• Ananthakrishnan, R., , and Soman M. K. , 1988: The onset of the southwest monsoon over Kerala: 1901-1980. J. Climatol., 8 , 283296.

  • Ananthakrishnan, R., , Acharya U. R. , , and Ramakrishnan A. R. , 1967: On the criteria for declaring the onset of the southwest monsoon over Kerala. India Meteorological Department (IMD) Forecasting Manual IV-18.1, 52 pp.

    • Search Google Scholar
    • Export Citation
  • Aviad, Y., , Kutiel H. , , and Lavee H. , 2004: Analysis of beginning, end, and length of the rainy season along a Mediterranean–arid climate transect for geomorphic purposes. J. Arid Environ., 59 , 189204. doi:10.1016/j.jaridenv.2004.01.013.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Bai, A., , Zhai P. , , and Liu X. , 2007: Climatology and trends of wet spells in China. Theor. Appl. Climatol., 88 , 139148.

  • Byun, H. R., , and Wilhite D. A. , 1999: Objective quantification of drought severity and duration. J. Climate, 12 , 27472756.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Byun, H. R., , and Lee D. K. , 2002: Defining three rainy seasons and the hydrological summer monsoon in Korea using Available Water Resources Index. J. Meteor. Soc. Japan, 80 , 3344.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Cook, G. D., , and Heerdegen R. G. , 2001: Spatial variation in the duration of the rainy season in monsoonal Australia. Int. J. Climatol., 21 , 17231732.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Dai, A., , Trenberth K. E. , , and Karl T. R. , 1998: Global variations in droughts and wet spells: 1900-1995. Geophys. Res. Lett., 25 (17) 33673370.

  • Deni, S. M., , Jemain A. A. , , and Ibrahim K. , 2008: The spatial distribution of wet and dry spells over Peninsular Malaysia. Theor. Appl. Climatol., 94 , 163173.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Houghton, J. T., , Meira Filho L. G. , , Callander B. A. , , Harris N. , , Kattenberg A. , , and Maskell K. , Eds.,. 1996: Climate Change 1995: The Science of Climate Change. Cambridge University Press, 572 pp.

    • Search Google Scholar
    • Export Citation
  • IMD, 1943: Climatological Atlas for Airmen. India Meteorological Department, 100 pp.

  • Jadhav, S. K., , and Munot A. A. , 2008: Warming SST of Bay of Bengal and decrease in formation of cyclonic disturbances over the Indian region during southwest monsoon season. Theor. Appl. Climatol., 96 , 327336.

    • Search Google Scholar
    • Export Citation
  • Mitchell J. M. Jr., , , Dzerdzeevskii B. , , Flohn H. , , Hofmeyr W. L. , , Lamb H. H. , , Rao K. N. , , and Walléen C. C. , 1966: Climatic Change. WMO Tech. Note 79, WMO 195-TP-100, 79 pp.

    • Search Google Scholar
    • Export Citation
  • NATMO, 1986: Physiographic regions of India. National Atlas of India, 3rd ed., National Atlas and Thematic Mapping Organisation, Plate 41.

    • Search Google Scholar
    • Export Citation
  • NATMO, 1996: Drainage. Land Resource Atlas, National Atlas and Thematic Mapping Organisation, Plate 3.

  • Rajeevan, M., , Bhate J. , , Kale J. , , and Lal B. , 2006: High resolution daily gridded rainfall data for the India region: Analysis of break and active monsoon spells. Curr. Sci., 91 , 296306.

    • Search Google Scholar
    • Export Citation
  • Raman, C. V. R., 1974: Analysis of commencement of monsoon rains over Maharashtra State for agricultural planning. India Meteorological Department Scientific Rep. 216, 23 pp.

    • Search Google Scholar
    • Export Citation
  • Ranade, Ashwini, , Singh N. , , Singh H. N. , , and Sontakke N. A. , 2008: On variability of hydrological wet season, seasonal rainfall and rainwater potential of the river basins of India (1813-2006). J. Hydrol. Res. Dev., 23 , 79108.

    • Search Google Scholar
    • Export Citation
  • Rao, K. N., , George C. J. , , and Ramasastri K. S. , 1971: Potential evapotranspiration (PE) over India. India Meteorological Department Scientific Rep. 136, 23 pp.

    • Search Google Scholar
    • Export Citation
  • Singh, N., 1986: On the duration of the rainy season over different parts of India. Theor. Appl. Climatol., 37 , 5162.

  • Sontakke, N. A., , and Singh N. , 1996: Longest instrumental regional and all-India summer monsoon rainfall series using optimum observations: Reconstruction and update. Holocene, 6 , 315331.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Sontakke, N. A., , Singh H. N. , , and Singh N. , 2008a: Chief features of physiographic rainfall variations across India during instrumental period (1813-2006). Indian Institute of Tropical Meteorology Research Rep. RR-121, 128 pp.

    • Search Google Scholar
    • Export Citation
  • Sontakke, N. A., , Singh N. , , and Singh H. N. , 2008b: Instrumental period rainfall series of the Indian region (1813-2005): Revised reconstruction, update and analysis. Holocene, 17 , 10551066.

