(i) Winter Snow Cover and Indian Summer Monsoon

The long-range forecasting (LRF) of the summer monsoon rainfall over India started following a devastating famine in India during 1860s and 70s. It has been one of the first systematic endeavours at seasonal climate forecasting. The first operational LRF of Indian summer monsoon rainfall for the region covering the whole of India and Burma was issued on June 4th, 1886 using an empirical method developed by Blandford who was the first Head of the India Meteorological Department (IMD). This forecast was based on the inverse relationship between Himalayan winter and spring snow accumulation and subsequent summer monsoon rainfall over India. It was assumed that, in general, varying extent and thickness of the Himalayan snow has a great and prolonged influence on the climate conditions and weather of the plains of northwest India. After this, the LRF of the monsoon rainfall became one of the important operational responsibilities of IMD and efforts for better forecasts continued.

This was later confirmed by many other scientists using additional observational data both from surface as well as satellite and model studies. It was observed that the Indian monsoon-snow teleconnection is derived from snow cover over the entire Eurasian region. These studies also suggested two main physical processes, which are responsible for the time-lag relationship between winter/spring Eurasian snow cover and ISMR. One is the albedo effect which impacts the monsoon through the changes in the land surface heating resulting in anomalous land-sea thermal contrast and changes in the strength of the monsoon circulation. The latter effect involves the melting of an anomalous snow mass, anomalous moistening of the soil and anomalous evaporation, which subsequently increases/reduces the heating of the atmosphere from the ground surface in the warmer season.

(ii) El Niño-Southern Oscillation (ENSO)

Sir Gilbert T. Walker who took over as the Director General of IMD in 1904 started systematic studies for the development of objective techniques for LRF (Walker, 1908). Search for the potential predictors led Walker to identify three large-scale seesaw variations in the global pressure patterns. These are Southern Oscillation (SO), North Atlantic Oscillation (NAO), and North Pacific Oscillation (NPO). Among these, SO was found to have the most significant influence on the climate variability of India as well as many parts of the globe. The SO, a see-saw between the sea level pressure at Tahiti (an island over the equatorial Pacific) and Darwin, was later linked to the unusual warming of sea surface waters in the eastern tropical Pacific Ocean or El Niño by Jacob Bjerknes in 1960s. Bjerknes and other climatologists later defined these linked phenomena as El Niño-Southern Oscillation (ENSO). Today, most scientists use the terms El Niño and ENSO interchangeably though El Nino is the warm phase of ENSO. After this in the 1980s, the terms La Niña (cold phase of ENSO) and Neutral also gained prominence. The opposite phases of ENSO have significant and opposite impacts on the temperature and precipitation patterns across the globe but primarily in tropical regions. It is also recognized that the combined ocean–atmosphere ENSO phenomenon is the dominant mode of Earth’s interannual climate variability.

(iii) Indian Ocean Dipole (IOD)

The Indian Ocean Dipole (IOD) phenomenon was first identified by climate researchers including Indian meteorologist Shaji N Hameed in 1999. The Indian Ocean Dipole (IOD) also known as the Indian Nino is a coupled ocean and atmosphere phenomenon and is characterised by an irregular oscillation of sea-surface temperatures in which the western Indian Ocean becomes alternately warmer and then colder than the eastern part of the ocean. A positive IOD period is characterised by cooler than normal water in the tropical eastern Indian Ocean and warmer than normal water in the tropical western Indian Ocean (see map below for an example of a typical positive IOD SST pattern). Generally, the dipole begins to be evident in early to mid-summer, reaches its peak in late fall to early winter, and then rapidly decays during the boreal spring. The negative phase has similar timing, magnitude, and decay. The IOD affects the climate of India and other countries that surround the Indian Ocean basin. The IOD is commonly measured by the Dipole Mode Index (DMI) which is the difference between sea surface temperature (SST) anomalies in the western and eastern equatorial Indian Ocean. In general, associated with the positive IOD, normal convection situated over the eastern Indian Ocean warm pool shifts to the west and brings heavy rainfall over east Africa and severe droughts/forest fires over the Indonesian region. It has been observed that the dipole mode event is independent of the ENSO in the Pacific Ocean. However, the IOD and the ENSO were found to have complementary influence over the Indian Summer Monsoon Rainfall (ISMR) in recent decades with the association of ENSO-ISMR being low when the association between the IOD-ISMR was high and vice versa.

