CLOUD SEEDING IN MAHARASHTRA

Based on IMD forecast in April 2015, the Government ofMaharashtra took a note of deficit rainfall forecast and plannedcloud seeding experiment as a mitigation measure inMaharashtra. The proposal was initiated by the DisasterManagement Unit (DMU) , Relief and RehabilitationDepartment.

Suhas Diwase and Dr. R. V. Sharma* Disaster Management Unit

Gov. of Maharashtra Mumbai-400021

---------------e-mail: dirdmumaha@gmail.com

* Former, Dy Director General Of Meteorology, IMD Mumbai 40005

The rapid Urbanization, Industrialization andDeforestation are increasing the environmentaldegradation / pollution and global warming which areinfluencing the rainfall pattern in different parts of theworld.

One of the adverse impact of climate change is toincrease the rainfall variability resulting excess rainfallin certain zone while deficit ( drought ) in other zone.

Marathwada is perennial drought prone region in theMaharashtra and is facing moderate to sever droughtduring last 2-3 years.

RAINFALL VARIABILITY Impact of Climate Change

Amid deficit rainfall prediction, scientists/technocrats are left with no alternative otherthan to try some technology/ methods toenhance the rainfall for betterment of thesociety.

The cloud seeding is one such experimentwhich has become a way to get more rainfall .

In the past Maharashtra conducted warm cloudmodification experiment during 11 year monsoonperiod (June - September) seasons (1973-74, 1976,1979-86).

As warm clouds generally do not contain sufficientnumber of bigger water drops or hygroscopic particles,they normally do not give more than 10% to 20% of itsmoisture as rainfall.

However, if selected clouds are injected with chemicalslike hygroscopic common salt or calcium powder thenthey may give more rains .

1. HYGROSCOPIC SEEDING:

The warm cloud seeding is done near the base

level of clouds where aircraft seeds the

hygroscopic flares at about 1000-2000 m height

around the cloud selected as shown in the

adjoining Fig. In our experiment, CaCl2 Hygroscopic

Burn-In-Place Cloud Seeding Flares have been used.

2. GLACIOGENIC SEEDING:

When clouds grow to higher height, the top

temperature will be about -10, -15 ° C, then top

seeding is done as shown in the adjoining Fig. In

such method, flares are injected into the colder

region and dry ice in super cooling increases the

growth of cloud and thus making cloud drop bigger

into rain drop. In our experiment, AgI Burn-In-Place

and injectable Cloud Seeding flares have been

used.sed.

Dry air 850hpa upwards

Vertical profile of the atmosphereindicating dry air above 850 hpalevel onward in the lowertroposphere on 28th September2015

Vertical profile (a) with cloud development and (b) without anycloud development

Histogram indicates 48.3 % of rains in different rainfall ranges occurred after the cloud seeding. The percentage includes the natural rainfall also.

(a) 09-09-2015 0637 UTC (b) 09-09-2015 0644 UTC

( c ) 09-09-2015 0652 UTC (d) 09-09-2015 0659 UTC

(e) 09-09-2015 0707 UTC (f) 9-09-2015 0715 UTC

A sequence of seeding impact as seen on radar echoes on 9th

Sept 2015 :

clearly indicates the increase in reflectivity and area of cloud development

Yellow colour shows the track of the aircraft and blue colour the track ofseeding portion with * location of Flares released on 12th August 2015. Therainfall on 13th August was recorded at Pathardi 15 mm, Parner 14 mm ofAhmednagar district and Ashi 35 mm in Beed Districts.

2nd Oct,2015

Reflectivity poor in shown area

watch development

2nd

Oct,2015

Cloud top

6.1 km

2nd

Oct,2015

Cloud top 9.1 km

22-08-2015 08:33:43 UTC

Max dN at CDP 2.5 µm = 57.1

22-08-2015 08:33:43 UTC

Longitude

Cloud Motion

(a ) 30-0802015 time : 12:19: 14 UTC (b) 30-08-2015 time: 12:19: 14 UTC

( c ) 30-08-2015 time : 12: 34: 17 UTC (d) 30-08-2015 time : 12: 34: 17 UTC

Radar images showing the cloud motion towards Aurangabad on 30th Aug,15.

Finally, cloud drifted towards Phulambi taluka in Auranagabad district and gave 5mm rainfall

speed 12 km/hr Max 44 dbz

speed 21 km/hr Max 40 dbz

• Rain occurred in 48.3 % of cloud seeding occasions .

• Radar reflectivity shows positive impact on cloud growth/rain enhancement.

• It is not possible to ascertain percentage increase of rainfall asit needs more dense rainfall monitoring in space and time .

• Disaster Management Unit , Gov. Of Maharashtra is ready toshare the data collected during experiment.

• More scientific institutions / organisations may takecollaborative initiative in such experiments.

• Such experiment should be continued for scientificconclusions.

OBSERVATIONS AND CONCLUSION

THANKING YOU

DMU invites research proposal using the Cloud Seeding data with action plan for mitigation

drought