The representation of nonlinear subgrid processes, especially clouds, has been a major source of uncertainty in climate models for decades. Cloud-resolving models better represent many of these ...processes and can now be run globally but only for short-term simulations of at most a few years because of computational limitations. Here we demonstrate that deep learning can be used to capture many advantages of cloud-resolving modeling at a fraction of the computational cost. We train a deep neural network to represent all atmospheric subgrid processes in a climate model by learning from a multiscale model in which convection is treated explicitly. The trained neural network then replaces the traditional subgrid parameterizations in a global general circulation model in which it freely interacts with the resolved dynamics and the surface-flux scheme. The prognostic multiyear simulations are stable and closely reproduce not only the mean climate of the cloud-resolving simulation but also key aspects of variability, including precipitation extremes and the equatorial wave spectrum. Furthermore, the neural network approximately conserves energy despite not being explicitly instructed to. Finally, we show that the neural network parameterization generalizes to new surface forcing patterns but struggles to cope with temperatures far outside its training manifold. Our results show the feasibility of using deep learning for climate model parameterization. In a broader context, we anticipate that data-driven Earth system model development could play a key role in reducing climate prediction uncertainty in the coming decade.
Climate changes will influence soil organisms both directly (warming) and indirectly (warming and elevated CO₂) via changes in quantity and quality of plant-mediated soil C inputs. Elevated ...atmospheric CO₂ commonly stimulates flow of organic C into the soil system, increases root production and exudation, but decreases litter quality. There is little evidence that atmospheric CO₂ enrichment will increase total soil organic matter content because greater C flow into soil stimulates the soil food web, often leading to equivalent increases in soil CO₂ efflux. Effects of warming on C allocation belowground, on the other hand, will depend largely on the temperature optima of different plant species. Warming is likely to increase the rate of soil organic matter decomposition by stimulating soil heterotrophic respiration, although some degree of acclimatization to warming is likely. Mycorrhizal and N₂-fixing relationships are generally enhanced by CO₂ enrichment, but effects of warming are highly variable. Data suggest that energy flow through fungal pathways may be enhanced relative to bacterial pathways by both warming and atmospheric CO₂ enrichment. Whether the shift toward fungal domination of soils will increase soilborne fungal disease occurrence in the future is still an open question. Plant heat and drought tolerance, along with resistance to pathogens in warmer and wetter soils, may be achieved, to some unknown extent, by exploitation and management of beneficial soil organisms. Further study is needed to develop a more holistic understanding of the effects of climate change on belowground processes.
BackgroundThe PD-1/PD-L1 checkpoint is a central mediator of immunosuppression in the tumor immune microenvironment (TME) and is primarily associated with IFN-g signaling. To characterize other ...factors regulating PD-L1 expression on tumor and/or immune cells, we investigated TME-resident cytokines and the role of transcription factors in constitutive and cytokine-induced PD-L1 expression.MethodsThirty-four cultured human tumor lines 18 melanomas (MEL), 12 renal cell carcinomas (RCC), 3 squamous cell carcinomas of the head and neck (SCCHN), and 1 non-small-cell lung carcinoma (NSCLC) and peripheral blood monocytes (Monos) were treated with cytokines that we detected in the PD-L1+ TME by gene expression profiling, including IFN-g, IL-1a, IL-10, IL-27 and IL-32g. PD-L1 cell surface protein expression was detected by flow cytometry, and mRNA by quantitative real-time PCR. Total and phosphorylated STAT1, STAT3, and p65 proteins were detected by Western blotting, and the genes encoding these proteins were knocked down with siRNAs. Additionally, the proximal promoter region of PDL1 (CD274) was sequenced in 33 cultured tumors.ResultsPD-L1 was constitutively expressed on 1/17 cultured MELs, 8/11 RCCs, 3/3 SCCHNs, and on Monos. Brief IFN-g exposure rapidly induced PD-L1 on all tumor cell lines and Monos regardless of constitutive PD-L1 expression. PD-L1 mRNA levels were associated with protein expression, which was diminished by exposure to transcriptional inhibitors. siRNA knockdown of STAT1 but not STAT3 reduced IFN-g- and IL-27-induced PD-L1 protein expression on tumor cells. In contrast, STAT3 knockdown in Monos reduced IL-10-induced PD-L1 protein expression, and p65 knockdown in tumor cells reduced IL-1a-induced PD-L1 expression. Notably, constitutive PD-L1 expression was not affected by knocking down STAT1, STAT3, or p65. Differential effects of IFN-g, IL-1a, and IL-27 on individual tumor cell lines were not due to PDL1 promoter polymorphisms.ConclusionsMultiple cytokines found in an immune-reactive TME may induce PD-L1 expression on tumor and/or immune cells through distinct signaling mechanisms. Factors driving constitutive PD-L1 expression were not identified in this study. Understanding complex mechanisms underlying PD-L1 display in the TME may allow treatment approaches mitigating expression of this immunosuppressive ligand, to enhance the impact of PD-1 blockade.
