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By comparing a single-column model (SCM) with closely related general circulation models (GCMs), precipitation changes that can be diagnosed from local changes in surface temperature (TS) and relative humidity (RHS) are separated from more complex responses. In the SCM setup, the large-scale tropical circulation is parameterized to respond to the surface temperature departure from a prescribed environment, following the weak temperature gradient (WTG) approximation and using the damped gravity wave (DGW) parameterization. The SCM is also forced with moisture variations. First, it is found that most of the present-day mean tropical rainfall and circulation pattern is associated with TS and RHS patterns. Climate change experiments with the SCM are performed, imposing separately surface warming and CO2 increase. The rainfall responses to future changes in sea surface temperature patterns and plant physiology are successfully reproduced, suggesting that these are direct responses to local changes in convective instability. However, the SCM increases oceanic rainfall too much, and fails to reproduce the land rainfall decrease, both of which are associated with uniform ocean warming. It is argued that remote atmospheric teleconnections play a crucial role in both weakening the atmospheric overturning circulation and constraining precipitation changes. Results suggest that the overturning circulation weakens, both as a direct local response to increased CO2 and in response to energy-imbalance driven exchanges between ascent and descent regions.

The fixed anvil temperature (FAT) theory describes a mechanism for how tropical anvil clouds respond to global warming and has been used to argue for a robust positive longwave cloud feedback. A constant cloud anvil temperature, due to increased anvil altitude, has been argued to lead to a “zero cloud emission change” feedback, which can be considered positive relative to the negative feedback associated with cloud anvil warming when cloud altitude is unchanged. Here, partial radiative perturbation (PRP) analysis is used to quantify the radiative feedback caused by clouds that follow the FAT theory (FAT–cloud feedback) and to set this in the context of other feedback components in two atmospheric general circulation models. The FAT–cloud feedback is positive in the PRP framework due to increasing anvil altitude, but because the cloud emission does not change, this positive feedback is cancelled by an equal and opposite component of the temperature feedback due to increasing emission from the cloud. To incorporate this cancellation, the thermal radiative damping with fixed relative humidity and anvil temperature (T-FRAT) decomposition framework is proposed for longwave feedbacks, in which temperature, fixed relative humidity, and FAT–cloud feedbacks are combined. In T-FRAT, the cloud feedback under the FAT constraint is zero, while that under the proportionately higher anvil temperature (PHAT) constraint is negative. The change in the observable cloud radiative effect with FAT–cloud response is also evaluated and shown to be negative due to so-called cloud masking effects. It is shown that “cloud masking” is a misleading term in this context, and these effects are interpreted more generally as “cloud climatology effects.”

Projections of future West African monsoon (WAM) precipitation change in response to increasing greenhouse gases are uncertain, and an improved understanding of the drivers of WAM precipitation change is needed to help aid model development and better inform adaptation policies in the region. This paper addresses one of those drivers, the direct radiative effect of increased CO2 (i.e., the impact of increased CO2 in the absence of SST warming and changes in plant physiology). An atmosphere-only model is used to examine both the equilibrium response and the evolution of the change over the days following the instantaneous CO2 increase. In response to the direct radiative effect, WAM precipitation increases due to a weakening of the shallow meridional circulation over North Africa, advecting less dry air into the convective column associated with the monsoon. Changes in the shallow circulation are associated with atmospheric and surface warming patterns over North Africa. A large-scale atmospheric warming pattern, whereby North Africa warms more than the monsoon region, leads to a northward shift in the Saharan heat low. In response to increased precipitation in the Sahel, local soil moisture feedbacks play a key role in determining the low-level circulation change and the location of the intertropical discontinuity. The large-scale warming patterns over North Africa result from differing levels of constraint applied by convective quasi-equilibrium. While this constraint acts strongly in the equatorial WAM region, preventing the region from warming in response to the direct radiative effect, North Africa is not strongly constrained and is therefore able to warm.

