@inproceedings{14187, abstract = {We propose a novel Stochastic Frank-Wolfe (a.k.a. conditional gradient) algorithm for constrained smooth finite-sum minimization with a generalized linear prediction/structure. This class of problems includes empirical risk minimization with sparse, low-rank, or other structured constraints. The proposed method is simple to implement, does not require step-size tuning, and has a constant per-iteration cost that is independent of the dataset size. Furthermore, as a byproduct of the method we obtain a stochastic estimator of the Frank-Wolfe gap that can be used as a stopping criterion. Depending on the setting, the proposed method matches or improves on the best computational guarantees for Stochastic Frank-Wolfe algorithms. Benchmarks on several datasets highlight different regimes in which the proposed method exhibits a faster empirical convergence than related methods. Finally, we provide an implementation of all considered methods in an open-source package.}, author = {Négiar, Geoffrey and Dresdner, Gideon and Tsai, Alicia and Ghaoui, Laurent El and Locatello, Francesco and Freund, Robert M. and Pedregosa, Fabian}, booktitle = {Proceedings of the 37th International Conference on Machine Learning}, location = {Virtual}, pages = {7253--7262}, title = {{Stochastic Frank-Wolfe for constrained finite-sum minimization}}, volume = {119}, year = {2020}, } @inproceedings{14188, abstract = {Intelligent agents should be able to learn useful representations by observing changes in their environment. We model such observations as pairs of non-i.i.d. images sharing at least one of the underlying factors of variation. First, we theoretically show that only knowing how many factors have changed, but not which ones, is sufficient to learn disentangled representations. Second, we provide practical algorithms that learn disentangled representations from pairs of images without requiring annotation of groups, individual factors, or the number of factors that have changed. Third, we perform a large-scale empirical study and show that such pairs of observations are sufficient to reliably learn disentangled representations on several benchmark data sets. Finally, we evaluate our learned representations and find that they are simultaneously useful on a diverse suite of tasks, including generalization under covariate shifts, fairness, and abstract reasoning. Overall, our results demonstrate that weak supervision enables learning of useful disentangled representations in realistic scenarios.}, author = {Locatello, Francesco and Poole, Ben and Rätsch, Gunnar and Schölkopf, Bernhard and Bachem, Olivier and Tschannen, Michael}, booktitle = {Proceedings of the 37th International Conference on Machine Learning}, location = {Virtual}, pages = {6348–6359}, title = {{Weakly-supervised disentanglement without compromises}}, volume = {119}, year = {2020}, } @article{14195, abstract = {The idea behind the unsupervised learning of disentangled representations is that real-world data is generated by a few explanatory factors of variation which can be recovered by unsupervised learning algorithms. In this paper, we provide a sober look at recent progress in the field and challenge some common assumptions. We first theoretically show that the unsupervised learning of disentangled representations is fundamentally impossible without inductive biases on both the models and the data. Then, we train over 14000 models covering most prominent methods and evaluation metrics in a reproducible large-scale experimental study on eight data sets. We observe that while the different methods successfully enforce properties “encouraged” by the corresponding losses, well-disentangled models seemingly cannot be identified without supervision. Furthermore, different evaluation metrics do not always agree on what should be considered “disentangled” and exhibit systematic differences in the estimation. Finally, increased disentanglement does not seem to necessarily lead to a decreased sample complexity of learning for downstream tasks. Our results suggest that future work on disentanglement learning should be explicit about the role of inductive biases and (implicit) supervision, investigate concrete benefits of enforcing disentanglement of the learned representations, and consider a reproducible experimental setup covering several data sets.