Aplicabilidade de um sistema de baixo custo para o monitoramento de dados meteoceanográficos na zona costeira Amazônica

Abstract

This study aimed to develop, implement, and validate a low-cost Continuous Monitoring Prototype (CMP) to collect meteoceanographic data in the Amazon Coastal Zone (ACZ), a region vulnerable to climate change and lacking environmental data. The system, built with an ESP32 microcontroller, integrates sensors for air temperature and relative humidity (HDC1080 and AM2302), atmospheric pressure (BMP280 and MS5611), water temperature (DS18B20), tide level (HC-SR04), precipitation, and wind speed and direction. Sensor validation was performed by comparing the collected data with reference equipment: a CICLUS PRO weather station (CWS) and a Sonlist Levelogger 5 LTC recorder (CTDlog). The CMP conducted four joint test campaigns with the CWS and CTDlog, totaling 56,221 records. Linear regression was applied to develop calibration equations for each sensor. Calibration quality was assessed using the coefficient of determination (R²), root mean square error (RMSE), Pearson correlation coefficient, and residual analysis. The HDC1080 and AM2302 sensors showed excellent performance for temperature measurement, with R² > 0.9, RMSE < 0.2 °C, mean absolute residual (MAE) < 0.12 °C, and very strong Pearson correlation (r ≥ 0.9). However, they exhibited instability in relative humidity measurements (R² ≈ 0.64; RMSE ≈ 3.46%; MAE ≈ 2.52%). The performance of the BMP280 and MS5611 pressure sensors was initially affected by internal heating, but after thermal compensation, they achieved R² values between 0.88 and 0.99, RMSE from 0.17 to 0.45 hPa, and MAE from 0.11 to 0.34 hPa, with the BMP280 showing superior performance. The DS18B20 water temperature sensor showed very strong correlation, with R² ≈ 0.94, RMSE ≈ 0.036 °C, and MAE ≈ 0.021 °C, proving highly promising. The HCSR04 sensor stood out as the most accurate, with R² ≈ 0.99, RMSE ≈ 2.6 cm, and MAE ≈ 1.9 cm. Precipitation and wind sensors presented inconsistencies and require further testing. The total production cost of the CMP was BRL 952.75, representing savings of 86.19% compared to the CWS (BRL 6,897.00) and 96.14% compared to the CTDlog (BRL 24,677.29). When compared to equivalent equipment, the CMP achieved at least 66.33% cost reduction compared to basic stations and 87.3% compared to lower-cost temperature and water level recorders. The CMP proved to be a viable, economical, and replicable solution for continuous environmental monitoring in the ACZ, with the potential to fill existing gaps in observation networks, although improvements are still needed to enhance its long-term performance.