A comparative study of temperatures of direct sunlight and air temperatures in a standard screen measured at Doha International Airport - a pilot study

An observational campaign was conducted at Doha International Airport, Arabian Gulf to find out difference between air temperature in a standard screen and direct sunlight. Hourly observations recorded during July-August 1998 and June-August 1999 formed the basis of the study. Difference between screen temperature (ST) and outside temperature (OT) in respect of all hourly data in the above period from 0600 to 1800 hrs of local time have been computed and analysed. In order to examine the difference before sunrise and after sunset, observations were also made during 1900-0500 hrs of local time from 1st to 18th of July 1998. Results of the study revealed that the magnitude of the differences between OT and ST is not as high as expected. The highest difference observed was 5.1° C on 16th July 1999 at 0900 hr. As anticipated, the temperature of direct sunlight between 0600 hr and 1700 hr were always higher than the screen temperature. However, after 0500 pm of local time, the screen temperatures are found to be higher than outside temperature though the sunset time in these months are after 0600 pm. The mean difference between ST and DT in June, July and August respectively found to be 1.43° C, 1.53° C and 1.67° C. The highest difference observed in these months was 3.8° C, 5.1° C and 4.1° C respectively. The study has also indicated that the difference between OT and ST is generally higher during 0900-1000 hrs of local time and lower during two hours before sunrise and sunset.

Local-time Dependence of Chemical Species in the Venusian Mesosphere

Observed chemical species in the Venusian mesosphere show local-time variabilities. SO2 at the cloud top exhibits two local maxima over local time, H2O at the cloud top is uniformly distributed, and CO in the upper atmosphere shows a statistical difference between the two terminators. In this study, we investigated these local-time variabilities using a three-dimensional (3D) general circulation model (GCM) in combination with a two-dimensional (2D) chemical transport model (CTM). Our simulation results agree with the observed local-time patterns of SO2, H2O, and CO. The two-maximum pattern of SO2 at the cloud top is caused by the superposition of the semidiurnal thermal tide and the retrograde superrotating zonal (RSZ) flow. SO2 above 85 km shows a large day–night difference resulting from both photochemistry and the subsolar-to-antisolar (SS-AS) circulation. The transition from the RSZ flows to SS-AS circulation can explain the CO difference between two terminators and the displacement of the CO local-time maximum with respect to the antisolar point. H2O is long-lived and exhibits very uniform distribution over space. We also present the local-time variations of HCl, ClO, OCS, and SO simulated by our model and compare to the sparse observations of these species. This study highlights the importance of multidimensional CTMs for understanding the interaction between chemistry and dynamics in the Venusian mesosphere.

Diurnal variation of outgoing longwave radiation derived from I NSA T-I B data

In this paper, 3-hourly values of Outgoing Long wave Radiation (OLR) for the years 1987 .to 1990 over the Indian Ocean region, derived from'1NSAT-IB VHRR observations, have been used to study the patterns of diurnal variation of OLR. The nature of the diurnal variations over different regions such as desert, ocean, monsoon area and equatorial trough in four representative months of the year is discussed. The variations in the diurnal range of OLR and the hours of occurrence of OLR minimum and maximum, are also presented.Daily means of TNSAT OLR using all.eight 3-hour samples and four different pairs of. 12-hour samples were computed. Results show that they are highly correlated. However, averages made with OLR values corresponding to 0230 and 1430 local time are slight underestimates compared to the 8-sample averages, whereas averages based upon 0830 and 2030 local time are slight overestimates.

Real-time chemical speciation and source apportionment of organic aerosol components in Delhi, India, using extractive electrospray ionization mass spectrometry

