Advertisement

Journal of Earth System Science

, Volume 115, Issue 2, pp 203–218 | Cite as

Spatio-temporal variability of summer monsoon rainfall over Orissa in relation to low pressure systems

  • M Mohapatra
  • U C Mohanty
Article

Abstract

The summer monsoon rainfall over Orissa occurs mostly due to low pressure systems (LPS) developing over the Bay of Bengal and moving along the monsoon trough. A study is hence undertaken to find out characteristic features of the relationship between LPS over different regions and rain-fall over Orissa during the summer monsoon season (June-September). For this purpose, rainfall and rainy days over 31 selected stations in Orissa and LPS days over Orissa and adjoining land and sea regions during different monsoon months and the season as a whole over a period of 20 years (1980-1999) are analysed. The principal objective of this study is to find out the role of LPS on spatial and temporal variability of summer monsoon rainfall over Orissa.

The rainfall has been significantly less than normal over most parts of Orissa except the eastern side of Eastern Ghats during July and hence during the season as a whole due to a significantly less number of LPS days over northwest Bay in July over the period of 1980-1999. The seasonal rainfall shows higher interannual variation (increase in coefficient of variation by about 5%) during 1980-1999 than that during 1901-1990 over most parts of Orissa except northeast Orissa. Most parts of Orissa, especially the region extending from central part of coastal Orissa to western Orissa (central zone) and western side of the Eastern Ghats get more seasonal monsoon rainfall with the development and persistence of LPS over northwest Bay and their subsequent movement and persistence over Orissa. The north Orissa adjoining central zone also gets more seasonal rainfall with development and persistence of LPS over northwest Bay. While the seasonal rainfall over the western side of the Eastern Ghats is adversely affected due to increase in LPS days over west central Bay, Jharkhand and Bangladesh, that over the eastern side of the Eastern Ghats is adversely affected due to increase in LPS days over all the regions to the north of Orissa. There are significant decreasing trends in rainfall and number of rainy days over some parts of southwest Orissa during June and decreasing trends in rainy days over some parts of north interior Orissa and central part of coastal Orissa during July over the period of 1980-1999

Keywords

Rainfall variability monsoon Orissa 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Dhar O N and Mhaiskar P R 1973 Areal and point distribution of rainfall associated with depressions/storms on the day of crossing the east coast of India;Indian J. Met. Geophys. 24 271–278.Google Scholar
  2. Dhar O N, Rackecha P R and Mandal B N 1981 Influence of cyclonic disturbances on monthly monsoon rainfall of India;Mon. Wea. Rev. 109 188–190.CrossRefGoogle Scholar
  3. IMD 1971 Monthly and annual rainfall and number of rainy days for the period of 1901-1950;Memoirs of IMD, Vol.XXXI, Part-I.Google Scholar
  4. IMD 2002 Climate of Orissa; Published by Controller of Publications Civil Lines New Delhi, pp. 5.Google Scholar
  5. Jadhav S K 2002 Summer monsoon low pressure systems over the Indian region and their relationship with the sub-divisional rainfall;Mausam 53 177–186.Google Scholar
  6. Joseph P V 1981 Ocean atmosphere interaction on a seasonal scale over north Indian Ocean and Indian monsoon rainfall and cyclonic track a preliminary study;Mausam 32 237–246.Google Scholar
  7. Mohapatra M and Mohanty U C 2004 Some characteristics of low pressure systems and summer monsoon rainfall over Orissa;Curr. Sci. 87 1245–1255.Google Scholar
  8. Mohapatra M and Mohanty U C 2005 Some characteristics of very heavy rainfall over Orissa during summer monsoon season;J. Earth Syst. Sci. (Formerly known as Proc. Indian Acad. Sci. (Earth Planet. Sci.) 114 17–36.Google Scholar
  9. Mooley D A 1973 Some aspects of Indian monsoon depression and associated rainfall;Mon. Wea. Rev. 101 271–280.CrossRefGoogle Scholar
  10. Mooley D A and Shukla J 1989 Main features of the westward moving low pressure systems which form over the Indian region during the summer monsoon season and their relation to the monsoon rainfall;Mausam 40 137–152.Google Scholar
  11. Parthasarathy B, Munot A A and Kothawale D R 1995 Monthly and seasonal rainfall series for all India homogeneous regions and meteorological subdivisions: 1871-1994;Research Report No.RR-065, Indian Institute of Tropical Meteorology, Pune, India.Google Scholar
  12. Pathan J M 1993 Latitudinal variation of rainfall during the month of July in relation to the axis of monsoon trough over India;Mausam 44 384–386.Google Scholar
  13. Pisharoty P R and Asnani G C 1957 Rainfall around monsoon depression over India;Indian J. Met. Geophys. 8 15–20.Google Scholar
  14. Raghavan K 1973 Break monsoon over India;Mon. Wea. Rev. 101 33–44.CrossRefGoogle Scholar
  15. Rajamani S and Rao K V 1981 On the occurrence of rainfall over southwest sector of monsoon depression;Mausam 32 215–220.Google Scholar
  16. Ramamurthy K 1969 Some aspects of break in the Indian southwest monsoon during July and August;India Met. Dept. FMU Rep.-IV-18.3.Google Scholar
  17. Rao Y P 1976 Southwest monsoon;India Met. Dept. Met. Monogr. Syno. Met. No. 1/1976, pp. 1–367.Google Scholar
  18. Saha N C and Saha S 1981 The vertical slope of monsoon trough and its association with distribution of rainfall over India;Mausam 32 79–84.Google Scholar
  19. Sikka D R 1980 Some aspects of the large scale fluctuation of summer monsoon rainfall over India in relation to fluctuation in the planetary and regional scale circulation parameters;Proc. Indian Acad. Sci. (Earth Planet. Sci.) 89 179–195.Google Scholar

Copyright information

© Indian Academy of Sciences 2006

Authors and Affiliations

  • M Mohapatra
    • 1
  • U C Mohanty
    • 2
  1. 1.India Meteorological DepartmentGuwahatiIndia
  2. 2.Centre for Atmospheric SciencesIndian Institute of TechnologyDelhi, New DelhiIndia

Personalised recommendations