New observations of upper tropospheric NO2 from TROPOMI

Nitrogen oxides (NOx ≡ NO + NO2) in the NOx-limited upper troposphere (UT) are long-lived and so have a large influence on the oxidizing capacity of the troposphere and formation of the greenhouse gas ozone. Models misrepresent NOx in the UT and observations to address deficiencies in models are sparse. Here we obtain a year of near-global seasonal mean mixing ratios of NO2 in the UT (450–180 hPa) at 1 ° x 1° by applying cloud-slicing to partial columns of NO2 from TROPOMI. This follows refinement of the cloud-slicing algorithm with synthetic partial columns from the GEOS-Chem chemical transport model. We find that synthetic cloud-sliced UT NO2 are spatially consistent (R = 0.64) with UT NO2 calculated across the same cloud pressure range and scenes as are cloud-sliced (“true” UT NO2), but the cloud-sliced UT NO2 is 11–22 % more than the "true" all-sky seasonal mean. The largest contributors to differences between synthetic cloud-sliced and “true” UT NO2 are target resolution of the cloud-sliced product and uniformity of overlying stratospheric NO2. TROPOMI, prior to cloud-slicing, is corrected for a 13 % underestimate in stratospheric NO2 variance and a 50 % overestimate in free tropospheric NO2 determined by comparison to Pandora total columns at high-altitude sites in Mauna Loa, Izaña and Altzomoni, and MAX-DOAS and Pandora tropospheric columns at Izaña. Two cloud-sliced seasonal mean UT NO2 products for June 2019 to May 2020 are retrieved from corrected TROPOMI total columns using distinct TROPOMI cloud products that assume clouds are reflective boundaries (FRESCO-S) or water droplet layers (ROCINN-CAL). TROPOMI UT NO2 typically ranges from 20-30 pptv over remote oceans to > 80 pptv over locations with intense seasonal lightning. Spatial coverage is mostly in the tropics and subtropics with FRESCO-S and extends to the midlatitudes and polar regions with ROCINN-CAL, due to its greater abundance of optically thick clouds and wider cloud top altitude range. TROPOMI UT NO2 seasonal means are spatially consistent (R = 0.6–0.8) with an existing coarser spatial resolution (5° latitude x 8° longitude) UT NO2 product from the Ozone Monitoring Instrument (OMI). UT NO2 from TROPOMI is 12–26 pptv more than that from OMI due to increase in NO2 with altitude from the OMI pressure ceiling (280 hPa) to that for TROPOMI (180 hPa), but possibly also systematic altitude differences between the TROPOMI and OMI cloud products. The TROPOMI UT NO2 product offers potential to evaluate and improve representation of UT NOx in models and supplement aircraft observations that are sporadic and susceptible to large biases in the UT

Protecting Endangered Species: Do the Main Legislative Tools Work?

It is critical to assess the effectiveness of the tools used to protect endangered species. The main tools enabled under the U.S. Endangered Species Act (ESA) to promote species recovery are funding, recovery plan development and critical habitat designation. Earlier studies sometimes found that statistically significant effects of these tools could be detected, but they have not answered the question of whether the effects were large enough to be biologically meaningful. Here, we ask: how much does the recovery status of ESA-listed species improve with the application of these tools? We used species' staus reports to Congress from 1988 to 2006 to quantify two measures of recovery for 1179 species. We related these to the amount of federal funding, years with a recovery plan, years with critical habitat designation, the amount of peer-reviewed scientific information, and time listed. We found that change in recovery status of listed species was, at best, only very weakly related to any of these tools. Recovery was positively related to the number of years listed, years with a recovery plan, and funding, however, these tools combined explain <13% of the variation in recovery status among species. Earlier studies that reported significant effects of these tools did not focus on effect sizes; however, they are in fact similarly small. One must conclude either that these tools are not very effective in promoting species' recovery, or (as we suspect) that species recovery data are so poor that it is impossible to tell whether the tools are effective or not. It is critically important to assess the effectiveness of tools used to promote species recovery; it is therefore also critically important to obtain population status data that are adequate to that task

Barriers to participation in mental health research: are there specific gender, ethnicity and age related barriers?

