Papers by Claudio Sanchez
How a warmer Mediterranean preconditions the upper-level environment for the development of Medicane Ianos
. Medicane Ianos in September 2020 was one of the strongest medicanes observed in the last 25 yea... more . Medicane Ianos in September 2020 was one of the strongest medicanes observed in the last 25 years. It was, like other medicanes, a very intense cyclone evolving from a baroclinic mid-latitude low into a tropical-like cyclone. The dynamical elements necessary to improve the predictability of Ianos are explored with the use of simulations with the Met Office Unified Model (MetUM) at 2.2 km grid spacing for five different initialisation times, from four to two days before Ianos's landfall. Simulations are also performed with the Sea Surface Temperature (SST) uniformly increased and decreased by 2 K from analysis to explore the impact of enhanced and reduced sea-surface surface fluxes on Ianos's evolution. All the simulations with +2 K SST are able to simulate medicane Ianos, albeit too intensely. The simulations with control SST initialised at the two earliest times fail to capture intense preceding precipitation events at the right locations, and the subsequent development of Ianos. Amongst the simulations with -2 K SST, only the one initialised at the latest time develops the medicane. Links between sea-surface fluxes and upper-level baroclinic processes are investigated. We find (i) a bubble of low-valued potential vorticity (PV) formed within a trough above where Ianos developed, diabatic processes associated with a preceding precipitation event triggered a balanced divergent flow in the upper-levels which contributed to the creation and maintenance this low-PV bubble, as shown by results from a semi-geostrophic inversion tool, (ii) Upper-level geostrophic vorticity advection associated with the low-PV bubble forced quasi-geostrophic ascent during Ianos's cyclogenesis, and (iii) diabatic processes dominated by deep convection formed a vertical PV tower in Ianos and continued to produce diabatically-induced divergent outflow aloft, thus sustaining Ianos's development. Simulations missing any of these three elements do not develop medicane Ianos. Our results imply that preceding convection was essential for the subsequent development of Ianos, highlighting the importance of the interactions between near-surface small-scale diabatic processes and the upper-level quasi-geostrophic flow. A warmer SST strengthens the processes and thus enables Ianos to be predicted in simulations initiated at the earlier times that failed to generate the medicane with control SSTs.
On 18 September 2020, Medicane Ianos hit the western coast of Greece, resulting in flooding and s... more On 18 September 2020, Medicane Ianos hit the western coast of Greece, resulting in flooding and severe damage at several coastal locations. In this work, we aim at evaluating its impact on sea conditions and the associated uncertainty through the use of an ensemble of numerical simulations. We applied a coupled wave-current model to an unstructured mesh, representing the whole Mediterranean Sea, with a grid resolution increasing in the Ionian Sea along the cyclone path and the landfall area. To investigate the uncertainty in modelling sea levels and waves for such an intense event, we performed an ensemble of ocean simulations using several coarse (10 km) and high-resolution (2 km) meteorological forcings from different mesoscale models. The performance of the ocean and wave models was evaluated against observations retrieved from fixed monitoring stations and satellites. All model runs emphasized the occurrence of severe sea conditions along the cyclone path and at the coast. Due to the rugged and complex coastline, extreme sea levels are localized at specific coastal sites. However, numerical results show a large spread of the simulated sea conditions for both the sea level and waves, highlighting the large uncertainty in simulating this kind of extreme event. The multi-model and multi-physics approach allows us to assess how the uncertainty propagates from meteorological to ocean variables and the subsequent coastal impact. The ensemble mean and standard deviation were combined to prove the hazard scenarios of the potential impact of such an extreme event to be used in a flood risk management plan.
NUMAC: Description of the Nested Unified Model with Aerosols and Chemistry, and evaluation with KORUS-AQ data
We describe and evaluate a system for regional modeling of atmospheric composition with the Met O... more We describe and evaluate a system for regional modeling of atmospheric composition with the Met Office Unified Model (UM), suitable for climate, weather forecasting and air quality applications. In this system, named NUMAC (‘Nested UM with Aerosols and Chemistry’), a global model provides boundary conditions for regional models nested within it, using the Met Office’s Regional Nesting Suite for multi-scale simulations. The regional models, which can run at convection-permitting or cloud-resolving scales, use the same code as the global model. The system includes double-moment prognostic aerosol microphysics with interactive chemistry of sulfur species, ozone, NO and CO as in the UK Earth System Model (UKESM). Double-moment prognostic cloud microphysics is optional. To test NUMAC, we compare simulations to surface and aircraft measurements from NASA’s KORUS-AQ campaign over South Korea. The performance of the regional model, which we run at 5 km resolution, is similar to the well-eva...