(iv) Equatorial Indian Ocean Oscillation (EQUINOO)

The Equatorial Indian Ocean Oscillation (EQUINOO) is an east-west oscillation manifested as the sea saw in the convection anomalies over the western and eastern equatorial Indian Ocean. It plays an important role in the interannual variation of Indian summer monsoon rainfall. It is considered to be the atmospheric component of the Indian Ocean dipole mode and was first introduced by Sulochana Gadgil an Indian meteorologist and her colleagues in 2004. Initially, an index based on the standardized zonal component of the surface wind averaged over the central equatorial Indian Ocean was used to represent the EQUINOO. Later the difference in the anomaly of outgoing longwave radiation (OLR) or precipitation between eastern and western parts of the equatorial Indian Ocean was used. In general, the positive phase of EQUINOO is favourable for stronger than normal Indian summer monsoon and vice versa. Recent studies have shown that though most of the latest state-of-the-art Ocean–atmosphere global coupled models successfully simulate the ENSO–Monsoon link realistically to some extent; cannot reproduce the EQUINOO-Monsoon link realistically. Some scientists are of the view that the inability of the models to simulate the EQUINOO is one of the reasons for these models not achieving their potential monsoon predictability.

(v) Lifted Minimum Temperature or Ramdas Layer

The phenomena of the Lifted Temperature Minimum were first reported in 1932 by Indian scientists L. A. Ramdas and S. Atmanathan. It was observed that on clear windless nights, the lowest temperature is not on the ground but is lifted by a height between 20 and 50 cm. The phenomenon has been named the Ramdas Layer, and is attributed to the interaction of thermal radiation effects on atmospheric aerosols and convection transfer close to the ground. This can be seen in thin layer fogs which are at some height above the ground. Later Kalus Raschke, a young German agronomist who worked as a researcher with Ramdas repeated the study with more accurate air temperature observations using special thermoelectric sensors and established the existence of the Ramdas layer without any doubt. This discovery is very important in understanding observed sub-micro climatology and predicting weather and climate in the lowest meter of the atmosphere and its impact on crops. L. A. Ramdas is known as the father of agricultural meteorology in India because of his significant contributions to the field of agricultural meteorology, including the development of crop weather calendars that examined detrimental weather in the phases of crop growth in various agro-climatic regions of India. He also studied microclimate in crop ecosystems, pest and disease relationships with weather apart from soil-water relationships.

(vi) Tropical Easterly Jet Stream During Southwest Monsoon Season

The Tropical Easterly Jet Stream (TEJ) is an important upper air circulation feature of the Indian summer monsoon manifested as a band of strong easterly airflow centred about 15°N, 50-80°E and extends from South-East Asia to north Africa across the Indian Ocean and south Indian peninsula. Over most of the Atlantic Ocean, continental America and Pacific Ocean, the easterly jet is not generally found. The term easterly jet was given by the Indian meteorologists P. Koteshwaram and P.R. Krishnan in 1952. Over the Indian region, the Tropical Easterly Jet (TEJ) appears just after the Sub Tropical westerly Jet (STWJ) shifts to the north of the Himalayas around late June and continues until early September. The strongest development of the jet is observed at about 15 Km with wind speeds of up to 40m/s over the Indian Ocean. Many subsequent studies have shown that the intensity and duration of heating of the Tibetan Plateau have a direct bearing on the amount of rainfall in India by the monsoons. When high air temperatures develop over Tibetan region for a sufficiently long time, it strengthens the TEJ resulting in heavy rainfall over the Indian monsoon region. On the other hand above normal snowfall during winter and spring a season delays formation of the TEJ and weakens the rainfall activity over India.

