Large Campaign Research Articles

CREATING MULTI-TEMPORAL MAPS OF URBAN ENVIRONMENTS FOR IMPROVED LOCALIZATION OF AUTONOMOUS VEHICLES

Abstract. The development of automated and autonomous vehicles requires highly accurate long-term maps of the environment. Urban areas contain a large number of dynamic objects which change over time. Since a permanent observation of the environment is impossible and there will always be a first time visit of an unknown or changed area, a map of an urban environment needs to model such dynamics.In this work, we use LiDAR point clouds from a large long term measurement campaign to investigate temporal changes. The data set was recorded along a 20 km route in Hannover, Germany with a Mobile Mapping System over a period of one year in bi-weekly measurements. The data set covers a variety of different urban objects and areas, weather conditions and seasons. Based on this data set, we show how scene and seasonal effects influence the measurement likelihood, and that multi-temporal maps lead to the best positioning results.

Prevalence of overweight/obesity among the adult population in Ethiopia: a systematic review and meta-analysis

BackgroundOverweight and obesity are emerging public health problems in Ethiopia. However, primary study findings on the prevalence of overweight and obesity in Ethiopia are inconsistent. Therefore, this study aimed to...

On the effect of free-stream turbulence on boundary-layer transition

Abstract

Self-organizing map of soil properties in the context of hydrological modeling

One of the most relevant inputs for hydrological modeling is the soil map. The soil sources and scales for the soil properties are diverse, and the quality of soil mapping is increasing, but soil surveying is time-consuming and large area campaigns are expensive. The taxonomic unit approach for soil mapping is common and limited to one layer of data. This limitation causes errors in simulated water fluxes through the soil when taxonomic units approach is implemented during hydrological modeling analysis. Some strategies using geostatistics and machine learning algorithms such as Kriging and Self-Organizing maps (SOM) are improving the taxonomic units’ approach and could serve as an alternative for soil mapping for hydrological purposes. The aim of this work is to study the influence of different soil maps and resolutions on the main hydrological components of a sub-arid watershed in central Spain. For this, the Soil Water and Assessment Tool (SWAT) was parameterized with three different soil maps. A first one was based on Harmonized World Soil database from FAO, at scale 1:1,000,000 (HWSD). The other two were based on a Kriging interpolation at 100 × 100 m from soil samples. To obtain soil properties map from it, two strategies were applied: one was to average the soil properties following the official taxonomic soil units at 1:400,000 scale (Agricultural Technological Institute of Castilla and Leon - ITACyL) and the other was to applied Self-organizing map (SOM) to create the soil units (SOMM).The results suggest that scale and soil properties mapping influence HRU definition, which in turn affects water flow through the soils. Statistical metrics of model performance were improved from R2 =0.62 and NSE=0.46 with HWSD soil map to R2 =0.86 and NSE=0.84 with SOM and similar values were achieved during validation. Thus, the SOM is presented as an innovative algorithm applied for hydrological modeling with SWAT, significantly increasing the level of model accuracy to stream flow in sub-arid watersheds.

Editorial

Boletín Geológico number 46 (2020) publishes three articles on the disciplines of economic geology, hydrocarbon genesis, and basin evolution in several zones of Colombia. The following fragments have been taken from these articles respectively and introduce their contents.
 The Servicio Geológico Colombiano – SGC has carried out a large geophysical exploration campaign to acquire data and make it available to the academic community and mining industry. The SGC overflew the Andean and eastern part of Colombia and got more than 700,000 km of high resolution airborne geophysical (magnetometry and gamma spectrometry). Moyano et al. present an interpretation of isolated magnetic anomalies located in three different geologic environments in Colombia: San Lucas range, The Andes Cordillera, and the Amazonian craton.
 Rossello and Saavedra present a discussion about the structural aspects that contribute to the creation of the genetic and morphological characteristics of the bedding surfaces underlying the petrophysical potential of the Matachines field located in the Girardot subbasin, within the Upper Magdalena Valley basin (Valle Superior del Magdalena – VSM), Colombia. The authors focus on sectors where the primary permeability and porosity values are usually too low to meet economic expectations in hydrocarbon exploration or production activities.
 Rodríguez and Obando report new petrography, total rock chemistry and U-Pb zircon geochronology data of the La Quinta Formation, Serranía de Perijá, at the northern Andes of Colombia. This new information is correlated with other volcano-sedimentary sequences, specifies the distribution of arc volcanism and with the analysis of the inherited zircons in volcanic rocks improves the understanding of the basement distribution on which the arc is founded. 
 The editor acknowledges the efforts of the following reviewers whose comments and recommendations, on the eleven manuscripts submitted, contributed to the improvement of the three articles that were ultimately approved: Ana Ibis Despaigne, Andrés Cárdenas, Ariel Cadena, Barbara Martiny, Camilo Bustamante, César Mora, Germán Bayona, Gustavo Córdoba, Hermann Bermúdez, Hugo Murcia, Jhon Jairo Sánchez, José Luis Arce, Juan Carlos Molano, Juan Diego Colegial, Luis Castillo, Luis Enrique Cruz, Mario Moreno, Mauricio Bermúdez, Umberto Cordani, Natalia Pardo, Oswaldo Ordóñez, Thomas Cramer, and Yamirka Rojas. We recognize the final content of the articles does not necessarily reflect the thoughts of the reviewers and editors.