Heterodera carotae, the carrot cyst nematode, is a significant pest affecting carrot globally. Here we present the draft genome of H. carotae, which was generated from short read libraries from Illumina HiSeq technology, and the corresponding genome annotation.

Using a 3D general circulation model, we demonstrate that a confirmed rocky exoplanet and a primary observational target, TRAPPIST-1e presents an interesting case of climate bistability. We find that the atmospheric circulation on TRAPPIST-1e can exist in two distinct regimes for a 1~bar nitrogen-dominated atmosphere. One is characterized by a single strong equatorial prograde jet and a large day-night temperature difference; the other is characterized by a pair of mid-latitude prograde jets and a relatively small day-night contrast. The circulation regime appears to be highly sensitive to the model setup, including initial and surface boundary conditions, as well as physical parameterizations of convection and cloud radiative effects. We focus on the emergence of the atmospheric circulation during the early stages of simulations and show that the regime bistability is associated with a delicate balance between the zonally asymmetric heating, mean overturning circulation, and mid-latitude baroclinic instability. The relative strength of these processes places the GCM simulations on different branches of the evolution of atmospheric dynamics. The resulting steady states of the two regimes have consistent differences in the amount of water content and clouds, affecting the water absorption bands as well as the continuum level in the transmission spectrum, although they are too small to be detected with current technology. Nevertheless, this regime bistability affects the surface temperature, especially on the night side of the planet, and presents an interesting case for understanding atmospheric dynamics and highlights uncertainty in 3D GCM results, motivating more multi-model studies., 31 pages, 14 figures, accepted to the Planetary Science Journal

To identify promising exoplanets for atmospheric characterization and to make the best use of observational data, a thorough understanding of their atmospheres is needed. 3D general circulation models (GCMs) are one of the most comprehensive tools available for this task and will be used to interpret observations of temperate rocky exoplanets. Due to parameterization choices made in GCMs, they can produce different results, even for the same planet. Employing four widely-used exoplanetary GCMs -- ExoCAM, LMD-G, ROCKE-3D and the UM -- we continue the TRAPPIST-1 Habitable Atmosphere Intercomparison by modeling aquaplanet climates of TRAPPIST-1e with a moist atmosphere dominated by either nitrogen or carbon dioxide. Although the GCMs disagree on the details of the simulated regimes, they all predict a temperate climate with neither of the two cases pushed out of the habitable state. Nevertheless, the inter-model spread in the global mean surface temperature is non-negligible: 14 K and 24 K in the nitrogen and carbon dioxide dominated case, respectively. We find substantial inter-model differences in moist variables, with the smallest amount of clouds in LMD-Generic and the largest in ROCKE-3D. ExoCAM predicts the warmest climate for both cases and thus has the highest water vapor content and the largest amount and variability of cloud condensate. The UM tends to produce colder conditions, especially in the nitrogen-dominated case due to a strong negative cloud radiative effect on the day side of TRAPPIST-1e. Our study highlights various biases of GCMs and emphasizes the importance of not relying solely on one model to understand exoplanet climates., Comment: 35 pages, 22 figures; Published in The Planetary Science Journal

Identification of habitable planets beyond our solar system is a key goal of current and future space missions. Yet habitability depends not only on the stellar irradiance, but equally on constituent parts of the planetary atmosphere. Here we show, for the first time, that radiatively active mineral dust will have a significant impact on the habitability of Earth-like exoplanets. On tidally-locked planets, dust cools the day-side and warms the night-side, significantly widening the habitable zone. Independent of orbital configuration, we suggest that airborne dust can postpone planetary water loss at the inner edge of the habitable zone, through a feedback involving decreasing ocean coverage and increased dust loading. The inclusion of dust significantly obscures key biomarker gases (e.g. ozone, methane) in simulated transmission spectra, implying an important influence on the interpretation of observations. We demonstrate that future observational and theoretical studies of terrestrial exoplanets must consider the effect of dust., 15 pages, 4 figures, 3 tables