The climate sensitivity of the Madden–Julian oscillation (MJO) is measured across a broad range of temperatures (1°–35°C) using a convection-permitting global climate model with homogenous sea ...surface temperatures. An MJO-like signal is found to be resilient in all simulations. These results are used to investigate two ideas related to the modern “moisture mode” view of MJO dynamics. The first hypothesis is that the MJO has dynamics analogous to a form of radiative convective self-aggregation in which longwave energy maintenance mechanisms shut down for SST ≪ 25°C. Inconsistent with this hypothesis, the explicitly simulated MJO survives cooling and retains leading moist static energy (MSE) budget terms associated with longwave destabilization even at SST < 10°C. Thus, if the MJO is a form of longwave-assisted self-aggregation, it is not one that is temperature critical, as is observed in some cases of radiative–convective equilibrium (RCE) self-aggregation. The second hypothesis is that the MJO is propagated by horizontal advection of column MSE. Inconsistent with this view, the simulated MJO survives reversal of meridional moisture gradients in the basic state and a striking role for horizontal MSE advection in its propagation energy budget cannot be detected. Rather, its eastward motion is balanced by vertical MSE advection reminiscent of gravity or Kelvin wave dynamics. These findings could suggest a tight relation between the MJO and classic equatorial waves, which would tend to challenge moisture mode views of MJO dynamics that assume horizontal moisture advection as the MJO’s propagator. The simulation suite provides new opportunities for testing predictions from MJO theory across a broad climate regime.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The Madden–Julian Oscillation (MJO) is widely acknowledged for its ability to modulate Northwest Pacific tropical cyclones (TCs), but a complete understanding of the underlying mechanisms remains ...uncertain. Beyond established effects of the MJO's relative humidity envelope, other dynamical factors have recently been invoked via new genesis potential indices and high‐resolution modeling studies. Here we revisit the ability of the MJO to modulate West Pacific TCs through a quasi‐explicit cyclone downscaling strategy driven by composited observations, paired later with a genesis index to investigate regional drivers of modulation. We reveal two distinct spatial modes of TC modulation in which the MJO's dynamic and thermodynamic effects act in tandem to increase TCs. In the South China Sea, for instance, shear reductions associated with the MJO's circulation lead to increasing potential intensity ahead of the arrival of a positive humidity anomaly, all of which combine for an extended period of cyclogenesis favorability.
Plain Language Summary
Society is bracing for future changes in large‐scale tropical weather patterns and especially extremes like tropical cyclones. But before we can hope to understand how these storms will change in the future, we must first understand how and why their formation varies with tropical weather today. The Northwest Pacific in particular is home to more of these storms annually than any other basin, but slow‐moving atmospheric patterns that modulate tropical cyclone formations there act in ways that remain to be fully understood. Here, we combine observations with a new downscaling strategy to reveal two distinct patterns of tropical cyclone modulation by an important tropical oscillation, the Madden–Julian Oscillation (MJO). The MJO has already been linked to Northwest Pacific cyclone formation in the past, but the mechanisms are in debate. We suggest that cyclogenesis in the South China Sea is particularly sensitive to the MJO, not just due its historically recognized humidity envelope but rather from a gradual progression of both dynamic and thermodynamic variables associated with this tropical oscillation's complex propagation pattern. This discovery will be important for understanding the effects of climate change on extremes, since the MJO itself is projected to intensify in coming decades.