Decadal shifts in soil pH and organic matter differ between land uses in contrasting regions in China

Soil organic matter (SOM) and pH are critical soil properties strongly linked to carbon storage, nutrient cycling and crop productivity. Land use is known to have a dominant impact on these key soil properties, but we often lack the ability to examine temporal trajectories across extensive spatial scales. Large-scale monitoring programmes provide the data to evaluate these longer-term changes, and under different climatic conditions. This study used data from Chinese soil surveys to examine changes in soil pH and SOM across different land uses (dry farmland, paddy fields, grassland, woodland, unused land), with surface soil (0–20 cm) collected in the periods 1985–90 (Survey 1; 890 samples) and 2006–10 (Survey 2; 5005 samples) from two contrasting areas. In the southern part of China the mean pH of paddy soils fell sharply over the two decades between surveys - from pH 5.81 to 5.19 (p < 0.001), while dry farmlands in the northern sampling area fell slightly (from pH 8.15 to 7.82; p < 0.001). The mean SOM content of dry farmland soil rose in both areas and the mean SOM of paddy fields in the southern area also rose (all p < 0.001). Woodland soil pH in the south showed an increase from 4.71 to 5.29 (p < 0.001) but no significant difference was measured in the woodlands of the northern area, although the trend increased. The SOM content of woodland top soils rose in the northern (p = 0.003) and southern (p < 0.001) study areas. The implications and potential causes of these changes over the two decade timespan between surveys are discussed and suggestions made as to how large scale soil sampling campaigns can be designed to monitor for changes and potential controlling factors.

Power Quality Assessment in Railway Traction Supply Systems

The assessment of the power quality (PQ) could be a valuable tool to foster the efficiency of the railway systems. PQ is a well-addressed topic in conventional ac 50/60 Hz power systems, and many procedures, algorithms and measurement systems were presented in the international standards and widely discussed in the scientific literature. A less explored research field is the assessment of the PQ in the railway traction supply systems, in particular with reference to the dc and 16.7 Hz systems. The article explores this theme, proposing an extension of the definitions and of the standard measurement procedures for some of the main PQ indexes, well defined and widely used for conventional power systems, in order to be used also in all railway traction supply systems. The limits or difficulties of applicability are discussed with reference to measurements performed both on-board and in substation. The proposed procedures are applied to an experimental case of a real dc railway system with a large measurement campaign.

The Zwicky Transient Facility Bright Transient Survey. I. Spectroscopic Classification and the Redshift Completeness of Local Galaxy Catalogs

Abstract The Zwicky Transient Facility (ZTF) is performing a three-day cadence survey of the visible northern sky (∼3π) with newly found transient candidates announced via public alerts. The ZTF Bright Transient Survey (BTS) is a large spectroscopic campaign to complement the photometric survey. BTS endeavors to spectroscopically classify all extragalactic transients with m peak ≤ 18.5 mag in either the g ZTF or r ZTF filters, and publicly announce said classifications. BTS discoveries are predominantly supernovae (SNe), making this the largest flux-limited SN survey to date. Here we present a catalog of 761 SNe, classified during the first nine months of ZTF (2018 April 1–2018 December 31). We report BTS SN redshifts from SN template matching and spectroscopic host-galaxy redshifts when available. We analyze the redshift completeness of local galaxy catalogs, the redshift completeness fraction (RCF; the ratio of SN host galaxies with known spectroscopic redshift prior to SN discovery to the total number of SN hosts). Of the 512 host galaxies with SNe Ia, 227 had previously known spectroscopic redshifts, yielding an RCF estimate of 44% ± 4%. The RCF decreases with increasing distance and decreasing galaxy luminosity (for z &lt; 0.05, or ∼200 Mpc, RCF ≈ 0.6). Prospects for dramatically increasing the RCF are limited to new multifiber spectroscopic instruments or wide-field narrowband surveys. Existing galaxy redshift catalogs are only ∼50% complete at r ≈ 16.9 mag. Pushing this limit several magnitudes deeper will pay huge dividends when searching for electromagnetic counterparts to gravitational wave events or sources of ultra-high-energy cosmic rays or neutrinos.