(vii) IMD’s Contribution to Atmospheric Ozone research and Monitoring

India Meteorological Department has long history of ozone research using measurements of all the three components of Ozone i.e. Total Columnar Ozone (TCO), Vertical Distribution and Surface Ozone measurement. The TCO measurements in India were first made during September 1928 to August 1929 by Dr Royds and Dr Narayan at Kodaikanal during 1928-29, as part of Dobson's programme of world-wide total ozone measurements with Dobson’s spectrograph. The same instrument was used for daily ozone measurements at the Colaba Observatoryduring October 1936 to September 1938. The measurements at Kodaikanal and Bombay established the existence of low values of total ozone over tropical region. The IMD acquired its first Dobson spectrophotometer in 1940 for regular measurements. In 1940's ozone observations from Kodaikanal, Pune, Delhi and Shimla using Dobson Ozone Spectrographs were taken. The observations devised ways of correcting the Ozone observations for atmospheric scattering by aerosols. Professor K. R. Ramanathan evolved and extended the use of the Gotz Umkehr method of finding the vertical distribution of ozone in the atmosphere. Ramanathan, Anna Mani and their associates did pioneer investigations of atmospheric ozone in India and carried out detailed measurements of total ozone and its vertical distribution in the atmosphere and established the main features of the horizontal and vertical distribution of ozone over the tropics. The studies from India presented the fact that the day-to-day variations in the ozone amounts in the tropics are small and showed that the level of maximum ozone is higher (25-28 km) in the tropics than at higher latitudes. The major contribution in the studies of atmospheric ozone are (i) the discovery of the quasi biennial oscillations of total ozone in the tropics, (ii) the dependence of ozone distribution on meteorological phenomena such as jet streams and their location, tropopause discontinuities and inter-latitudinal air exchange, and (iii) on the whole its relationship with the general circulation of the atmosphere. These studies led to a large number of theoretical investigations by several authors on the behaviour and transport of ozone in the upper atmosphere. The systematic ozone monitoring in India was started by IMD from first International Geophysical Year 1957-58.

IMD tested the first successful ozone-sounding from Pune in September 1964 using IMD make Ozonesonde. During the next five years the sonde was improved to such an extent that systematic soundings were started from Thiruvananthapuram, Pune and New Delhi. In 1970 the Indian ozone-sonde was intercompared in the International Ozone-sonde inter-comparisons held in Germany. IMD started ozone monitoring over Antarctica since second expedition(1982-83) during which Ozonesonde ascents were taken to obtain the vertical profile of ozone at the Indian station using IMD make electro-chemical ozonesonde. IMD further strengthened the ozone observations at Dakshin Gangotri to join the international efforts for Antarctica Ozone-Hole Investigation. In 1974, Molina and Rowland published their theory about catalytic destruction of ozone involving CFCs. In 1985, Joe Farman, Brian Gardiner and Jonathan Shanklin reported large decreases in stratospheric ozone levels over the Antarctic stations of Halley and Faraday which led to the discovery of Ozone Hole. Global efforts were mobilized for the systematic measurement of atmospheric ozone. The ozone soundings had become a routine part of the Indian scientific expeditions to Antarctica from second expedition (1982-83) onwards almost three years before discovery of ozone hole. The Indian ozone sounding clearly showed the 'ozone hole' over Antarctica and corroborated Farman's discovery. The soundings have yielded an accurate assessment of the vertical distribution of ozone in the tropics and its temporal and spatial variations.The soundings over Antarctica provided clear evidence of the dramatic ozone depletion. Subsequently, Montreal Protocol, came in to existence in 1987, to protect the stratospheric ozone layer by phasing out the production and consumption of ozone-depleting substances.Regular ozone profile measurement continued at Dakshin Gangotri till it was abandoned in 1989. The surface and profile ozone observations started at second station Maitri. Brewer Spectrophotometer was operated at Maitri, from 1999 to 2011 for the measurement of TCO. The ozone measurement programme startedat third Indian Antarctic stations Bharati from 2015. The Indian ozone soundings assume special significance because India is the only country conducting systematic ozone measurements from the tropical and Antarctic region. All other countries that make ozone soundings do it from the middle and high latitudes. Surface ozone is also measured at Indian stations in Antarctica. As anthropogenic pollution is almost negligible at Maitri, the in-situ photochemical production of ozone may not be very significant. Depletion in the stratospheric ozone during ozone hole period gives way to highly energetic UV radiation to reach to the surface layer and initiate photolysis of oxygen and NOx molecules in the surface boundary layer leading to production of surface ozone. The NOx is produced from surface snow pack. Moreover, the surface ozone concentrations can also be increased by the downward transport of stratospheric ozone rich air during deep convection and stratosphere-to-troposphere exchange event. Episodes of high surface ozone in the Antarctica region associated with stratospheric intrusion have been reported at Maitri.