Key Points
Two flavors of MJO‐induced cyclogenesis modulation are found in the Northwest Pacific, created by different processes in opposing phases
TCs in the South China Sea are highly sensitive to the MJO due to combined influences of MJO‐induced thermodynamic and dynamic anomalies
Anomaly phasing leading to wind speed shutdown enables strong MJO control through SSTs in subregions: germane to climate change analysis
Despite their crucial role in health and disease, our knowledge of immune cells within human tissues remains limited. We surveyed the immune compartment of 16 tissues from 12 adult donors by ...single-cell RNA sequencing and VDJ sequencing generating a dataset of ~360,000 cells. To systematically resolve immune cell heterogeneity across tissues, we developed CellTypist, a machine learning tool for rapid and precise cell type annotation. Using this approach, combined with detailed curation, we determined the tissue distribution of finely phenotyped immune cell types, revealing hitherto unappreciated tissue-specific features and clonal architecture of T and B cells. Our multitissue approach lays the foundation for identifying highly resolved immune cell types by leveraging a common reference dataset, tissue-integrated expression analysis, and antigen receptor sequencing.
The decades between 1670 and 1730 were the most formative in the history of the French colonies in the Americas. A sufficient number of migrants arrived from France and Africa to create settlements, ...establish economies of production, develop networks of exchange and trade, and adapt institutions of government and law to give substance and form to their resulting societies. Elusive Empire was the first full account of how during these years French settlers came to the Americas. It examines how they and thousands of African slaves together with Amerindians constructed settlements and produced and traded commodities for export. Bringing together much evidence, the author explores how the newly constructed societies and new economies, without precedent in France, interacted with the growing international violence in the Atlantic world in order to present a fresh perspective of the multifarious French colonizing experience in the Americas.
Background
Previous assessments of colon morphology have relied on tests which were either invasive or used ionizing radiation. We aimed to measure regional volumes of the undisturbed colon in ...healthy volunteers (HV) and patients with diarrhea‐predominant irritable bowel syndrome (IBS‐D).
Methods
3D regional (ascending, transverse, and descending) colon volumes were measured in fasting abdominal magnetic resonance (MR) images of 75 HVs and 25 IBS‐D patients. Thirty‐five of the HV and all 25 IBS‐D subjects were fed a standard meal and postprandial MRI data obtained over 225 min.
Key Results
Colonic regions were identified and 3D maps from cecum to sigmoid flexure were defined. Fasted regional volumes showed wide variation in both HVs being (mean ± SD) ascending colon (AC) 203 ± 75 mL, transverse (TC) 198 ± 79 mL, and descending (DC) 160 ± 86 mL with no difference from IBS‐D subjects (AC 205 ± 69 mL, TC 232 ± 100 mL, and DC 151 ± 71 mL, respectively). The AC volume expanded by 10% after feeding (p = 0.007) in the 35 HV possibly due to increased ileo‐colonic inflow. A later rise in AC volume occurred from t = 90 to t = 240 min as the meal residue entered the cecum. In contrast, IBS‐D subjects showed a much reduced postprandial response of the AC (p < 0.0001) and a greater increase in TC volume after 90 min (p = 0.0244) compared to HV.
Conclusions & Inferences
We have defined a normal range of the regional volumes of the undisturbed colon in fasted and fed states. The AC in IBS‐D appeared less able to accommodate postprandial inflow which may account for faster colonic transit.
Serial MRI regional volume measurements of the undisturbed colon show the ascending (AC) and transverse (TC) colon volumes to both be approximately 200 mL whereas the descending colon is about 25% smaller, volumes which are similar in health and IBS. Although the AC expanded 10% immediately after eating in health, this increase was not seen in IBS‐D subjects implying failure to accommodate which may account for faster colonic transit.
Regional climate modeling addresses our need to understand and simulate climatic processes and phenomena unresolved in global models. This paper highlights examples of current approaches to and ...innovative uses of regional climate modeling that deepen understanding of the climate system. High-resolution models are generally more skillful in simulating extremes, such as heavy precipitation, strong winds, and severe storms. In addition, research has shown that finescale features such as mountains, coastlines, lakes, irrigation, land use, and urban heat islands can substantially influence a region’s climate and its response to changing forcings. Regional climate simulations explicitly simulating convection are now being performed, providing an opportunity to illuminate new physical behavior that previously was represented by parameterizations with large uncertainties. Regional and global models are both advancing toward higher resolution, as computational capacity increases. However, the resolution and ensemble size necessary to produce a sufficient statistical sample of these processes in global models has proven too costly for contemporary supercomputing systems. Regional climate models are thus indispensable tools that complement global models for understanding physical processes governing regional climate variability and change. The deeper understanding of regional climate processes also benefits stakeholders and policymakers who need physically robust, high-resolution climate information to guide societal responses to changing climate. Key scientific questions that will continue to require regional climate models, and opportunities are emerging for addressing those questions.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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