Retrieval of columnar aerosol size distributions from spectral attenuation measurements over Central Himalayas

Extensive measurements of spectral aerosol optical depths (AODs) were made at Manora Peak, Nainital (29.4°N, 79.5°E, ~1958 m above mean sea level) in the central Himalayas, using a ten channel multi-wavelength solar radiometer during January 2002 to December 2005. Using these spectral AOD values, the columnar size distribution [CSD; nc(r)] function of aerosols have been derived. The CSD, retrieved from spectral AODs are, in general, bimodal (combination of power law and unimodal log normal distribution) with a prominent secondary (or coarse) mode occurring at a fairly large value of radius (r >0.5 µm), while the primary (or fine) mode either does not appear explicitly or perhaps occurs below the radius ≅ 0.1 µm. The bimodal nature of CSDs indicates the presence of fine as well as coarse mode aerosols over the observational site. The effective radius, total aerosol number content and columnar mass loading computed from deduced CSD shows minimum values during winter (November to February) and maximum during summer (March to June) months. The share of sub micron and super micron aerosols to the total aerosol number concentration (Nt) indicates the dominance of sub micron aerosols to the Nt and it accounts for > 90% during the study period

Aerosol Characteristics at a high-altitude station Nainital during the ISRO-GBP Land Campaign-II

During the second land campaign (LC-II) organised by ISRO-GBP, extensive ground-based measurements of aerosol characteristics were carried out over Manora Peak (29.4oN; 79.5oE; 1951 metres above mean sea level), Nainital (a high altitude station located in the Shivalik ranges of Central Himalayas) during the dry, winter season (December) of 2004. These measurements included the spectral aerosol optical depths (AOD), columnar water vapour content (W), Total Columnar Ozone (TCO), total number concentration (NT) of near surface aerosols, mass concentration of black carbon (MB), aerosol mass loading (MT), and Global Solar Radiation. Based on these measured parameters, we present the results on the near-surface and columnar properties of atmospheric aerosols at Nainital.Comment: Published in the Proceedings of the ISRO-GBP Land-Campaign-II meeting, Physical Research Laboratory, Ahmadabad (Inida), March 200

Characteristics of black carbon over Delhi and Manora Peak - a comparative study

The characteristics of aerosol black carbon (BC) were studied at two different climatic regimes, i.e. Delhi and Manora Peak during winter and spring of 2007. Spring BC was found to be similar to 59% lower at Delhi and similar to 23% higher at Manora Peak than their corresponding winter BC. Diurnal BC variation showed two enhanced peaks at Delhi (morning and night) whereas a single late afternoon peak at Manora Peak. Delhi BC showed a clear correlation with prevailing winds whereas no correlation was observed at Manora Peak. The major contribution of BC at Manora Peak can be expected from biomass burning while at Delhi fossil fuel dominates

Short-period modulations in aerosol optical depths over the central Himalayas: role of mesoscale processes

Multiyear measurements of spectral aerosol optical depths (AODs) were made at Manora Peak in the central Himalaya Range (29°22N, 79°27E, ~1950 m above mean sea level), using a 10-channel multiwavelength solar radiometer for 605 days during January 2002-December 2004. The AODs at 0.5μm were very low (≤0.1) in winter and increased steeply to reach high values (~0.5) in summer. It was observed that monthly mean AODs vary significantly (by more than a factor of 6) from January to June. Strong short-period fluctuations (within a daytime) were observed in the AODs. Further investigations of this aspect have revealed that boundary layer dynamics plays a key role in transporting aerosols from the polluted valley region to higher altitudes, causing large contrast in AODs between forenoon and afternoon. The seasonal variations in AODs, while examined in conjunction with synoptic-scale wind fields, have revealed that the transport of dust aerosols from arid regions to the valley regions adjacent to the observational site and their subsequent transport upward by boundary layer dynamics are responsible for the summer increases

Physical and optical characteristics of atmospheric aerosols during ICARB at Manora Peak, Nainital: a sparsely inhabited, high-altitude location in the Himalayas

