This work presents results of Aerosol Optical Depth (AOD) and Direct Radiative Force (DRF) at the top of the atmosphere (TOA), obtained during monitoring campaigns carried out at the Huancayo Observatory of the Geophysical Institute of Peru (OH-IGP ) in April and August 2022. In these campaigns, a Sun CIMEL photometer was used to measure the microphysical and optical properties of aerosols at wavelengths ranging from 340 to 1020 nm, and a low-cost Purple-air sensor to quantify the concentration of material particulate (PM), in fine and coarse modes. The AOD results indicated values in the range 0.06-0.22. The daily averages of PM2.5 and PM10 did not exceed Peru’s current Environmental Quality Standards (50 μg/m³ and 100 μg/m³). The air quality index (AQI) calculated for PM2.5 and PM10 was classified as good. On some days during the campaigns, the air quality was classified as moderate. These results contribute to a better understanding of the current climatic conditions of the Peruvian Altiplano.

This contribution estimates the intensity of Urban Heat Island (UHI) during the period 2001 - 2020 for the city of Santos (CS), located in São Paulo, Brazil. The formation of the Surface Urban Heat Island (SUHI) was quantified from 2 methods: the first was Streutker’s method, which adjusts the surface soil temperature (LST) (urban and rural surface) to a Gaussian surface. The second, the quantile method proposed by Jose Flores, uses the difference between the 0.95 quantile of the LST of the urban area and the median of the LST of the rural area. Both methods use remote sensing data of LST at 0.05° resolution, obtained from the MODIS sensor on board the TERRA and AQUA satellites. In general, the quantile method can be used as a complementary analysis to the Streutker method for cities with high LST. The results of the CS analysis, during diurnal periods, indicate maximum values in May (5.09°C) and minimum values in August (3.87°C). During the night period, it presented maximum values in February (3.94°C) and minimum values in August (2.40°C) with the quantile method, and due to its proximity to the Small Ocean, the Streutker method presents interferences.

This study presents an in-depth analysis of precipitation patterns, surface energy balance (SEB) components, and atmospheric vertical gradients (AVG) in the Huancayo Geophysical Observatory (HYGO) situated in an agricultural region inside the Mantaro valley within the central Andes of Peru, utilizing data from January 2018 to April 2022 and climatic-scale data from 1965 to 2018. Our findings reveal distinct daily and seasonal precipitation patterns, with peak occurrences in the late afternoon and early evening hours, and a pronounced seasonal variation aligning with dry and rainy periods. Analysis of 21 intense precipitation events linked to convective activity offers crucial insights for weather forecasting and disaster preparedness. These events were identified using in situ gauge pluviometers, the MIRA-35c vertical profiler radar and GPM-IMERG rainfall products. The turbulent energy fluxes: sensible (Qₕ) and latent (Qₑ) were estimated using the aerodynamic flux-gradient method and the ground heat flux to the surface was estimated with the scheme of Foken and Napo. Moreover, the study evaluates the efficacy of the Advanced Regional Prediction System (ARPS) model in analyzing turbulent energy fluxes during these events. A comparison with the bulk aerodynamic method indicated underestimations and overestimations by the ARPS model in predicting Qₕ and Qₑ, respectively, necessitating focused calibration and updates in satellite-derived data. Key observations include significant increases in Qe and horizontal momentum flux (𝜏) before convective precipitation events, marking them as potential precursor variables. Additionally, notable decreases in water vapor mixing ratio vertical gradient (WMVG) and Richardson number (RIN), along with increases in horizontal wind gradient (HWVG), suggest changes in surface moisture fluxes and boundary layer dynamics, crucial for convective rainfall initiation. This comprehensive analysis underscores the importance of understanding atmospheric dynamics for improved prediction and preparedness strategies in the face of climatic variability.

La rápida urbanización de las ciudades está cambiando el clima local, lo que genera altas temperaturas y entornos urbanos densos y difíciles, carentes de agua y vegetación[1]. La presente contribución estima la intensidad de Isla de Calor Urbano Superficial (ICUS) durante el periodo 2001 – 2022 para el Área Metropolitana de Huancayo (AMH), Perú. Se cuantificó formación de la Isla de Calor Urbano Superficial, a partir de 2 métodos: el primero es el método de Streutker, el cual ajusta la temperatura superficial del suelo (LST) (superficie urbana y rural) a una superficie Gaussiana. El segundo, método de cuantil propuesto por José Flores, usa la diferencia entre el cuantil 0.95 de LST del área urbana y la mediana del LST del área rural. Ambos métodos usan data de sensoramiento remoto de LST a 0.05⁰ de resolución, obtenido del sensor MODIS a bordo del satélite TERRA y AQUA. Para el AMH, durante los periodos diurnos, la intensidad de ICUS en marzo y julio representan el máximo y mínimo incremento. El periodo nocturno, presentó valores máximo y mínimo en agosto y diciembre respectivamente. En general se consiguió mostrar las principales causas del incremento de temperatura superficial es el pavimento asfaltado, donde la temperatura puede ser hasta 60 °C. Por ello es importante proponer medidas de mitigación como construcciones y pavimentos sostenible que ayuden a mitigar el incremento de temperatura superficial. Así como la importancia de considerar la Floresta o plantaciones vegetales en un diseño o zonificación urbana.

Currently, cities are experiencing increased urbanization and population density, leading to an increase in natural areas covered by paved and built-up areas, with a very rapid rate of urban expansion, as in the case of the capital Brasilia, Brazil. This has led to changes in local climates, increasing land surface temperature (LST) and causing an effect known as the Surface Urban Heat Island (SUHI) directly related to natural vegetation and urban and rural areas— which has become a major challenge for societies around the world due to its implications for public health and the environment. In this regard, the objective was to compare the temporal variation (2001-2016) of the SUHI in the Metropolitan Region of Brasilia (MRG) with MODIS satellite images, using the quantile method and Streutker method. The results indicate a maximum daytime SUHI in January (3.08 °C) and minimum in July (1.51 °C); the nighttime SUHI had maximums in July (2.36 °C) and minimums in April (1.72 °C). The Quantile-Streutker correlation ≈ 0.10, highlighting the usefulness of the quantile method for cities with different maximum temperature centers on a non-Gaussian surface.