MOHC HadGEM3-GC31-LL model output prepared for CMIP6 CFMIP aqua-p4K
Coupled Model Intercomparison Project Phase 6 (CMIP6) data sets: These data includes all datasets... more Coupled Model Intercomparison Project Phase 6 (CMIP6) data sets: These data includes all datasets published for 'CMIP6.CFMIP.MOHC.HadGEM3-GC31-LL.aqua-p4K' according to the Data Reference Syntax defined as 'mip_era.activity_id.institution_id.source_id.experiment_id.member_id.table_id.variable_id.grid_label.version'. The model used in climate research named HadGEM3-GC3.1-N96ORCA1, released in 2016, includes the components: aerosol: UKCA-GLOMAP-mode, atmos: MetUM-HadGEM3-GA7.1 (N96; 192 x 144 longitude/latitude; 85 levels; top level 85 km), land: JULES-HadGEM3-GL7.1, ocean: NEMO-HadGEM3-GO6.0 (eORCA1 tripolar primarily 1 deg with meridional refinement down to 1/3 degree in the tropics; 360 x 330 longitude/latitude; 75 levels; top grid cell 0-1 m), seaIce: CICE-HadGEM3-GSI8 (eORCA1 tripolar primarily 1 deg; 360 x 330 longitude/latitude). The model was run by the Met Office Hadley Centre, Fitzroy Road, Exeter, Devon, EX1 3PB, UK (MOHC) in native nominal resolutions: aero...
MOHC HadGEM3-GC31-MM model output prepared for CMIP6 PAMIP pdSST-futOkhotskSIC
Coupled Model Intercomparison Project Phase 6 (CMIP6) data sets: These data includes all datasets... more Coupled Model Intercomparison Project Phase 6 (CMIP6) data sets: These data includes all datasets published for 'CMIP6.PAMIP.MOHC.HadGEM3-GC31-MM.pdSST-futOkhotskSIC' according to the Data Reference Syntax defined as 'mip_era.activity_id.institution_id.source_id.experiment_id.member_id.table_id.variable_id.grid_label.version'. The model used in climate research named HadGEM3-GC3.1-N216ORCA025, released in 2016, includes the components: aerosol: UKCA-GLOMAP-mode, atmos: MetUM-HadGEM3-GA7.1 (N216; 432 x 324 longitude/latitude; 85 levels; top level 85 km), land: JULES-HadGEM3-GL7.1, ocean: NEMO-HadGEM3-GO6.0 (eORCA025 tripolar primarily 0.25 deg; 1440 x 1205 longitude/latitude; 75 levels; top grid cell 0-1 m), seaIce: CICE-HadGEM3-GSI8 (eORCA025 tripolar primarily 0.25 deg; 1440 x 1205 longitude/latitude). The model was run by the Met Office Hadley Centre, Fitzroy Road, Exeter, Devon, EX1 3PB, UK (MOHC) in native nominal resolutions: aerosol: 100 km, atmos: 100 km, land...
SINGV: A convective‐scale weather forecast model for Singapore
Quarterly Journal of the Royal Meteorological Society, 2020
Numerical weather prediction (NWP) capabilities in the Maritime Continent are not as developed as... more Numerical weather prediction (NWP) capabilities in the Maritime Continent are not as developed as in the midlatitudes. Countries in the region do not develop their own modelling systems; rather they adapt models primarily developed for the midlatitudes. Due to the complexity of processes involved in the region, this adaptation is non‐trivial. In this article the developments made by the Meteorological Service Singapore (MSS) and the United Kingdom Met Office (UKMO) to implement a convective‐scale NWP system for short‐range weather prediction for Singapore and the surrounding regions are presented. In particular, this article describes the changes to the initial model configuration, which was based on the UKMO's convective‐scale NWP system (the UKV), to produce operational forecasts over this region. Results presented here demonstrate the benefit of convection‐permitting simulations over convection parametrized simulations and show that the model performance is greatly affected b...
Urban intensification of convective rainfall over the Singapore – Johor Bahru region
Quarterly Journal of the Royal Meteorological Society, 2021
Simulations of five November months (2010–2014) using the urban version of the numerical weather ... more Simulations of five November months (2010–2014) using the urban version of the numerical weather prediction system of the Meteorological Service Singapore (uSINGV) are used to analyse the urban effect on convective precipitation over Singapore and Johor Bahru (Malaysia). The model is able to closely predict locations where rainfall peaks occur, but rainfall totals are overestimated compared to radar data. The temporal variability of rainfall in the region shows that urban areas increase the frequency and severity of rainfall events and that such impact increases with the rainfall intensity. Results show that low‐level moisture advection is enhanced in this coastal conurbation as a result of the strengthening of wind convergence. The latter is likely caused by increasing sea‐breeze strength due to lower surface pressure over the urban area, and higher urban surface roughness, respectively. As a consequence, more precipitable water is available in the region, enhancing convection and ...
