## 4 Conclusions  
The lower layers account for more than 80 percent of the entire Earth's atmosphere and directly impact weather and climate. Most natural hazards are affected in the lower atmosphere. The environmental response characteristics of volcanic eruptions are generally obtained from a single environmental factor. In this paper, the environmental response characteristics and evolution of the 2022 Tonga volcanic eruption in the lower space were obtained from the combined analysis of multiple environmental factors such as PWV, circulation, water vapor flux, surface temperature, and precipitation. Two cyclones appeared in the east and south of Tonga before and after the HTHH eruption. The southern cyclone strongly influenced water vapor transport and precipitation around Tonga, and the intensity of water vapor flux in the south of Tonga reached its maximum on the second day of the eruption (16 January). The eastern cyclone appeared after the volcanic eruption and was probably regulated by the volcanic eruption on the atmospheric and oceanic circulation, resulting in a new cyclone. The two cyclones affect water vapor, precipitation, and temperature around Tonga. PWV also appeared to be anomalous after the eruption, with anomalous values reaching a maximum on the day after the violent eruption (16 January 2022). After the volcanic eruption, the southern cyclone of Tonga moved toward New Zealand, and the eastern cyclone gradually formed and moved toward Tonga. After obtaining the anomalous water vapor flux through the climate state, it could be found that a large amount of water vapor released from the HTHH volcanic eruption on 15 January may have been transported to the cyclone in the eastern part of Tonga and brought a large amount of rainfall to the area. The changes in PWV, surface temperature, and precipitation before and after the HTHH volcanic eruption are closely related. It could be found that when PWV increased in Tonga, the surface temperature increased and precipitation increased in February 2022. When PWV decreases, surface temperature decreases, and precipitation decreases. Figure 12: Distribution of precipitation anomalies for January (**a**) and February (**b**) 2022 in Tonga color shaded areas, unit: mm), with areas of increased rainfall in red and decreased rainfall in blue. **Author Contributions:** [PERSON] and [PERSON] conceived and designed the experiments; [PERSON] and [PERSON] performed the experiments; [PERSON] and [PERSON] analyzed the data; [PERSON] contributed materials; [PERSON] wrote the paper. Provision of meteorological data and mapping by [PERSON] All authors have read and agreed to the published version of the manuscript. **Funding:** The Natural Science Foundation of Jiangsu Province (grant no. BK20211037), the National Natural Science Foundation of China (grant no. 41674036), and Talents of Six Peaks in Jiangsu Province (grant no. XYDDX-045). **Institutional Review Board Statement:** Not applicable. **Informed Consent Statement:** Not applicable. **Data Availability Statement:** Landsat OLI/TIRS sensor data is downloaded from [[https://earthexplorer.usgs.gov/](https://earthexplorer.usgs.gov/)]([https://earthexplorer.usgs.gov/](https://earthexplorer.usgs.gov/)) from April 2019 to April 2022. The Circulation, Water vapor flux and Precipitation datasets are available from the European Centre for Medi-um-Range Weather Forecasts ([[https://cds.climate.copernicus.eu/cdsappp#/search?type=dataset](https://cds.climate.copernicus.eu/cdsappp#/search?type=dataset)]([https://cds.climate.copernicus.eu/cdsappp#/search?type=dataset](https://cds.climate.copernicus.eu/cdsappp#/search?type=dataset))). Global Positioning System raw data of IGS are downloaded via [[https://cddis.nasa.gov/archive/gnss/data/](https://cddis.nasa.gov/archive/gnss/data/)]([https://cddis.nasa.gov/archive/gnss/data/](https://cddis.nasa.gov/archive/gnss/data/)).