Total Column Ozone Retrieval from Novel Array Spectroradiometer

This study presents total column ozone (TCO) retrieval from a new system, called Koherent, developed at PMOD/WRC. The instrument is based on a small, cost effective, robust, low-maintenance and state-of-the-art technology array&nbsp; spectroradiometer. It consists of a BTS-2048-UV-S-F array spectroradiometer from Gigahertz-Optik GmbH, coupled with an optical fiber to a lens-based telescope mounted on a sun tracker for measuring direct UV irradiance in the ultraviolet wavelength band between 305 nm to 345 nm. Two different algorithms are developed for retrieving TCO from these spectral measurements: 1) TCO retrieved by a minimal least squares fit algorithm (LSF) and 2) a Custom Double Ratio (CDR) technique using four specifically selected wavelengths from the spectral measurements. The double ratio technique is analogous to the retrieval algorithm applied for the Dobson and the Brewer but adopted and optimized here for TCO retrieval with Koherent. The instrument was calibrated in two different ways: a) absolute calibration of the spectra using the portable reference for ultraviolet radiation QASUME for the LSF retrieval and b) relative calibration of the extraterrestrial constant (ETC) of the CDR retrieval, by minimizing the slope between air mass and the relative differences of TCO from QASUME and Koherent. This adjustment of the ETC allows the instrument to be calibrated with standard TCO reference instruments during calibration campaigns, such as a double monochromator Brewer. A two-year comparison in Davos, Switzerland, between Koherent and the Brewer 156 (double monochromator) shows that TCO derived from Koherent and the Brewer 156 agree in average over the entire period within less than 0.7 % for all retrievals in terms of offset. The performance in terms of slant path depends on the selected retrieval and the applied corrections. The stray light corrected LSF retrieval exhibits a smaller slant path dependency than the CDR retrieval and performs almost as for a double monochromator system. The slant path dependency of the CDR is comparable to the slant path dependency of a single Brewer monochromator. The combination of both retrievals leads to performance with an offset close to zero compared to Brewer 156, a seasonal amplitude of the relative difference of 0.08 % and a slant path dependency of maximum 1.64 %, which is similar as other standard TCO instruments such as single Brewer or Dobson. Applying the double ratio technique by selecting the wavelengths and slit functions from Brewer and Dobson, respectively, allow to determine the effective ozone temperature within 3 K on daily averages. With the improved TCO retrieval, Koherent serves as a new low maintenance instrument to operationally monitor TCO at remote sites. The presented TCO retrieval may be applied to other array based spectroradiometers providing direct spectral measurements in the ultraviolet.</p

Quality control concept and recent developments of the light climatic observatory at Arosa: Ozone measuring station of the Swiss Meteorological Institute (LKO)

Total ozone observations of two Dobson instruments (D15 and D101, C- and AD wavelength pair observations) and of two Brewer instruments (Br40 and Br72) are currently performed at the LKO at Arosa. A quality control concept is presented in order to make best use of the large number of quasi-simultaneous measurements. The longest ozone series of the world is mainly based on the measurements of the Dobson instrument D15 (wavelength pair C). Since the last years D15 has suffered from instrumental problems. The transformation of the longterm series to the measurements of D101(AD) is described

Sanctioned Quotas Versus Information Provisioning for Community Wildlife Conservation in Zimbabwe: A Framed Field Experiment Approach

We investigate the behavioural responses of natural common-pool resource users to three policy interventions—sanctioned quotas, information provisioning, and a combination of both. We focus on situations in which users find utility in multiple resources (pastures and wild animal stocks) that all stem from the same ecosystem with complex dynamics, and management could trigger a regime shift, drastically altering resource regrowth. We performed a framed field experiment with 384 villagers from communities managing common-pool wildlife in Zimbabwe. We find that user groups are likely to manage these natural resources more efficiently when facing a policy intervention (either a sanctioned quota, receiving information about a drastic drop in the stocks’ regrowth below a threshold, or a combination of both), compared to groups facing no intervention. A sanctioned quota is likely to perform better than providing information about the existence of a threshold. However, having information about the threshold also leads to higher efficiency and fewer depletion cases, compared to a situation without any intervention. The main contribution of this study is to provide insights that can inform policymakers and development practitioners about the performance of concrete and feasible policy interventions for community wildlife conservation in Southern Africa

