scholarly journals STUDIES OF RADIO REFRACTIVE INDEX IN ASSOCIATION WITH ONSET OF MONSOON

MAUSAM ◽  
2021 ◽  
Vol 44 (1) ◽  
pp. 15-18
Author(s):  
R. V. SHARMA ◽  
THAKUR PRASAD ◽  
SHRAVAN KUMAR
Keyword(s):  
Refractive Index ◽  
Lower Troposphere ◽  
Significant Rise ◽  
Km Value ◽  
Onset Of Monsoon

Variations of radio refractive index (RRI) in the lower troposphere over Bombay and Thiru-vananthapuram have been studied for the months from April to July for the years 1979 to 1987. It is seen that in most of the years, the radio refractive index at 900 hPa over Bombay increased significantly prior to onset of monsoon over Kerala (Thiruvananthapuram) and well in advance of the arrival monsoon over Bom-bay. Variation of RRI at 850 hPa level over Bombay also shows significant increase a few days later than at 900 liPa level. At higher levels no such significant changes are observed. The KM value over Thinivanantha-purain at 900 hPa or at 850 hPa does not show significant rise from pre-monsoon to monsoon months. The results show a slight decreasing trend during the same period.

scholarly journals Another Look at the Refractive Index Structure Function

2013 ◽  
Vol 52 (2) ◽  
pp. 498-506 ◽  
Author(s):  
T. Cherubini ◽  
S. Businger
Keyword(s):  
Numerical Modeling ◽  
Refractive Index ◽  
Structure Function ◽  
Potential Temperature ◽  
Lower Troposphere ◽  
Its Region ◽  
Index Structure ◽  
Accurate Estimation ◽  
Radar Meteorology ◽  
New Formulation

AbstractThis paper discusses the derivation of the refractive index structure function. It shows that the traditional formulation, which is based on the hydrostatic assumption, leads to increasing errors with height when compared with a formulation that is based on the potential temperature. The paper corrects a long-standing problem of extrapolating the traditional boundary layer approximation beyond its region of validity (i.e., to the upper troposphere and lower stratosphere). The new derivation may have applications in observational work to measure and seeing and in numerical modeling efforts. A preliminary analysis of the influence of the new formulation in numerical modeling of seeing suggests that impact on seeing will be small in general, because the largest contribution to seeing generally comes from the lower troposphere. However, an accurate profile is needed because other astroclimatic parameters, such as the isoplanatic angle, can suffer from the lack of accuracy at high altitude. This work may also have application in radar meteorology, since clear-air radar sensitivity depends on accurate estimation of .

scholarly journals On the determination of the structure and refractive index of the lower troposphere (lowest 1000 ft) over Dum Dam Airport

MAUSAM ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 399-408
Author(s):  
A. C. DE
Keyword(s):  
Refractive Index ◽  
Mass Concentration ◽  
Monsoon Season ◽  
Meteorological Data ◽  
Winter Season ◽  
Lower Troposphere ◽  
Masking Effect ◽  
Tabular Form ◽  
Water Droplets

The results of special radiosonde soundings extending upto 1000 ft made on certain selected dates and at certain selected hours during the winter season 1957-58 and pre-monsoon season 1958 over Dum Dum airport are discussed. The results indicated the formation of ducts at certain hours. The variations of the meteorological data with the progress of night are shown in a tabular form. The radarscope observations at the corresponding hours are also discussed. On some occasions the duet heights were as high as 600 ft and prevailed for the whole night. These duets extended horizontally in all directions to about 50 miles. The attenuation produced by appearance of fog/mist over the station and its masking effect on the ground clutters are also discussed. The mass concentration of water droplets on different dates has been calculated and shown in a tabular form.

scholarly journals Seasonal, annual and inter-annual features of turbulence parameters over the tropical station Pune (18°32' N, 73°51' E) observed with UHF wind profiler

2008 ◽  
Vol 26 (12) ◽  
pp. 3677-3692 ◽  
Author(s):  
Narendra Singh ◽  
R. R. Joshi ◽  
H.-Y. Chun ◽  
G. B. Pant ◽  
S. H. Damle ◽  
...  
Keyword(s):  
Refractive Index ◽  
Lower Troposphere ◽  
Spectral Width ◽  
Index Structure ◽  
Wind Profiler ◽  
Structure Parameter ◽  
Post Monsoon ◽  
Tropical Station ◽  
Refractive Index Structure Parameter ◽  
Turbulence Parameters

