Atmósfera

Air quality in the Metropolitan Zone of the Valley of Puebla: Comparative evaluation of CAMS and persistence forecasts

Javier Omar Castillo-Miranda — 2025-01-08

Background on air quality in the Metropolitan Zone of the Valley of Puebla shows that suspended particles smaller than 10 micrometers (PM₁₀) and smaller than 2.5 micrometers (PM_2.5) represent a health risk. Puebla’s automatic air quality monitoring system measures PM₁₀ and PM_2.5at five stations in the municipalities of Puebla and Coronango. These measurements allow for determining the Air and Health Index according to the NOM-172-SEMARNAT-2019 standard for these pollutants. The advancement of global pollutant modeling techniques represents an opportunity for air quality management in areas with scarce terrestrial measurements. However, it is necessary to validate global forecasts with ground measurements from georeferenced monitoring stations to reduce uncertainties and determine reliability. The Copernicus Atmospheric Monitoring Service (CAMS) forecast allows atmospheric pollution exploration processes in the study region. This study presents an analysis of the CAMS forecast against the Persistence forecast. The results show that the persistence forecast performs better than the CAMS forecast in general, both for PM₁₀ and for PM_2.5. However, using the CAMS forecast for a preliminary evaluation of the prediction of PM_2.5is feasible due to its acceptable values in the comparison criteria of the dichotomous statistics ACCURACY, probability of detection (POD), false alarm rate (FAR), probability of false detection (POFD), success ratio (SR), threat score (TS), equitable threat score (ETS), Heidke skill score (HSS), and odds ratio skill score (ORSS). This work provides valuable insights to both the population and decision-makers, aiding in the enhancement of air quality management and public health strategies.

Satellite precipitation product assessment and correction technique selection at sub-basin scale for maximum annual events. Case study: Acaponeta River basin

Edith Bonilla-López — 2025-01-07

Satellite precipitation products (SPP) are increasingly being used for detailed hydrological studies due to scarce and discontinuous precipitation observations at different spatial and temporal scales. However, to evaluate its full utility, it is necessary to assess and correct the bias between estimated and observed precipitation (OP). The aim of this paper is to evaluate the CHIRPSv2.0 product for maximum annual events and different climatological conditions based on in-situ observations, using statistical metrics and selecting from linear scaling (LS), local intensity scaling (LOCI) and power transformation (PT) the appropriate bias correction technique (CT), at point and sub-basin scale, improving the maximum annual precipitation records for the period 2001-2020 in the Acaponeta River basin, Mexico. Previous applications of bias CT have focused on broader temporal scales rather than specific maximum events. Differences in the performance of the correction methods were identified between point and sub-basin scales. PT presented a good performance at the point scale, in contrast to percentual bias (PBIAS), which resulted in a great overestimation at the sub-basin scale in the upper zone for the average and dry years, while for the wet year, it overestimated in the lower part. Although LS and LOCI generally observed a good PBIAS reduction at the gauge stations, LS overestimated at the sub-basin scale overall. LOCI showed better SPP corrections in the middle and lower zones and a wider range of overestimation for the upper basins in the middle and wet years. The corrected annual maximum estimated values for the revised period are useful for hydrological analysis in the context of flood risk assessment.

Diurnal to seasonal meteorological cycles along an equatorial Andean elevational gradient

Luis Silva — 2025-01-07

The climate of the Andean equatorial mountains has a pronounced spatiotemporal variability, which, coupled with limited meteorological monitoring, hampers our understanding of the regional and local atmospheric processes that govern this variability. To deepen our understanding of this region’s climate, we analyzed diurnal to seasonal meteorological patterns of the main meteorological variables: precipitation, air temperature, relative humidity, incident solar radiation, and wind speed and direction. We used a unique 10-year high-resolution dataset from March 2013 to February 2023 along an elevation gradient located in southern Ecuador. Our analyses reveal a trimodal regime of precipitation; two wet seasons are associated with convective processes influenced by the position of the Intertropical Convergence Zone (ITCZ) over the study area during the equinoxes, and the less humid season is due to the intensification of the Walker circulation, which produces subsidence over the study area. The relative humidity shows distinct daily and seasonal variations, reaching minimum daily values around noon when the air temperature is the highest, and an annual minimum in November. Incident solar radiation reaches its maximum values around the equinoxes when sunlight is almost perpendicular, which produces greater heating on the surface and, hence, a more humid atmosphere. The meridional displacement of the ITCZ around the year influences the climate, increasing humidity from March to May and wind speed from April to July. Our research reveals significant differences between diurnal and seasonal meteorological cycles, highlighting the importance of altitude, topography, and wind patterns in the climate dynamics of the equatorial Andes.

Satellite-based analysis of climate oscillations: Implications for precipitation in an arid watershed in Mexico

David Eduardo Guevara-Polo — 2025-01-07

Climate oscillations are known to have an important influence on weather patterns across the world. While the impact of El Niño Southern Oscillation (ENSO) has been well documented, there is a scarcity of studies examining the effects of the Pacific Decadal Oscillation (PDO) and the Atlantic Multidecadal Oscillation (AMO). This study uses satellite data to confirm that ENSO significantly influences precipitation in the Nazas-Aguanaval watershed from October to March, as evidenced by Spearman correlation coefficients. In contrast, the PDO influence is registered during specific months (January, March, November and December), while AMO impacts precipitations during April-June, November, and December. These results were corroborated using ANOVA, reinforcing the influence of ENSO and indicating a limited impact of PDO and AMO on this watershed. Finally, a linear model was developed to estimate monthly precipitation anomalies based on the phase of these three indices for the different sub-basins. Notably, monthly precipitation anomalies ranged between 140% and –78% in dry months. Our results demonstrate the influence of climate oscillations in precipitation in the Nazas-Aguanaval watershed and the usefulness of satellite data for conducting these analyses. Likewise, we set a starting point for investigating the implications of climate oscillation phases for water management and drought disaster prevention.