(i) IMD Make Electrochemical Ozonesonde

The first Indian balloon-borne electrochemical ozonesonde was developed under the supervision of Ms Anna Mani in 1964 and the first surface ozone recorder in 1970 at the Instruments Division of the Meteorological Office at Poona (now Pune). The IMD make ozonesonde is a modified version of the Brewer electrochemical sonde The ozone sensor transmits values of air temperature, air pressure, relative humidity, detector current, detector temperature, and pump speed to a ground receiving station. The air containing the ozone sample is pumped through Potassium Iodide solution which is oxidized by ozone producing an electrical current. The electrical current is proportional to the flow of ozone. The instrument became operational at the India Meteorological Department in 1971 and from Antarctica from 1983.

(ii) Modification of IMD Ozonesonde for measuring Surface Ozone

The electrochemical bubbler ozone sensor used in ozonesonde was modified and used as surface ozone recorder which consists of (a) a bubbler ozone sensor with reservoir, (b) a non-reactive teflon pump unit to bubble air through the sensor, (c) an electrical network for supplying a polarising potential to the bubbler, and (d) a continuous chart recorder capable of full scale deflection for two (2) microampere output. Later the chart recorder was replaced with the data logger and online display system. The ozone current is read directly from the record and ozone partial pressure.

(iii) IMD Make Thermo electric Pyronometer

The First Indigenous and IMD make Solar Radiation sensor was designed and developed at Radiation Lab, IMD, Pune during 1972. The sensor gives Solar Radiation in Watts per Square Meter. The sensor uses a thermocouple junction. A copper constantan Thermo junction is created on top and bottom surface. The Top surface is coated with optically black paint for absorbing 98% of solar Radiation with reference to black body. The Top surface absorbs solar Radiation and acts as a hot junction. The bottom surface in shadow acts as a cold junction. A hemispherical glass dome on the sensor allow only short wave Radiation coming from Sun.

(iv) Madras huts or Bengal huts for housing Thermometers

In tropical regions, thermometer sheds were constructed to protect thermometers from radiation from the sun and sky, precipitation and any invasion of birds and animals. They could also allow free circulation of air around the thermometers. Thermometer sheds were first used in India in the last quarter of the nineteenth century. They were called Madras huts or Bengal huts. The construction varied from place to place and the thermometers were mounted in a cage suspended in the shed. The shed normally had double leaf roof with a 6-inch air space between the two roofs.

Though these huts have been replaced with Stevenson Screens all across India, Hong Kong Observatory (HKO) still maintains a hut in its HQs. A comparison of temperature readings taken from the thermometer shed, from a Stevenson screen and from a rotating thermometer was carried out in 1978; and the differences were very low.

(v) IMD make snow depth sensor

IMD designed and developed a snow depth sensor during year 2021. The first sensor was installed at Tawang Arunachal Pradesh during February 2022. The System record and sends snow depth in meters through Automatic Weather station. The Data are available in AWS server every 15min interval along with other parameters.

The basic sensor is an ultrasonic Transducer emitting sharp ultrasonic sound pulse at 40 KHZ frequency. The pulse is reflected by the snow and returned back to the Transceiver. A micro controller PCB control Ultrasonic Transceiver for Transmission/reception of sharp sound pulse and Timer circuit in micro controller counts Travel time. Micro controller computes the level of snowfall using Speed of sound at prevailing temperature. The current level is subtracted from the level where there was no snow fall and it computes the snow depth in meters.

