Aerosol observation results in Hanoi at Nghia Do Aeronet.
The research team conducted aerosol measurements at Nghia Do Aeronet station in 2018 and 2019. The obtained parameters include: aerosol optical thickness (AOD: Aerosol Optical Depth), amount of water vapor in the atmosphere , Angstrom parameters, fine-grain aerosol ratio, aerosol size distribution, single scattering albedo, phase function, ...
Results of learning and exchanging with Belarus (or Russia) on cross-border aerosol observing, researching and monitoring methods, and methods of assessing the influence of aerosol concentrations on the territory of Vietnam using the surface observation and remote sensing system.
- Combined method of surface and satellite observation to observe the aerosol
Within the framework of the mission, we also learned and exchanged the combining methods of surface and satellite observations of aerosols (LRS) from foreign partners. This method uses observation data from the Lidar system and the Aeronet system at the surface to calculate the distribution of aerosol concentrations according to altitude. The results are compared with the results calculated from the Lidar data placed on the CALIOP satellite.
- Research on perfecting the aerosol observation using Lidar system
The task group has researched, designed, manufactured and completed the aerosol observing Lidar system with the following main objectives: Measuring the Lidar signal obtained by Rayleigh scattering of the aerosol to an altitude of 15 km with about 30m resolution in favorable weather conditions; Comparing aerosol observing data with aerosol measurement data of other equipment or methods; There is a set of signal data for measuring clouds and aerosols in the Hanoi area and calculating the altitude of the atmospheric boundary layer (LBKQ) from the data obtained to use for calculation and correction of the influence of aerosols on satellite images and is the input variable to run the aerosol transport model.
- Method to evaluate the effect of transboundary transport on aerosol concentrations using the model.
To study regional and global aerosol transport, the most effective method is to use simulation models. In this mission, we and our foreign partners exchanged experiences in applying HYSPLIT (HYbrid Single-Particle Lagrangian Integrated Trajectory) flow model in studying the transboundary transport of aerosols. HYSPLIT is one of the widely used models in atmospheric research.
Results of evaluating the effect of biomass burning aerosol in Indochina on aerosol optical thickness in Hanoi area through long-range transportation.
- Characteristics of fire activity in Indochina
The spatial distribution and time variation of fire activities in Indochina during the period between 2001and 2019 are shown in Figure 5. The results show that fire activity in Indochina started appeared in December, fire activity increased gradually in January and February, peaked in March, then gradually decreased in April and May when the rainy season started.
- Aerosol characteristics in Hanoi area
Anomalous characteristics of AOD in Hanoi area: The results of AOD anomaly research in Hanoi show that there have been 4 anomalies (anomalous episode is a 3-day period in which an anomaly is observed) in March 2012, end of March and beginning of April. 2014, April 2016 and April 2019 during the period of 10 years (table 2).
Annual evolution of AOD in Hanoi area: The annual variation of AOD observed at Nghia Do AERONET station between 2010 and 2019 has 2 maxima: the first maximum is in the spring months (March, April), the second one is in late autumn (October). The rainy season months have low AOD (June, July and August).
Effects of biomass burning activities in Indochina on AOD in Hanoi area.
In this section, we use the HYSPLIT streamline trajectory model to analyze the pollutant transport capacity of circulation in Southeast Asian area. The results show that the air-flow to Hanoi (at an altitude of 2500m) is mainly from the west and southwest direction. In which, the westward airflow passes through Myanmar, Thailand and Laos with an altitude of over 2000m, the southwester air-flow passes through the middle region of Thailand and Laos with an average altitude of about 1500-2000m and less than 1500m. This airflow can transport dust from biomass fires in Myanmar, Thailand, and Laos to Hanoi area, causing AOD in this area to increase in the spring.
The annual variation of the total fire points/day in Indochina (10-25N, 90-110E) from 2001 to 2019 (blue) and the other one of the station AOD AERONET Hanoi during the period between 2010 and 2019 (red) show that there is a match between the change of fire activities in Indochina and the change of AOD in Hanoi area (with correlation R=0.77). | 