}, author = {Locatello, Francesco and Bauer, Stefan and Lucic, Mario and Rätsch, Gunnar and Gelly, Sylvain and Schölkopf, Bernhard and Bachem, Olivier}, journal = {Journal of Machine Learning Research}, publisher = {MIT Press}, title = {{A sober look at the unsupervised learning of disentangled representations and their evaluation}}, volume = {21}, year = {2020}, } @inproceedings{9001, abstract = {Quantum illumination is a sensing technique that employs entangled signal-idler beams to improve the detection efficiency of low-reflectivity objects in environments with large thermal noise. The advantage over classical strategies is evident at low signal brightness, a feature which could make the protocol an ideal prototype for non-invasive scanning or low-power short-range radar. Here we experimentally investigate the concept of quantum illumination at microwave frequencies, by generating entangled fields using a Josephson parametric converter which are then amplified to illuminate a room-temperature object at a distance of 1 meter. Starting from experimental data, we simulate the case of perfect idler photon number detection, which results in a quantum advantage compared to the relative classical benchmark. Our results highlight the opportunities and challenges on the way towards a first room-temperature application of microwave quantum circuits.}, author = {Barzanjeh, Shabir and Pirandola, Stefano and Vitali, David and Fink, Johannes M}, booktitle = {IEEE National Radar Conference - Proceedings}, isbn = {9781728189420}, issn = {1097-5659}, location = {Florence, Italy}, number = {9}, publisher = {IEEE}, title = {{Microwave quantum illumination with a digital phase-conjugated receiver}}, doi = {10.1109/RadarConf2043947.2020.9266397}, volume = {2020}, year = {2020}, } @article{9007, abstract = {Motivated by a recent question of Peyre, we apply the Hardy–Littlewood circle method to count “sufficiently free” rational points of bounded height on arbitrary smooth projective hypersurfaces of low degree that are defined over the rationals.}, author = {Browning, Timothy D and Sawin, Will}, issn = {14208946}, journal = {Commentarii Mathematici Helvetici}, number = {4}, pages = {635--659}, publisher = {European Mathematical Society}, title = {{Free rational points on smooth hypersurfaces}}, doi = {10.4171/CMH/499}, volume = {95}, year = {2020}, } @article{9011, abstract = {Distributed ledgers provide high availability and integrity, making them a key enabler for practical and secure computation of distributed workloads among mutually distrustful parties. Many practical applications also require strong confidentiality, however. This work enhances permissioned and permissionless blockchains with the ability to manage confidential data without forfeiting availability or decentralization. The proposed Calypso architecture addresses two orthogonal challenges confronting modern distributed ledgers: (a) enabling the auditable management of secrets and (b) protecting distributed computations against arbitrage attacks when their results depend on the ordering and secrecy of inputs. Calypso introduces on-chain secrets, a novel abstraction that enforces atomic deposition of an auditable trace whenever users access confidential data. Calypso provides user-controlled consent management that ensures revocation atomicity and accountable anonymity. To enable permissionless deployment, we introduce an incentive scheme and provide users with the option to select their preferred trustees. We evaluated our Calypso prototype with a confidential document-sharing application and a decentralized lottery. Our benchmarks show that transaction-processing latency increases linearly in terms of security (number of trustees) and is in the range of 0.2 to 8 seconds for 16 to 128 trustees.}, author = {Kokoris Kogias, Eleftherios and Alp, Enis Ceyhun and Gasser, Linus and Jovanovic, Philipp and Syta, Ewa and Ford, Bryan}, issn = {2150-8097}, journal = {Proceedings of the VLDB Endowment}, number = {4}, pages = {586--599}, publisher = {Association for Computing Machinery}, title = {{CALYPSO: Private data management for decentralized ledgers}}, doi = {10.14778/3436905.3436917}, volume = {14}, year = {2020}, } @article{9039, abstract = {We give a short and self-contained proof for rates of convergence of the Allen--Cahn equation towards mean curvature flow, assuming that a classical (smooth) solution to the latter exists and starting from well-prepared initial data. Our approach is based on a relative entropy technique. In particular, it does not require a stability analysis for the linearized Allen--Cahn operator. As our analysis also does not rely on the comparison principle, we expect it to be applicable to more complex equations and systems.