Collocated measurements of the optical and physical properties of columnar and near-surface aerosols were carried out from Manora Peak, Nainital (a sparsely inhabited, high altitude location, ~2 km above mean sea level, in the Himalayas), during the Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB) under the Geosphere Biosphere Programme of the Indian Space Research Organization (ISRO-GBP). Under this, observational data of spectral aerosol optical depths (AOD), mass concentration of aerosol black carbon (MB ), mass concentration (MT ) and number concentration (Nt ) of composite (total) aerosols near the surface and meteorological parameters were collected during the period February 15 to April 30, 2006. Though very low (<0.1 at 500 nm) AODs were observed during clear days, as much as a four-fold increase was seen on hazy days. The Ångström exponent (α), deduced from the spectral AODs, revealed high values during clear days, while on hazy days α was low; with an overall mean value of 0.69 ± 0.06 for the campaign period. BC mass concentration varied between 0.36 and 2.87 μg m-3 and contributed in the range 0.7 to 1.8% to the total aerosol mass. Total aerosol number concentration and BC mass concentration showed diurnal variation with a midnight and early morning minimum and a late afternoon maximum; a pattern quite opposite to that seen in low altitude stations. These are attributed to the dynamics of the atmospheric boundary layer

Characteristics of Aerosol Spectral Optical Depths over Manora Peak, Nainital −- A High Altitude Station in the Central Himalayas

We present, for the first time, spectral behaviour of aerosol optical depths (AODs) over Manora Peak, Nainital located at an altitude of $\sim$ 2 km in the Shivalik ranges of central Himalayas. The observations were carried out using a Multi-Wavelength solar Radiometer during January to December 2002. The main results of the study are extremely low AODs during winter, a remarkable increase to high values in summer and a distinct change in the spectral dependencies of AODs from a relatively steeper spectra during winter to a shallower one in summer. During transparent days, the AOD values lie usually below 0.08 while during dusty (turbid) days, it lies between 0.08 to 0.69 at 0.5 $\mu$m. The average AOD value at 0.5 $\mu$m during winters, particularly in January and February, is $\sim 0.03\pm0.01$. The mean aerosol extinction law at Manora Peak during 2002 is best represented by $0.10 \lambda^{-0.61}$. However during transparent days, which almost covers 40% of the time, it is represented by $0.02 \lambda^{-0.97}$. This value of wavelength exponent, representing reduced coarse concentration and presence of fine aerosols, indicates that the station measures aerosol in the free troposphere at least during part of the year.Comment: 10 pages, 5 figures, significantly shortened, main conclusions unchanged, accepted for publication in Jr. of Geophys. Reasearch - Atmosphere

Aerosol Characteristics at a High Altitude Location in Central Himalayas: Optical Properties and Radiative Forcing

Collocated measurements of the mass concentrations of aerosol black carbon (BC) and composite aerosols near the surface were carried out along with spectral aerosol optical depths (AODs) from a high altitude station, Manora Peak in Central Himalayas, during a comprehensive aerosol field campaign in December 2004. Despite being a pristine location in the Shivalik Ranges of Central Himalayas, and having a monthly mean AOD (at 500 nm) of 0.059 $\pm$ 0.033 (typical to this site), total suspended particulate (TSP) concentration was in the range 15 - 40 micro g m^(-3) (mean value 27.1 $\pm$ 8.3 micro g m^(-3)). Interestingly, aerosol BC had a mean concentration of 1.36 $\pm$ 0.99 micro g m^(-3), contributed to ~5.0 $\pm$ 1.3 % to the composite aerosol mass. This large abundance of BC is found to have linkages to the human activities in the adjoining valley and to the boundary layer dynamics. Consequently, the inferred single scattering albedo lies in the range of 0.87 to 0.94 (mean value 0.90 $\pm$ 0.03), indicating significant aerosol absorption. The estimated aerosol radiative forcing was as low as 4.2 W m^(-2) at the surface, +0.7 W m^(-2) at the top of the atmosphere, implying an atmospheric forcing of +4.9 W m^(-2). Though absolute value of the atmospheric forcing is quite small, which arises primarily from the very low AOD (or the column abundance of aerosols), the forcing efficiency (forcing per unit optical depth) was $\sim$88 W m^(-2), which is attributed to the high BC mass fraction.Comment: 32 Pages, Accepted in JGR (Atmosphere

