Friday, March 28, 2014

ENSO and its effect on the South West Monsoon: Images to Illustrate Narration Newly Added

Basically, the South West Monsoon advances and covers the entire Sub Continent region in June and completes its advance around early July.
Now, these advancing parameters and criteria are not linked or affected by the El Nino or the La Nina.                               vagaries

The advancing parameters are initiated from the South Indian Ocean, and are largely influenced by the Mascrene Highs between Madagascar and Australia.
Other parameters, which largely influence the advance is the seasonal low over the sub continent and the pressure gradient thus created. Many of the initial parameters are discussed in the Vagaries' Monsoon Watch Series, which are found in the Archives Page of this blog.
The ENSO factors affect the subsequent performance of the Monsoon rains.

In an El -Nino year, the waters of the Pacific Ocean off the Peru Coast in South American Continent heats up by 2/4c. Now, as a result, the Central Pacific Ocean , roughly where the "tongue" of the heated waters end, rise, and form rain bearing clouds, and precipitation in the Central Pacific Region. 
El- Nino induced warm zones in the Pacific cause the warm air over them to rise and initiate circulation cells. Such cells along northern Australia, Indonesia and the eastern edge of the Indian Ocean could have their down draft sides over a nascent monsoon circulation cell in the Indian Ocean, which would disrupt Monsoon Depression  formation, causing poor monsoon rains over the subcontinent. 
Thus, there is a marked reduction in Typhoons and Depressions forming. Consequently, in an El Nino year, we would expect lesser depressions and lows forming in the Bay. This sequence  implies that El Nino years should coincide with deficient monsoon rains.

Normally, when in a neutral or La Nina year, the waters normally heat up towards the far West of the Pacific Ocean, rain bearing clouds are formed much to the West and near the Philippines.

Now, Typhoons and Lows forming from these regions travel West, and send Low pulses into the Bay. These are the "life giving" depressions in the Bay which criss- cross across the Indian regions.

But, that does not mean lower rainfall all over the Sub Continent. Absence of Lows from the Bay will keep the WDs active, and may increase the number of WDs crossing the Northern Regions even till July/August. This has happened, when the Lows from the Bay do not "interfere" and WDs are given a "free hand".

But, the above sequence may not necessarily happen, and sometimes, even in an El Nino year, the Central Regions of India get good rains from Line of Wind Discontinuity forming from localised heat developments. Deeps troughs in the jet streams could bring or create UAC in the Gujarat regions, even in an El Nino year.
So, all El -Nino years are not bad for Monsoons.This Graphical Plotting from IITM, shows  the inconsistency of 130  years..


Rajesh said...

Vagaries' Monsoon Watch Series Starts around 10th April Every Year

Rawat said...

Yesterday evening heavy shower with hails and stormy winds lashed Faridabad . Rain amount (in cms) Faridabad - 3 . Ballabgarh -1 . Sir can we expect squall today as well

Abhijit Modak said...

Many parts of West, East & South India having hot conditions !!

So some max temp below for today (29-03-2014):

Bankura 41.9°C
Bhubaneswar 41.8°C
Kurnool 41.3 °C
Jamshedpur 40.8°C
Jharsuguda 40.3°C
Ramgundam 40.3°C
Anantapur 40.2°C
Nellore 40.0°C
Nizamabad 39.9°C
Raipur 39.9°C

Metro cities max temp :

Kolkata max temp for today : Alipore 39.3°C & Dum Dum 39.5°C with min humidity of 19%.

Bangalore max temp for today : BLR City 36.0°C & BLR AP 38.6°C with min humidity of 10% !!

Chennai max temp for today : Ngbkm 35.6°C & Mnbkm 37.0°C

Mumbai max temp for today : Colaba 30.2°C & S'cruz 35.0°C with min humidity of 28%..

Mumbai's eastern townships hot !!

Badlapur (private reading) max temp 38.1°C with min humidity of 11% today.

Thane IMD AWS estimated max temp 38.5c with min humidity of 21% today.

Karjat IMD AWS estimated max temp 40.5c with min humidity of 11% today.

Interior Maharashtra hot !!

Nashik 37.3°C
Aurangabad 37.4°C
Pune max temp 37.9°C with min humidity of 8% today.
Pune AP 38.5°C
Ahmadnagar 38.7°C
Jalgaon 39.6°C
Nagpur 39.8°C
Solapur 40.1°C
Akola & Bramhapuri 40.5°C

Rajesh said...

On Saturday 29th, Bhubaneshwar AP was 41.8c...Jamshedpur was 40.8c and Akola 40.5c.

Hottest in Asia was Nyaung Pagan ( Malaysia) at 43c

Hyderabad AP was 39c and Bangalore AP 38.6c, and was 5c above normal.

Abhijit Modak said...

Many parts of West, East & South India continues to be under hot conditions !!

Some max temp below for today(30-03-2014) :

Bhubaneswar 42.0°C (Last 10 yrs record has been equaled today)
Kurnool 41.7°C
Bankura 41.5°C
Jharsuguda 41.3°C
Jamshedpur 41.2°C
Anantapur & Ramgundam 41.0°C
Nellore 40.6°C
Raipur 40.3°C
Vellore 40.2°C

Metro cities max temp :

Kolkata max temp for today : Alipore 39.9°C & Dum Dum 39.8°C with min humidity of 16% !!

Hyderabad max temp 39.1°C with min humidity of 12% !!

Bangalore max temp for today : BLR City 36.0°C & BLR AP 38.5°C with min humidity of 10% !!

Chennai max temp for today : Ngbkm 36.6°C & Mnbkm 38.4°C with min humidity of 18% !!

Mumbai max temp for today : Colaba 32.5c & S'cruz 36.0c with min humidity of 31%.

Heat wave in Interior North Konkan today !!

Mumbai's eastern towns recorded first 40c temp of year 2014 today dated (30-03-2014 ):

Thane Envirocon AWS max temp 40.0°C with min humidity of 20% & Thane IMD AWS estimated max temp 40.5°C

Badlapur(private reading) max temp 40.0°C with min humidity of 14% @ today.

Karjat max temp 42.0°C with min humidity of 14% today.

Interior Maharashtra also hot !!

Aurangabad 38.2c
Pune max temp 38.4c with min humidity of 9% today.
Nashik 38.8c with min humidity of 8% today.
Pune AP 39.1c
Ahmadnagar 39.7c
Jalgaon 39.8c
Nagpur 40.2c
Akola 40.7c
Nanded 40.8c
Solapur 40.9c

Vinod Desai said...

This is very hot for thane and karjat.

Nimish Thaker said...

A quick glance at the chart on the El Nino and Rains (normal / drought / flood) indicates that an El Nino year can either bring in Drought or Normal rains. Floods (excess rains) have never happened in an El Nino year as per the chart.

Let's see how 2014 fares.

Weather outlook till Friday 31st March - As we calculated in mid March after the Heat spell,  remaining days of March stayed below 40c in In...