<p>Abstract</p> <p>Background</p> <p>It is well established that the incidence, prevalence and presentation of mental disorders differ by gender, ethnicity and age, and there is evidence that there is also differential representation in mental health research by these characteristics. The aim of this paper is to a) review the current literature on the nature of barriers to participation in mental health research, with particular reference to gender, age and ethnicity; b) review the evidence on the effectiveness of strategies used to overcome these barriers.</p> <p>Method</p> <p>Studies published up to December 2008 were identified using MEDLINE, PsycINFO and EMBASE using relevant mesh headings and keywords.</p> <p>Results</p> <p>Forty-nine papers were identified. There was evidence of a wide range of barriers including transportation difficulties, distrust and suspicion of researchers, and the stigma attached to mental illness. Strategies to overcome these barriers included the use of bilingual staff, assistance with travel, avoiding the use of stigmatising language in marketing material and a focus on education about the disorder under investigation. There were very few evaluations of such strategies, but there was evidence that ethnically matching recruiters to potential participants did not improve recruitment rates. Educational strategies were helpful and increased recruitment.</p> <p>Conclusion</p> <p>Mental health researchers should consider including caregivers in recruitment procedures where possible, provide clear descriptions of study aims and describe the representativeness of their sample when reporting study results. Studies that systematically investigate strategies to overcome barriers to recruitment are needed.</p

Satellite observations of tropospheric nitrogen dioxide : retrieval, interpretation, and modelling

The research questions set out in Chapter 1 that guided the investigation in this thesis are repeated here. The answers to these questions contain the most important conclusions of the various chapters and are given below. 1. How can we retrieve accurate information on total and tropospheric NO2 from the backscatter UV-VIS measurements by the Ozone Monitoring Instrument? 2. Can we develop a concept that relates a vertical distribution of a trace gas to a satellite observed column? 3. What is the error buget for tropospheric NO2 retrievals for an operational backscatter instrument like GOME? 4. How can we use GOME tropospheric NO2 observations to constrain estimates of the tropical lightning NOx production? The first research question is topic of chapter 2. One of the ‘Science questions’ posed in the framework of the EOS-AURA mission is: "Is air quality changing?". A contribution to anwering this question may be provided by accurate and precise measurements of tropospheric NO2 columns from the Ozone Monitoring Instrument that become widely available for scientific purposes. To this end, an algorithm for the retrieval of total and tropospheric NO2 has been developed and tested in Chapter 2. This algorithm has been implemented for the operational retrieval of the standard KNMI/NASA OMI NO2 "product". The OMI algorithm builds on the heritage of GOME tropospheric NO2 retrievals, and contains a number of important improvements over previous algorithms. In principle, one of these improvements is the extended size of the spectral fitting window: sensitivity studies indicated that a significant reduction in the slant column uncertainty can be attained for a 405-465 nm window. The derivation of the stratosferische background is improved by accounting for variability along a zonal band. Application of a low-pass filter approach on GOME data shows significant variability in stratospheric NO2 along locations of the same latitude that would lead to otherwise significant systematic errors. Climatological NO2 profiles can be used for troposferic air mass factor calculations. In situations of urban pollution, climatological NO2 profiles simulated with TM3 do not show large variability in their shape. In situations of biomass burning and outflow of NOx-related pollution over comparatively clean areas, the vertical distribution is quite different with NO2 peaking at higher altitudes. We estimate that OMI NO2 columns will be retrieved with a precision of approximately 5% for unpolluted situations, largely due to the uncertainty in the spectral fitting. For situations with NOx levels in the troposphere that are far above background, we expect to measure tropospheric columns with errors up to 60%, largely due to retrieval assumptions on the state of the atmosphere. In Chapter 3, the second research question is adressed. This chapter discussed the strong height-dependent sensitivity of a satellite instrument to a tracer density is discussed in relation to the averaging kernel. This sensitivity was already topic of Chapter 2, but is here discussed in the context of general retrieval theory as developed by Rodgers. It is shown that the averaging kernel provides a direct interpretation of the satellite retrieved column density to users. For intercomparisons with independent data, such as vertical profiles from models or validation measurements, the dependence on a priori assumptions about the profile shape dissapears when the averaging kernel is used. The third Chapter on the retrieval of tropospheric NO2, is Chapter 4. In this Chapter, an extensive error analysis of tropospheric NO2 retrievals is presented in order to answer the third research question. It is shown that GOME tropospheric NO2 retrievals have errors in the 35-60% range, largely determined by air mass factor errors. The most important errors -in order of importance- are errors due to uncertainty in model parameters such as clouds, surface albedo and a priori profile shape. Apart from the error analysis, a number of retrieval improvements has been suggested in Chapter 4. Most relevant is a new method to estimate the stratospheric background from an assimilation approach. This approach has the advantage of accounting for dynamical features in stratospheric NO2, and reduces the otherwise large systematic error in the estimate of stratopheric NO2. A correction for the temperature-dependence of the NO2 cross-section is demonstrated to remove systematic errors on the order of 10%. Finally, we conclude that a correction for the presence of aerosols needs to be accompanied by aerosol corrections in cloud retrieval schemes. Chapter 5 relies on the previous chapters and focuses on the fourth and last research question. In Chapter 5, columns and their error estimates (Chapter 4) are used in an extensive comparison -through the averaging kernel (Chapter 3)- with modelled lightning NO2 columns in order to test lightning parametrisations in TM3 and to impose top-down constraints on the global lightning NOx production. First, it is shown that tropospheric measurements by GOME are sensitive to NO2 produced by lightning. Tropospheric NO2 columns show a rapid increase with the fifth power of the cloud top height for clouds with tops higher than 6.5 km. This estimate of the cloud height-dependence of LNO2 is consistent with the observed power-law relationship of lightning frequencies and cloud top height. Second, a statistical comparison of simulated LNO2 and observed NO2 columns in the tropical region between 40??S and5??N shows that the TM3 model is well capable of reproducing observed patterns of LNO2. This is true for two different lightning parameterisations in TM3. Moreover, the absolute values of modelled and observed (L)NO2 are in good agreement over tropical continents. However, over tropical oceans, the model appears to overestimate the LNO2 contribution to the total tropospheric column. This model bias is likely due to assumptions on the assumed energy ratio (10:1) between cloud-to-ground and intra-cloud lightning, and on the assumed ratio (10:1) between continent-to-ocean convective intensity. For the scheme based on convective precipitation, there are significant regional differences in rainfall-to-lightning ratios that may also lead to the bias over the tropical ocean. From rescaling the modelled LNOx production between 40??S and 5??N, we arrive at a LNOx production estimate of ??1.0 Tg[N] in the 40??S118 Summary, conclusions, and outlook 5??N region. Based on assumptions for rescaling factors in the rest of the world, the global LNOx production in 1997 is estimated to be in the 1.1-6.4 Tg[N] range

