pinecone/core-2020-05-10-deduplication huggingface dataset:
Digraphs with Distinguishable Dynamics under the Multi-Agent Agreement
  Protocol

In this work, the ability to distinguish digraphs from the output response of
some observing agents in a multi-agent network under the agreement protocol has
been studied. Given a fixed observation point, it is desired to find sufficient
graphical conditions under which the failure of a set of edges in the network
information flow digraph is distinguishable from another set. When the latter
is empty, this corresponds to the detectability of the former link set given
the response of the observing agent. In developing the results, a powerful
extension of the all-minors matrix tree theorem in algebraic graph theory is
proved which relates the minors of the transformed Laplacian of a directed
graph to the number and length of the shortest paths between its vertices. The
results reveal an intricate relationship between the ability to distinguish the
responses of a healthy and a faulty multi-agent network and the inter-nodal
paths in their information flow digraphs. The results have direct implications
for the operation and design of multi-agent systems subject to multiple link
losses. Simulations and examples are presented to illustrate the analytic
findings
Smooth Output Reconstruction for Linear Systems with Quantized Measurements

Article first published online: 31 JUL 2014This paper presents a novel approach to reconstruct the output of linear systems in the case where the measured output is uniformly quantized. By fitting the quantized measurements with polynomials in a moving horizon manner, a smooth signal is reconstructed by solving a convex optimization problem with ℓ1-norm regularization. The quantization feature and the system models are taken into account in the optimization. A numerical example is given to show the excellent reconstruction performance of the proposed method. In addition, the proposed method is implemented in a high-precision linear stage through DSP, and its effectiveness is verified through experiments using a real positioning system
Precompensated Second Order Repetitive Control of an Active Filter Under Varying Network Frequency

Network frequency variations cause a dramatic performance decay in repetitive controller-based shunt active power filters. This problem may be solved by adapting the sampling period in order to keep the ratio between the network period and the sampling period at a constant value. However, these changes may yield closed-loop instability. The introduction of a precompensator that forces the plant to remain invariant despite sampling rate changes allows the use of standard LTI methods in control design and stability analysis as well. Moreover, in order to improve robustness in the face of network frequency estimation uncertainty and sampling time quantization, the regular repetitive controller is replaced by a high order one. Experimental results show the validity of the proposal.Peer ReviewedPostprint (author's final draft
Fault-Tolerant Stabilization in Discrete-Time Multiple-Integrator Networks with General Information Sharing

The paper considers a network of agentswith identical discrete-timemultiple-integrator dynamics. The agents share\ud
information according to an arbitrary topology. The information is relative to the states corresponding to some of the\ud
highest integration levels.With reference to this setting, a decentralized stabilization problem is faced, under the further\ud
assumption that faults may occur in the communication apparatus of one or several of the agents. A necessary and\ud
sufficient solvability condition is presented for the problem, together with formulas for a class of least-order regulators
Eastern Antarctic Peninsula precipitation delivery mechanisms: Process studies and back trajectory evaluation

Copyright @ 2008 Royal Meteorological SocietyThe atmospheric circulation patterns that result in precipitation events at a site on the eastern Antarctic Peninsula (AP) are investigated using back trajectories (BTs) driven by ERA-40 data. Moisture delivery occurs from the east and west depending on the location of blocking events in the South Atlantic and Pacific Oceans. Observations are sparse in this region, so our process studies compare the trajectories (and the ERA-40 fields from which they were derived) with advanced very high resolution radiometer (AVHRR) satellite images. It is found that the trajectories represent these transport mechanisms very well and that they are relatively insensitive to the initial trajectory elevation
Development of a high resolution daily gridded temperature data set (1969-2005) for the Indian region

A high resolution daily gridded temperature data set for the Indian region was developed using temperature data of 395 quality controlled stations for the period 1969–2005. A modified version of the Shepard's angular distance weighting algorithm was used for interpolating the station temperature data into 1° latitude × 1° longitude grids. Using the cross validation, errors were estimated and found less than 0.5 °C. The data set was also compared with another high resolution data set and found comparable. Mean frequency of cold and heat waves, temperature anomalies associated with the monsoon breaks have been presented
Antarctic winter tropospheric warming - the potential role of polar stratospheric clouds, a sensitivity study

Over the last 30 years, Antarctic mid-tropospheric temperatures in winter have increased by 0.5 K per decade, the largest regional tropospheric warming observed. Over this period, amounts of polar stratospheric cloud(PSC) have also increased, as rising CO2 concentrations cooled the stratosphere. By imposing an idealisation of these increases in PSC within the radiation scheme of an atmosphere-only general circulation model, we find that they could have contributed to the observed warming. The present generation of global climate models do not properly represent PSCs, and so these results demonstrate the need to improve the representation of PSCs. Copyright. (C) 2009 Royal Meteorological Society and Crown Copyrigh
A diagnosis of warm-core and cold-core extratropical cyclone development using the Zwack–Okossi equation