Abstract. The present study is specifically focused on the seasonal, annual and inter-annual variations of the refractive index structure parameter (Cn2) using three years of radar observations. Energy dissipation rates (ε) during different seasons for a particular year are also computed over a tropical station, Pune. Doppler spectral width measurements made by the Wind Profiler, under various atmospheric conditions, are utilized to estimate the turbulence parameters. The refractive index structure parameter varies from 10−17.5 to 10−13 m−2/3 under clear air to precipitation conditions in the height region of 1.05 to 10.35 km. During the monsoon months, observed Cn2 values are up to 1–2 orders of magnitude higher than those during pre-monsoon and post-monsoon seasons. Spectral width correction for various non-turbulent spectral broadenings such as beam broadening and shear broadening are made in the observed spectral width for reliable estimation of ε under non-precipitating conditions. It is found that in the lower tropospheric height region, values of ε are in the range of 10−6 to 10−3 m2 s−3. In summer and monsoon seasons the observed values of ε are larger than those in post-monsoon and winter seasons in the lower troposphere. A comparison of Cn2 observed with the wind profiler and that estimated using Radio Sonde/Radio Wind (RS/RW) data of nearby Met station Chikalthana has been made for the month of July 2003.

scholarly journals A unified approach to infrared aerosol remote sensing and type specification

2013 ◽  
Vol 13 (4) ◽  
pp. 2195-2221 ◽  
Author(s):  
L. Clarisse ◽  
P.-F. Coheur ◽  
F. Prata ◽  
J. Hadji-Lazaro ◽  
D. Hurtmans ◽  
...  
Keyword(s):  
Refractive Index ◽  
Sulfuric Acid ◽  
Atmospheric Aerosols ◽  
Global Climate ◽  
Lower Troposphere ◽  
Detection Methods ◽  
Aerosol Composition ◽  
Modis Aod ◽  
Infrared Measurements ◽  
Windblown Sand

Abstract. Atmospheric aerosols impact air quality and global climate. Space based measurements are the best way to observe their spatial and temporal distributions, and can also be used to gain better understanding of their chemical, physical and optical properties. Aerosol composition is the key parameter affecting the refractive index, which determines how much radiation is scattered and absorbed. Composition of aerosols is unfortunately not measured by state of the art satellite remote sounders. Here we use high resolution infrared measurements for aerosol type differentiation, exploiting, in that part of spectrum, the dependency of their refractive index on wavelength. We review existing detection methods and present a unified detection method based on linear discrimination analysis. We demonstrate this method on measurements of the Infrared Atmospheric Sounding Interferometer (IASI) and five different aerosol types, namely volcanic ash, windblown sand, sulfuric acid droplets, ammonium sulfate and smoke particles. We compare these with traditional MODIS AOD measurements. The detection of the last three types is unprecedented in the infrared in nadir mode, but is very promising, especially for sulfuric acid droplets which are detected in the lower troposphere and up to 6 months after injection in the upper troposphere/lower stratosphere.

scholarly journals A STUDY OF RADIO REFRACTIVE INDEX AND WIND INDEX ASSOCIATED WITH ONSET OF MONSOON OVER CHANDIGARH

MAUSAM ◽  
2022 ◽  
Vol 53 (2) ◽  
pp. 241-244
Author(s):  
MANMOHAN SINGH ◽  
K. L. KHARBANDA ◽  
S. C. BHAN
Keyword(s):  
Refractive Index ◽  
Onset Of Monsoon

scholarly journals A unified approach to aerosol remote sensing and type specification in the infrared

2012 ◽  
Vol 12 (10) ◽  
pp. 26871-26928 ◽  
Author(s):  
L. Clarisse ◽  
P.-F. Coheur ◽  
F. Prata ◽  
J. Hadji-Lazaro ◽  
D. Hurtmans ◽  
...  
Keyword(s):  
Refractive Index ◽  
Sulfuric Acid ◽  
Atmospheric Aerosols ◽  
Global Climate ◽  
Lower Troposphere ◽  
Detection Methods ◽  
Aerosol Composition ◽  
Infrared Measurements ◽  
Windblown Sand ◽  
Climate Space