Enquête sur la certification aux bonnes pratiques cliniques en recherche académique

Good clinical practice (GCP) is an international ethical and scientific quality standard for the design, conduct, performance, monitoring, auditing, recording, analyses and reporting of clinical trials. Before the start of a clinical trial, investigators commit to perform the research in accordance with GCPs, regulatory dispositions and protocol. The sponsors are responsible for investigators' selection and for controlling their skills. Whereas industrial sponsors systematically require a certificate of GCP training, academic sponsors seem to be less demanding. We have carried out two surveys between April and June 2018. A first questionnaire was sent to the 40 French academic directions of clinical research and innovation in order to determine their requirements about the GCP training of the investigators participating in their trials. The second questionnaire was transmitted to physicians of the "Bretagne recherche clinique hospitalière network": Rennes, Saint-Malo, Saint-Brieuc, Vannes, Lorient and Pontivy hospitals, in order to determine the GCP certification rate, and their needs in terms of clinical research training. Twenty-eight (70%) directions of clinical research answered the first survey, among which 18 (64%) required systematically the investigators' GCP certification in case of category 1 interventional studies. This rate decreased for category 2 (50%) and non-interventional category 3 (18%) studies. A total of 345 physicians answered the second survey, among which 263 (76%) had already been clinical trial investigators. However, only 29% of all physicians and 54% of those who had been principal investigator were certified for GCP training. These results support the need for large campaigns of GCP training in public hospitals.

Method for in situ acoustic calibration of smartphone-based sound measurement applications

Participatory measurement of environmental sound levels has gained interest in recent years. The calibration of measuring instruments is currently the main technical limitation. It is often the responsibility of the users and can be a potential source of error or add costs to the measurement protocol. In this article, a calibration protocol is proposed, based on the low variability of the average noise emission of individual vehicles. The advantage of this protocol for the user is that it does not require specific equipment, i.e. reference sound source or device, or special knowledge in acoustics. The method consists in measuring the noise level of a few vehicles as they pass through at different measuring points. The measured levels are compared to the levels expected by a numerical model, the difference serving as an offset for subsequent measurements. The robustness of the protocol is first tested over a large experimental campaign, and it turns out that measuring the passage of 15 vehicles at 3 different locations limits the error to −1.8 ± 1.0 dB(A). Then, the protocol is tested in real conditions with a set of 8 smartphones. The comparison with a class 1 sound level meter on 6 control points shows an average error on all phones of −0.6 ± 1.2 dB(A).

Building the Largest Spectroscopic Sample of Ultracompact Massive Galaxies with the Kilo Degree Survey

Abstract Ultracompact massive galaxies (ucmgs), i.e., galaxies with stellar masses and effective radii , are very rare systems, in particular at low and intermediate redshifts. Their origin as well as their number density across cosmic time are still under scrutiny, especially because of the paucity of spectroscopically confirmed samples. We have started a systematic census of ucmg candidates within the ESO Kilo Degree Survey, together with a large spectroscopic follow-up campaign to build the largest possible sample of confirmed ucmgs. This is the third paper of the series and the second based on the spectroscopic follow-up program. Here, we present photometrical and structural parameters of 33 new candidates at redshifts and confirm 19 of them as ucmgs, based on their nominal spectroscopically inferred and . This corresponds to a success rate of , nicely consistent with our previous findings. The addition of these 19 newly confirmed objects allows us to fully assess the systematics on the system selection—and to finally reduce the number density uncertainties. Moreover, putting together the results from our current and past observational campaigns and some literature data, we build the largest sample of ucmgs ever collected, comprising 92 spectroscopically confirmed objects at . This number raises to 116, allowing for a 3σ tolerance on the and thresholds for the ucmg definition. For all these galaxies, we have estimated the velocity dispersion values at the effective radii, which have been used to derive a preliminary mass–velocity dispersion correlation.