A Computational Approach to Analyze the Mechanism of Action of the Kinase Inhibitor Bafetinib

Prediction of drug action in human cells is a major challenge in biomedical research. Additionally, there is strong interest in finding new applications for approved drugs and identifying potential side effects. We present a computational strategy to predict mechanisms, risks and potential new domains of drug treatment on the basis of target profiles acquired through chemical proteomics. Functional protein-protein interaction networks that share one biological function are constructed and their crosstalk with the drug is scored regarding function disruption. We apply this procedure to the target profile of the second-generation BCR-ABL inhibitor bafetinib which is in development for the treatment of imatinib-resistant chronic myeloid leukemia. Beside the well known effect on apoptosis, we propose potential treatment of lung cancer and IGF1R expressing blast crisis

Accelerated apoptotic death and <i>in vivo</i> turnover of erythrocytes in mice lacking functional mitogen- and stress-activated kinase MSK1/2

The mitogen- and stress-activated kinase MSK1/2 plays a decisive role in apoptosis. In analogy to apoptosis of nucleated cells, suicidal erythrocyte death called eryptosis is characterized by cell shrinkage and cell membrane scrambling leading to phosphatidylserine (PS) externalization. Here, we explored whether MSK1/2 participates in the regulation of eryptosis. To this end, erythrocytes were isolated from mice lacking functional MSK1/2 (msk−/−) and corresponding wild-type mice (msk+/+). Blood count, hematocrit, hemoglobin concentration and mean erythrocyte volume were similar in both msk−/− and msk+/+ mice, but reticulocyte count was significantly increased in msk−/− mice. Cell membrane PS exposure was similar in untreated msk−/− and msk+/+ erythrocytes, but was enhanced by pathophysiological cell stressors ex vivo such as hyperosmotic shock or energy depletion to significantly higher levels in msk−/− erythrocytes than in msk+/+ erythrocytes. Cell shrinkage following hyperosmotic shock and energy depletion, as well as hemolysis following decrease of extracellular osmolarity was more pronounced in msk−/− erythrocytes. The in vivo clearance of autologously-infused CFSE-labeled erythrocytes from circulating blood was faster in msk−/− mice. The spleens from msk−/− mice contained a significantly greater number of PS-exposing erythrocytes than spleens from msk+/+ mice. The present observations point to accelerated eryptosis and subsequent clearance of erythrocytes leading to enhanced erythrocyte turnover in MSK1/2-deficient mice

Direct solar ultraviolet irradiance over Nainital, India, in the central Himalayas for clear-sky day conditions during December 2004

From a high-altitude station, Nainital, India (29.4 degrees N, 79.5 degrees E, 1958 masl), located in the central part of lower Himalayas, the observations made during December 2004 using a pair of Sun photometers (Microtops II) at wavelengths ranging from 305 to 1020 nm are reported. The observed parameters are the direct solar UV irradiance, column ozone, water vapor, and aerosol optical depths (AOD). The results are presented for the full day clear-sky conditions that prevailed for about 16 days during the whole month. It is found that Nainital is a comparatively pristine site with average AOD at 500 nm ranging between 0.03 and 0.09 and Angstrom exponent generally close to 1. The high AOD values occurred on 2 and 25 December due to winds from populated north Indian plains as revealed by the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) backward trajectory model. The total column ozone varies between 251 and 308 DU during the entire period of observations. The maximum diurnal UV irradiance values in the 2.4 nm bandwidth centered at 305.5, 312.5, and 320.0 nm varied between 0.027 and 0.049, 0.15 and 0.20, and 0.29 and 0.37 W m(-2), respectively. The measured UV irradiances are compared with the Tropospheric Ultraviolet Visible (TUV) radiation model and show a good agreement