Raul R. Cordero

• Dr. rer. nat.; Dr. Eng.
• Professor (Associate) at University of Santiago Chile

Black carbon (BC) from fossil fuel and biomass combustion darkens the snow and makes it melt sooner. The BC footprint of research activities and tourism in Antarctica has likely increased as human presence in the continent has surged in recent decades. Here, we report on measurements of the BC concentration in snow samples from 28 sites across a tr...

Sustainable development requires climate change mitigation and thereby a fast energy transition to renewables. However, climate change may affect renewable power outputs by enhancing the weather variability and making extreme conditions more frequent. High temperature or clouds, for example, can lead to poorer photovoltaic (PV) power outputs. Here,...

Satellites have consistently pointed to the Altiplano of the Atacama Desert as the place on Earth where the world’s highest surface irradiance occurs. This region, near the Tropic of Capricorn, is characterized by its high elevation, prevalent cloudless conditions, and relatively low concentrations of ozone, aerosols, and precipitable water. Aimed...

Attributable to the Montreal Protocol, the most successful environmental treaty ever, human-made ozone-depleting substances are declining and the stratospheric Antarctic ozone layer is recovering. However, the Antarctic ozone hole continues to occur every year, with the severity of ozone loss strongly modulated by meteorological conditions. In late...

This Assessment Update by the Environmental Effects Assessment Panel (EEAP) of the United Nations Environment Programme (UNEP) addresses the interacting effects of changes in stratospheric ozone, solar ultraviolet (UV) radiation, and climate on the environment and human health. These include new modelling studies that confirm the benefits of the Mo...

Several publications have reported that total column ozone (TCO) may oscillate with an amplitude of up to 10 DU (Dobson units) during a solar eclipse, whereas other researchers have not seen evidence that an eclipse leads to variations in TCO beyond the typical natural variability. Here, we try to resolve these contradictions by measuring short-ter...

This study investigates black carbon (BC) concentrations in the seasonal snowpack on the Godwin-Austen Glacier and in surface snow at K2 Camps 1 and 2 (Karakoram Range), assessing their impact on snowmelt during the 2019 ablation season. Potential BC and moisture sources were identified through back-trajectory analysis and atmospheric reanalyses. V...

Reliable and continuous meteorological data are crucial for modeling the responses of energy systems and their components to weather and climate conditions, particularly in densely populated urban areas. However, existing long-term datasets often suffer from spatial and temporal gaps and inconsistencies, posing great challenges for detailed urban e...

Recent extremes in Antarctic temperature, surface melt and sea ice loss have been robustly linked to the occurrence of atmospheric rivers (ARs). However, the precise mechanisms that generate variations in the surface impacts of ARs are poorly understood, especially in the Antarctic. Based on Arctic evidence that the vertical and horizontal advancem...

Seasonal snow in the extratropical Andes is a primary water source for major rivers supplying water for drinking, agriculture, and hydroelectric power in Central Chile. Here, we used estimates from the Moderate Resolution Imaging Spectroradiometer (MODIS) to analyze changes in snow cover extent over the period 2001–2022 in a total of 18 watersheds...

Several publications have reported that total column ozone (TCO) may oscillate with an amplitude of up to 10 Dobson Units during a solar eclipse while other researchers have not seen evidence that an eclipse leads to variations in TCO beyond the typical natural variability. Here, we try to resolve these contradictions by measuring short-term (secon...

South America is experiencing severe impacts from climate change. Although the warming of the subcontinent closely follows the global path, the rise of temperatures has been more pronounced in some regions, which have also seen a parallel increment in the occurrence of droughts and weather conditions associated with enhanced fire risk. Here, we use...

The Year of Polar Prediction in the Southern Hemisphere (YOPP-SH) held seven Targeted Observing Periods (TOPs) during the 2022 austral winter to enhance atmospheric predictability over the Southern Ocean and Antarctica. The TOPs of 5-10 days duration each featured the release of additional radiosonde balloons, more than doubling the routine soundin...

Plain Language Summary The Antarctic Peninsula is increasingly witnessing climate extremes during summer, while the understanding of such extremes in winter remains limited. Our study explores a significant warming event in the northern Peninsula in early July 2023, utilizing recent winter in situ observations and atmospheric analysis. On 2 July, a...

