MONTBLEX data archival centre

A co-ordinated project Monsoon Trough Boundary Layer Experiment (MONTBLEX) to study the atmospheric boundary layer in the monsoon trough region was taken up during 1990. 30-m high instrumented towers were erected at Kharagpur, Banaras, Delhi and Jodhpur. Sophisticated equipment like Doppler sodar and Kytoon were used at Kharagpur. Sodars were exposed at Calcutta, Delhi and Jodhpur. ORV Sagarkanya cruises were arranged in the Bay of Bengal. The India Meteorological Department set up new surface and radiation observatories and released special radio-sonde, pilot balloons. Using the above mentioned platforms, data were collected during April - September 1990 and after proper editing the entire data were archived at the Indian Institute of Tropical Meteorology, Pune. The DST-MONTBLEX data bank was started at IITM on 25th November 1991. The paper contains the details of this data

Fluxes of heat and momentum over sea surface during the passage of ε depression in the north Bay of Bengal

Tims variation of surface Fluxes of heat, moisture and momentum over a sea station (20:N89E) in the norm Bay of Bengal Mas been computed bv srofiie method lor the Period IK;:-, 25th Angus; 1990 using meteorological data of MOSTBL EX-90 from OR Y Sayarkniyii. The fluxes showed synoptic and uiurnal variations nnich ars rrarked during oppression (20th-21st August) comparée to their variation prior to and after tais period. Variations of heal and water vapour fluxes were in phase. Nigh- time fluxes are ralati.eiy high ccmpared to day time. Average ir.orner.tam transfer during depressor. two io three times large. Variations in Bowen ratio wers relatively large during day time. During depression, it varied between 0-2 in day lime and about 00 A., nignt and in the undisturbed period between 0-1 jnd 0-2 during day time and 0-2 and 025 at nigh:. The study shows that the assumption of the exchange coefficients normaiiy used ir. estimating the Ruxes by the buk Lu-rodyr.umic method is not appropriate because Cy/C- C and CH/C14

A study of turbulent characteristics of atmospheric boundary layer over monsoon trough region using Kytoon and Doppler sodar

As a part of the MONTBLEX-90 observational programme, Kytoon and Doppler sodar observations were taken at Kharagpur. These data are analysed to study the turbulent characteristics of the atmospheric boundary layer in terms of stability, temperature structure function (CT2 ) and velocity structure function (Cv2 ). CT2 follows a Z-4/3 law on most of the days, whereas the variation of CV2 is not systematic. CV2 and CT2 values are found to vary between 10-5-10-1 m4/3s-2 and 10-5-10-2°C2 m-2/3 respectively

Wind profiles in the boundary layer over Kharagpur associated with synoptic scale systems

Doppler sodar wind data for the boundary layer over Kharagpur obtained during MONTBLEX-1990 at a height interval of 30 m from surface up to 1500 m have been analysed for the periods when intense synoptic scale disturbances from north Bay of Bengal moved along the eastern end of the monsoon trough. The variation in the vertical wind profile in the lower boundary layer over Kharagpur during the passage of synoptic scale disturbances has been discussed in the paper. The analysis indicates that the mean winds over Kharagpur veered with height in the lower boundary layer near the surface suggesting divergence over Kharagpur when the system lay south/southwest of the station. No such veering has been noticed when the centre of the system lay very close to the station

Estimated Temperature Corrections for the Menaka-II Meteorological Rocket Payload

281-284The temperature as indicated by the meteorological payload is not the real temperature of the environment. The indicated temperature has to be corrected to get the exact temperature at the particular height. There are various corrections due to the thermistor inertia, its mounting position, descent rate of the parachute and the effect of solar radiation at each height. All these corrections are calculated at intervals of 10 km and the order of correction is calculated in terms of degrees Centigrade for the meteorological payload to be launched with an Indian Rocket Menaka-II. The temperature correction varies from 0·3°C at the ground to 10-15°C at 80 km