(i) Long Range Forecasting of Monsoon Rainfall over India

First attempt for the operational forecasting of seasonal rainfall was made for the 1886 southwest monsoon season for the Indian subcontinent including Burma (now Myanmar) using empirical subjective method by Sir Hendry Blandford. Over the years, the operational long range forecast (LRF) system in India underwent many changes in its approach and scope. The first operational objective forecast was issued in 1909 based on regression technique, resulted from the extensive and pioneering work of Sir Gilbert Walker. Later, on realizing that the entire country cannot be taken as homogenous rainfall region, operational forecasts during 1924 to 1987 were issued for Northwest India and Peninsular India using regression models initially developed by Walker and updated time to time. Forecast for the geographical regions was discontinued during 1988-1998. During 1988-2002, operational forecast for the season rainfall over the country as a whole was based on the 16 parameter power regression and parametric models. In view of increasing user demands, the operational forecasts for three geographical regions of the country namely, Northwest India, Peninsular India and Northeast India were reintroduced in 1999. The areas of these geographical regions were however different from that of Walker’s geographical regions with the same names.

From 2003, the lead time for issuing seasonal monsoon rainfall forecast was increased. The first forecast for the seasonal rainfall over the country as a whole was issued in April and update was issued in June along with seasonal rainfall forecast for the four geographical sub regions of the country and monthly rainfall forecast for the country as a whole. During 2003 to 2006, the operational first and update long range forecasts for the seasonal rainfall over the country as a whole was issued using the 8 and 10 parameter models based on power regression and probabilistic discriminant analysis techniques. In 2004, the country was reclassified into 4 sub geographical regions (Northwest India, Northeast India, Central India and South Peninsular India). In 2005, forecasting of date of monsoon onset over Kerala was introduced. In 2007, a new state of the art statistical ensemble forecasting system (SEFS) was introduced for the seasonal rainfall forecasting over the country as a whole.

The new strategy implemented since 2021 uses a Multi-Model Ensemble (MME) forecasting system developed by IMD based on coupled global climate models (CGCMs) from different global climate prediction and research centers including IMD’s Monsoon Mission climate Forecast system (MMCFS) coupled model developed by IITM-MoES. The MME is a universally accepted technique, which is used to improve skill of forecasts and reduce forecast errors when compared to a single model-based approach. MME is also used to issue spatial distribution of the probabilistic monthly and seasonal rainfall forecast over country, which is the first in the history of the operational seasonal forecasting in the country. IMD also has extended this methodology to prepare climate outlook summary over south Asia under the South Asia Seasonal Climate Outlook Forum (SASCOF) activities recognized by the World Meteorological Organization (WMO).

Since the introduction of Statistical Ensemble Forecasting System (SEFS) in 2007 and use of dynamical models for the seasonal forecasting, IMD operational forecast for the monsoon rainfall has shown noticeable improvement. For example, the absolute forecast error in forecasting all India seasonal rainfall reduced by about 22% during the recent 17 years (2007-2023) compared to the previous period (1990-2006). Similarly, the anomaly correlation between the observed and forecast Indian Summer Monsoon Rainfall (ISMR) during 2007-2023 was 0.5 compared to -0.25 during 1990-2006. It may be noted that IMD was able to correctly forecast the twin deficient monsoon years of 2014-2015.

(ii) Innovation in Impact Based Forecasting in India

There have been major advances in the last few decades in our understanding of severe weather due to substantial progress in both observation and numerical modelling. All these resulted in more accurate forecasts of severe weather in the short to medium range (upto five days) with 40% improvement in accuracy in recent five years (2019-2023) as compared to the previous five years. However, improvement of forecast and warning skill is not sufficient to minimize damage to lives and property. It is essential to extend to hazard forecast systems (hazard models) and then to impact and risk with stakeholder interaction for risk-based warning (RBW) and response action to protect lives and livelihoods.

Considering all these, India Meteorological Department (IMD) has introduced impact-based forecast (IBF) at the district and city scale since August 2019 in its short to medium-range forecasts and nowcasts indicating the likely impact of the heavy rainfall in different sectors and required response actions. Since then IBF has undergone several changes. Currently, the IBF provided by IMD includes (i) meteorological hazards like cyclones, heavy rainfall, heat and cold waves, thunderstorms, and fog, (ii) secondary hazards, (iii) geospatial applications and (iv) socio-economic conditions. It utilises a web-GIS based decision support system (DSS). It has been successfully implemented in a dynamic platform in a collaborative mechanism with other organizations like National Disaster Management Authority (NDMA), National Remote Sensing Centre (NRSC), Indian Space Research Organisation (ISRO), state Governments etc. The success of IBF enhances the management of critical resources like agriculture, water & power and supports urban & disaster management sectors among others while reducing loss of life and property. While issuing the warning suitable colour code is used to bring out the impact of the severe weather expected and to signal the Disaster Management about the course of action to be taken concerning impending disaster weather events. The green color corresponds to no warning hence no action is needed, yellow colour corresponds to be watchful and get updated information, orange colour to be alert and be prepared to take action whereas red colour signals to take action.

