Industrial heat island: a case study of Angul-Talcher region in India

Most of the urban heat island (UHI) studies are carried out in densely populated cities but core industrial areas are also potential sites of heat island effect despite having a comparatively lower population. In the present study, heat island assessment has been carried out for Angul-Talcher industrial area (ATIA) which is one of the oldest industrial areas of India and is still undergoing a transformation to accommodate more industries and mining operations. As the major contributors towards influencing local meteorology were expected to be industrial (and mining) activities, the heat island was studied as "industrial heat island" (IHI) rather than urban heat island. Industrial and mining sites were the most frequent nighttime canopy-layer heat island intensity (HIN) hotspots due to anthropogenic heat of associated industrial processes as well as built structures. During the daytime, croplands experienced the most frequent canopy-layer HIN hotspots which could be attributed to low moisture of the soils during the non-farming period of the field campaign. Hourly maximum atmospheric heat island intensities were observed in the range of 7-9 degrees C. Monthly maximum HINs ranged from 2.97 to 4.04 degrees C while 3-month mean HINs varied from 1.45 to 2.74 degrees C. Amongst different land use/land cover classes, the highest mean canopy-layer heat island intensity for the entire 3-month-long duration of field campaign during nighttime was assessed at the mining sites (3-month mean 2.74 degrees C) followed in decreasing order by the industrial sites (2.52 degrees C), rural and urban settlements (2.13 degrees C), and croplands (2.06 degrees C). Corresponding daytime canopy-layer heat island intensity was highest for the croplands (2.07 degrees C) followed in decreasing order by the mining sites (1.70 degrees C), rural and urban settlements (1.68 degrees C), and industry (1.45 degrees C)

Near-terminator Martian ionosphere during sunspot cycle 23 from Mars Global Surveyor radio science measurements

Radio Science experiment on the Mars Global Surveyor (MGS) has measured a large number of electron density pro-files in the near-terminator Martian ionosphere, from December 1998 to March 2005, thus covering rising, maximum and declining phase of sunspot cycle 23. More than a dozen data sets, EDS 1 to EDS 13, are now available at the public website and these sets contain profiles numbering from a few tens in some sets to several hundreds in others. On any one day, several profiles were measured at a constant solar zenith angle (x) but at different longitudes. However, x varied considerably during each data set and in this paper about 2000 profiles have been analysed to study the height (hm) and density (Nm) of the primary peak as a function of solar zenith angle. A significant decrease of Nm is seen with increasing x, but hm starts increas-ing at x above 80° only. To examine how close the Martian primary peak is to an ideal Chapman layer, values of exponent, k and sub-solar peak density, No in the equation Nm = No (cos x)k were obtained by using the largest number of profiles em-ployed ever before. A value of 0.45 for the exponent k deduced is somewhat smaller than the value of 0.5 expected for an ideal Chapman layer. Value of No was found to be 1.75 × 1011 m-3. Anomalous features in the Mars ionosphere seen in the earlier MGS data are found to be present in the latest data also

Observations of electron density and electron temperature during large scale magnetic fields in the dayside Venus ionosphere and lesson for Mars

We first present several dayside electron density (Ne) and electron temperature (Te) profiles observed by the Langmuir probe experiment aboard Pioneer Venus Orbiter when the Venus ionosphere was in a magnetised state and then examine the effect of large scale magnetic fields on the Venus ionosphere. We find that for the magnetised ionospheres, the “top” moves down to altitudes near 200 km and the ionopause layers with steep altitude gradients in Ne and Te start above this altitude. No significant change in electron density and electron temperature is seen within the ionosphere. Occasionally a second ionopause layer is also seen at higher altitudes and the ionospheric region between the two ionopause layers, which is seen to extend to altitudes up to 250 km, too does not indicate any significant change in Ne and Te for these cases. These results have direct relevance to Mars where large scale ionospheric fields have also been observed