We applied a perfect prognosis approach to downscale four meteorological variables that affect photovoltaic (PV) power output using four machine learning (ML) algorithms. In addition to commonly investigated variables, such as air temperature and precipitation, we also focused on wind speed and surface solar radiation, which are not frequently exam...

Immersion microscope objectives stand out for their large numerical aperture, which improves the optical resolution of imaging systems such as those used in microscopic interferometry. These objectives increase the gradient forces of a beam focused through them, forming an Optical Trap (OT). However, many studies on microscopic interferometry negle...

In this study, we assessed air quality and urban climate during the mobility restrictions implemented in the Greater Tokyo Area, Japan, the world's most populated region, in response to the COVID-19 pandemic. Observations from dense surface networks were analyzed using an interpretable machine learning approach. In parallel with a ~50% reduction in...

A string of fierce fires broke out in Chile in the austral summer 2023, just six years after the record-breaking 2017 fire season. Favored by extreme weather conditions, fire activity has dramatically risen in recent years in this Andean country. A total of 1.7 million ha. burned during the last decade, tripling figures of the prior decade. Six of...

Climate warming is expected to increase global methane (CH 4 ) emissions from wetland ecosystems. Although in situ eddy covariance (EC) measurements at ecosystem scales can potentially detect CH 4 flux changes, most EC systems have only a few years of data collected, so temporal trends in CH 4 remain uncertain. Here, we use established drivers to h...

The Antarctic Peninsula (AP) experienced a new extreme warm event and record-high surface melt in February 2022, rivaling the recent temperature records from 2015 and 2020, and contributing to the alarming series of extreme warm events over this region showing stronger warming compared to the rest of Antarctica. Here, the drivers and impacts of the...

In February 2023, the sea-ice extent around Antarctica dropped to 1.79×106 km2, setting a satellite-era record low for the second straight year. Recent records stress the need for further research into the factors behind record-breaking Antarctic sea-ice anomalies. By influencing the circumpolar westerly winds, the stratospheric polar vortex has pl...

The Antarctica Peninsula (AP) has experienced more frequent and intense surface melting recently, jeopardizing the stability of ice shelves and ultimately leading to ice loss. Among the key phenomena that can initiate surface melting are atmospheric rivers (ARs) and leeside foehn; the combined impact of ARs and foehn led to moderate surface warming...

The angular distribution of the sky radiance determines the energy generation of solar power technologies as well as the ultraviolet (UV) doses delivered to the biosphere. The sky-diffuse radiance distribution depends on the wavelength, the solar elevation, and the atmospheric conditions. Here, we report on ground-based measurements of the all-sky...

By influencing the circumpolar westerly winds, the stratospheric polar vortex has played a major role in the Antarctic surface climate in recent decades. However, the footprint of the polar vortex variability in the year-to-year changes of the Antarctic sea ice cover remains obscured. Here, we combine satellite retrievals and reanalysis data to stu...

Cities in the global south face dire climate impacts. It is in socioeconomically marginalized urban communities of the global south that the effects of climate change are felt most deeply. Santiago de Chile, a major mid-latitude Andean city of 7.7 million inhabitants, is already undergoing the so-called “climate penalty” as rising temperatures wors...

The Antarctic Peninsula (AP) experienced a new extreme warm event and record high surface melt in February 2022, rivaling the recent temperature records from 2015 and 2020, and contributing to an alarming series of extreme warm events there. The northern/northwestern AP was directly impacted by an intense atmospheric river (AR) bringing anomalous h...

The Antarctica Peninsula (AP) has experienced more frequent and intense surface melting in recent years, jeopardizing the stability of ice shelves and ultimately leading to ice loss. Among the key phenomena that can initiate surface melting are atmospheric rivers (ARs) and leeside foehn; the combined impact of ARs and foehn led to moderate surface...

This study investigated the spatiotemporal variabilities in nitrogen dioxide (NO2), formaldehyde (HCHO), ozone (O3), and light-absorbing aerosols within the Greater Tokyo Area, Japan, which is the most populous metropolitan area in the world. The analysis is based on total tropospheric column, partial tropospheric column (within the boundary layer)...

