Use of Interactions between NAO and MJO for the Prediction of Dry and Wet Spell in Monsoon Season

Abstract The Indian summer monsoon exhibits prominent 30-40 day fluctuations with "active" periods of heavy rain interrupted by dry periods i.e. "Breaks". The circulation anomalies associated with active/break monsoon cover the entire Indian Ocean remote tropics and North Pacific Ocean. A prolonged dry/wet period will result in severe drought/flooding, which have profound influences on the south Asia water cycle, agriculture and societal activity of more than one billion people. The atmospheric general circulation models have great difficulty in simulating the Intraseasonal oscillation (ISO). Therefore, it is necessary to study the empirical relationship between various atmospheric processes, which are responsible for the ISO. In this paper, the analysis of North Atlantic Oscillation Index (NAOI) and Madden Julian Oscillation Index (MJOI) on daily scale is carried out in relation to daily Indian summer monsoon rainfall (June-September). The analysis is carried out for the period 1979-2001. Since the potential predictability limit for monsoon break is about 20 days, the 20 days running lag/lead correlation analysis between the NAOI and MJOI is found out for each year. It is observed that 20-day lag relationship between NAO and MJO is inverse and significant (0.1 level) and this relationship remains negative throughout the break monsoon period and in active phase it reverses. This twenty days lag relationship between NAO and MJO is potential predictor for break/ active monsoon conditions over the Indian region. The analysis is verified for major drought year 2002

Polymethyl Methacrylate as a Binder for Pyrotechnic Compositions

Studies on polymethyl methacrylate (PMMA) as a binder for igniter and delay compositions are reported. Igniter compositions based on magnesium and boron as fuels and potassium nitrate as oxidiser, delay compositions comprising ferrosilicon and red lead, have been investigated. These compositions were subjected to various tests, such as linear burning rate, sensitivity, calorimetric value, compatibility, pelleting properties, spark sensitivity, ignition temperatures and performance characteristics. The results indicate that the igniter compositions Mg:KNO/sub 3/:PMMA (42:50:8) and B:KNO/sub 3/:PMMA (30:70:10) as well as the delay composition comprising FeSi:Pb/sub 3/O/sub 4:PMMA (25:75:1) have improved properties and therefore could find practical applications

Variability of NAO, northern and southern hemisphere temperature in relation to Indian summer monsoon rainfall rainfall

Variability of NAO, northern and southern hemisphere temperature in relation to Indian summer monsoon rainfall rainfall. S.B. Kakade and S.S. Dugam Email: [email protected] Abstract In recent decades, Indian summer monsoon rainfall is not showing significant association with northern hemispheric surface air temperature in winter season but shows consistent and satisfactory linkage with NAO related parameters. It suggests the necessity to understand the variability and relationship of NAO with northern and southern hemispheric temperature anomaly in relation to the monsoon circulation over Indian subcontinent. 50-year running Correlation coefficients between northern hemispheric surface air temperature anomaly and Indian summer monsoon rainfall suggests that the significant (direct) association between them for the period 1923-94. Similar analysis for the relationship between northern and southern hemispheric (south of 30°S) temperature anomaly during winter season is performed. It reveals that the relationship between these two temperature fields is statistically significant (direct) except for the period 1925-92. 50-year running correlation coefficients between NAO and southern hemisphere (south of 30°S) in winter season suggest that the relationship is negative from 1901 to 1924 (though it is not significant) and becomes positive from 1925 onwards with statistically significant relationship from 1932 till today. Similar analysis is performed for the relationship between NAO and northern hemispheric surface air temperature anomaly. This analysis suggests that the direct association between NAO and northern hemisphere temperature is statistically significant for the period 1923-94 only. The correlation analysis between winter-NAO and seasonal temperature anomaly over south of 30°S, for 1951-2000, reveals that the relationship is direct and is statistically significant in winter and spring seasons only..Pages: 1535-153

Antarctica sea-ice and monsoon variability

306-309This study statistically evaluates the relationship between satellite derived Antarctic sea ice extent and Indian summer monsoon variability over the various homogeneous regions of India. Analysis is carried out for 22 years (1979-2000). From the analysis it is observed that preceding winter (December-January-February) sea-ice anomaly has an inverse association with the performance of the following monsoon.It is observed that deficient monsoon years are preceded by more than normal sea-ice extent, and in excess or normal monsoon years the sea ice extent is less than the normal. The relationship is statistically significant at 1% level. From the study it is found that southern peninsular India does not show a significant relationship