Various atmospheric instruments pioneered and developed by SAMEER include:
- ST Radar- Visit our ST Radar page
- Ka band Polarimetric Doppler Cloud Radar
- MST Radar
- UHF Wind Profiler
- Phased Array Doppler Sodar
- CW Bistatic RASS for Doppler SODAR
- Radio Theodolite
- ST Radar
2) Ka band Polarimetric Doppler Radar for Cloud Profiling
Apart from radar windprofilers, SAMEER has also developed a zenith looking Ka band polarimetric Cloud Radar and is developing a scanning Cloud Radar shown in Fig.1a and Fig.1b.
Fig 1a: A scanning Ka band polarimetric Cloud Radar
Fig.1B- Ka band scanning Cloud Radar positioned outdoors for data collection
3) MST Radar
A state of the art atmospheric radar system called Mesospheric Stratospheric Tropospheric [MST] radar has been designed, developed and installed at Gadanki village , near Tirupati . This radar, which is considered second largest in the world , is capable of detecting and measuring wind velocities, wind shear and other atmospheric turbulences upto a height of 100 kms into the sky. The radar was commissioned in 1993 and since then it is fully operational. Scientists from all over the country primarily use the radar for atmospheric research.
The Indian MST radar is a highly sensitive pulse coded, coherent VHF phased array radar operating at 53 MHz with an average power aperture product of 7 x 108 Wm2. The system design specifications are presented in Table 1.
Various aspects of the turbulence characteristics and wind fields in the middle atmosphere with resolutions of the order of a few tens of meters in height and a few tens of second in time may be studied using this radar. The MST Radar antenna array has been shown in Fig.2.
Fig 2: MST Radar Antenna array
The doppler spectra for this radar operated in ST mode has been shown in Fig.3.
Fig 3: Doppler spectra for MST Radar operated in ST Mode
The measured pattern using Virgo-A radio-source has been shown in Fig.4.
Fig 4: Measured Antenna Pattern of MST Radar using Virgo-A Radio Source
The end user for this MST Radar was National Atmospheric Research Laboratory (NARL, then NMRF), Tirupati. All the signal processing and all the subsystems were designed and developed in-house.
4) UHF wind profiler
This ground based clear air pulsed Doppler radar working at 404.37 Mhz transmits 16KW pulsed RF power using a 40ft x 40 ft coaxial collinear antenna and receives echoes from various atmospheric layers. A sensitive receiver with state of art signal processing system has been used to detect the return echoes and derive wind parameters upto about 12km height with range resolution of 300m. This is also equipped with RASS attachment which gives temperature profiles upto 3kms.
The wind and temperature profiler developed by SAMEER for IMD, Pune provides vertical profiles of horizontal winds in the troposphere and also gives temperature profile information upto 3 km. Wind profiler system as designed is a ground based clear air coherent doppler radar. It employs pulse coding and FFT techniques. RASS attachment has been provided for temperature profiling using FMCW acoustic sweep to ensure Bragg matching condition. The wind profiler has been shown in in Fig.5 and the specifications have been shown in Fig.6. The results have been shown in Fig.7.
Fig 5: Windprofiler installed at IMD, Pune
Fig 6: Windprofiler specifications
Fig 7: Windprofiler results
An HF Ionosonde for ionospheric studies has also been developed and a block diagarm for the same has been shown in Fig.8.
4) Phased Array Doppler Sodar
Doppler Sodar [Acoustic sounder] is a standard technique used for measurement of atmospheric wind and turbulence parameters in the lowest 1000 m of atmosphere. The data obtained from such instruments is needed for environmental impact assessment due to thermal as well as high risk chemical industries.
An acoustic radar called SODAR has also been developed by SAMEER and has been shown in Fig.9. SODAR systems installed at various locations by SAMEER have been shown in Fig.10. The time vs height plot is shown in Fig.11.
Fig 9: SODAR developed by SAMEER
Fig 10: SODAR systemsinstalled at various locations by SAMEER
Fig 11: Time vs height plot of wind from SODAR
This CW bistatic radar operates at 712 MHz as an attachment to Doppler Sodar. Normally Doppler Sodars are capable of giving wind speeds and wind direction profiles upto a height of 1km. This when combined with RF Radar system works as a RASS [Radio Acoustic Sounding System], giving temperature profile upto about 1 km.A Radio Acoustic Sounding system attachment for windprofiler has been shown in Fig.12 whereas a 401 MHz Radio theodolite for tracking a radiosonde balloon has been shown in Fig.13.