Immunogenicity of a killed bivalent whole cell oral cholera vaccine in forcibly displaced Myanmar nationals in Cox's Bazar, Bangladesh

After the large influx of Rohingya nationals (termed Forcibly Displaced Myanmar National; FDMN) from Rakhine State of Myanmar to Cox’s Bazar in Bangladesh, it was apparent that outbreaks of cholera was very likely in this setting where people were living under adverse water and sanitation conditions. Large campaigns of oral cholera vaccine (OCV) were carried out as a preemptive measure to control cholera epidemics. The aim of the study was to evaluate the immune responses of healthy adults and children after administration of two doses of OCV at 14 days interval in FDMN population and compare with the response observed in Bangladeshi’s vaccinated earlier. A cross-sectional immunogenicity study was conducted among FDMNs of three age cohort; in adults (18+years; n = 83), in older children (6–17 years; n = 63) and in younger children (1–5 years; n = 80). Capillary blood was collected at three time points to measure vibriocidal antibodies using either plasma or dried blood spot (DBS) specimens. There was a significant increase of responder frequency of vibriocidal antibody titer at day 14 in all groups for Vibrio cholerae O1 (Ogawa/Inaba: adults-64%/64%, older children-70%/89% and younger children-51%/75%). There was no overall difference of vibriocidal antibody titer between FDMN and Bangladeshi population at baseline (p = 0.07–0.08) and at day 14, day 28 in all age groups for both serotypes. The seroconversion rate and geometric mean titer (GMT) of either serotype were comparable using both plasma and DBS specimens. These results showed that OCV is capable of inducing robust immune responses in adults and children among the FDMN population which is comparable to that seen in Bangladeshi participants in different age groups or that reported from other cholera endemic countries. Our results also suggest that the displaced population were exposed to V. cholerae prior to seeking shelter in Bangladesh.

On the usability of transport protocols other than TCP: A home gateway and internet path traversal study

Network APIs are moving towards protocol agility, where applications express their needs but not a static protocol binding, and it is up to the layer below the API to choose a suitable protocol. The IETF Transport Services (TAPS) Working Group is standardizing a protocol-independent transport API and offering guidance to implementers. Apple’s recent “Network.framework” is specifically designed to allow such late and dynamic binding of protocols. When the network stack autonomously chooses and configures a protocol, it must first test which protocols are locally available and which work end-to-end (“protocol racing”). For this, it is important to know the set of available options, and which protocols should be tried first: Does it make sense to offer unchecked payload delivery, as with UDP-Lite? Is a UDP-based protocol like QUIC always a better choice, or should native SCTP be tried? This paper develops answers to such questions via (i) a NAT study in a local testbed, (ii) bidirectional Internet tests, (iii) a large scale Internet measurement campaign. The examined protocols are: SCTP, DCCP, UDP-Lite, UDP with a zero checksum and three different UDP encapsulations.

Increasing Awareness of a Provincial Mental Health Resource for Boys and Young Men 12 to 17 Years: Reflections From Foundry's Province-Wide Campaign.

Foundry empowers youth and young adults aged 12 to 24 years to lead healthy lives through a province-wide network of centers and online resources in British Columbia, Canada. However, initial evaluation data gathered from Foundry centers have shown that boys and young men are half as likely to access Foundry compared to girls and young women. To address this need, we set out to understand why boys and young men aged 12 to 17 years aren’t accessing mental health supports and to develop a promotional campaign to connect them with the resources available through Foundry. A campaign concept called “Everything Is Fine” was chosen; the campaign depicts boys and young men trying to appear as if they are OK, even though their facial expressions clearly show they are holding back stress. The campaign concept was chosen through an iterative process of research and testing. Promotion materials were created for social media (Instagram, Snapchat) and school posters, which were distributed across British Columbia, Canada . Evaluation was conducted through social media analytics and google analytics. Pre- and postsurveys were also distributed to two school districts to assess recognition of Foundry. Approximately 160,000+ persons viewed the media on Instagram, while 170,000+ viewed on Snapchat. There was a 70% increase in website traffic compared with the 3 months prior (18,881 vs. 11,126). In the surveyed school districts, Foundry awareness increased by 10% and 15%. The lessons learned from our campaign were to prioritize research and to leverage media agency experience for large campaigns.