}, author = {Fischer, Julian L and Laux, Tim and Simon, Theresa M.}, issn = {10957154}, journal = {SIAM Journal on Mathematical Analysis}, number = {6}, pages = {6222--6233}, publisher = {Society for Industrial and Applied Mathematics}, title = {{Convergence rates of the Allen-Cahn equation to mean curvature flow: A short proof based on relative entropies}}, doi = {10.1137/20M1322182}, volume = {52}, year = {2020}, } @inproceedings{9040, abstract = {Machine learning and formal methods have complimentary benefits and drawbacks. In this work, we address the controller-design problem with a combination of techniques from both fields. The use of black-box neural networks in deep reinforcement learning (deep RL) poses a challenge for such a combination. Instead of reasoning formally about the output of deep RL, which we call the wizard, we extract from it a decision-tree based model, which we refer to as the magic book. Using the extracted model as an intermediary, we are able to handle problems that are infeasible for either deep RL or formal methods by themselves. First, we suggest, for the first time, a synthesis procedure that is based on a magic book. We synthesize a stand-alone correct-by-design controller that enjoys the favorable performance of RL. Second, we incorporate a magic book in a bounded model checking (BMC) procedure. BMC allows us to find numerous traces of the plant under the control of the wizard, which a user can use to increase the trustworthiness of the wizard and direct further training.}, author = {Alamdari, Par Alizadeh and Avni, Guy and Henzinger, Thomas A and Lukina, Anna}, booktitle = {Proceedings of the 20th Conference on Formal Methods in Computer-Aided Design}, isbn = {9783854480426}, issn = {2708-7824}, location = {Online Conference}, pages = {138--147}, publisher = {TU Wien Academic Press}, title = {{Formal methods with a touch of magic}}, doi = {10.34727/2020/isbn.978-3-85448-042-6_21}, year = {2020}, } @article{9054, abstract = {The fundamental and practical importance of particle stabilization has motivated various characterization methods for studying polymer brushes on particle surfaces. In this work, we show how one can perform sensitive measurements of neutral polymer coating on colloidal particles using a commercial zetameter and salt solutions. By systematically varying the Debye length, we study the mobility of the polymer-coated particles in an applied electric field and show that the electrophoretic mobility of polymer-coated particles normalized by the mobility of non-coated particles is entirely controlled by the polymer brush and independent of the native surface charge, here controlled with pH, or the surface–ion interaction. Our result is rationalized with a simple hydrodynamic model, allowing for the estimation of characteristics of the polymer coating: the brush length L, and the Brinkman length ξ, determined by its resistance to flows. We demonstrate that the Debye layer provides a convenient and faithful probe to the characterization of polymer coatings on particles. Because the method simply relies on a conventional zetameter, it is widely accessible and offers a practical tool to rapidly probe neutral polymer brushes, an asset in the development and utilization of polymer-coated colloidal particles.}, author = {Youssef, Mena and Morin, Alexandre and Aubret, Antoine and Sacanna, Stefano and Palacci, Jérémie A}, issn = {1744-6848}, journal = {Soft Matter}, keywords = {General Chemistry, Condensed Matter Physics}, number = {17}, pages = {4274--4282}, publisher = {Royal Society of Chemistry }, title = {{Rapid characterization of neutral polymer brush with a conventional zetameter and a variable pinch of salt}}, doi = {10.1039/c9sm01850f}, volume = {16}, year = {2020}, } @article{9059, abstract = {From rock salt to nanoparticle superlattices, complex structure can emerge from simple building blocks that attract each other through Coulombic forces1-4. On the micrometre scale, however, colloids in