Urban‐induced modifications to the diurnal cycle of rainfall over a tropical city
Quarterly Journal of the Royal Meteorological Society, 2021
There is still no consensus on the mechanisms that modify precipitation over and around cities, e... more There is still no consensus on the mechanisms that modify precipitation over and around cities, especially for those located in the tropics where convective processes primarily drive rainfall. Here we contribute to the ongoing discussion about the urban‐associated precipitation by investigating the urban effect on the diurnal cycle of rainfall over Singapore. We use the urban version of the numerical weather prediction system of the Meteorological Service Singapore (hereafter called uSINGV) at a 300 m horizontal resolution to simulate the rainfall conditions over Singapore and its surroundings during the inter‐monsoon period between 2010 and 2014. Two simulations with different land surface conditions are conducted: one with urban areas (i.e. present conditions) and one without urban areas. uSINGV is shown to perform well for rainfall when compared to observations. Comparison between simulations reveals that the urban area is responsible for the formation of a rainfall “hot spot” ov...
Quarterly Journal of the Royal Meteorological Society, 2019
A tropical version of the high‐resolution (300 m) UK Met Office forecast model (UM) using the MOR... more A tropical version of the high‐resolution (300 m) UK Met Office forecast model (UM) using the MORUSES urban canopy parametrization (UCP) is adapted for Singapore. High‐resolution urban surface parameters are determined using a methodology based on Voronoi polygons applied to a 3D building database. The model is evaluated for clear sky and calm conditions at the neighbourhood scale by comparing its predictions with two sources of observations: energy balance data from an eddy covariance flux tower located in a low‐rise residential area, and a network of sensors measuring screen‐level temperature across the city. The model is able to reproduce the diurnal cycle of the surface energy balance fluxes. Net radiation is overestimated which likely follows from an underestimation in cloud cover and effective surface albedo. This overestimation partly explains the overestimation of the sensible‐ and latent‐heat fluxes. The higher model sensible‐heat flux is further hypothesised to be related ...
Climate Dynamics, 2018
The article describes the configuration and preliminary assessment of a high-resolution atmospher... more The article describes the configuration and preliminary assessment of a high-resolution atmosphere-ocean coupled model developed for the western Maritime Continent (MC). Regional configurations of the UK Met Office Unified Model (MetUM) and the Nucleus for European Modelling of the Ocean (NEMO) model are used as the atmosphere and ocean components of the coupled system. The OASIS3-MCT libraries have been employed for the exchange of heat, fresh water and momentum fluxes between these two components. Both models have a same horizontal resolution of 4.5 km × 4.5 km and similar domain. The atmospheric and ocean initial condition to the coupled model is derived from ERA-interim reanalysis and ocean-only model hindcast simulation, respectively. First, we compare the ocean-only surface as well as subsurface temperature and salinity simulations with observations/reanalysis. Then to assess the performance of the coupled model, 5-day forecast of a cold surge event on 23-27 January 2016 and typhoon Sarika on 16-20 October 2016 are performed. Further, to investigate the impact of air-sea coupling, the model simulations are compared with the atmosphere-only and ocean-only model simulations. The coupled forecast shows improvement in the simulation of low level winds, surface air temperature, sea surface height and sea surface temperature during the cold surge. Though the influence of coupling on the typhoon track prediction is mixed, the coupled model performs better in terms of the intensity, structure and dissipation of the typhoon. Overall, the coupling has improved the model skill in predicting the atmosphere/ocean variables, and the impact of coupling on atmospheric parameters is particularly noticeable over the oceanic region.
2013 Evaluation of Sunday Friends: The Working Alternative to Charity
Immigrant status and neighborhood context on perceptions of police procedural justice
Social Science Quarterly
ObjectiveThis study examines the relationship between immigration generational status and people&... more ObjectiveThis study examines the relationship between immigration generational status and people's perception of police procedural justice, net of individual‐level and neighborhood‐level control variables. It also explores the importance of contextual variables, particularly neighborhood foreign‐born concentration and collective efficacy, on residents’ perceptions of police procedural justice.MethodsWith a multi‐stage, clustered sample approach, we randomly selected census tracts in San José, California, and then households inside each tract were chosen to participate in a survey. We used multi‐level modeling to explore factors that were associated with procedural justice.ResultsResults show first‐generation immigrants, compared to second or third‐and‐plus‐generation immigrants, are more positive in their evaluations of police procedural justice. Results also show that neighborhood collective efficacy can significantly affect people's perceptions of procedural justice, even ...
Procedural justice, neighbourhood context, and domestic violence reporting intention among subgroups of immigrants
Policing and Society, 2022
S2 Example rose namelists for RCS-IND1 configurations of UM, JULES, NEMO and WAVEWATCH III nameli... more S2 Example rose namelists for RCS-IND1 configurations of UM, JULES, NEMO and WAVEWATCH III namelists The provided text file gmd-2022-rcs-ind1-namelists.txt includes a set of UM, JULES, NEMO and WAVEWATCH III rose namelists for an atmosphere-ocean-wave simulation run of the RCS-IND1 configuration, using UM code base vn11.1, JULES vn5.2, NEMO vn4.1, WAVEWATCHIII vn4.18.
