2. Materials and
methods
Sampling Procedure and Sampling Stations
Sampling Stations:
The sampling strategy for this study involved simultaneous collection of
a pair of samples of ambient atmospheric water vapor by two different
methods, namely, (1) complete cryogenic trapping at -78°C; and (2)
liquid condensation at 0°. The sampling was done at three stations
(Ahmedabad, Latitude:23.0225°N, longitude:72.5714°E; Hyderabad,
Latitude:17.3850°N, longitude:78.4867°E; and Roorkee,
Latitude:29.8543°N, longitude:77.8880°E;) located far away from each
other in different parts of India and having different
hydrometeorological aspects. The sampling at Ahmedabad, Hyderabad and
Roorkee was carried out respectively by Physical Research Laboratory
(PRL), National Geophysical Research Institute (NGRI) and National
Institute of Hydrology (NIH) under the aegis of IWIN National Programme,
using the same procedure and devices as described below.
Ahmedabad is a city in warm semi-arid western India with annual average
rainfall of 80 cm received on ~35 rainy days during
rainy season of southwest (SW) summer monsoon in the months of June to
September. Hyderabad is a city in south-eastern India and has
predominantly a tropical wet and dry climate with average annual
rainfall of 76.6 cm. It receives its 76% of annual rain during
southwest summer monsoon and remaining 24% during northeast (NE) winter
monsoon. Roorkee is in north India and has a warm and temperate climate.
It receives annual rainfall of 117 cm of which 59-84% received in SW
monsoon season and remaining in NE winter monsoon season.