Urbanisation main cause for rise in Maximum and Minimum temperature over Delhi during Pre monsoon season in last 3 years
Urbanisation is one of main causes that can influence the
changes in temperature pattern within the city and form heat islands: Earth Sciences
Minister Dr Jitendra Singh
Union Minister of State (Independent Charge) Science
& Technology; Minister of State (Independent Charge) Earth Sciences; MoS
PMO, Personnel, Public Grievances, Pensions, Atomic Energy and Space, Dr
Jitendra Singh said, the steep rise in pre-monsoon surface air temperature,
land surface temperature and relative humidity in Delhi/NCR off late is a cause
of concern.
In reply to a question in the Rajya today, Dr Jitendra
Singh in a statement laid on the table of the House said, there has been a rise
in Maximum and Minimum temperature over Delhi during Pre monsoon season during
last three years whereas there is no such increase in Relative Humidity.
The details of average
values of maximum and minimum temperature and relative humidity (RH) over Delhi
during the season for the last three years with respect to Safdarjung station
are given below:
Year |
Average Pre monsoon Max temp ( ̊ C) |
Average Pre monsoon Min Temp ( ̊ C) |
Average Pre monsoon RH 0300 UTC (%) |
Average Pre monsoon RH 1200 UTC (%) |
|
|
|
|
|
2020 |
34.4 |
20.7043 |
68.4 |
43.5 |
2021 |
36.0 |
21.35484 |
61.4 |
37 |
2022 |
37.9 |
21.96667 |
60 |
31 |
Several studies have
been carried out on the pre-monsoon temperature pattern of Delhi and the likely
causes. Urbanization is one of main causes that can influence the changes in
temperature pattern within the city and form heat islands. This is reflected by
the trends of difference in annual mean minimum temperature of the two stations
of which one (Safdarjung) is within the city and the other is in the outer
periphery in Delhi NCR (Palam).
A recent article
published in Nature, describes the reason for India’s prolonged spell of heat
wave experienced during pre-monsoon season 2022. The causes were mentioned as
the absence of rainfall and convective activities for a long period, absence of
Western Disturbances and the subsidence of warm and dry air in lower and middle
tropospheic levels over North Arabian sea and adjoining South Pakistan and
Gujarat.
It
is mentioned that, Heat wave is one of the severe weather phenomena for which
IMD issues early warning. In the country, appreciable rise in maximum
temperatures as well as heat waves are found to be more in the months of April,
May & June. As an initiative IMD is issuing Seasonal Outlook for
temperatures for the months of April, May & June in the last week of March
for planning purpose. This outlook brings out the expected scenario of heat
waves also during the period. The seasonal outlook is followed by Extended
Range Outlook issued on every Thursday for next two weeks. In addition to this,
the forecast and the colour coded warnings for severe weather including heat
wave warning over Delhi is issued on daily basis for next five days with
outlook for another two days.
IMD has started
Forecast Demonstration Project (FDP) on heat waves for the hot weather season
under which a detailed daily report including realized data of heat waves,
weather systems leading to the occurrence of heat waves, diagnosis on the basis
of Numerical Model outputs and forecast and warnings for five days is prepared.
This bulletin is disseminated to all concerned including health departments.
IMD started issuing an additional bulletin on heat wave in the morning (8 a.m.)
valid for 24 hours for supporting the planning of activities for the day and
this bulletin is also disseminated to all concerned. All these bulletins are
posted to IMD website also, on a special page created for Heatwaves.
As an adaptive
measure, IMD in collaboration with local health departments have started heat
action plan in many parts of the country to forewarn about the heat waves and
also advising action to be taken during such occasions. NDMA and IMD are
working with 23 states prone to high temperatures leading to heat-wave
conditions to develop heat action plans.