The Donald F. Thomson Collection of Australian Aboriginal artefacts collected between 1928 and 1965 in Cape York, Central Australia and North-East Arnhem Land is housed in the National Museum of Victoria. The Collection is an amalgamation of three major components - the artefacts themselves, a large field note section and photographic evidence of all aspects of the artefacts. The Thomson Collection has only been available for detailed anthropological investigation since Thomson's death in 1970. Since 1973 the Thomson Collection has been on loan for a period of 25 years to the Museum from the University of Melbourne with the sanction of Thomson's widow who still maintains control over the field note and photographic components of the Collection. This present study analyses only a small section of the entire Thomson Collection - that section dealing with the fishing technology from the North-East Arnhem Land region. This technology has been divided into 13 functional classes or techniques for analysis and description. This descriptive analysis is seen as a vital first step which has recognisable limitations. The limitations of such an approach have been adequately expressed by the literature dealing with material culture studies based on extant museum collections. A summary of this literature is included. While accepting that this section of the Thomson Collection is an outstanding example of an ethnographic study from the 1930's, the present study examines the possibility of updating the documentation of the Thomson Collection in the light of more recent developments in the study of material culture. To reveal any such shortcomings, Thomson's data on each of the 13 techniques is tested to see if it fulfils a set of 9 criteria concerning the manufacture and sociocultural use of the artefacts. The gaps revealed can be filled by contemporary ethnographic research. It is argued that the chances of gathering this information from contemporary Aboriginal groups to fill these gaps, rapidly diminishes with the passage of time and therefore that periodic re-studying of Thomson's collection would enable its maximum potential to be realised as well as revealing aspects of cultural change among the North-East Arnhem Land communities of today.

Low-level cloud feedbacks vary in magnitude but are positive in most climate models, due to reductions in low-level cloud fraction. This study explores the impact of surface evaporation on low-level cloud fraction feedback by performing climate change experiments with the aquaplanet configuration of the HadGEM2-A climate model, forcing surface evaporation to increase at different rates in two ways. Forcing the evaporation diagnosed in the surface scheme to increase at 7% K−1with warming (more than doubling the hydrological sensitivity) results in an increase in global mean low-level cloud fraction and a negative global cloud feedback, reversing the signs of these responses compared to the standard experiments. The estimated inversion strength (EIS) increases more rapidly in these surface evaporation forced experiments, which is attributed to additional latent heat release and enhanced warming of the free troposphere. Stimulating a 7% K−1increase in surface evaporation via enhanced atmospheric radiative cooling, however, results in a weaker EIS increase compared to the standard experiments and a slightly stronger low-level cloud reduction. The low-level cloud fraction response is predicted better by EIS than surface evaporation across all experiments. This suggests that surface-forced increases in evaporation increase low-level cloud fraction mainly by increasing EIS. Additionally, the results herein show that increases in surface evaporation can have a very substantial impact on the rate of increase in radiative cooling with warming, by modifying the temperature and humidity structure of the atmosphere. This has implications for understanding the factors controlling hydrological sensitivity.

Large uncertainty remains in future projections of tropical precipitation change under global warming. A simplified method for diagnosing tropical precipitation change is tested here on present-day El Niño–Southern Oscillation (ENSO) precipitation shifts. This method, based on the weak temperature gradient approximation, assumes precipitation is associated with local surface relative humidity (RH) and surface air temperature (SAT), relative to the tropical mean. Observed and simulated changes in RH and SAT are subsequently used to diagnose changes in precipitation. Present-day ENSO precipitation shifts are successfully diagnosed using observations (correlationr= 0.69) and an ensemble of atmosphere-only (0.51 ≤r≤ 0.8) and coupled (0.5 ≤r≤ 0.87) climate model simulations. RH (r= 0.56) is much more influential than SAT (r= 0.27) in determining ENSO precipitation shifts for observations and climate model simulations over both land and ocean. Using intermodel differences, a significant relationship is demonstrated between method performance over ocean for present-day ENSO and projected global warming (r= 0.68). As a caveat, the authors note that mechanisms leading to ENSO-related precipitation changes are not a direct analog for global warming–related precipitation changes. The diagnosis method presented here demonstrates plausible mechanisms that relate changes in precipitation, RH, and SAT under different climate perturbations. Therefore, uncertainty in future tropical precipitation changes may be linked with uncertainty in future RH and SAT changes.