(iii) Agricultural Meteorological Services

Given the dependence of Agriculture mostly on rainfall before independence, the government realized, as early as in 1920s, that a thorough understanding of the relationship between weather and crops was necessary to improve crop growth and productivity where monsoon rainfall was uncertain. As a result, as per the recommendation of the Royal Commission on Agriculture, the Agricultural Meteorology Division was established in 1932 in Pune. During the formative years, initiative was taken to carry out research activities in collaboration with various organizations to understand crop stresses and related remedial measures led by Dr. L. Ramdas, IMD, Senior Scientist.

To cater to the needs of the farming community, weather services for Agriculture commenced in IMD with “Farmers’ Weather Bulletin (FWB)” in 1945 to provide district-wise weather forecast twice a day. Following that, as it was difficult for the farmers to interpret weather forecasts, provided through FWBs, in their day-to-day farm operations, IMD started issuing agrometeorological advisories based on state-level short-range weather forecasts in July 1977 from the then-Madras (now RMC, Chennai), by the recommendations of the National Commission on Agriculture (1971). National Centre for Medium-Range Weather Forecasting (NCMRWF) started NWP model forecast-based Agromet Advisory Services (AAS) at the Agroclimatic Zone level in collaboration with IMD, Indian Council of Agricultural Research (ICAR) and various State Agricultural Universities (SAUs) since 1991 which was later extended in a phased manner to all the 127 Agroclimatic zones spread all over India.

In 2007, AAS provided by two organizations were integrated into a single window system and brought under IMD, named as “Integrated Agrometeorological Advisory Services (IAAS)”. Subsequently in June 2008, led by Dr. L. S. Rathore, Former DGM IMD, District level AAS was initiated in collaboration with ICAR and SAUs through the network of 130 Agrometeorological Field Units (AMFUs) located across the country to provide more relevant weather information and location and crop specific advisories.

IAAS scheme has been extended in XIIth Five Year Plan as ‘Gramin Krishi Mausam Sewa (GKMS)’ scheme to improve the District level AAS and extend to the Block / Sub-district level. With the introduction of upgraded high-resolution models, the service has been further extended to the block level from 2018 with the establishment of District Agro-Met Units (DAMUs).

Presently agreement advisories are being prepared at the district and block level, every Tuesday and Friday, by 130 AMFUs, co-located with SAUs, institutes of ICAR, Indian Institute of Technology (IIT) etc., and 199 DAMUs established in the premises of Krishi Vigyan Kendras (KVKs) under the network of ICAR. Block-level weather forecasts and Agromet Advisories aid the farmers in deciding on day-to-day agricultural operations at the micro-level. Thus, the main emphasis of the AMFUs and DAMUs under the existing AAS system is to collect and organize climate/weather, soil and crop information, and to amalgamate them with weather forecasts to assist farmers in making decisions on day-to-day farm operations.

Agromet Advisories are disseminated to the farmers through multichannel dissemination systems like print and electronic media, Door Darshan, radio, internet etc. including SMS using mobile phones through m-Kisan Portal, launched by the Ministry of Agriculture and Farmers’ Welfare (MoA & FW), and through private agencies under Public Private Partnership (PPP) mode. More than 30 Million farmers are receiving weather information through different dissemination channels.

It is revealed from the recent studies, conducted by the National Council of Applied Economic Research (NCAER) in 2019, on the assessment of the economic impact of weather forecast-based advisories that an additional annual income was estimated at Rs. 12,500 per agricultural household belonging to Below Poverty Line category in rain-fed areas, while total income gain was estimated at Rs. 13,331 crore per annum in rain-fed districts.

