Evidence of surface cooling from absorbing aerosols

Anthropogenic emissions over the Asian region have grown rapidly with increase in population and industrialization. Air-pollutants from this region lead to a brownish haze over most of the North Indian Ocean and South Asia during winter and spring. The haze, with as much as 10-15 of black carbon (by mass), is known to reduce the surface solar insolation by about 10 (-15 Wm -2) and nearly double the lower atmospheric solar heating. Here we present an analysis of observed surface-temperature variations over the Indian subcontinent, which filters out effects of greenhouse gases and natural variability. The analysis reveals that the absorbing aerosols have led to a statistically significant cooling of about 0.3°C since the 1970s. The seasonally asymmetric cooling, which is consistent with the seasonality of the South Asian aerosol forcing, raises the new possibility that the surface cooling underneath the polluted regions, is balanced by warming elsewhere

On the association between the Indian summer monsoon and the tropical cyclone activity over northwest Pacific

An analysis of observed typhoon tracks and daily global wind data for 56 years (1948-2003) reveals that large-scale circulation anomalies associated with the interannual variability of the Indian monsoon play an important role in influencing the tropical Pacific cyclone activity. The cyclogenesis over northwest and tropical west-central Pacific is found to be about 1.33 times higher during weak monsoon years compared to strong monsoon years. Also, there is greater tendency for the Pacific cyclones to move northward and recurve (to the north of 20°N) during weak monsoon years. The enhanced cyclogenesis during weak monsoon years is found to be associated with enrichment of low-level cyclonic vorticity anomalies over a wide region of the subtropical Pacific extending from the China Sea, Taiwan and the Philippines region to the central Pacific; while the movement of the tropical cyclones is associated with anomalies of upper-tropospheric steering currents. Given that the interannual variability of the large-scale circulation over the Indo-Pacific sector is crucially determined by the El Nino/Southern Oscillation (ENSO) conditions, the present findings raise several questions pertaining to interactions among the large-scale circulation anomalies, tropical convection and the Pacific cyclonic disturbances, which are likely to provide better understanding of the dynamical linkages between monsoon variability and ENSO

Evidence of surface cooling from absorbing aerosols

Anthropogenic emissions over the Asian region have grown rapidly with increase in population and industrialization. Air-pollutants from this region lead to a brownish haze over most of the North Indian Ocean and South Asia during winter and spring. The haze, with as much as 10–15% of black carbon (by mass), is known to reduce the surface solar insolation by about 10% (−15 Wm−2) and nearly double the lower atmospheric solar heating. Here we present an analysis of observed surface-temperature variations over the Indian subcontinent, which filters out effects of greenhouse gases and natural variability. The analysis reveals that the absorbing aerosols have led to a statistically significant cooling of about 0.3°C since the 1970s. The seasonally asymmetric cooling, which is consistent with the seasonality of the South Asian aerosol forcing, raises the new possibility that the surface cooling underneath the polluted regions, is balanced by warming elsewhere

Giant coherence in driven systems

We study the noise-induced currents and reliability or coherence of transport in two different classes of rocking ratchets. For this, we consider the motion of Brownian particles in the over damped limit in both adiabatic and non-adiabatic regimes subjected to unbiased temporally symmetric and asymmetric periodic driving force. In the case of a time symmetric driving, we find that even in the presence of a spatially symmetric simple sinusoidal potential, highly coherent transport occurs. These ratchet systems exhibit giant coherence of transport in the regime of parameter space where unidirectional currents in the deterministic case are observed. Outside this parameter range, i.e., when current vanishes in the deterministic regime, coherence in transport is very low. The transport coherence decreases as a function of temperature and is a non-monotonic function of the amplitude of driving. The transport becomes unreliable as we go from the adiabatic to the non-adiabatic domain of operation.Comment: 15 pages, 9 figures, replaced by the version to appear in JSTA

Probing subtle fluorescence dynamics in cellular proteins by streak camera based Fluorescence Lifetime Imaging Microscopy

We report the cell biological applications of a recently developed multiphoton fluorescence lifetime imaging microscopy system using a streak camera (StreakFLIM). The system was calibrated with standard fluorophore specimens and was shown to have high accuracy and reproducibility. We demonstrate the applicability of this instrument in living cells for measuring the effects of protein targeting and point mutations in the protein sequence which are not obtainable in conventional intensity based fluorescence microscopy methods. We discuss the relevance of such time resolved information in quantitative energy transfer microscopy and in measurement of the parameters characterizing intracellular physiology

Coupling of mixed layer processes and thermocline variations in the Arabian Sea

This study presents an analysis of observed data sets from multiple sources, including observations from a network of Argo floats during (2002–2003), with the aim of investigating the role of the southwest monsoon circulation in affecting the interactions between the oceanic mixed layer and the underlying thermocline in the northern Indian Ocean. Examination of the seasonal cycle of the upper-ocean thermal structure shows that the surface cooling of the Arabian Sea, during the southwest monsoon season, is accompanied by significant warming of the thermocline. It is seen that the thermocline is warmer by about 1.2°C in the south-central Arabian Sea during the southwest monsoon season relative to other months. Offline computations of the profiles of vertical diffusivity of heat reveal stronger and deeper penetration of heat into the Arabian Sea during the southwest monsoon season. The results presented in the paper demonstrate that the combined effects of strong wind-driven mixing by the monsoonal winds, weak density stratification in the upper-ocean, and downwelling in south-central Arabian Sea, along with strong vertical diffusivity, favor downward transfer of warm waters from the surface into the thermocline. Besides the climatological seasonal cycle, the present study also examines the impact of monsoon interannual variability on the upper-ocean response, by analysis of long-term observed records during (1955–2001) as well as the Argo observations for (2002–2003). It is found that the interannual variations in the ocean response reveal signatures of the influence of strong and weak southwest monsoons on the mixed layer and thermocline variabilities

Role of Associated Complex in Determining the Magnitude of Excess Volumes of Binary Liquid Mixtures: Part I - Aniline & Methyl-substituted Anilines with Cyclohexane as Inert Diluent

377-37

Electrochemical Oxidation of p-Chloroaniline at a Platinum Electrode

96-9