In this study, the development of a warm-core and cold-core extratropical cyclone over
North Atlantic is examined. The geostrophic relative vorticity tendency used to diagnose
the development is calculated utilizing the so-called extended form of the Zwack–Okossi
development equation. In both cases, the cyclonic vorticity advection acted to develop
the system, but warm-air advection (diabatic heating) made the largest contribution to
explosive development in the cold-core (warm-core) case. Further, a vertical cross section of
the temperature advection in the warm-core case reveals that the largest values of this
contributor are located far and ahead of the cyclone center
Equatorial upper-ocean dynamics and their interaction with the West African monsoon

Zonal wind anomalies in the western equatorial Atlantic during late boreal winter to early summer precondition boreal summer cold/warm events in the eastern equatorial Atlantic (EEA) that manifest in a strong interannual Atlantic cold tongue (ACT) variability. Local intraseasonal wind fluctuations, linked to the St. Helena anticyclone, contribute to the variability of cold tongue onset and strength, particularly during years with preconditioned\ud
shallow thermoclines. The impact of cold tongue sea surface temperature (SST) anomalies on the wind field in the Gulf of Guinea is assessed. It contributes to the northward migration of humidity and convection and possibly the West African monsoon (WAM) jump. Copyright @ 2010 Royal Meteorological Societ
Nanoparticle emissions from biofuelled vehicles - their characteristics and impact on the number-based regulation of atmospheric particles

The transport sector is the dominant source of nanoparticles in the urban atmosphere. It is also responsible for about 20-25% of current global CO2 emissions, a figure that is expected to grow to about 30-50% by 2050 (Fuglestvedt et al., 2008). One option to counter this trend and contribute to the attainment of carbon emission reduction targets is the use of biofuels in road vehicles. This leads to a reduction in CO, CO2 and particle mass emissions, though particle number emissions may increase. This article discusses the potential impact of the particle number concentrations derived from biofuel vehicles on existing regulatory concerns over atmospheric nanoparticles. Copyright (C) 2010 Royal Meteorological Societ
AMMA's contribution to the evolution of prediction and decision-making systems for West Africa

The AMMA (African Monsoon Multidisciplinary Analysis) project set out to better understand the geophysical processes which govern the evolution of the monsoon and provide the science needed to improve prediction and decision-support systems. The control exerted by weather and climate on agronomic production, water resources and public health was studied to evaluate the potential for populations to adapt. AMMA made advances which have the potential to improve forecasts from weather to climate scales. Translating them into operational tools for decision making will require improvements to the observational networks, and stronger support for the organizations which generate and disseminate application forecast
The AMMA Field Campaigns: accomplishments and lessons learned

The AMMA (African Monsoon Multidiscplinary Analysis) field programme aimed at documenting the West African Monsoon (WAM) climate system, in all its geophysical components. It also includes an important socio-economic component. Encompassing a wide range of spatial and time scales, AMMA is one of the most ambitious such programmes ever set up. While the key accomplishments of AMMA are summarised in this paper, a few lessons of broad interest are also drawn both as a tribute to the extraordinary efforts made by a community of several hundreds of people and as possible guidelines for ensuring a long lasting future to integrated climate and environmental studies in West Africa
Modeled and observed soil moisture variability over a region of Argentina

The aim of this study is to document how soil moisture variability is represented by global analyses and regional atmospheric models compared with a unique dataset of sparse measurements over an agricultural productive area of Argentina. Results show that normalized simulated soil moisture values and their temporal variability are largely different from the observations. However, there is a strong agreement among values derived using the same land surface model, suggesting a strong influence of the forcing fields used by the different analyses/simulations. This work also discusses possible sources of model limitations for representing soil moisture variability over the region.Fil: Ferreira, Lorena Judith. Ministerio de Defensa. Secretaria de Planeamiento. Servicio Meteorológico Nacional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Salgado, Hector. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval; ArgentinaFil: Saulo, Andrea Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmosfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmosfera; ArgentinaFil: Collini, Estela Angela. Ministerio de Defensa. Secretaria de Planeamiento. Servicio Meteorológico Nacional; Argentina. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval; Argentin
Tropical influence on th﻿e summer Mediterranean climate