Identifiability of single crystal plasticity parameters from residual topographies in Berkovich nanoindentation on FCC nickel

The information richness of imprints topographies obtained after Berkovich nanoindentation tests at grain scale is assessed for identifying all or part of the parameters of a single crystal plasticity law. In a previous paper (Renner et al., 2016), the strong potential of imprints topographies has been shown through a large experimental campaign conducted on nickel samples. A 3D crystal plasticity finite element modelling (CPFEM) of the nanoindentation experiment using the Méric-Cailletaud has also showed a large sensitivity of residual topographies to the indenter/grain orientation and to the plastic parameters, including the interaction matrix coefficients specifying the interactions between dislocations on different slip systems. This makes imprints topographies very good candidates to provide information for the single crystal parameters identification. The present paper focuses on the Méric-Cailletaud law parameters identifiability using residual topographies. A method is built to define the best well-posed inverse problem to ensure the parameters identification using a crystal plasticity finite element modelling updating (CPFEMU) method. An identifiability index proposed by Richard et al. (Richard et al., 2013) for measuring the information richness of the indentation curve is extended to the analysis of residual topographies. This index quantifies the possibility to achieve a stable/unstable solution using an inverse method. For the studied behaviour, the results show that eight of the nine Méric-Cailletaud law parameters can be identified using three topographies.

Evaluating techniques for mapping island vegetation from unmanned aerial vehicle (UAV) images: Pixel classification, visual interpretation and machine learning approaches

We evaluate three approaches to mapping vegetation using images collected by an unmanned aerial vehicle (UAV) to monitor rehabilitation activities in the Five Islands Nature Reserve, Wollongong (Australia). Between April 2017 and July 2018, four aerial surveys of Big Island were undertaken to map changes to island vegetation following helicopter herbicide sprays to eradicate weeds, including the creeper Coastal Morning Glory (Ipomoea cairica) and Kikuyu Grass (Cenchrus clandestinus). The spraying was followed by a large scale planting campaign to introduce native plants, such as tussocks of Spiny-headed Mat-rush (Lomandra longifolia). Three approaches to mapping vegetation were evaluated, including: (i) a pixel-based image classification algorithm applied to the composite spectral wavebands of the images collected, (ii) manual digitisation of vegetation directly from images based on visual interpretation, and (iii) the application of a machine learning algorithm, LeNet, based on a deep learning convolutional neural network (CNN) for detecting planted Lomandra tussocks. The uncertainty of each approach was assessed via comparison against an independently collected field dataset. Each of the vegetation mapping approaches had a comparable accuracy; for a selected weed management and planting area, the overall accuracies were 82 %, 91 % and 85 % respectively for the pixel based image classification, the visual interpretation / digitisation and the CNN machine learning algorithm. At the scale of the whole island, statistically significant differences in the performance of the three approaches to mapping Lomandra plants were detected via ANOVA. The manual digitisation took a longer time to perform than others. The three approaches resulted in markedly different vegetation maps characterised by different digital data formats, which offered fundamentally different types of information on vegetation character. We draw attention to the need to consider how different digital map products will be used for vegetation management (e.g. monitoring the health individual species or a broader profile of the community). Where individual plants are to be monitored over time, a feature-based approach that represents plants as vector points is appropriate. The CNN approach emerged as a promising technique in this regard as it leveraged spatial information from the UAV images within the architecture of the learning framework by enforcing a local connectivity pattern between neurons of adjacent layers to incorporate the spatial relationships between features that comprised the shape of the Lomandra tussocks detected.

Galactic archaeology with asteroseismic ages

Context. With the wealth of information from large surveys and observational campaigns in the contemporary era, it is critical to properly exploit the data to constrain the parameters of Galactic chemical evolution models and quantify the associated uncertainties. Aims. We aim to constrain the two-infall chemical evolution models for the solar annulus using the measured chemical abundance ratios and seismically inferred age of stars in the APOKASC sample. Recently, in revised two-infall chemical evolution models, a significant delay of ∼4.3 Gyr has been invoked between the two episodes of gas accretion. In this work, we wish to test its robustness and statistically confirm and quantify the delay. Methods. We took a novel approach, using Bayesian framework based on Markov chain Monte Carlo methods to fit the two-infall chemical evolution models to the data. Results. In addition to fitting the data for stars in the APOKASC sample, our best fit models also reproduce other important observational constraints of the chemical evolution of the disk: i) present day stellar surface density; ii) present-day supernova and star formation rates; iii) the metallicity distribution function; and iv) solar abundance values. We find a significant delay between the two gas accretion episodes for various models explored with different values for the star formation efficiencies. The values for the delay lie in the range 4.5−5.5 Gyr. Conclusions. The results suggest that the APOKASC sample carries the signature of a delayed gas-rich merger, with dilution being the main process determining the shape of low-α stars in the abundance ratios space.