Abstract. Atmospheric aerosols impact air quality and global climate. Space based measurements are the best way to observe their spatial and temporal distributions, and can also be used to gain better understanding of their chemical, physical and optical properties. Aerosol composition is the key parameter affecting the refractive index, which determines how much radiation is scattered and absorbed. Composition of aerosols is unfortunately not measured by state of the art satellite remote sounders. Here we use high resolution infrared measurements for aerosol type differentiation, exploiting, in that part of spectrum, the dependency of their refractive index on wavelength. We review existing detection methods and present a unified detection method based on linear discrimination analysis. We demonstrate this method on measurements of the Infrared Atmospheric Sounding Interferometer (IASI) and six different aerosol types, namely volcanic ash, windblown sand, ice crystals, sulfuric acid droplets, ammonium sulfate and smoke particles. The detection of the last three types is unprecedented in the infrared in nadir mode, but is very promising, especially for sulfuric acid droplets which are detected in the lower troposphere and up to 6 months after injection in the upper troposphere/lower stratosphere.

scholarly journals Simultaneous observations of structure function parameter of refractive index using a high-resolution radar and the DataHawk small airborne measurement system

2016 ◽  
Vol 34 (9) ◽  
pp. 767-780 ◽  
Author(s):  
Danny E. Scipión ◽  
Dale A. Lawrence ◽  
Marco A. Milla ◽  
Ronald F. Woodman ◽  
Diego A. Lume ◽  
...  
Keyword(s):  
Refractive Index ◽  
High Resolution ◽  
Structure Function ◽  
Lower Troposphere ◽  
Unmanned Aircraft ◽  
Function Parameter ◽  
High Temporal Resolution ◽  
Atmospheric Measurements ◽  
Range Resolution

Abstract. The SOUSY (SOUnding SYstem) radar was relocated to the Jicamarca Radio Observatory (JRO) near Lima, Peru, in 2000, where the radar controller and acquisition system were upgraded with state-of-the-art parts to take full advantage of its potential for high-resolution atmospheric sounding. Due to its broad bandwidth (4 MHz), it is able to characterize clear-air backscattering with high range resolution (37.5 m). A campaign conducted at JRO in July 2014 aimed to characterize the lower troposphere with a high temporal resolution (8.1 Hz) using the DataHawk (DH) small unmanned aircraft system, which provides in situ atmospheric measurements at scales as small as 1 m in the lower troposphere and can be GPS-guided to obtain measurements within the beam of the radar. This was a unique opportunity to make coincident observations by both systems and to directly compare their in situ and remotely sensed parameters. Because SOUSY only points vertically, it is only possible to retrieve vertical radar profiles caused by changes in the refractive index within the resolution volume. Turbulent variations due to scattering are described by the structure function parameter of refractive index Cn2. Profiles of Cn2 from the DH are obtained by combining pressure, temperature, and relative humidity measurements along the helical trajectory and integrated at the same scale as the radar range resolution. Excellent agreement is observed between the Cn2 estimates obtained from the DH and SOUSY in the overlapping measurement regime from 1200 m up to 4200 m above sea level, and this correspondence provides the first accurate calibration of the SOUSY radar for measuring Cn2.

scholarly journals Changes in Blood Lymphocyte Cytoplasmic Refractive Index Following Skin Grafting in Rabbits

Blood ◽  
1972 ◽  
Vol 39 (1) ◽  
pp. 113-116 ◽  
Author(s):  
S. Laaveg ◽  
W. K. Metcalf
Keyword(s):  
Refractive Index ◽  
Graft Rejection ◽  
Blood Lymphocyte ◽  
Skin Grafting ◽  
Significant Rise ◽  
Normal Range ◽  
Blood Lymphocytes ◽  
The Third ◽  
Early Predictor

Abstract A technique for measuring the refractive index of the cytoplasm of the circulating blood lymphocytes of rabbits is described. This parameter is remarkably constant in normal animals but shows a significant rise following the application of skin homografts, but not of skin autographs, in rabbits. The rise in refractive index reaches or exceeds the extreme normal range between the third and fifth day after application of the graft, with rejection coming on the tenth day. It is suggested that this technique is worth further investigation as a possible early predictor of graft rejection.

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