Observational evidence shows that, during 1979–2001, the summer Atlantic Niño is related to an increase in the precipitation over the Central Mediterranean and a decrease in the west and east of the basin, a relation absent in previous decades. Using a set of integrations with a global climate model, this work investigates the dynamics underlying such change before and after the 1970s.\ud
\ud
We find that the post-1970's response depends on the interactions between the influences from different tropical regions, and that one needs to consider the different impacts of the tropical oceans for the correct prediction of summer Mediterranean climatePeer reviewe
Atmospheric water parameters measured by a ground-based microwave radiometer and compared with the WRF model

The microwave radiometer TROWARA measures integrated water vapour (IWV) and integrated cloud liquid water (ILW) at Bern since 1994 with a time resolution of 7 s. In this study, we compare TROWARA measurements with a simulation of summer 2012 in Switzerland performed with the Weather Research and Forecasting (WRF) model. It is found that the WRF model agrees very well with TROWARA’s IWV variations with a mean bias of only 0.7 mm. The ILW distribution of the WRF model, although similar in shape to TROWARA’s distribution, overestimates the fraction of clear sky periods (83% compared to 60%)
Seasonal winter forecasts and the stratosphere

Published© 2016 Royal Meteorological Society. We investigate seasonal forecasts of the winter North Atlantic Oscillation (NAO) and their relationship with the stratosphere. Climatological frequencies of sudden stratospheric warming (SSW) and strong polar vortex (SPV) events are well represented and the predicted risk of events varies between 25 and 90% from winter to winter, indicating predictability beyond the deterministic range. The risk of SSW and SPV events relates to predicted NAO as expected, with NAO shifts of -6.5 and +4.8hPa in forecast members containing SSW and SPV events. Most striking of all is that forecast skill of the surface winter NAO vanishes from these hindcasts if members containing SSW events are excluded.This work was supported by the Joint DECC/Defra Met Office
Hadley Centre Climate Programme (GA01101), the UK Public
Weather Service research program and the European Union
Framework 7 SPECS project. The contribution of AYK is funded
by FMI’s tenure track program and the Academy of Finland
under grant 286298
Indian summer monsoon prediction and simulation in CFSv2 coupled model

Using carefully designed coupled model experiments, we have demonstrated that the prediction skill of the all India summer monsoon rainfall (AISMR) in Climate Forecast System version 2 (CFSv2) model basically comes from the El-Niňo Southern Oscillation-Monsoon teleconnection. On the other hand, contrary to observations, the Indian Ocean coupled dynamics do not have a crucial role in controlling the prediction skill of the AISMR in CFSv2. We show that the inadequate representation of the Indian Ocean coupled dynamics in CFSv2 is responsible for this dichotomy. Hence, the improvement of the Indian Ocean coupled dynamics is essential for further improvement of the AISMR prediction skill in CFSv2
Development of a non-hydrostatic atmospheric model using the Chimera grid method for a steep terrain

In a high-resolution atmospheric model, the terrain is resolved in detail, and thus steeper and more complex terrain can be represented. Thus, we developed an atmospheric model that represents the terrain by using the Chimera grid method, which represents the computational region as a composite of overlapping grids. To test this model, we simulated a lee wave over a semicircular mountain and one over a tall semi-elliptical mountain. The results show that the Chimera grid method can be used to represent a very steep terrain which terrain-following coordinates and numerically generated coordinates cannot represent appropriately
Land surface atmosphere interaction in future South American climate using a multi-model ensemble

The land-atmosphere interaction for reference and future climate is estimated with a regional climate model ensemble. In reference climate, more than 50% of the models show interaction in southeastern South America during austral spring, summer and autumn. In future climate, the region remains a strong hotspot although somewhat weakened due to the wet response that enhance energy limitation on the evapotranspiration. The region of the Brazilian Highlands and Matto Grosso appears as a new extensive hotspot during austral spring. This is related to a dry response which is probably accentuated by land surface feedbacks.Fil: Ruscica, Romina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera; ArgentinaFil: Menendez, Claudio Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera; ArgentinaFil: Sörensson, A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera; Argentin
Entrainment and droplet spectral characteristics in convective clouds during transition to monsoon

In situ observations in growing deep cumulus in polluted and clean environments during the transition to monsoon over Indian peninsula are used to investigate entrainment effects on droplet size distribution and the width of possible cloud cores. Pre-monsoon clouds indicate reduction in spectral width in the diluted cloud volumes due to lateral entrainment whereas monsoon cloud has higher spectral width. Relative dispersion is observed to increase with the distance from cloud core of monsoon cloud while for pre-monsoon clouds it remained almost constant. Enhanced entrainment in polluted pre-monsoon clouds is responsible for narrow cloud core compared to monsoon cloud
Orographic effect on tropical rain physics in the Asian monsoon region