water defy the intuitively simple idea of forming crystals from oppositely charged partners, instead forming non-equilibrium structures such as clusters and gels5-7. Although various systems have been engineered to grow binary crystals8-11, native surface charge in aqueous conditions has not been used to assemble crystalline materials. Here we form ionic colloidal crystals in water through an approach that we refer to as polymer-attenuated Coulombic self-assembly. The key to crystallization is the use of a neutral polymer to keep particles separated by well defined distances, allowing us to tune the attractive overlap of electrical double layers, directing particles to disperse, crystallize or become permanently fixed on demand. The nucleation and growth of macroscopic single crystals is demonstrated by using the Debye screening length to fine-tune assembly. Using a variety of colloidal particles and commercial polymers, ionic colloidal crystals isostructural to caesium chloride, sodium chloride, aluminium diboride and K4C60 are selected according to particle size ratios. Once fixed by simply diluting out solution salts, crystals are pulled out of the water for further manipulation, demonstrating an accurate translation from solution-phase assembly to dried solid structures. In contrast to other assembly approaches, in which particles must be carefully engineered to encode binding information12-18, polymer-attenuated Coulombic self-assembly enables conventional colloids to be used as model colloidal ions, primed for crystallization. }, author = {Hueckel, Theodore and Hocky, Glen M. and Palacci, Jérémie A and Sacanna, Stefano}, issn = {1476-4687}, journal = {Nature}, keywords = {Multidisciplinary}, number = {7804}, pages = {487--490}, publisher = {Springer Nature}, title = {{Ionic solids from common colloids}}, doi = {10.1038/s41586-020-2205-0}, volume = {580}, year = {2020}, } @article{9067, abstract = {Gadolinium silicide (Gd5Si4) nanoparticles are an interesting class of materials due to their high magnetization, low Curie temperature, low toxicity in biological environments and their multifunctional properties. We report the magnetic and magnetothermal properties of gadolinium silicide (Gd5Si4) nanoparticles prepared by surfactant-assisted ball milling of arc melted bulk ingots of the compound. Using different milling times and speeds, a wide range of crystallite sizes (13–43 nm) could be produced and a reduction in Curie temperature (TC) from 340 K to 317 K was achieved, making these nanoparticles suitable for self-controlled magnetic hyperthermia applications. The magnetothermal effect was measured in applied AC magnetic fields of amplitude 164–239 Oe and frequencies 163–519 kHz. All particles showed magnetic heating with a strong dependence of the specific absorption rate (SAR) on the average crystallite size. The highest SAR of 3.7 W g−1 was measured for 43 nm sized nanoparticles of Gd5Si4. The high SAR and low TC, (within the therapeutic range for magnetothermal therapy) makes the Gd5Si4 behave like self-regulating heat switches that would be suitable for self-controlled magnetic hyperthermia applications after biocompatibility and cytotoxicity tests.}, author = {Nauman, Muhammad and Alnasir, Muhammad Hisham and Hamayun, Muhammad Asif and Wang, YiXu and Shatruk, Michael and Manzoor, Sadia}, issn = {2046-2069}, journal = {RSC Advances}, keywords = {General Chemistry, General Chemical Engineering}, number = {47}, pages = {28383--28389}, publisher = {Royal Society of Chemistry}, title = {{Size-dependent magnetic and magnetothermal properties of gadolinium silicide nanoparticles}}, doi = {10.1039/d0ra05394e}, volume = {10}, year = {2020}, } @article{9069, abstract = {In the quest for alternate and efficient electrode materials, ternary metal electrocatalysts (TMEs), part of the perovskite family, were synthesized and tested for methanol electro-oxidation in alkaline media. La0.5Ca0.5MO3 (M = Ni, Co, or Mn) was synthesized via sol-gel method. X-ray diffraction analysis revealed that the perovskite crystal structure possesses characteristic sharp and crystalline peaks for all synthesized ternary electrocatalysts. The average particle size calculated using Debye–Scherrer equation was in the order of La0.5Ca0.5NiO3 (LCNO) > La0.5Ca0.5CoO3 (LCCO)> La0.5Ca0.5MnO3 (LCMO). The elemental composition of as prepared sample, LCCO