Indian Journal of Radio & Space Physics

                     CODEN: IJRSAK        ISSN: 0367-8393 (print); 0975-105X (online)

                                http://www.niscair.res.in; http://nopr.niscair.res.in

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VOLUME 38

NUMBER 6

DECEMBER 2009

 

CONTENTS

 

Characteristic features of large geomagnetic storms observed during solar cycle 23

305

        S K Pandey & S C Dubey*

 

 

Ozone depletion, worst not yet over

313

        R P Kane

 

 

Atmospheric stability estimation using radio occultation data over India and surrounding region

317

        Neerja Sharma*, D Jagadheesha, P C Joshi & P K Pal

 

 

Number concentration characteristics of ultrafine aerosols (atmospheric nanoparticles / aitken nuclei) during 2008 over western Himalayan region, Kullu-Manali, India

326

        Nand Lal Sharma*, J C Kuniyal, Mahavir Singh, Ajay K Negi, Kesar Singh & Priyanka Sharma

 

 

Horizontal gradients of traffic related air pollutants near a major highway in Agra, India

338

        Anshumala Sharma, David D Massey & Ajay Taneja*

 

 

Analysis of data on net longwave, shortwave and global radiation during transition period in a tropical station in Southwestern Nigeria

347

E O Ogolo*, S E Falodun, S S Oluyamo & E F Nymphas

 

 

Joint statistics of rain rate and event duration for a tropical location in India

353

Animesh Maitra*, Saurabh Das & Ashish K Shukla

 

 

Annual Index

 

Subject Index

361

 

 

Author Index

363

 

 

Acknowledgement to Reviewers

365

__________

 

*Authors for correspondence

 

 

 

 

Indian Journal of Radio & Space Physics

Vol. 38, December 2009, pp. 305-312

 

Characteristic features of large geomagnetic storms observed
during solar cycle 23

S K Pandey1, $ & S C Dubey2,#,*

1Department of Physics, Rewa Engineering College, Rewa (MP) 486 001, India

2Department of Physics, S G S Govt P G College, Sidhi (MP) 486 661, India

E-mail: $skpandeygecrewa@yahoo.co.in; #subhas1236@rediffmail.com

Received 16 January 2009; revised 20 August 2009; accepted 26 October 2009

A set of 90 large geomagnetic storms, associated with disturbance storm time (Dst) (decreases of more than 100 nT) observed during 1997-2007, have been analysed. The analysis included various characteristics features as well as seasonal and solar cycle dependence of these storm events. It has been found that all severe geomagnetic storms are associated with coronal mass ejections (CMEs) during the solar cycle 23. A comparative study of 11 severe geomagnetic storms (Dst £ -250 nT) and their associative solar driver have also been discussed.

Keywords: Geomagnetic storms, Coronal mass ejection, Disturbance storm time (Dst), Solar cycle 23

PACS Nos: 92.60.Qx; 94.20.Vv; 96.60.qd

 

Indian Journal of Radio Space & Space Physics

Vol. 38, December 2009, pp. 313-316

 

Ozone depletion, worst not yet over

R P Kane

Instituto Nacional de Pesquisas Espaciais—INPE, C P 515, São Jose´ dos Campos, 12245-970 SP, Brazil
E-mail:kane@dge.inpe.br

Received 22 April 2009; revised and accepted 26 October 2009

The ozone depletion which started in late 1970s, reached a maximum level (minimum ozone content) in 1993 and thereafter a partial recovery seemed to have occurred up to 2002. But that was a false signal. From 2003 onwards, there seems to have a relapse and the level has been low even in 2009 implying that a permanent damage might have occurred.

