Ground-based method for measuring thermal infrared effective emissivities: Implications and perspectives on the measurement of land surface temperature from satellite data

Thermal infrared emissivity is an important parameter for surface characterization and for determining surface temperature. The field-based measurements for ground and vegetation emissivities in 8-14 w m waveband were performed with an emissivity box. A theoretical analysis was carried out using the box and a correcting factor has been determined. The average value for thermal band emissivity of the exposed bare soil was found to be around 0.909; the average value measured for most of the varieties of vegetation present were in the range of 0.980-0.985. A theoretical model is used for obtaining effective emissivity in the 8-14 w m region from Advanced Very High Resolution Radiometer (AVHRR) data considering the proportion of vegetation cover in a pixel and the field-measured emissivity values. The error of the methodology is found to be within 1.5%. Narrow band emissivities for AVHRR channels 4 and 5 have been derived from the emissivity values in the 8-14 w m waveband. The surface temperature has been derived from AVHRR data using a split-window algorithm as a function of emissivities derived in narrow bands. The split-window algorithm accounted for absorption effects of the atmosphere by incorporating the water vapour concentration measured in the campaign. A good agreement was obtained between the satellite-derived surface temperature and the in situ observations. The result suggest that the methodology allows us to derive land surface temperature with an accuracy better than 1.5° C provided the surface emissivity is known. The paper describes the field-based emissivity measurement and approach for deriving surface temperature over land surface.     

Biomass burning and related trace gas emissions from tropical dry deciduous forests of India: A study using DMSP-OLS data and ground-based measurements

Biomass burning is one of the major sources of trace gas emissions in the atmosphere. In India the major sources of biomass burning include deforestation, shifting cultivation, accidental fires, controlled burning, fire wood burning, burning from agricultural residues and burning due to fire lines. Studies on biomass burning practices gain importance due to increasing anthropogenic activities and increasing rates of deforestation. Satellite data have been widely used over the globe to monitor the rates of deforestation and also with respect to biomass burning studies. But, much of the polar orbiting satellites, due to their repetitive cycle, have limitations in observing such events and in the tropics, due to cloud cover, getting a cloud-free image during the daytime is difficult. In this study we used Defence Meteorological Satellite Program Operational Line Scanner (DMSP-OLS) night-time data to study the biomass burning events over a period of 10 years from 1987 to 1998 for the Eastern Ghats region, covering the northern part of Andhra Pradesh, India. Two ground-based experiments were carried out to quantify the emissions from biomass burning practices. The results of the study with respect to trace gases suggested emission ratios for CO, CH4, NOx and N20 during the burning to be about 12.3%, 1.29%, 0.29% and 0.07% at the first site and 12.5%, 1.59%, 0.29% and 0.05% at the second site, suggesting low inter-fire variability between the sites. The variation has been attributed to the fuel load, vegetation characteristics, site conditions and local meteorological parameters affecting the relative amounts of combustion. Using the DMSP OLS derived areal estimates of active fires, the trace gas emissions released from the biomass burning were quantified. The results suggested the emissions of 8.2 2 10 10 g CO 2, 1.8 2 10 8 g CO, 6.0 2 10 6 g N 2 O, 3.0 2 10 6 g NO x and 1.2 2 10 8 8 g CH 4 during March 1987. The emissions increased to 1.0 2 10 11 g CO 2, 2.3 2 10 g CO, 7.8 2 10 6 g N 2 O, 3.9 2 10 7 g NO x and 1.6 2 10 8 g CH 4, over a period of 10 years. The results of the analysis suggest the possible use of monitoring biomass burning events from DMSP-OLS night-time data.     

Cognitive Task Performance Time And Accuracy In Supervisory Process Control

Research is reported on several types of cognitive tasks that are performed by industrial process controllers. Statistics of performance time and accuracy are examined as a function of task repetitions and complexity variables. Performance plateaus were found in these statistics when the tasks were held at an average complexity level. A distribution of performance time is identified. As the reference and/or field size increased or other complexity variables changed, the means and variances of performance time for within- and between-persons changed with those variables in different ways with the type of cognitive task. Some of these complexity variables accounted for about 90 percent of the time variation within a typical subject. Accuracy was found to be about 95 percent, varying slightly by the type of task but not with the complexity variables.     