was investigated via x-ray fluorescence spectroscopy. The qualitative and quantitative analysis revealed the presence of La, Ca and Co in parent crystal structure with percentage compositions of 9.0, 3.12 and 87.82% respectively. The particle size distribution was homogenous, as determined by scanning electron and transmission electron microscopes. The electrocatalytic activity of the synthesized ternary electrocatalysts was studied electrochemically by cyclic voltammetry. The calculated diffusion coefficient values showed that electrode surface of LCNO and LCCO have limited efficiency for diffusion related phenomenon. The heterogeneous rate constants inferred better electrode kinetics of LCCO and LCNO which exhibited good electrocatalytic behavior; sharp anodic peaks were observed in the potential range of +0.3 to 0.6 V and +0.6 to 0.8 V, respectively. Methanol electro-oxidation was found minimal in case of LCMO sample. We have observed that Co substitution at B-site of perovskite electrode materials attains better electrochemical properties, thus in relation with reported literature.}, author = {Hussain, Tayyaba and Nauman, Muhammad and Sabahat, Sana and Arif, Saira}, issn = {2053-1591}, journal = {Materials Research Express}, keywords = {Electronic, Optical and Magnetic Materials, Surfaces, Coatings and Films, Polymers and Plastics, Metals and Alloys, Biomaterials}, number = {12}, publisher = {IOP Publishing}, title = {{Synthesis of ternary electrocatalysts for exploration of methanol electro-oxidation in alkaline media}}, doi = {10.1088/2053-1591/ab6886}, volume = {6}, year = {2020}, } @inbook{9096, author = {Schmid-Hempel, Paul and Cremer, Sylvia M}, booktitle = {Encyclopedia of Social Insects}, editor = {Starr, C}, isbn = {9783319903064}, publisher = {Springer Nature}, title = {{Parasites and Pathogens}}, doi = {10.1007/978-3-319-90306-4_94-1}, year = {2020}, } @inproceedings{9103, abstract = {We introduce LRT-NG, a set of techniques and an associated toolset that computes a reachtube (an over-approximation of the set of reachable states over a given time horizon) of a nonlinear dynamical system. LRT-NG significantly advances the state-of-the-art Langrangian Reachability and its associated tool LRT. From a theoretical perspective, LRT-NG is superior to LRT in three ways. First, it uses for the first time an analytically computed metric for the propagated ball which is proven to minimize the ball’s volume. We emphasize that the metric computation is the centerpiece of all bloating-based techniques. Secondly, it computes the next reachset as the intersection of two balls: one based on the Cartesian metric and the other on the new metric. While the two metrics were previously considered opposing approaches, their joint use considerably tightens the reachtubes. Thirdly, it avoids the "wrapping effect" associated with the validated integration of the center of the reachset, by optimally absorbing the interval approximation in the radius of the next ball. From a tool-development perspective, LRT-NG is superior to LRT in two ways. First, it is a standalone tool that no longer relies on CAPD. This required the implementation of the Lohner method and a Runge-Kutta time-propagation method. Secondly, it has an improved interface, allowing the input model and initial conditions to be provided as external input files. Our experiments on a comprehensive set of benchmarks, including two Neural ODEs, demonstrates LRT-NG’s superior performance compared to LRT, CAPD, and Flow*.}, author = {Gruenbacher, Sophie and Cyranka, Jacek and Lechner, Mathias and Islam, Md Ariful and Smolka, Scott A. and Grosu, Radu}, booktitle = {Proceedings of the 59th IEEE Conference on Decision and Control}, isbn = {9781728174471}, issn = {07431546}, location = {Jeju Islang, Korea (South)}, pages = {1556--1563}, publisher = {IEEE}, title = {{Lagrangian reachtubes: The next generation}}, doi = {10.1109/CDC42340.2020.9304042}, volume = {2020}, year = {2020}, } @article{9104, abstract = {We consider the free additive convolution of two probability measures μ and ν on the real line and show that μ ⊞ v is supported on a single interval if μ and ν each has single interval support. Moreover, the density of μ ⊞ ν is proven to vanish as a square root near the edges of its support if both μ and ν have power law behavior with exponents between −1 and 1 near their edges. In particular, these results show the ubiquity of the conditions in our recent work on optimal local law at the spectral edges for addition of random matrices [5].