2:00 PM - 2:15 PM
[AAS10-02] Observation of material transport associated with monsoon circulations and intraseasonal variations over the western Pacific during the R/V Mirai cruise in 2021 summer
Keywords:Material transport, Balloon observation, R/V Mirai
1. Introduction
Convective activities associated with the monsoon and intraseasonal variations (BSISO) are thought to cause changes in the atmospheric flow field and associated transport of materials between the mid-latitudes and tropics and between the troposphere and stratosphere over the western Pacific in summer. In addition, various types of waves excited by convective activity affect the atmospheric general circulation and material transport by changing the flow field of the upper atmosphere. However, the actual behaviors of such material transports is not clear due to the lack of in-situ observations. In particular, ozone and water vapor play an essential role in the formation of the climate, and it is important to clarify the their distributions and fluctuations in order to understand global climate change. In addition, there are still many uncertainties about atmospheric waves that affect the variability of material transport processes, especially at altitudes above 30 km, which are unreachable by conventional balloon observations. In the summer of 2021, we conducted balloon observations over the western Pacific on board the R/V Mirai with the aim of capturing the actual spatial distribution of ozone and water vapor and the dynamical processes at higher altitudes. Here, we report on the results of the observation.
2. Observation
The observations were conducted as part of the YMC (Years of the Maritime Continent) from May 24 to July 8, 2021, during the cruise of the R/V Mirai over the western Pacific (Figure 1). After departing from Japan, 11 ozone and water vapor sondes, 15 ozonesondes, and 27 super high altitude sondes were launched on the way southward, westward, at the fixed observation point, and on the way northward (see Figure 1 for details). A new-type chilled mirror hygrometer, Skydew, from Meisei Electric Co was used for the water vapor soundings. The super high altitude observation was conducted using a 3,000 g (or 4,000 g in some cases) balloon to which the Meisei iMS-100 radiosonde is attached. It measures the temperature and wind speed up to an altitude of about 40 km, which is beyond the reach of ordinary radiosonde observations. An En-sci Model-1Z ECC was used for ozone sondings.
3. Background fields during the observation period
During the observation period, convections over the western Pacific was relatively inactive, and the BSISO signal was unclear. On the other hand, monsoon convection was enhanced over Southeast Asia, and associated anticyclonic circulation was forming in the upper troposphere. The R/V Mirai's observations may have captured the transport of materials from the mid-latitudes associated with this anticyclonic circulation.
4. Summary
From late May to early July 2021, observation of ozonesondes, water vapor sondes, and super high altitude sondes were conducted on board the R/V Mirai with the aim of capturing the material transport and dynamics associated with the summer monsoon and convections over the western Pacific. We obtained ozone and water vapor data, as well as temperature and wind velocity data at the high-altitude ranges, during the development of the monsoon circulation. We will analyze the process of material distribution modulation by the monsoon circulation and various disturbances, evaluate the quality of the water vapor sondes, analyze the mechanism of cloud formation and water vapor transport, and analyze the dynamics mainly of waves observed with the super high altitude sondes, and report the results in the presentation.
Acknowledgments
We would like to express our deepest gratitude to the crew of the R/V Mirai and the staff of Nippon Marine Enterprises, Ltd. for their cooperation in conducting the observations.
Convective activities associated with the monsoon and intraseasonal variations (BSISO) are thought to cause changes in the atmospheric flow field and associated transport of materials between the mid-latitudes and tropics and between the troposphere and stratosphere over the western Pacific in summer. In addition, various types of waves excited by convective activity affect the atmospheric general circulation and material transport by changing the flow field of the upper atmosphere. However, the actual behaviors of such material transports is not clear due to the lack of in-situ observations. In particular, ozone and water vapor play an essential role in the formation of the climate, and it is important to clarify the their distributions and fluctuations in order to understand global climate change. In addition, there are still many uncertainties about atmospheric waves that affect the variability of material transport processes, especially at altitudes above 30 km, which are unreachable by conventional balloon observations. In the summer of 2021, we conducted balloon observations over the western Pacific on board the R/V Mirai with the aim of capturing the actual spatial distribution of ozone and water vapor and the dynamical processes at higher altitudes. Here, we report on the results of the observation.
2. Observation
The observations were conducted as part of the YMC (Years of the Maritime Continent) from May 24 to July 8, 2021, during the cruise of the R/V Mirai over the western Pacific (Figure 1). After departing from Japan, 11 ozone and water vapor sondes, 15 ozonesondes, and 27 super high altitude sondes were launched on the way southward, westward, at the fixed observation point, and on the way northward (see Figure 1 for details). A new-type chilled mirror hygrometer, Skydew, from Meisei Electric Co was used for the water vapor soundings. The super high altitude observation was conducted using a 3,000 g (or 4,000 g in some cases) balloon to which the Meisei iMS-100 radiosonde is attached. It measures the temperature and wind speed up to an altitude of about 40 km, which is beyond the reach of ordinary radiosonde observations. An En-sci Model-1Z ECC was used for ozone sondings.
3. Background fields during the observation period
During the observation period, convections over the western Pacific was relatively inactive, and the BSISO signal was unclear. On the other hand, monsoon convection was enhanced over Southeast Asia, and associated anticyclonic circulation was forming in the upper troposphere. The R/V Mirai's observations may have captured the transport of materials from the mid-latitudes associated with this anticyclonic circulation.
4. Summary
From late May to early July 2021, observation of ozonesondes, water vapor sondes, and super high altitude sondes were conducted on board the R/V Mirai with the aim of capturing the material transport and dynamics associated with the summer monsoon and convections over the western Pacific. We obtained ozone and water vapor data, as well as temperature and wind velocity data at the high-altitude ranges, during the development of the monsoon circulation. We will analyze the process of material distribution modulation by the monsoon circulation and various disturbances, evaluate the quality of the water vapor sondes, analyze the mechanism of cloud formation and water vapor transport, and analyze the dynamics mainly of waves observed with the super high altitude sondes, and report the results in the presentation.
Acknowledgments
We would like to express our deepest gratitude to the crew of the R/V Mirai and the staff of Nippon Marine Enterprises, Ltd. for their cooperation in conducting the observations.