In recent years, the Indian capital city of Delhi has been impacted by very high levels of air pollution, especially during winters. Comprehensive knowledge of the composition and sources of the organic aerosol (OA), which constitutes a substantial fraction of total particulate mass (PM) in Delhi, is central to formulating effective public health policies. Previous source apportionment studies in Delhi identified key sources of primary OA (POA) and showed that secondary OA (SOA) played a major role, but were unable to resolve specific SOA sources. We address the latter through the first field deployment of an extractive electrospray ionization time-of-flight mass spectrometer (EESI-TOF) in Delhi, together with a high-resolution aerosol mass spectrometer (AMS). Measurements were conducted during the winter of 2018/2019, and positive matrix factorization (PMF) was used separately on AMS and EESI-TOF datasets to apportion the sources of OA. AMS PMF analysis yielded three primary and two secondary factors which were attributed to hydrocarbon-like OA (HOA), biomass burning OA (BBOA-1 and 2), more oxidized oxygenated OA (MO-OOA), and less oxidized oxygenated OA (LO-OOA). On average, 40 % of the total OA mass was apportioned to the secondary factors. The SOA contribution to total OA mass varied greatly between daytime (76.8 %, 10:00–16:00 local time (LT)) and nighttime (31.0 %, 21:00–04:00 local time). The higher chemical resolution of EESI-TOF data allowed identification of individual SOA sources. The EESI-TOF PMF analysis in total yielded six factors, two of which were primary factors (primary biomass burning and cooking-related OA). The remaining four factors were predominantly of secondary origin: aromatic SOA, biogenic SOA, aged biomass burning SOA, and mixed urban SOA. Due to the uncertainties in the EESI-TOF ion sensitivities, mass concentrations of EESI-TOF SOA dominated factors were related to the total AMS SOA (i.e., MO-OOA + LO-OOA) by multi-linear regression (MLR). Aromatic SOA was the major SOA component during the day-time, with 55.2 % contribution to total SOA mass (42.4 % contribution to total OA). Its contribution to total SOA, however, decreased to 25.4 % (7.9 % of total OA) during night-time. This factor was attributed to the oxidation of light aromatic compounds emitted mostly from traffic. Biogenic SOA accounted for 18.4 % of total SOA mass (14.2 % of total OA) during day-time and 36.1 % of total SOA mass (11.2 % of total OA) during night-time. Aged biomass burning and mixed urban SOA accounted for 15.2 % and 11.0 % of total SOA mass ( 11.7 % and 8.5 % of total OA mass) during day-time respectively and 15.4 % and 22.9 % of total SOA mass (4.8 % and 7.1 % of total OA mass) during night-time, respectively. A simple dilution/partitioning model was applied on all EESI-TOF factors to estimate the fraction of observed day-time concentrations resulting from local photochemical production (SOA) or emissions (POA). Aromatic SOA, aged biomass burning, and mixed urban SOA were all found to be dominated by local photochemical production, likely from the oxidation of locally emitted VOCs. In contrast, biogenic SOA was related to the oxidation of diffuse regional emissions of isoprene and monoterpenes. The findings of this study show that in Delhi, the night-time high concentrations are caused by POA emissions led by traffic and biomass burning, and the daytime OA is dominated by SOA, with aromatic SOA accounting for the largest fraction. Because aromatic SOA is possibly more toxic than biogenic SOA and primary OA, its dominance during the day-time suggests an increased OA toxicity and health-related consequences for the general public.

(Post)colonial Chronopolitics and Mapping the Depth of Local Time(s) in Global Literary Studies: an Itinerary to Guinea-Bissau

This article is an attempt at deconstructing the chronopolitics inherent to the (post)colonial way of thinking about the world. As it is argued, what should replace it is a vision of multiple, overlying temporalities and forms of time awareness, reaching deeper than a literary history reduced to the cycle of colonisation – decolonisation – postcolonial becoming, originating from just a single maritime event: the European exploration and conquest of the world. The essay brings forth a choice of interwoven examples illustrating the variability of local time depths, associated with a plurality of origins, narrations, forms of awareness and cultivation of cultural belonging. It shows the lack of coincidence between the dominant and non-dominant perceptions of the past in such places as the archipelagos of São Tomé and Príncipe, Maldives, the Gambia, Cape Verde and Guinea-Bissau. Their ways of living the global time, as well as embodying significant texts (rather than simply preserving them) stretch far beyond the frameworks created by competing colonial empires, such as the Portuguese or the British one.

Temporal Eating Patterns and Eating Windows among Adults with Overweight or Obesity

We aim to describe temporal eating patterns in a population of adults with overweight or obesity. In this cross-sectional analysis, data were combined from two separate pilot studies during which participants entered the timing of all eating occasions (>0 kcals) for 10–14 days. Data were aggregated to determine total eating occasions, local time of the first and last eating occasions, eating window, eating midpoint, and within-person variability of eating patterns. Eating patterns were compared between sexes, as well as between weekday and weekends. Participants (n = 85) had a median age of 56 ± 19 years, were mostly female (>70%), white (56.5%), and had a BMI of 31.8 ± 8.0 kg/m2. The median eating window was 14 h 04 min [12 h 57 min–15 h 21 min], which was significantly shorter on the weekend compared to weekdays (p < 0.0001). Only 13.1% of participants had an eating window <12 h/d. Additionally, there was greater irregularity with the first eating occasion during the week when compared to the weekend (p = 0.0002). In conclusion, adults with overweight or obesity have prolonged eating windows (>14 h/d). Future trials should examine the contribution of a prolonged eating window on adiposity independent of energy intake.

An encounter-based approach for restricted diffusion with a gradient drift

We develop an encounter-based approach for describing restricted diffusion with a gradient drift towards a partially reactive boundary. For this purpose, we introduce an extension of the Dirichlet-to-Neumann operator and use its eigenbasis to derive a spectral decomposition for the full propagator, i.e., the joint probability density function for the particle position and its boundary local time. This is the central quantity that determines various characteristics of diffusion-influenced reactions such as conventional propagators, survival probability, first-passage time distribution, boundary local time distribution, and reaction rate. As an illustration, we investigate the impact of a constant drift onto the boundary local time for restricted diffusion on an interval. More generally, this approach accesses how external forces may influence the statistics of encounters of a diffusing particle with the reactive boundary.

On the local time of a recurrent random walk on ℤ²

We prove a functional limit theorem for the number of visits by a planar random walk on Z 2 \mathbb {Z}^2 with zero mean and finite second moment to the points of a fixed finite set P ⊂ Z 2 P\subset \mathbb {Z}^2 . The proof is based on the analysis of an accompanying random process with immigration at renewal epochs in case when the inter-arrival distribution has a slowly varying tail.