A compositing scheme that predicts changes in tropical precipitation under climate change from changes in near-surface relative humidity (RH) and temperature is presented. As shown by earlier work, regions of high tropical precipitation in general circulation models (GCMs) are associated with high near-surface RH and temperature. Under climate change, it is found that high precipitation continues to be associated with the highest surface RH and temperatures in most CMIP5 GCMs, meaning that it is the “rank” of a given GCM grid box with respect to others that determines how much precipitation falls rather than the absolute value of surface temperature or RH change, consistent with the weak temperature gradient approximation. Further, it is demonstrated that the majority of CMIP5 GCMs are close to a threshold near which reductions in land RH produce large reductions in the RH ranking of some land regions, causing reductions in precipitation over land, particularly South America, and compensating increases over ocean. Recent work on predicting future changes in specific humidity allows the prediction of the qualitative sense of precipitation change in some GCMs when land surface humidity changes are unknown. However, the magnitudes of predicted changes are too small. Further study, perhaps into the role of radiative and land–atmosphere feedbacks, is necessary.

BACKGROUND: The aim of this study was to assess diagnosis severity, perioperative management and outcomes of two common urgent general surgery situations, appendicitis and cholecystitis, during the COVID-19 outbreak in a region with a high incidence of COVID. METHODS: Retrospective analysis of all appendicitis and cholecystitis cases in a region of western Switzerland (population 850,000) during the first pandemic peak. Primary endpoints were delay after first symptoms to consultation and delay to surgery. Secondary endpoints were disease severity and postoperative outcome compared with the same period in 2019. RESULTS: 214 patients were included: 99 during the 2020 pandemic and 115 in 2019. Median time to consultation for appendicitis was 48 hours (interquartile range [IQR] 24–96) in 2020 and 24 hours (12–36) in 2019 (p = 0.004); for cholecystitis, it was 48 hours (24–96) in 2020 and 36 hours (24–72) in 2019 (p = 0.28). Median time to surgery after consultation for appendicitis was 6.5 hours (IQR 4–18) in 2020 and 7.3 hours (5–9) in 2019 (p = 0.68), for cholecystitis 20 hours (12–48) in 2020 and 23 hours (14–39) in 2019 (p = 0.91). More antibiotics were prescribed after appendectomy in 2020 (46 vs 31%, p = 0.026). Significantly more perforations/abscesses related to appendicitis and cholecystitis were observed in 2020 during the COVID-19 outbreak (p = 0.007 and p = 0.044, respectively). No differences were found for postoperative complications and length of stay. CONCLUSIONS: A delay in patients’ arrival at the emergency room was observed for appendicitis. No delay to surgery during the pandemic was observed. A higher rate of perforations and abscesses associated with appendicitis and cholecystitis was observed during the pandemic period. Morbidity and reoperation rate did not change.