Keywords: Atmospheric ozone, Ozone depletion, Total ozone mapping spectrometer (TOMS)

PACS No: 92.70.Cp

 

 

Indian Journal of Radio & Space Physics

Vol. 38, December 2009, pp 317-325

 

Atmospheric stability estimation using radio occultation data over India and surrounding region

Neerja Sharma$,*, D Jagadheesha, P C Joshi & P K Pal

Atmospheric Sciences Division, Remote Sensing Applications Area, Space Applications Centre, ISRO, Ahmedabad 380 015

$E-mail: neerja@sac.isro.gov.in, neerja_s@rediffmail.com

Received 26 May 2009; revised 16 September 2009; accepted 22 September 2009

The paper presents analysis of occurrence and intensity of rainfall with the lifted index (LI), total precipitable water (TPW), average relative humidity (ARH) and average refractivity (RI) derived from radio occultation (RO) data. Constellation Observing System has been used for meteorology, ionosphere and climate (COSMIC) refractivity and 1-d variational assimilation retrievals of pressure, temperature and water vapour pressure during May-August 2007 over India and the surrounding region. The results mainly indicate that RO data can be a sensitive measure of rainfall. LI, TPW and ARH together are linked to give 90% probability of occurrence of rainfall events. Almost similar probability of rainfall occurrence and its intensity is captured when RI is used in place of LI. The results emphasize that RO average refractivity (above a certain threshold) is a measure of instability of the atmosphere and can be used as stability index instead of LI. RI in combination with moisture indices is able to give potential signature of rainfall occurrence and its intensity.

Keywords: Radio occultation data, Atmospheric stability indices, Refractivity index, Rainfall intensity

PACS Nos: 92.40.eg; 95.10.Gi

 

 

Indian Journal of Radio & Space Physics

Vol. 38, December 2009, pp 326-337

 

Number concentration characteristics of ultrafine aerosols (atmospheric nanoparticles / aitken nuclei) during 2008 over western Himalayan region,
Kullu-Manali, India

Nand Lal Sharma1,$,*, J C Kuniyal2, Mahavir Singh3, Ajay K Negi2, Kesar Singh2 & Priyanka Sharma2

1Govt Post Graduate College, Kullu 175 101, Himachal Pardesh, India

2G B Pant Institute of Himalayan Environment & Development, Himachal Unit, Mohal-Kullu 175 126, Himachal Pradesh

3Himachal Pradesh University, Shimla 171 005, India

$E-mail: nlsharmakullu@hotmail.com

Received 29 September 2008; revised 9 June 2009; re-revised received and accepted 9 November 2009

The ultrafine particles of three sizes 200, 30 and 10 A [20 nm (aitken mode), 3 nm, 1 nm (nucleation mode / nano particles)] were monitored with water based condensation particle counter during January-December 2008 at Mohal in Kullu-Manali area of North western Himalayas. The results indicate that diurnal pattern has faint bimodal structure with two peaks, one in morning and other in evening but is not as distinct as found in plains. There is rather constant particle density pattern consistent with vehicular movement from morning till evening. This may also be due to abnormally large bursts of particles (nucleation bursts) which are found to be more in summer than winter, more during sunrise and less during afternoon. The weak nucleation bursts are found to be frequent throughout the year than very strong nucleation bursts which are mostly found during months of June, July and August. The monthly 24 h average density gradually picks up from January, increases rapidly in summer months and then decreases in winter. The density is more in summer than in winter, a trend opposite to plains, may be due to development of warm thermal layer on valley floor while cold layer developed along snowy hilltops in winter leading to convection of fine particles up the slopes of valley during daytime. The relatively more value in September and October is due to month long international Dussehra festival in the valley and unexpected lower values in November and December may be due to low local as well as tourist traffic flow; washout/rainout effects; and higher inversion layer. The vehicular survey conducted agrees well with diurnal, monthly as well as yearly averaged diurnal variation of fine particles. The annual average of 24 h average value of ultrafine particles of three size range is 18045±1212, 16811±2790, and 15407±3109 N cm-3, respectively. The comparison with earlier results shows significant increase of ultrafine particles indicating impact of vehicular increase in the region.