In photovoltaic power ratings, a single solar spectrum, AM1.5, is the de facto standard for record laboratory efficiencies, commercial module specifications, and performance ratios of solar power plants. More detailed energy analysis that accounts for local spectral irradiance, along with temperature and broadband irradiance, reduces forecast error...

This study investigated the spatiotemporal variabilities in nitrogen dioxide (NO2), formaldehyde (HCHO), ozone (O3), and light-absorbing aerosols within the Greater Tokyo Area, Japan, the most populous metropolitan area in the world. The analysis was based on total column, partial column, and in situ observations retrieved from multiple platforms a...

The Andes span more than 7,000 km along western South America and its snowpack is an important source of water for many communities. As other snow-covered regions around the world, the Andes are sensitive to Black Carbon (BC) deposition from fossil fuel and biomass combustion. BC darkens the snow surface, reduces the albedo, and accelerates melting...

This work demonstrates, for the first time to our knowledge, that it is possible to measure the temperature of an optical trap (OT) using an optical fiber sensor tip. A polymer capped fiber optic Fabry-Perot interferometer, which is structure and temperature sensing characteristics have been well studied, was used. The surface of the polymer cavity...

Surface albedo is an important forcing parameter that drives the radiative energy budget as it determines the fraction of the downwelling solar irradiance that the surface reflects. Here we report on ground-based measurements of the spectral albedo (350–2200 nm) carried out at 20 sites across a North–South transect of approximately 1300 km in the A...

Summer temperatures are often above freezing along the Antarctic coastline, which makes ice shelves and coastal snowpacks vulnerable to warming events (understood as periods of consecutive days with warmer than usual conditions). Here, we project changes in the frequency, duration and amplitude of summertime warming events expected until end of cen...

In comparisons of solar photovoltaic performance, variation in the spectrum of sunlight is often neglected. A single spectrum, AM1.5, is used as the standard condition both for comparison of competing solar cell technologies and evaluation of energy generation from solar power plants. The addition of solar spectrum variation provides a more relevan...

The chemical composition of snow provides insights on atmospheric transport of anthropogenic contaminants at different spatial scales. In this study, we assess how human activities influence the concentration of elements in the Andean mountain snow along a latitudinal transect throughout Chile. The concentration of seven elements (Al, Cu, Fe, Li, M...

From 16 November 2018 to 15 February 2019, the Year of Polar Prediction (YOPP) in the Southern Hemisphere (SH) held a special observing period (SOP). YOPP is a flagship activity of the Polar Prediction Project (PPP), a 10- year (2013–22) WMO/WWRP initiative. Seventeen nations contributed to greatly enhanced observations during the SOP—primarily fro...

Predicting radiative forcing due to Antarctic stratospheric ozone recovery requires detecting changes in the ozone vertical distribution. In this endeavor, the Limb Profiler of the Ozone Mapping and Profiler Suite (OMPS-LP), aboard the Suomi NPP satellite, has played a key role providing ozone profiles over Antarctica since 2011. Here, we compare o...

Recent changes in the near-surface air temperature (nSAT) in the Antarctic Peninsula (AP) suggest that the absence of 21st century warming on the Antarctic Peninsula may be coming to end. To examine this, the long-term annual and seasonal variability of the nSAT at eight Antarctic stations located in the AP are analyzed using available data from th...

Here, we present radiative forcing (RF) estimates by snow algae in the Antarctic Peninsula (AP) region from multi-year measurements of solar radiation and ground-based hyperspectral characterization of red and green snow algae collected during a brief field expedition in austral summer 2018. Our analysis includes pigment content from samples at thr...

The chemical composition of snow provides insights on atmospheric transport of anthropogenic contaminants at different spatial scales. In this study, we assess how human activities influence the concentration of elements in the Andean mountain snow along a latitudinal transect throughout Chile. The concentration of seven elements (Al, Cu, Fe, Li, M...

Five decades of precipitation data are available from the Chilean Antarctic weather stations located in the northern tip of the Antarctic Peninsula. Data include daily accumulation and type of precipitation registered at the time of the observation at the Meteorological Antarctic Center located at Base Eduardo Frei Montalva, King George Island. Thi...