Long-term trends in the upper atmosphere and ionosphere: Models and observations

543-555Theoretical models predict a 10 K cooling in the mesosphere and 50 K cooling in the thermosphere in response to doubling of CO₂ and CH₄ from present day mixing ratios. In the mesosphere this cooling is expected to bring-in considerable changes in the individual ion concentration, but no significant change in the total ion density. In the thermosphere, atmospheric density would decrease and the heights of the ionospheric E- and F2-layers will drop by about 2 and 20 km, respectively. There would be little change in the critical frequency of these layers but electron density will decrease in the topside and increase in the bottomside ionosphere due to this lowering. Early results from some individual ionosonde stations showed the predicted decrease in the height of the F2-peak, but statistical analysis of ionospheric data from stations spread all over the globe did not indicate any significant trend in this parameter, as well as in the height of the E-layer and density of the F2-layer. The E and F1 layers peak densities, however, showed negative trends. Satellite drag data have provided convincing evidence of decrease in atmospheric density in the thermosphere during the last few decades. Better statistical methods are needed to filter out long-term solar activity and magnetic activity influences for detecting long-term trends in the F2 layer. Measurements of low frequency reflection heights from 1959 to 2003 at the mid-latitude station Kuhlungsborn show a long-term decreasing trend, an observation in agreement with the expected cooling in the mesosphere

Long-term trends in the upper atmosphere and ionosphere: Models and observations

Theoretical models predict a 10 K cooling in the mesosphere and 50 K cooling in the thermosphere in response to doubling of CO2 and CH4 from present day mixing ratios. In the mesosphere this cooling is expected to bring-in considerable changes in the individual ion concentration, but no significant change in the total ion density. In the thermosphere, atmospheric density would decrease and the heights of the ionospheric E- and F2-layers will drop by about 2 and 20 km, respectively. There would be little change in the critical frequency of these layers but electron density will decrease in the topside and increase in the bottomside ionosphere due to this lowering. Early results from some individual ionosonde stations showed the predicted decrease in the height of the F2-peak, but statistical analysis of ionospheric data from stations spread all over the globe did not indicate any significant trend in this parameter, as well as in the height of the E-layer and density of the F2-layer. The E and F1 layers peak densities, however, showed negative trends. Satellite drag data have provided convincing evidence of decrease in atmospheric density in the thermosphere during the last few decades. Better statistical methods are needed to filter out long-term solar activity and magnetic activity influences for detecting long-term trends in the F2 layer. Measurements of low frequency reflection heights from 1959 to 2003 at the mid-latitude station Kuhlungsborn show a long-term decreasing trend, an observation in agreement with the expected cooling in the mesosphere

Observations of X-ray and EUV fluxes during X-class solar flares and response of upper ionosphere

Most studies dealing with solar flare effects in the upper ionosphere, where ionization is caused by EUV photons, have been based upon X-ray fluxes measured by the SOLRAD and GOES series of satellites. To check the validity of such studies, we compare simultaneous observations of GOES X-ray fluxes and SOHO EUV fluxes for 10 X-class solar flares which occurred during the maximum phase of sunspot cycle 23. These include the greatest flare of 4 November 2003, the fourth greatest flare of 28 October 2003 and the 14 July 2000 Bastille Day flare. We find that the peak intensities of the X-ray and EUV fluxes for these flares are poorly correlated, and this poor correlation is again seen when larger data containing 70 X-class flares, which occurred during the period January 1996 to December 2006, are examined. However, this correlation improves vastly when the central meridian distance (CMD) of the flare location is taken into account. We also study the response of the upper ionosphere to these fluxes by using the midday total electron content (TEC), observed for these flares by Liu et al. (2006). We find that peak enhancement in TEC is highly correlated with peak enhancement in EUV flux. The correlation, though poor with the X-ray flux, improves greatly when the CMD of flare location is considered