The El Niño–Southern Oscillation (ENSO) is the most important source of global climate variability on interannual timescales and has substantial environmental and socio-economic consequences. However, it is unclear how it interacts with large-scale climate states over longer (decadal to centennial) timescales. The instrumental ENSO record is too short for analysing long-term trends and variability and climate models are unable to accurately simulate past ENSO states. Proxy data are used to extend the record, but different proxy sources have produced dissimilar reconstructions of long-term ENSO-like climate change, with some evidence for a temperature–precipitation divergence in ENSO-like climate over the past millennium, in particular during the Medieval Climate Anomaly (MCA; AD ∼ 800–1300) and the Little Ice Age (LIA; AD ∼ 1400–1850). This throws into question the stability of the modern ENSO system and its links to the global climate, which has implications for future projections. Here we use a new statistical approach using weighting based on empirical orthogonal function (EOF) to create two new large-scale reconstructions of ENSO-like climate change derived independently from precipitation proxies and temperature proxies. The method is developed and validated using model-derived pseudo-proxy experiments that address the effects of proxy dating error, resolution, and noise to improve uncertainty estimations. We find no evidence that temperature and precipitation disagree over the ENSO-like state over the past millennium, but neither do they agree strongly. There is no statistically significant difference between the MCA and the LIA in either reconstruction. However, the temperature reconstruction suffers from a lack of high-quality proxy records located in ENSO-sensitive regions, which limits its ability to capture the large-scale ENSO signal. Further expansion of the palaeo-database and improvements to instrumental, satellite, and model representations of ENSO are needed to fully resolve the discrepancies found among proxy records and establish the long-term stability of this important mode of climatic variability.

There is a growing desire for reliable 21st-century projections of water availability at the regional scale. Global climate models (GCMs) are typically used together with global hydrological models (GHMs) to generate such projections. GCMs alone are unsuitable, especially if they have biased representations of aridity. The Budyko framework represents how water availability varies as a non-linear function of aridity and is used here to constrain projections of runoff from GCMs, without the need for computationally expensive GHMs. Considering a Chinese case study, we first apply the framework to observations to show that the contribution of direct human impacts (water consumption) to the significant decline in Yellow River runoff was greater than the contribution of aridity change by a factor of approximately 2, although we are unable to rule out a significant contribution from the net effect of all other factors. We then show that the Budyko framework can be used to narrow the range of Yellow River runoff projections by 34 %, using a multi-model ensemble and the high-end Representative Concentration Pathway (RCP8.5) emissions scenario. This increases confidence that the Yellow River will see an increase in runoff due to aridity change by the end of the 21st century. Yangtze River runoff projections change little, since aridity biases in GCMs are less substantial. Our approach serves as a quick and inexpensive tool to rapidly update and correct projections from GCMs alone. This could serve as a valuable resource when determining the water management policies required to alleviate water stress for future generations.

This work investigates the space-division multiple access grouping problem in multiuser massive multiple input multiple output (MIMO). The adopted approach consists in performing firstly the K-means algorithm, that is a classification algorithm well known in machine learning field, to split mobile stations (MSs) into spatially compatible clusters based on the knowledge of the users' spatial covariance matrices. Secondly, it schedules a sub-set of MSs from each cluster thus supporting multiple spatial streams per cluster. Furthermore, the MSs are selected based on a metric that accounts for the trade-off between their spatial channel correlation and channel gain. The corresponding scheduling is optimally solved by using branch and bound (BB) and best fit (BF) algorithms. Moreover, we compare the proposed solutions with the random scheduler that performs clustering and chooses the MSs to compose the groups at random. The simulation results show that the two proposed solutions, BB and BF outperform, the random scheduler. The BB and BF solutions achieve similar capacity performance, but the first has polynomial-time computational complexity while the second a exponential computational complexity.