}, author = {Bao, Zhigang and Erdös, László and Schnelli, Kevin}, issn = {15658538}, journal = {Journal d'Analyse Mathematique}, pages = {323--348}, publisher = {Springer Nature}, title = {{On the support of the free additive convolution}}, doi = {10.1007/s11854-020-0135-2}, volume = {142}, year = {2020}, } @article{9114, abstract = {Microwave photonics lends the advantages of fiber optics to electronic sensing and communication systems. In contrast to nonlinear optics, electro-optic devices so far require classical modulation fields whose variance is dominated by electronic or thermal noise rather than quantum fluctuations. Here we demonstrate bidirectional single-sideband conversion of X band microwave to C band telecom light with a microwave mode occupancy as low as 0.025 ± 0.005 and an added output noise of less than or equal to 0.074 photons. This is facilitated by radiative cooling and a triply resonant ultra-low-loss transducer operating at millikelvin temperatures. The high bandwidth of 10.7 MHz and total (internal) photon conversion efficiency of 0.03% (0.67%) combined with the extremely slow heating rate of 1.1 added output noise photons per second for the highest available pump power of 1.48 mW puts near-unity efficiency pulsed quantum transduction within reach. Together with the non-Gaussian resources of superconducting qubits this might provide the practical foundation to extend the range and scope of current quantum networks in analogy to electrical repeaters in classical fiber optic communication.}, author = {Hease, William J and Rueda Sanchez, Alfredo R and Sahu, Rishabh and Wulf, Matthias and Arnold, Georg M and Schwefel, Harald G.L. and Fink, Johannes M}, issn = {2691-3399}, journal = {PRX Quantum}, number = {2}, publisher = {American Physical Society}, title = {{Bidirectional electro-optic wavelength conversion in the quantum ground state}}, doi = {10.1103/prxquantum.1.020315}, volume = {1}, year = {2020}, } @inbook{9123, abstract = {Inversions are chromosomal rearrangements where the order of genes is reversed. Inversions originate by mutation and can be under positive, negative or balancing selection. Selective effects result from potential disruptive effects on meiosis, gene disruption at inversion breakpoints and, importantly, the effects of inversions as modifiers of recombination rate: Recombination is strongly reduced in individuals heterozygous for an inversion, allowing for alleles at different loci to be inherited as a ‘block’. This may lead to a selective advantage whenever it is favourable to keep certain combinations of alleles associated, for example under local adaptation with gene flow. Inversions can cover a considerable part of a chromosome and contain numerous loci under different selection pressures, so that the resulting overall effects may be complex. Empirical data from various systems show that inversions may have a prominent role in local adaptation, speciation, parallel evolution, the maintenance of polymorphism and sex chromosome evolution.}, author = {Westram, Anja M and Faria, Rui and Butlin, Roger and Johannesson, Kerstin}, booktitle = {eLS}, isbn = {9780470016176}, publisher = {Wiley}, title = {{Inversions and Evolution}}, doi = {10.1002/9780470015902.a0029007}, year = {2020}, } @unpublished{9124, abstract = {The couplings among clouds, convection, and circulation in trade-wind regimes remain a fundamental puzzle that limits our ability to constrain future climate change. Radiative heating plays an important role in these couplings. Here we calculate the clear-sky radiative profiles from 2001 in-situ soundings (978 dropsondes and 1023 radiosondes) collected during the EUREC4A field campaign, which took place south and east of Barbados in January–February 2020. We describe the method used to calculate these radiative profiles and present preliminary results sampling variability at multiple scales, from the variability across all soundings to groupings by diurnal cycle and mesoscale organization state, as well as individual soundings associated with elevated moisture layers. This clear-sky radiative profiles data set can provide important missing detail to what can be learned from calculations based on passive remote sensing and help in investigating the role of radiation in dynamic and thermodynamic variability in trade-wind regimes. All data are archived and freely available for public access on AERIS (Albright et al. (2020), https://doi.org/10.25326/78).