Here, we present radiative forcing (RF) estimates by snow algae in the Antarctic Peninsula (AP) region from multi-year measurements of solar radiation and ground-based hyperspectral characterization of red and green snow algae collected during a brief field expedition in austral summer 2018. Our analysis includes pigment content from samples at thr...

The Year of Polar Prediction in the Southern Hemisphere (YOPP-SH) had a special observing period (SOP) that ran from 16 November 2018 to 15 February 2019, a period chosen to span the austral warm season months of greatest operational activity in the Antarctic. Some 2,200 additional radiosondes were launched during the 3-month SOP, roughly doubling...

In this study, we explored the connection between anomalies in springtime Antarctic ozone and all-year precipitation in the Southern Hemisphere by using observations from 1960–2018 and coupled simulations for 1960–2050. The observations showed that this correlation was enhanced during the last several decades, when a simultaneously increased coupli...

The Year of Polar Prediction in the Southern Hemisphere (YOPP-SH) had a special observing period (SOP) from November 16, 2018 to February 15, 2019, during which observational activity during austral summer in the Antarctic was greatly enhanced. More than 2000 additional radiosondes were launched during this 3-month period, roughly doubling the amou...

We examine the hydrographic variability induced by tides, winds, and the advance of the austral summer, in Maxwell Bay and tributary fjords, based on two recent oceanographic campaigns. We provide the first description in this area of the intrusion of relatively warm subsurface waters, which have led elsewhere in Antarctica to ice-shelf disintegrat...

Esta publicación de divulgación científica tiene fines educativos. Aunque alentamos su uso y reproducción parcial o total, sugerimos citar la fuente. Los autores forman parte del grupo de investigación www.antarctica.cl, cuya misión es estudiar el rol de la Antártica en el clima global y los impactos del Cambio Climático en el Hemisferio Sur.

The Andean snowpack is the primary source of water for many communities in South America. We have used Landsat imagery over the period 1986–2018 in order to assess the changes in the snow cover extent across a north-south transect of approximately 2,500 km (18°–40°S). Despite the significant interannual variability, here we show that the dry-season...

Abstract Although Heat Waves (HWs) are expected to increase due to global warming, they are a regional phenomenon that demands for local analyses. In this paper, we assess four HW metrics (HW duration, HW frequency, HW amplitude, and number of HWs per season) as well as the share of extremely warm days (TX95, according to the 95th percentile) in So...

The snowpack is an important source of water for many Andean communities. Because of its importance, elemental and mineralogical composition analysis of the Andean snow is a worthwhile effort. In this study, we conducted a chemical composition analysis (major and trace elements, mineralogy, and chemical enrichment) of surface snow sampled at 21 sit...

Vertical profiles of black carbon (BC) and other light-absorbing impurities were measured in seasonal snow and permanent snowfields in the Chilean Andes during Austral winters 2015 and 2016, at 22 sites between latitudes 18°S and 41°S. The samples were analyzed for spectrally-resolved visible light absorption. For surface snow, the average mass mix...

El agujero de ozono que aparece sobre la Antártica cada año desde fines de la década del 70 (entre agosto y diciembre) provoca cambios en la circulación atmosférica de alcance hemisférico que generan a su vez anomalías en patrones de vientos, nubosidad y precipitación. En Sudamérica, estas anomalías han afectado particularmente la costa del Pacífic...

Against the background of supply deficiency and citizen opposition to the construction of large-scale hydro power plants, numerous movements against energy projects emerged during the last decade and ultimately paved the way for a participatory energy policy design process in Chile. The “Energy 2050” strategy was developed through a participative p...

The socio-ecological sensitivity to water deficits makes Chile highly vulnerable to global change. New evidence of a multi-decadal drying trend and the impacts of a persistent drought that since 2010 has affected several regions of the country, reinforce the need for clear diagnoses of the hydro-climate changes in Chile. Based on the analysis of lo...

Soiling by dry deposition afects the power output of photovoltaic (PV) modules, especially under dry and arid conditions that favor natural atmospheric aerosols (wind-blown dust). In this paper, we report on measurements of the soiling efect on the energy yield of grid-connected crystalline silicon PV modules deployed in fve cities across a north-s...