Nanodosimetry of light ions in targets of different size

Nanodosimetry measures the frequency distribution of the number of ionizations produced by primary particles in target volumes of nanometric size. At the Legnaro National Laboratories of INFN, a large measurement campaign was carried out with the Startrack nanodosimetric counter, which showed a consistent characterization of the ionization yield produced by different primary particles when the counter is filled at the design gas pressure of 300 Pa, corresponding to a mass thickness of 2.0 μg/cm2, i.e. about 20 nm at unit density. In order to investigate the operative limits of the Startrack counter and analyse the stochastics of the ionization yield also in targets of other sizes, new measurements were carried out at lower gas pressure. A first set of measurement was carried out with different primary ions at pressures of 200 Pa and 170 Pa, corresponding to a site size in mass per area of 1.4 μg/cm2 and 1.1 μg/cm2, respectively. A second set of measurements was carried out with low-energy lithium ions, varying the pressure in the range 150–300 Pa, i.e. down to a site size of 1.0 μg/cm2 (10 nm at unit density). The measured ionization cluster-size distributions were compared with Monte Carlo simulations performed with the MC-Startrack track structure code, in order to obtain a first estimation of the decrease in detection efficiency with decreasing gas pressure. The new results and their consistency with previous measurements are presented and discussed in this paper.

EAgLE: Equivalent Acoustic Level Estimator Proposal.

Road infrastructures represent a key point in the development of smart cities. In any case, the environmental impact of road traffic should be carefully assessed. Acoustic noise is one of the most important issues to be monitored by means of sound level measurements. When a large measurement campaign is not possible, road traffic noise predictive models (RTNMs) can be used. Standard RTNMs present in literature usually require in input several information about the traffic, such as flows of vehicles, percentage of heavy vehicles, average speed, etc. Many times, the lack of information about this large set of inputs is a limitation to the application of predictive models on a large scale. In this paper, a new methodology, easy to be implemented in a sensor concept, based on video processing and object detection tools, is proposed: the Equivalent Acoustic Level Estimator (EAgLE). The input parameters of EAgLE are detected analyzing video images of the area under study. Once the number of vehicles, the typology (light or heavy vehicle), and the speeds are recorded, the sound power level of each vehicle is computed, according to the EU recommended standard model (CNOSSOS-EU), and the Sound Exposure Level (SEL) of each transit is estimated at the receiver. Finally, summing up the contributions of all the vehicles, the continuous equivalent level, Leq, on a given time range can be assessed. A preliminary test of the EAgLE technique is proposed in this paper on two sample measurements performed in proximity of an Italian highway. The results will show excellent performances in terms of agreement with the measured Leq and comparing with other RTNMs. These satisfying results, once confirmed by a larger validation test, will open the way to the development of a dedicated sensor, embedding the EAgLE model, with possible interesting applications in smart cities and road infrastructures monitoring. These sites, in fact, are often equipped (or can be equipped) with a network of monitoring video cameras for safety purposes or for fining/tolling, that, once the model is properly calibrated and validated, can be turned in a large scale network of noise estimators.

Modeling air quality in the San Joaquin valley of California during the 2013 Discover-AQ field campaign

Abstract The San Joaquin Valley (SJV) of California has one of the nation's most severe wintertime PM2.5 pollution problems. The DISCOVER-AQ (Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality) field campaign took place in the SJV from January 16 to February 6, 2013. It captured two PM2.5 pollution episodes with peak 24-h concentrations approaching 70 μg/m3. Using meteorological fields generated from WRFv3.6, CMAQv5.0.2 was applied to simulate PM2.5 formation in the SJV from January 10 through February 10, 2013. Overall, the model was able to capture the observed accumulation of PM2.5 within the simulation period. The model was able to produce increased concentrations of ammonium nitrate and organic carbon, which are two major components of wintertime PM2.5 in the SJV. Comparison to measurements made by aircraft showed that there was general agreement between observed and modeled daytime vertical distributions of selected gas and particulate species, reflecting the adequacy of modeled daytime mixing layer heights. Excess ammonia predicted by the model implied that ammonium nitrate formation was limited by the availability of nitric acid, consistent with observations. Evaluation of the ammonium nitrate diurnal profile revealed that the observed morning increase of ammonium nitrate was also evident from the model. This paper demonstrates that the CMAQ model is able to simulate elevated wintertime PM2.5 formation observed in the SJV during the DISCOVER-AQ 2013 period, which featured both climatic (i.e., 2011–2014 California Drought) and emissions differences compared to a previous large air quality field campaign in the SJV during 1999–2000.