Environmental exposure to polychlorinated biphenyls (PCBs) and dioxins: Consequences for longterm neurological and cognitive development of the child lactation

Polychlorinated biphenyls (PCBs) and dioxins are environmental pollutants. Prenatally, as well as postnatally through breast feeding, large amounts are transferred from mother to the child. Formula is free of these substances. Considering their potential developmental neurotoxicity, we investigated long term effects of perinatal exposure to PCBs and dioxins on neurological and cognitive development. Given the evidence that PCBs exert oestrogenic effects, and oestrogens are known to suppress lactation, we investigated the effect of maternal PCB body load on lactation performances as well. Methods. A group of 418 infants were followed from birth up to 6 years of age. Half of them were fully breast fed CBF) for at least 6 weeks. Prenatal PCB exposure was measured from cord and maternal blood. Postnatal exposure was reflected by PCB and dioxin levels in breast and formula milk and plasma PCB levels at 42 months of age. Both neurological and cognitive development were taken as outcome variable at 18, 42 months and at 6 years of age. At 18 and 42 months of age neurological condition was evaluated according to Hempel and at 6 years of age according to Touwen. Condition was evaluated in terms of optimality. Separately, the fluency of movements was scored. Cognitive abilities were measured at Is months by the Bayley Scales of Infant Development, at 42 months of age by the Kaufman Assessment Battery for Children (K-ABC) and at 6 years of age by the McCarthy Scares. Daily breast milk volume and milk fat content in relation to PCB body load was evaluated in 102 mothers. Multivariate regression models were applied to analyse associations of measured exposure variables with independant variables adjusted for confounders. Results. At 18 months of age cognitive development was not affected by either pre- or postnatal exposure to the measured PCBs and dioxins. However, neurological examination showed an adverse effect of prenatal exposure to the measured pollutants on neurological optimality score. At 42 months of age we found negative associations between prenatal PCB exposure on cognitive development. However no effect was demonstrated on postnatal exposure to the measured pollutants. Neurological development was not affected by either pre- or postnatal exposure to PCBs and dioxins. At 6 years of age the preliminary results revealed evidence that cognitive development is affected by prenatal exposure to these pollutants in children from young mothers. An adverse effect of prenatal exposure on neurological outcome was also demonstrated in the formula fed group but not in the breast fed group. Despite a higher PCB exposures from breast milk we found at 18 months, 42 months of age, and at 6 years of age a beneficial effect of breast feeding on the quality of movements, in terms of fluency, and on the cognitive development tests. Maternal PCB body load was inversely related to 24-h breast milk volume and milk fat content. Conclusion. These data give evidence that prenatal exposure to PCBs do have subtle negative effects on neurological and cognitive development of the child up to school-age. Human breast milk volume and fat content is adversely affected by the presently encountered PCB levels in W. Europe. Our studies showed evidence that breast feeding counteracts the adverse developmental effects of PCBs and dioxins