the available forecasts, and this means that monsoon 2014 will begin August with far fewer districts registering normal rainfall than they should at this stage.

The NOAA map of the land and sea percentiles. Note the warm water south of India and to the east of the Philippines.

The NOAA map of the land and sea percentiles. Note the warm water south of India and to the east of the Philippines.

With many sowing cycles beginning belatedly between now and the end of July, the Ministry of Earth Sciences, the India Meteorology Department, the Ministry of Agriculture and the Ministry of Water Resources are advised to work together (why aren’t they doing so already – or at least mandating ICAR institutes to supply them with analysis which they must absorb jointly?) to understand the impacts of regional, tropical and global climate trends that affect the Indian summer monsoon.

There is good reason to. According to NOAA, for 2014 June land and ocean surface temperatures jumped 0.72 Celsius above the 20th century average. These new records were pushed upwards by a broad warming of the ocean surface, and not only by an Equatorial Pacific whose waters are approaching the warmth usually seen during an El Nino. NOAA has said there was “extreme warming of almost every major world ocean zone” which warmed local air masses and had a far-reaching impact on global climate, “likely delaying the Indian monsoon”.

A month of truant rain

with one comment

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

with one comment

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

An epidemic of misreading rain

leave a comment »

RG_rain_misreadings_201406

Who can you turn to? It’s easier to list those whom you shouldn’t turn to, the top rankers being the country’s press and television wallahs, followed at a not respectable distance by academic commentators, then come the government blokes and bureaucrats (some of whom do know the difference between isobars and salad bars, I’ll give them that). Lurking behind this cacophonous mob are the boffins of the IMD and its associated scientific chapters, a number of whom have got their sums right, but who aren’t given the space and encouragement to tell the great Bharatiya public what said public is yearning to hear simply because regulations forbid, just like it was in 1982, 1957, whenever.

As I may have mentioned before, this is Not A Good Thing. It has taken about a decade of mission mode tutoring (how the UPA bureaucrats loved that phrase, mission mode) to get the media wallahs to see the difference between weather and climate. A few may even have learned to read a wet bulb thermometer and puzzle their way through precipitation charts.

RG_rain_misreadings_2But overall, the profusion of android apps that profess to show cool graphics of clouds with lightning bolts erupting topside so that our humble ‘kisans’ know when it’s going to rain (i.e., by looking down at their screens instead of up at the sky) has not helped the Bharatiya public make more sense of less rain. We have squadrons of Insats and Kalpanas buzzing around the globe beaming pictures from the infra-red to the infra dig back home, every 60 or 90 minutes, busy enough to crash a flickr photo server, but the knowledge that said public can sift from it is sparse, rather like the rainfall over Barmer, Bikaner and Ajmer.

And so it goes, with the waiting for rain replacing with an equal banality waiting for Godot but with a far larger cast of characters, most of them insensible to the greater climatic drama being played out, 30,000 feet overhead, and at the poles, in the vast turquoise swells of the eastern Pacific where a malignant El Nino is brooding, in the Himalayan valleys where crystal zephyrs have been shoved aside by an airborne mat of PM2.5, or to the desiccation that creeps outwards from our towns and cities (7,935 of them, India’s triumphant ‘growth story’) that have enclosed sweeping hectares with cement, asphalt, and the hot foetid belches of factories and air-conditioners. GDP, they have been told, is the great liberator.

And that is why we have in place of the quiet concern of our forefathers in their dhotis, an electronic jumble of shrill alarm. “Weak monsoon intensifies drought like conditions in India” was one such headline, the text beneath finding the most ludicrous connections: “… threat of food inflation and weak rural demand in the first year of the Narendra Modi government”. Naturally, the cheerleaders of a demand-centric world cannot do otherwise.

RG_rain_misreadings_1And likewise with “Weak rains deliver India’s new Modi government its first economic challenge” that desultorily spies impending delays in the “sowing of main crops such as paddy, corn and sugarcane” and which notes mournfully that “about half of all farms lack irrigation systems” and, even worse, that “reservoir levels are only a fourth of last year’s levels”, this last despite the best efforts, ham-handed though they are, by the Central Water Commission to show India (for Bharat knows) that the reservoir levels in the 85 major reservoirs are low, but not much lower at this point in 2014 than they were in 2013. The GDP bullies dislike contrary numbers, and would go cross-eyed were someone to mischievously mention the existence of 4,845 large dams in India (the blue-ribboned 85 included) whose many water levels we don’t in fact know at all.

And similar vapidity from another quarter, which like its peers cloaks ineptitude with what it takes to be appropriate jargon, “The cumulative rainfall across the country has so far been 45 per cent below the Long Period Average (LPA) for 1951-2000” and brandishes even more frightful credentials with “a further breakdown of rain data recorded in different meteorological subdivisions shows that normal rainfall has been recorded in only seven of the 36 regions”. But which sere farmer and her wise daughters consider in their universe such things as meteorological subdivisions, when their world is what Balraj Sahni and Nirupa Roy in 1953 showed us so lambently, is no more than ‘do bigha zamin’?

But still the misreading gathers pace, as vexed fixations upon an existence merely economic chase away plain common-sense. For rains may come or rains may go, but in tractors – for so we are instructed by the agents of hardened merchants – we trust. To wit: “… tractor sales have typically expanded at a double-digit pace in the years when rains have disappointed… In the 11 years between fiscal 2003 and fiscal 2013, rains fell short by 5% or more on six occasions… In four of those six years, tractor sales grew at a double-digit pace”. Let us then leave behind our cares and go rollicking over the dusty, still dustier now, plains of the Deccan in tractors tooting red.

But a shadow of monsoon yet for Bharat, and at June’s end. It is past time that the prattling ceased and the learning began.

The new measure of monsoon

with 4 comments

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.