The study of atmospheric ice-nucleating particles via microfluidically generated droplets

Ice-nucleating particles (INPs) play a significant role in the climate and hydrological cycle by triggering ice formation in supercooled clouds, thereby causing precipitation and affecting cloud lifetimes and their radiative properties. However, despite their importance, INP often comprise only 1 in 10³–10⁶ ambient particles, making it difficult to ascertain and predict their type, source, and concentration. The typical techniques for quantifying INP concentrations tend to be highly labour-intensive, suffer from poor time resolution, or are limited in sensitivity to low concentrations. Here, we present the application of microfluidic devices to the study of atmospheric INPs via the simple and rapid production of monodisperse droplets and their subsequent freezing on a cold stage. This device offers the potential for the testing of INP concentrations in aqueous samples with high sensitivity and high counting statistics. Various INPs were tested for validation of the platform, including mineral dust and biological species, with results compared to literature values. We also describe a methodology for sampling atmospheric aerosol in a manner that minimises sampling biases and which is compatible with the microfluidic device. We present results for INP concentrations in air sampled during two field campaigns: (1) from a rural location in the UK and (2) during the UK’s annual Bonfire Night festival. These initial results will provide a route for deployment of the microfluidic platform for the study and quantification of INPs in upcoming field campaigns around the globe, while providing a benchmark for future lab-on-a-chip-based INP studies

Sanctioned Quotas Versus Information Provisioning for Community Wildlife Conservation in Zimbabwe: A Framed Field Experiment Approach

We investigate the behavioural responses of natural common-pool resource users to three policy interventions—sanctioned quotas, information provisioning, and a combination of both. We focus on situations in which users find utility in multiple resources (pastures and wild animal stocks) that all stem from the same ecosystem with complex dynamics, and management could trigger a regime shift, drastically altering resource regrowth. We performed a framed field experiment with 384 villagers from communities managing common-pool wildlife in Zimbabwe. We find that user groups are likely to manage these natural resources more efficiently when facing a policy intervention (either a sanctioned quota, receiving information about a drastic drop in the stocks’ regrowth below a threshold, or a combination of both), compared to groups facing no intervention. A sanctioned quota is likely to perform better than providing information about the existence of a threshold. However, having information about the threshold also leads to higher efficiency and fewer depletion cases, compared to a situation without any intervention. The main contribution of this study is to provide insights that can inform policymakers and development practitioners about the performance of concrete and feasible policy interventions for community wildlife conservation in Southern Africa.Validerad;2023;Nivå 2;2023-03-13 (joosat);Funder: Environment for Development Initiative, the Center for Collective Action Research (University of Gothenburg); Economic Research Southern Africa (ERSA); Beijer Institute of Ecological Economics (Royal Swedish Academy of Sciences); IKEA foundationLicens fulltext: CC BY License</p

Representativeness of the Arosa/Davos Measurements for the Analysis of the Global Total Column Ozone Behavior

The study investigates the representativeness of the total column ozone (TCO) measurements from the ground-based instruments located at the Arosa/Davos stations in Switzerland to analyze the global ozone layer behavior in the past and future. The statistical analysis of the satellite and model data showed a high correlation of the ground-based TCO data with the near-global and northern hemisphere annual mean TCO for the 1980–2018 period. Addition of the Arosa/Davos TCO data as a proxy to the set of standard explanatory variables for multiple linear regression analysis allows estimating the TCO behavior from 1926 up to the present day. We demonstrate that the real-time measurements and high homogeneity level of the Arosa/Davos TCO time series are also beneficial for quick estimates of the future ozone layer recovery.ISSN:2296-646