The world’s highest levels of surface ultraviolet (UV) irradiance have been measured in the Atacama Desert. This area is characterized by its high altitude, prevalent cloudless conditions, and a relatively low total ozone column. In this paper, we provide estimates of the surface UV (monthly UV index at noon and annual doses of UV-B and UV-A) for a...

Peru has historically been among the Latin-American countries with a low rural electrification rate. Aiming to improve this situation, the country conducted several electrification efforts in the last few decades that included off-grid photovoltaic (PV) solutions for remote areas (where the grid expansion was unviable). More recently, the governmen...

Observations from the new Japanese geostationary satellite Himawari-8 permit quasi-real-time estimation of global shortwave radiation at an unprecedented temporal resolution. However, accurate comparisons with ground-truthing observations are essential to assess their uncertainty. In this study, we evaluated the Himawari-8 global radiation product...

Questions: - How do variations in cloud cover and cloud properties impact the energy balance on the Antarctic Peninsula? -How do products of cloud top properties derived from the A-Train’ satellite sensors MODIS (onboard Aqua satellite), CALIOP (onboard CALIPSO satellite) and AIRS (onboard Aqua satellite) agree with radiosonde data? - How reliable...

In order to recover the holographic object information, a method based on the recording of two digital holograms, not only at different planes but also in a slightly off-axis scheme, is presented. By introducing a π -phase shift in the reference wave, the zero-order diffracted term and the twin image are removed in the frequency domain during the p...

Ventilation of the eastern South Pacific Oxygen Minimum Zone (ESP-OMZ) is quantified using climatological Argo and dissolved oxygen data, combined with reanalysis wind stress data. We (1) estimate all oxygen fluxes (advection and turbulent diffusion) ventilating this OMZ, (2) quantify for the first time the oxygen contribution from the subtropical...

Observations from the new Japanese geostationary satellite Himawari-8 permit quasi-real-time estimation of global shortwave radiation at an unprecedented temporal resolution. However, accurate comparisons with ground truthing observations are essential to assess their uncertainty. In this study, we evaluated the Himawari-8 global radiation product...

In this paper, we comparatively assess the sustainability of rural electrification efforts based on off-grid solutions in Chile, Ecuador, and Peru. Our assessment considers four dimensions of sustainability (institutional, economic, environmental, and socio-cultural). We found that Ecuador and Chile have consistently failed to ensure mechanisms for...

A simple strategy based on wavefront propagation in Fresnel regime to reduce ringing effect by using an ideal filter in off-axis digital holography is presented. In addition, we demonstrate a better focusing capacity by using this ideal filter than Butterworth and Gaussian. The reconstructed and enhanced image is obtained from the averaging operati...

3D shape recovery systems, based on structured light projection, allow recovering three-dimensional shape from complex opaque surfaces. Particularly, when a fringe pattern with sinusoidal profile is projected on a surface and algorithms for recovering optical phase are performed for its demodulation, sub-micrometer resolutions can be obtained. The...

We show how a sinusoidal fringe pattern can be obtained by using a single cube beam splitter based on the Gates' interferometer configuration. When an expanded and collimated laser beam hits the binding edge of a nonpolarizing cube beam splitter parallel to the splitter coating, it generates interference fringes at the exit due to the internal refl...

The refocusing capacity is a unique feature of digital holography. In this chapter, we show the capability of reconstructing digital holograms at different planes for different purposes. One of such purposes is to increase the focus depth of the microscope system. First, we show experimental results of the feasibility to perform digital holographic...

Background Mainly based on expanding the grid, Chile has reached an impressive electrification rate. However, due to unviable grid expansion to islands and remote areas of the country, the government started implementing off-grid electrification programs. In this paper, we assess the sustainability of rural electrification efforts in Chile paying s...

The aim of the present work was the examination of deformation distribution in cuticles material under bulge test using the technique of projected fringes. It will be presented experimental results to isolated cuticles of tomato.

In this paper, we assess the sustainability of rural electrification programs in Ecuador, paying special attention to programs targeting small indigenous communities in the Amazon basin. Our assessment considers four dimensions of sustainability (institutional, economic, environmental, and socio-cultural) and is based on an exhaustive qualitative d...