NOPR Community:

On the stability of atmospheric surface layer along the monsoon rough region over India

Mon, 01 Oct 2001 00:00:00 GMT

Title: On the stability of atmospheric surface layer along the monsoon rough region over India Authors: Patil, M N; Parasnis, S S Abstract: Stability characteristics in the atmospheric surface layer over dry convection, moist convection and alternate deep moist/unsaturated convection zones of the monsoon trough have been explored using the tower data of wind and temperature obtained during monsoon trough boundary layer experiment (MONTBLEX). In general, different characteristics in three sub-layers of a 1-30 m layer were observed before, during and after the onset of monsoon. Before onset of the monsoon, 1-4 m layer was stably stratified over dry convection (western end) and moist convection (eastern end) zones of the monsoon trough. After the onset of monsoon, inversion in this layer was not noticed. These results may possibly be attributed to the local effect. Page(s): 266-272

Characteristics of turbulence in the atmospheric surface layer over a complex terrain

Mon, 01 Oct 2001 00:00:00 GMT

Title: Characteristics of turbulence in the atmospheric surface layer over a complex terrain Authors: Murthy, B S; Dharmaraj, T Abstract: Measurements of fluctuating wind components and temperature have been made in the atmospheric surface layer over a complex terrain in the campus of the Indian Institute of Tropical Meteorology, Pune, using sonic anemorneter at 5.2 m above the surface. Characteristics of turbulence, i.e. spectra of wind velocity components and turbulence statistics of wind are presented. The peak of normalized w-spectrum over a complex terrain for near-neutral condition was found to be ~ 0.6 as compared to ~ 0.4 over homogeneous terrain. The non-dimensional frequency maximum for w-component spectrum was observed to be 0.9 as compared to ~ 0.5 over homogeneous terrain. Empirical formulae for standard deviation of velocity components have been tested against observations over hilly terrain. Vertical flux of turbulence kinetic energy as a function of stability is also discussed. Page(s): 260-265

A model study of the atmospheric heating rates due to O₃, H₂O and O₂

Mon, 01 Oct 2001 00:00:00 GMT

Title: A model study of the atmospheric heating rates due to O₃, H₂O and O₂ Authors: Lal, M Abstract: The height distribution of solar heating rate due to ozone, water vapour and oxygen molecule from ground to 100 km altitude has been examined in this study. The cooling rate due to infrared emission of CO₂, O₃ and water vapour molecules has also been studied for middle atmospheric region. The heating and cooling rates have been calculated for midlatitude and equinox condition. The diurnal variation of net radiative temperature change in tropospheric and stratospheric region causes I generation of waves, which propagate in the mesospheric region and affects the climatology of the upper atmosphere. The heating rate due to water vapour is found to be important in the troposphere, ozone heating is Significant in the stratosphere, and oxygen heating rate is found to be important in the mesospheric region. The maximum ozone heating rate in the stratospheric region is found to be ~ 15 K/day. The cooling rate is due to CO₂ is very significant in the stratospheric region and its found to be about -12 K/day. The net radiative temperature change due to heating and cooling has been obtained to be similar to the atmospheric temperature profile. Page(s): 254-259

Study of travelling ionospheric disturbances using IPS array at Rajkot

Mon, 01 Oct 2001 00:00:00 GMT

Title: Study of travelling ionospheric disturbances using IPS array at Rajkot Authors: Jadeja, A K; Jadav, R M; Vats, Hari Om; Iyer, K N Abstract: Using a novel radio astronomical technique, the presence of travelling ionospheric disturbances (TIDs) are detected from observations of radio star signals by the interplanetary scintillation (IPS) system at Rajkot for the first time in India. The periods of the TIDs (20-24 min) and north-south component of their velocity (66-273 m/s) indicate that they belong to the medium scale category. The results are discussed in the light of a model of atmospheric gravity waves (AGWs) originating in auroral electrojet region and propagating meridionally equatorward. Page(s): 249-253

NOPR Community:

On the stability of atmospheric surface layer along the monsoon rough region over India

Characteristics of turbulence in the atmospheric surface layer over a complex terrain

A model study of the atmospheric heating rates due to O3, H2O and O2

Study of travelling ionospheric disturbances using IPS array at Rajkot

A model study of the atmospheric heating rates due to O₃, H₂O and O₂