A new regional coupled modelling framework is introduced-the Regional Coupled Suite (RCS). This p... more A new regional coupled modelling framework is introduced-the Regional Coupled Suite (RCS). This provides a flexible research capability with which to study the interactions between atmosphere, land, ocean and wave processes resolved at km-scale, and the effect of environmental feedbacks on the evolution and impacts of multi-hazard weather events. A configuration of the RCS focussed on the Indian region, termed RCS-IND1, is introduced. RCS-IND1 includes a regional configuration of the Unified Model (UM) atmosphere, directly coupled to the JULES land surface model, on a grid with horizontal spacing of 4.4 km, enabling convection to be explicitly simulated. These are coupled through OASIS3-MCT libraries to 2.2 km grid NEMO ocean and WAVEWATCH III wave model configurations. To examine a potential approach to reduce computation cost, and simplify ocean initialisation, the RCS includes an alternative approach to couple the atmosphere to a 1ower resolution Multi-Column K Profile Parameterization (KPP) for the ocean. Through development of a flexible modelling framework, a variety of fully and partially coupled experiments can be defined, along with traceable uncoupled simulations and options to use external input forcing in place of missing coupled components. This offers a wide scope to researchers designing sensitivity and case study assessments. Case study results are presented and assessed to demonstrate the application of RCS-IND1 to simulate two tropical cyclone cases which developed in the Bay of Bengal, namely Titli in October 2018 and Fani in April 2019. Results show realistic cyclone simulations, and that coupling can improve the cyclone track and produces more realistic intensification than uncoupled simulations for Titli but prevents sufficient intensification for Fani. Atmosphere-only UM regional simulations omit the influence of frictional heating on the
A substantial segment of the error in numerical weather prediction and climate projections comes ... more A substantial segment of the error in numerical weather prediction and climate projections comes from the intrinsic uncertainties of General Circulation Models of the atmosphere. Stochastic physics schemes are one of the preferred methods to represent the model uncertainty in Ensemble Prediction Systems, where different realizations of the same forecast are created to quantify the probabilities of different outcomes in the atmospheric flow. Stochastic physics schemes have been successfully employed in medium-range and seasonal forecasting systems, as they increase the skill of probabilistic forecasts. Similarly it has been demonstrated than these schemes can improve certain aspects of the model’s climate. However, it is still not clear whether they are a truthful representation of the model uncertainties they aim to represent. In this thesis, a collection of stochastic physics schemes are evaluated using a seamless approach. It is found that they can improve the representation of th...
Migration to well-off countries has been well documented. However, the reasons why migrants retur... more Migration to well-off countries has been well documented. However, the reasons why migrants return to their home countries, which often face severe economic disadvantages, are examined less frequently. The return migration of Japanese-Brazilians (Brazilian citizens of ethnic Japanese descent) who migrate to Japan and return again to Brazil has not been studied to any great extent. To understand the factors associated with Japanese-Brazilians’ return migration, using Gmelch's (1983) model of push and pull factors, we examined what motivated Japanese-Brazilian migrant laborers to return to Brazil from Japan. With a mixed method including in-person interviews, a total of n=47 Brazilian migrants to Japan were sampled in São Paulo, Brazil. The present examination resulted in a pattern similar to the one Gmelch (1983) observed in his study on Irish and Newfoundlander return migrants. In the current study, pull factors were more important than push factors in terms of repatriation. Per...
Bulletin of the American Physical Society, 2014
La Red de coordinacion y seguimiento del master en Gestion Sostenible y Tecnologias del Agua inte... more La Red de coordinacion y seguimiento del master en Gestion Sostenible y Tecnologias del Agua integra profesores del master, responsables de asignaturas, el gestor administrativo y la coordinadora, para supervisar el desarrollo de este master. Ademas participan tambien 3 alumnos del curso 2016-17, como portavoces de otros companeros, para la transmision de informacion actualizada con respecto al proceso de ensenanza-aprendizaje. Las actas de las reuniones con los alumnos proporcionaran las herramientas para estudiar las acciones de mejora, que deberan ser analizadas por el profesorado. En este curso las encuestas sobre el profesorado tuvieron mayor participacion (>88 %) que anteriormente, al ser realizadas en horarios del master. Los resultados medios para cada modulo tematico no muestran diferencias significativas entre profesores externos y de la UA, con buenos resultados. La valoracion de las visitas realizadas es excelente. Los resultados de las encuestas de los modulos a nive...
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Papers by Claudio Sanchez