Previous studies have demonstrated that continental carbon-silicate weathering is important to the continued habitability of a terrestrial planet. Despite this, few studies have considered the influence of land on the climate of a tidally-locked planet. In this work we use the Met Office Unified Model, coupled to a land surface model, to investigate the climate effects of a continent located at the sub-stellar point. We choose to use the orbital and planetary parameters of Proxima Centauri B as a template, to allow comparison with the work of others. A region of the surface where $T_{\text{s}} > 273.15\,\text{K}$ is always retained, and previous conclusions on the habitability of Proxima Centauri B remain intact. We find that sub-stellar land causes global cooling, and increases day-night temperature contrasts by limiting heat redistribution. Furthermore, we find that sub-stellar land is able to introduce a regime change in the atmospheric circulation. Specifically, when a continent offset to the east of the sub-stellar point is introduced, we observe the formation of two mid-latitude counterrotating jets, and a substantially weakened equatorial superrotating jet., 19 pages, 8 figures, Accepted for publication in The Astrophysical Journal

Full-scale accelerated pavement testing with a mobile load simulator 66 (MLS66) was conducted on a semi-rigid base asphalt pavement on a highway in Chongming Island, Shanghai, China. The goal was to investigate performance behaviour of an asphalt pavement with fine-sand subgrade in the river bed. Chongming is the terminal of G40 highway where fine sand is abundant. Although commonly found, there are little published data on its performance in a pavement structure. If found reliable in the accelerated test, the design would be used for the construction of G40 highway, which can lower the construction costs greatly and provide an engineering practice for follow-up research. Performance of the pavement structure was evaluated under high-frequency heavy trafficking while being subject to high-temperature and ambient environmental impact. This included monitoring of strains, temperature, modulus, rutting deformation, pavement depth and water level. This paper discusses the cumulative and instantaneous three-di...

The global and tropical mean water vapor and lapse rate radiative feedbacks are anticorrelated across contemporary climate models. Hence, despite substantial uncertainty in both, uncertainty in total clear-sky modeled radiative feedback is small compared with other sources of feedback spread. Previous work has demonstrated that no such correlation exists when grid point water vapor and lapse rate feedbacks are considered within one model. Here we show that robust physical processes nevertheless determine significant aspects of both the water vapor and particularly the lapse rate feedbacks within the tropics. The lapse rate feedback increases with surface temperature change because the tropical troposphere cannot maintain strong temperature gradients. The water vapor feedback increases weakly with surface temperature over tropical ocean but slightly decreases over land, associated with moisture availability. Water vapor feedback is more strongly related to precipitation changes, increasing most strongly in the heaviest precipitating regions and least in the weakest.

This study seeks to explain the effects of cloud on changes in atmospheric radiative absorption that largely balance changes in global mean precipitation under climate change. The partial radiative perturbations (PRPs) due to changes in cloud and due to the effects of the pre-existing climatological cloud distribution on non-cloud changes, known as “cloud masking”, are calculated when atmospheric CO2 concentration is doubled for the HadSM3 and MIROC models and for a large ensemble of parameter perturbed models based on HadSM3. Because the effect of cloud on changes in atmospheric shortwave absorption is almost negligible, longwave fluxes are analysed alone. We find that the net effects of cloud masking and cloud PRP on atmospheric absorption are both substantial. For the tropics, our results are reviewed in light of hypotheses put forward to explain cloud and radiative flux changes. We find that the major effects of clouds on radiation change are linked to known physical processes that are quite consistently simulated by models. Cloud top height changes are quite well described by the fixed anvil temperature hypothesis of Hartmann and Larson; cloud base heights change little, remaining near the same pressure. Changes in cloud geographical location and cloud amount are significant, but play a smaller role in driving radiative flux changes. Finally, because clouds are a large source of modelling uncertainty, we consider whether resolving errors in cloud simulation could reconcile modelled global mean precipitation trends of about 1–3 %\(\hbox {K}^{-1}\) with some estimates of observed trends of 7 %\(\hbox {K}^{-1}\) or more. This would require the radiative effect of clouds to change from one that increases atmospheric radiative absorption by about \(0.5\,\hbox {Wm}^{-2}\,\hbox {K}^{-1}\) to one that decreases it by \(-3.5\,\hbox {Wm}^{-2}\,\hbox {K}^{-1}\). Based on our results, this seems difficult to achieve within our current rationale for the tropics at least.