Case study of a dust storm over Hyderabad area, India: its impact on solar radiation using satellite data and ground measurements

According to the Earth Observatory dust outbreaks are considered as natural hazards, which affect the ecosystems and human life. The main objective of this study is to assess and monitor the movement of aerosols and pollutants from local or other sources, both natural and anthropogenic, using a combination of ground-based monitoring and satellite data. The turbid and polluted atmosphere in the densely-populated area of Hyderabad, India is further degradated from dust outbreaks originated from Thar desert. A dust event occurred during 10th to 11th April 2006 in the northwest region of India; its plume substantially spreaded across the downwind direction affecting the study region. Using both irradiance measurements and satellite data this dust event is investigated. The analysis shows a significant change in Aerosol Optical Depth (AOD), Aerosol Index (AI) and aerosol-particle size during the dust event. The Aerosol Optical Depth in the dusty day is about 0.2 higher than the previous non-dusty days, while the Angstr?m exponent rapidly decreases when the dust plume affected the study area. The surface PM concentrations show enhanced values during the dusty day directly influenced by the dust deposition. There is also a remarkable decrease in ground-reaching global radiation, UV erythemal (UV(ery)) and other irradiance components. The analysis suggested that the use of the diffuse-to-direct-beam ratio is the most appropriate parameter for the dust monitoring since its values at the longer wavelengths are not affected by the solar zenith angle.     

Direct radiative forcing of aerosols over a typical tropical urban environment

Aerosols reduce the surface reaching solar flux by scattering the incoming solar radiation out to space. Various model studies on climate change suggest that surface cooling induced by aerosol scattering is the largest source of uncertainty in predicting the future climate. In the present study measurements of aerosol optical depth (AOD) and its direct radiative forcing efficiency has been presented over a typical tropical urban environment namely Hyderabad during 2001 and 2002. Diurnal variation of AOD suggesting that AOD is high during afternoon hours. AOD decreases with increase in wavelength, i.e. maximum AOD observed at 380 nm. Average monthly variation of AOD at different wavelengths observed to be minimum in January, moderately high in February to March, maximum in April and decreasing in May. AOD has been observed to be high during 2002 compared to 2001. AOD showed positive correlation with air temperature and negative correlation with rainfall. A statistical fit between AOD (500 nm) and photosynthetic active radiation (PAR which is in the range of 400–700 nm solar spectrum) shows negative correlation. The present study suggests −23 W m⁻² reduction in the ground reaching solar flux for every 0.1 increase in aerosol optical depth over the study area.     

Purification of New β-Galactosidase from Enterococcus faecium MTCC 5153 with Transgalactosylation Activity

A new β-galactosidase (β-gal) was purified from a lactic acid bacterial strain of Enterococcus faecium MTCC5153 by chromatographic techniques. The purified enzyme had a specific activity of 24.06 U/mg of protein with k _m and V_max values of 2 mM and 18.2 mM/min/mg of protein, respectively. The yield of purified β-gal was 10.65% and estimated molecular weight found to be ～90 kDa, consisting of two homodimeric subunits of 43kDa. The enzyme was stable in pH range of 8.0–9.0 with an optimum pH of 8 and the optimum temperature of 40°C. The enzyme was activated in the presence of metal ions such as Mg⁺², Mn⁺², Ca⁺², K⁺ and Na⁺ and was inhibited by Zn⁺², Co⁺² and Cu⁺². Chemical modifiers (N-bromosuccinamide and Diethylpyro carbonate) inactivated the enzyme indicating the role of tryptophan and histidine moieties for activity. The purified β-gal was able to synthesize oligosaccharides from lactose. This study suggests that the β-gal of Enterococcus faecium MTCC5153 could be applied in dairy industry for hydrolysis of lactose and to improve its digestibility. β-gal of probiotic cultures are of particular interest due to their transgalactosylation properties.     

Salt-losing syndrome in newborn infants with hyperaldosteronism. Presenting a sensitivity to mineralocorticoids. Pseudohypoaldosteronism

A case of salt-loosing syndrome in infancy with hyperaldosteronism is reported. This patient was given high doses of 9 alpha Fluorocortisol (0.1 mg/kg/24 h), together with salt supplements. This treatment corrected the abnormality, while higher doses of salt supplements without such large amounts of Flurocortisol were ineffective.     

Studies on land surface temperature over heterogeneous areas using AVHRR data

The study addresses the use of the split-window method in tropical regions for estimation of surface temperature over heterogeneous surfaces from satellite sensor data. An attempt has been made to derive emissivity in the thermal channels using the NDVI in conjunction with fractional vegetation cover at pixel level. The estimated surface temperature values are compared with the in situ data over the region and are found to be within error limits of +/- 1.8°C. The utility of fractional vegetation cover in controlling surface temperature has been studied for the selected features over the area. The results suggest the utility of emissivity estimated from the NDVI in land surface temperature estimation.