Keywords: Ultrafine aerosol density, Nucleation bursts, Nanoparticle concentration, Aitken nuclei concentration

PACS No: 92.60.Mt

 

 

 

Indian Journal of Radio & Space Physics

Vol. 38, December 2009, pp. 338-346

 

Horizontal gradients of traffic related air pollutants near a major
highway in Agra, India

Anshumala Sharma#, David D Massey & Ajay Taneja$,*

School of Chemical Sciences, Department of Chemistry, St John’s College, Agra 282 002, India
E-mail: #amsharma_13@yahoo.co.in; $ataneja5@hotmail.com

Received 18 July 2008; revised 1 October 2009; accepted 12 October 2009

In the present study, horizontal gradients of airborne particles and gases were observed perpendicular to the national highway (NH-2) in Agra, India. A negative association was found between distance (from the highway) and ambient concentrations of pollutants. Gradients suggest that the major impact of traffic flow on the pollutants concentration lies within 250 m distance. Over the total measured distance (0-500 m), the maximum percent decrease in concentrations was  observed for total suspended particulate matter (TSPM), particulate matter with aerodynamic diameter less than 10 mm (PM10), sulphur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3) and carbon monoxide (CO) within 0-250 m distance range. However, no significant decrease in concentrations of carbon dioxide (CO2) was obtained. Correlations between all of the pollutants considered in this study are positive with many of them being highly correlated and significant, which shows that their sources are almost similar. On comparing the pollutants concentrations with available standards of Central Pollution Control Board (CPCB), SO2, CO, NO2 and O3 concentrations were found within the permissible limits, whereas PM10 concentration was found higher. This study generates data which can be useful for Asian city planners for planning residential colonies so as to cause minimum exposure to the residents.

Keywords: Horizontal gradient, Air pollutants, Pollutant concentration, Traffic exhaust pollutants

PACS No: 92.60.Sz

 

 

Indian Journal of Radio & Space Physics

Vol. 38, December 2009, pp. 347-352

 

Analysis of data on net longwave, shortwave and global radiation during transition period in a tropical station in Southwestern Nigeria

E O Ogolo1,$.*, S E Falodun1, S S Oluyamo1 & E F Nymphas2

1Department of Physics, Federal University of Technology, Akure

2Department of Physics, University of Ibadan, Ibadan

$E-mail: emogolo@yahoo.com, efnda@yahoo.co.uk

Received 8 April 2009; revised 1 October 2009; accepted 12 October 2009

The present study examines the distribution of surface radiation balance components measured during the Nigerian Micrometeorological Experiment (NIMEX-1). A field study was conducted to measure surface heat fluxes in the boundary layer during the transition period which marks the end of dry season and the onset of wet season (15 February and 10 March 2004) in Southwestern part of Nigeria. Regression equations were obtained using daily average values and hourly mean values between net shortwave and net longwave radiation, respectively with the global radiation. Higher correlations with low standard error of measurement were obtained for daily mean values than hourly mean values. It was also observed that the peak value of each radiation during the period occurred for two hours in the afternoon on an average as expected.

Keywords: Shortwave radiation, Longwave radiation, Radiation balance, Transition correlation

PACS Nos: 92.60.Vb; 94.20.wq

 

 

Indian Journal of Radio & Space Physics

Vol. 38, December 2009, pp. 353-360

 

Joint statistics of rain rate and event duration for a tropical location in India

Animesh Maitra1,$,*, Saurabh Das2,# & Ashish K Shukla2

1Institute of Radio Physics and Electronics, University of Calcutta, Kolkata 700 009, India

2Space Applications Center, Indian Space Research Organization, Ahmedabad 380015, India

E-mail: $animesh.maitra@gmail.com, #das.saurabh01@gmail.com

Received 12 January 2009; revised 30 June 2009; re-revised received and accepted 27 October 2009

The optimum microwave link design requires the knowledge of rain rate distribution as well as of the duration statistics of the rain events. The rain rates measurements at Ahmedabad, a tropical location in India, are analysed and models for various event parameters are developed using three years of continuous measurements. The average number of cases with at least 1 min event duration shows an exponential dependence on the rainfall rate with a correlation coefficient of 0.93. Also, the average durations for different rainfall rates are found to follow a power law with a correlation coefficient of 0.97. It is found that the average duration more effectively represent the event duration at higher rain rates. The results are compared with those obtained for the temperate and other tropical locations to indicate the distinctiveness of the studied parameters over the location. It has been observed that although the tropical locations show similar qualitative features, the characteristics of the Indian region show quantitative difference from other tropical regions.

Keywords: Tropical rain, Rain rate, Event duration, Joint distribution

PACS No.: 92.40.eg