}, author = {Albright, Anna Lea and Fildier, Benjamin and Touzé-Peiffer, Ludovic and Pincus, Robert and Vial, Jessica and Muller, Caroline J}, booktitle = {Earth System Science Data}, publisher = {Copernicus Publications}, title = {{Atmospheric radiative profiles during EUREC4A}}, doi = {10.5194/essd-2020-269}, year = {2020}, } @article{9125, abstract = {This study investigates the feedbacks between an interactive sea surface temperature (SST) and the self‐aggregation of deep convective clouds, using a cloud‐resolving model in nonrotating radiative‐convective equilibrium. The ocean is modeled as one layer slab with a temporally fixed mean but spatially varying temperature. We find that the interactive SST decelerates the aggregation and that the deceleration is larger with a shallower slab, consistent with earlier studies. The surface temperature anomaly in dry regions is positive at first, thus opposing the diverging shallow circulation known to favor self‐aggregation, consistent with the slower aggregation. But surprisingly, the driest columns then have a negative SST anomaly, thus strengthening the diverging shallow circulation and favoring aggregation. This diverging circulation out of dry regions is found to be well correlated with the aggregation speed. It can be linked to a positive surface pressure anomaly (PSFC), itself the consequence of SST anomalies and boundary layer radiative cooling. The latter cools and dries the boundary layer, thus increasing PSFC anomalies through virtual effects and hydrostasy. Sensitivity experiments confirm the key role played by boundary layer radiative cooling in determining PSFC anomalies in dry regions, and thus the shallow diverging circulation and the aggregation speed.}, author = {Shamekh, S. and Muller, Caroline J and Duvel, J.‐P. and D'Andrea, F.}, issn = {1942-2466}, journal = {Journal of Advances in Modeling Earth Systems}, keywords = {Global and Planetary Change, General Earth and Planetary Sciences, Environmental Chemistry}, number = {11}, publisher = {American Geophysical Union}, title = {{Self‐aggregation of convective clouds with interactive sea surface temperature}}, doi = {10.1029/2020ms002164}, volume = {12}, year = {2020}, } @article{9126, abstract = {The goal of this study is to understand the mechanisms controlling the isotopic composition of the water vapor near the surface of tropical oceans, at the scale of about a hundred kilometers and a month. In the tropics, it has long been observed that the isotopic compositions of rain and vapor near the surface are more depleted when the precipitation rate is high. This is called the “amount effect.” Previous studies, based on observations or models with parameterized convection, have highlighted the roles of deep convective and mesoscale downdrafts and rain evaporation. But the relative importance of these processes has never been quantified. We hypothesize that it can be quantified using an analytical model constrained by large‐eddy simulations. Results from large‐eddy simulations confirm that the classical amount effect can be simulated only if precipitation rate changes result from changes in the large‐scale circulation. We find that the main process depleting the water vapor compared to the equilibrium with the ocean is the fact that updrafts stem from areas where the water vapor is more enriched. The main process responsible for the amount effect is the fact that when the large‐scale ascent increases, isotopic vertical gradients are steeper, so that updrafts and downdrafts deplete the subcloud layer more efficiently.}, author = {Risi, Camille and Muller, Caroline J and Blossey, Peter}, issn = {1942-2466}, journal = {Journal of Advances in Modeling Earth Systems}, keywords = {Global and Planetary Change, General Earth and Planetary Sciences, Environmental Chemistry}, number = {8}, publisher = {American Geophysical Union}, title = {{What controls the water vapor isotopic composition near the surface of tropical oceans? Results from an analytical model constrained by large‐eddy simulations}}, doi = {10.1029/2020ms002106}, volume = {12}, year = {2020}, }