(iv) Innovation in Cyclone Forecasting Services in India

The tropical warm north Indian Ocean (NIO), like the tropical North Atlantic, the South Pacific and the NW Pacific, is a breeding ground for the disastrous tropical cyclone (TC). Historically, in terms of loss to human life, the Bay of Bengal (BoB) TCs accounted for deaths exceeding thousands. However, during recent years, there has been a significant reduction in loss of life, cost of evacuation and loss in government exchequer towards payment of exgratia etc. through the proactive involvement of three-tier disaster management agencies at central, state, and district levels based on accurate and timely warnings by India Meteorological Department (IMD). It has been possible due to the continuous upgradation of all the components of early warning based on the latest technology for effective management of TCs. The early warning component includes skill in monitoring and prediction of TCs, research and development leading to the introduction of scientific methods, tools and technology, effective warning products generation and dissemination, coordination with emergency response units and the public perception about the credibility of the official predictions and warnings.

The cyclone warning helped in better management of cyclones by disaster managers leading to minimum loss of human lives (double digits) since 2010, a decrease in area of evacuation by 300 km in 20 years, evacuation cost by 60 percent and exgratia payments by 99 percent compared to Odisha Super Cyclone (1999) and Kandla Cyclone (1998).

• Accurate prediction of Biparjoy cyclone (2023) enabled disaster managers to achieve zero deaths over Gujarat.
• India received worldwide accolades due to remarkable improvement in cyclone warning services by IMD enabling a reduction in human deaths to less than 100 due to any landfalling cyclone since 2010.
• Commencing with the era of Henry Edington who coined the word Cyclone in 1840, the dedicated research and innovation along with the intervention of Science and Technology helped continuous improvement in cyclone warning services from 1865 with port warning to dynamic impact-based warning in 2020.
• The significant achievement in recent years was possible with the highly exceptional contribution of IMD led by Dr. M. Mohapatra. The upgradation of early warning services for severe weather including cyclones, impact-based forecast (IBF) and risk-based warnings (RBW) was addressed holistically through (i) policy, (ii) planning, (iii)vision, (iv)strategy, (v) observations, (vi) monitoring, (vii) analysis, (viii) modelling, (ix)forecasting, (x)early warning generation, (xi)dissemination, (xii) capacity building, (xiii)confidence building and (xiv) outreach. It led to the development and modernization of end to end cyclone warning system in India which is better than many leading centres of the world today.
• For improvement in policy and planning, the Vision-2020 in 2010 and Vision-2030 documents in 2015 were prepared. It helped in planning of cyclone observational, monitoring, analysis, modeling and forecasting system. There is an improvement in cyclone track (path) forecast accuracy by 60 to 70 percent and landfall forecast accuracy by 70 to 80 percent by 2020 compared to 2010. While 48-hour track forecast accuracy was 50% less than that of USA in 2010, it is better than USA by 30% in 2020.
• IMD standardized the procedure in accordance with the National and International Guidelines for monitoring and prediction of cyclones and updated the annual cyclone operational plan every year for WMO ESCAP Panel countries (since 2010). IMD developed NDMA guidelines for Cyclone Management (2008) and revised these guidelines in 2018. IMD introduced an indigenously development Decision Support System (DSS) for cyclone monitoring and forecasting.
• Many new technologies were introduced like (i) automated weather stations, high wind speed recorders, buoys, Doppler weather radars, satellite-based monitoring tools, (ii) digitised forecasting platforms, (iii) new global and regional deterministic and ensemble prediction models, storm surge model. Further, IMD and MoES introduced high-resolution models and implementation of multi-model ensemble techniques for cyclone and associated adverse weather prediction.
• IMD also introduced scientific methodology like (i)extension of lead period of cyclogenesis forecast from 1 day (2008) to 3 days (2014), 5 days (2018), 7 days(2023), (ii)cyclone track and intensity forecast from 24 hrs (2009) to 120 hrs(2013), (iii)2 weeks advance forecast for cyclogenesis (2018), (iv)fishermen warning for next 5 days for entire North Indian Ocean(2018) against previous one day forecast along Indian coast, (v)impact based forecast(IBF) and risk-based warning(RBW) upto district level for severe weather(2019), (vi)web GIS tool, (vii)customized objective sectoral forecast for ports, shipping, offshore operations, fisheries, power, urban, hydrology, health, transport and agriculture.
• The cyclone warning services of IMD were adjudged as one of the 75 most important innovations (Sharma 2022).