    • Search Google Scholar
    • Export Citation
  • Stern, R. D., , Dennett M. D. , , and Garbutt D. J. , 1981: The start of the rains in West Africa. J. Climatol., 1 , 5968.

  • Wilks, D. S., 2006: Statistical Methods in the Atmospheric Sciences. 2nd ed. Elsevier, 627 pp.

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The Wet and Dry Spells across India during 1951–2007

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  • 1 Indian Institute of Tropical Meteorology, Pune, India
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Abstract

Characteristics of wet spells (WSs) and intervening dry spells (DSs) are extremely useful for water-related sectors. The information takes on greater significance in the wake of global climate change and climate-change scenario projections. The features of 40 parameters of the rainfall time distribution as well as their extremes have been studied for two wet and dry spells for 19 subregions across India using gridded daily rainfall available on 1° latitude × 1° longitude spatial resolution for the period 1951–2007. In a low-frequency-mode, intra-annual rainfall variation, WS (DS) is identified as a “continuous period with daily rainfall equal to or greater than (less than) daily mean rainfall (DMR) of climatological monsoon period over the area of interest.” The DMR shows significant spatial variation from 2.6 mm day−1 over the extreme southeast peninsula (ESEP) to 20.2 mm day−1 over the southern-central west coast (SCWC). Climatologically, the number of WSs (DSs) decreases from 11 (10) over the extreme south peninsula to 4 (3) over northwestern India as a result of a decrease in tropical and oceanic influences. The total duration of WSs (DSs) decreases from 101 (173) to 45 (29) days, and the duration of individual WS (DS) from 12 (18) to 7 (11) days following similar spatial patterns. Broadly, the total rainfall of wet and dry spells, and rainfall amount and rainfall intensity of actual and extreme wet and dry spells, are high over orographic regions and low over the peninsula, Indo-Gangetic plains, and northwest dry province. The rainfall due to WSs (DSs) contributes ∼68% (∼17%) to the respective annual total. The start of the first wet spell is earlier (19 March) over ESEP and later (22 June) over northwestern India, and the end of the last wet spell occurs in reverse, that is, earlier (12 September) from northwestern India and later (16 December) from ESEP. In recent years/decades, actual and extreme WSs are slightly shorter and their rainfall intensity higher over a majority of the subregions, whereas actual and extreme DSs are slightly (not significantly) longer and their rainfall intensity weaker. There is a tendency for the first WS to start approximately six days earlier across the country and the last WS to end approximately two days earlier, giving rise to longer duration of rainfall activities by approximately four days. However, a spatially coherent, robust, long-term trend (1951–2007) is not seen in any of the 40 WS/DS parameters examined in the present study.

Corresponding author address: Dr. Nityanand Singh, Climatology and Hydrometeorology Division, Indian Institute of Tropical Meteorology, Dr. Homi Bhabha Road, Pashan, Pune 411008, India. Email: nsingh@tropmet.res.in

Abstract

Characteristics of wet spells (WSs) and intervening dry spells (DSs) are extremely useful for water-related sectors. The information takes on greater significance in the wake of global climate change and climate-change scenario projections. The features of 40 parameters of the rainfall time distribution as well as their extremes have been studied for two wet and dry spells for 19 subregions across India using gridded daily rainfall available on 1° latitude × 1° longitude spatial resolution for the period 1951–2007. In a low-frequency-mode, intra-annual rainfall variation, WS (DS) is identified as a “continuous period with daily rainfall equal to or greater than (less than) daily mean rainfall (DMR) of climatological monsoon period over the area of interest.” The DMR shows significant spatial variation from 2.6 mm day−1 over the extreme southeast peninsula (ESEP) to 20.2 mm day−1 over the southern-central west coast (SCWC). Climatologically, the number of WSs (DSs) decreases from 11 (10) over the extreme south peninsula to 4 (3) over northwestern India as a result of a decrease in tropical and oceanic influences. The total duration of WSs (DSs) decreases from 101 (173) to 45 (29) days, and the duration of individual WS (DS) from 12 (18) to 7 (11) days following similar spatial patterns. Broadly, the total rainfall of wet and dry spells, and rainfall amount and rainfall intensity of actual and extreme wet and dry spells, are high over orographic regions and low over the peninsula, Indo-Gangetic plains, and northwest dry province. The rainfall due to WSs (DSs) contributes ∼68% (∼17%) to the respective annual total. The start of the first wet spell is earlier (19 March) over ESEP and later (22 June) over northwestern India, and the end of the last wet spell occurs in reverse, that is, earlier (12 September) from northwestern India and later (16 December) from ESEP. In recent years/decades, actual and extreme WSs are slightly shorter and their rainfall intensity higher over a majority of the subregions, whereas actual and extreme DSs are slightly (not significantly) longer and their rainfall intensity weaker. There is a tendency for the first WS to start approximately six days earlier across the country and the last WS to end approximately two days earlier, giving rise to longer duration of rainfall activities by approximately four days. However, a spatially coherent, robust, long-term trend (1951–2007) is not seen in any of the 40 WS/DS parameters examined in the present study.

Corresponding author address: Dr. Nityanand Singh, Climatology and Hydrometeorology Division, Indian Institute of Tropical Meteorology, Dr. Homi Bhabha Road, Pashan, Pune 411008, India. Email: nsingh@tropmet.res.in

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