Limniotis, Marina

When solar wind dynamic pressure is close to or more than the subsolar ionospheric thermal pressure (overpressure conditions), the Venus ionosphere is permeated with large scale horizontal magnetic fields. There were speculations that these fields basically represented conditions, which could inhibit: (1)vertical diffusive transport, thereby affecting the vertical ion and electron distribution and (2) vertical thermal conduction, thereby affecting the vertical ion and electron temperatures. We therefore first review the main features of these fields and then present and discuss different results reported by various authors on the effects of these fields on the ionospheric plasma. We point out that an important feature of the ionospheric plasma as well as of the magnetic fields, in this context, is that both of these are limited to altitudes below 200 km during these overpressure conditions and here local equilibrium conditions prevail. Latest observational results indicate that these solar wind induced fields that do not have any detectable effect on the Venus ionosphere. These observational results are also discussed in the light of ionospheric measurements at Mars

Assessment of satellite-retrieved surface UVA and UVB radiation by comparison with ground-measurements and trends over Mega-city Delhi

Solar UV radiation reaching the Earths surface is known to have various effects on human health and on the ecosystem. Ground-based measurements of surface UV radiation are spatially sparse and in many cases do not provide long time series. Higher spatial coverage can be provided by measurements from satellite based instruments, but these measurements need to be compared to ground-based measurements of sufficient quality before they can be used in health and ecosystem applications. Here, we compare the measurements of surface solar UV radiation in UVA (315-400 nm) and UVB (280-315 nm) bands with the satellite retrievals (CERES) and validate the latter at an urban location, Delhi, India. We have also used MODIS-retrieved aerosol optical depth (AOD) and cloud optical depth (COD) data to see the effect of atmospheric opacity on UV radiation. Ground based measurements of UVA and UVB were performed from 01 October, 2012 to 30 September, 2015: Correlations between daily surface measurements and CERES-derived surface UV fluxes showed very good agreement (r similar to 0.92-0.93) over Delhi. We found a negative correlation between UV fluxes and AOD over Delhi during all seasons. A unit increase in AOD leads to a decrease of similar to 4-5 Wm(-2) in UVA and similar to 0.09-0.14 Wm(-2) in UVB over Delhi. The trend analysis from monthly mean CERES-derived UV fluxes for 17 years data reveals that UVA and UVB are decreasing similar to 0.07 Wm(-2) yr(-1) and 0.003 Wm(-2) yr(-1), respectively with AOD increase (similar to 0.005 yr(-1)) over Delhi. The simultaneous increase in aerosol loading with decrease in UV fluxes at the surface may be explained as a masking effect of ever increasing pollution on surface UV radiation over Delhi. Our results show similar to 10% and similar to 20% decrease (with respect to mean) in UVA and UVB surface fluxes, respectively during last 17 years

Physico-chemical characterization of individual Antarctic particles: Implications to aerosol optics

Aerosols affect the Earth's radiation budget by interacting with the incoming solar radiation. The physicochemical properties, particularly morphological parameters (Aspect Ratio, AR and Circulatory Factor, CIR) and composition at individual particle level are important inputs to the optical model for assessing the optical sensitivity towards said properties. The observation of these properties is limited over Antarctica which has been studied in detail in the present work. The PM5 particles (particulate matter with aerodynamic diameter less than 5 mu m) over Antarctica were collected at Indian Antarctic station, Maitri (70.77 degrees S, 11.73 degrees E) from Dec 2013-Feb 2014. The individual particle analysis revealed that particles were mainly composed of Si, Fe, Al, Ca and Mg. Most of the particles were observed in layered, flattened, aggregated and glass-like shapes. The frequency distributions of the morphological parameters, AR and CIR were observed to be bimodal with respective mode peaks 1.3 and 1.9 for AR; 0.4 and 0.7 for CIR. The spectral refractive indices of individual particles were estimated. The imaginary part of the refractive indices was observed to be maximum for chromium (Cr) and iron (Fe) rich particle and nearly negligible for aluminum (Al) rich particle. At 0.58 mu m wavelength, the difference in SSA with respect to Al rich particle was found to be maximum for Ca rich particles (i.e. 43%) followed with Cr and Fe rich particle (i.e. 42.08%) and Cr rich particle (i.e. 39.32%)