Effect of orography on tropical rain drop size distribution (DSD), which was not well known, is evidenced through the present study. DSD is the number of raindrops/unit volume/diameter interval, which tells about the underlying physics of rainfall process. Rain DSD was studied, using a Joss-Waldvogel disdrometer, at three coastal and a hill station in the Tropics. The variation in the characteristics of three physically significant parameters derived from the DSD with rain rate clearly unraveled the effect of orography on rain physics. The orographic rain appears to have larger drops compared with nonorographic rains when rain rate is high
Different long-term trends of extra-tropical cyclones and windstorms in ERA-20C and NOAA-20CR reanalyses

NOAA 20th century and ERA-20C reanalysis datasets are evaluated regarding the representation of extra-tropical cyclones and windstorms over the Northern and Southern Hemisphere during the respective 6-month winter seasons. The results indicate substantial differences in low-frequency variability between the two datasets – especially in the first half of the 20th century – expressed in different signs and/or magnitudes of long-term trends. This is hampering a reliable analysis of real long-term trends of cyclone and windstorm activity. However, higher-frequency variability is in good agreement between both datasets especially for the Northern Hemisphere
Multidecadal convection permitting climate simulations over Belgium: Sensitivity of future precipitation extremes

We performed five high resolution (2.8 km) decadal convection permitting scale (CPS) climate simulations over Belgium using the COSMO-CLM regional climate model and examined the future changes in daily precipitation extremes compared to coarser resolution simulations. The CPS model underestimates the higher percentiles during both seasons, however, some improvements in the higher percentile values are noticed during the summer season. Analysis of three future climate simulations indicates that the CPS model modifies the future signals of daily precipitation extremes compared to their forcing non-CPS simulations during summer. During this season, the increase (decrease) in the daily precipitation extremes is stronger in the CPS compared to the non-CPS simulations. During winter, no significant changes between CPS and non-CPS were found.status: publishe
Projection in snowfall characteristics over the European Alps and its sensitivity to the SST changes: results from a 50 km resolution AGCM

The end-of-century projection of the snowfall characteristics over the Alps region is studied using the 50-km resolution atmospheric global climate model, HiRAM (high-resolution atmospheric model). The model is forced by three different patterns of projections in the sea surface temperature (SST) in order to assess the sensitivity of snowfall characteristics to theses patterns. It is found that the mean snowfall intensity and frequency is poorly affected by the differences in SST forcing. However, the projections of heavy snowfall events strongly depend on the SST scenario. The changes in temperature and frequency of precipitation and freezing days over the Alps were investigated. We found that these variables did not exhibit a clear dependence to the SST scenario and could not explain the differences observed in snowfall projections. Changes in the moisture transport from the Atlantic Ocean to Europe were found significantly different between each scenario and are assumed to be the main factor affecting the projections of snowfalls, by providing more or less moisture supply
Quantifying the extremity of windstorms for regions featuring infrequent events

This paper introduces the Distribution-Independent Storm Severity Index (DI-SSI). The DI-SSI represents an approach to quantify the severity of exceptional surface wind speeds of large scale windstorms that is complementary to the SSI introduced by Leckebusch et al. While the SSI approaches the extremeness of a storm from a meteorological and potential loss (impact) perspective, the DI-SSI defines the severity in a more climatological perspective. The idea is to assign equal index values to wind speeds of the same singularity (e.g. the 99th percentile) under consideration of the shape of the tail of the local wind speed climatology. Especially in regions at the edge of the classical storm track, the DI-SSI shows more equitable severity estimates, e.g. for the extra-tropical cyclone Klaus. In order to compare the indices, their relation with the North Atlantic Oscillation is studied, which is one of the main large scale drivers for the intensity of European windstorms
Analogous seasonal evolution of the South Atlantic SST dipole indices

Two variants of sea-surface temperature (SST) dipole indices for the South Atlantic Ocean (SAO) has been previously described representing: (1) the South Atlantic subtropical dipole (SASD) supposedly peaking in austral summer and (2) the SAO dipole (SAOD) in winter. In this study, we present the analysis of observational data sets (1985–2014) showing the SASD and SAOD as largely constituting the same mode of ocean–atmosphere interaction reminiscent of the SAOD structure peaking in winter. Indeed, winter is the only season in which the inverse correlation between the northern and southern poles of both indices is statistically significant. The observed SASD and SAOD indices exhibit robust correlations (P ≤ 0.001) in all seasons and these are reproduced by 54 of the 63 different models of the Coupled Models Intercomparison Project analysed. Their robust correlations notwithstanding the SASD and SAOD indices appear to better capture different aspects of SAO climate variability and teleconnection