3 results
Search Results
2. A Dipole Mode of Spring Precipitation between Southern China and Southeast Asia Associated with the Eastern and Central Pacific Types of ENSO.
- Author
-
CHANG-KYUN PARK, PARK, DOO-SUN R., CHANG-HOI HO, TAE-WON PARK, JINWON KIM, SUJONG JEONG, and BAEK-MIN KIM
- Subjects
SOUTHERN oscillation ,PRECIPITATION anomalies ,EL Nino ,PRECIPITATION variability ,OCEAN temperature ,SPRING - Abstract
Because spring precipitation in East Asia is critical for recharging water resources after dry winters, its spatiotemporal variations and related mechanisms need in-depth research. This study analyzed a leading spatiotemporal variability of precipitation over East Asia for boreal spring (March-May) during 1979 to 2017. We found that a dipole mode dominates the anomalous spring precipitation between southern China and Southeast Asia with significant interannual and decadal variations. The interannual dipole mode is attributable to the eastern Pacific (EP)-type El Niño-Southern Oscillation (ENSO) while the decadal dipole mode is related to the decadal variation of the central Pacific (CP)-type ENSO. In the El Niño phases of both time scales, the anticyclonic anomaly over the South China Sea and Philippines causes moisture convergence (divergence) over southern China (Southeast Asia), resulting in positive (negative) precipitation anomalies therein; the opposite occurs in the La Niña phases. The ensemble experiments using the Community Atmosphere Model version 5.1 confirmed that the tropical sea surface temperature (SST) in the EP- and CP-type ENSO can be the major drivers of the interannual and decadal dipole modes, respectively. About half of 15 climate models participating in phase 5 of the Coupled Model Intercomparison Project (CMIP5) showed that the El Niño phase of dipole mode will become dominant in the future. The individual models' future projections however considerably vary, implying that there is still large uncertainty. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
3. Twenty‐Five Years of Lower Tropospheric Ozone Observations in Tropical East Asia: The Influence of Emissions and Weather Patterns.
- Author
-
Wang, Tao, Dai, Jianing, Lam, Ka Se, Nan Poon, Chun, and Brasseur, Guy P.
- Subjects
TROPOSPHERIC ozone ,AIR masses ,WEATHER ,OZONE ,TROPOSPHERIC chemistry ,AIR quality ,TROPOSPHERE - Abstract
Tropospheric ozone affects the Earth's radiative balance, oxidative capacity, and air quality, yet the long‐term ozone trend in East Asia and its driver(s) remain poorly understood. Here we present ozone measurements obtained during 1994–2018 on China's southern coast. The measurement location intercepts China's outflow most of the time and the inflow of tropical maritime air during summer. We found an overall increase in the ozone level (0.35 ppbv/year), and the increase occurred mainly during the first half of the 25‐year period but appeared to level off in recent years in Chinese outflow. Large ozone increase (~20% per decade) was found in the maritime air. Model simulations show that recent weather conditions have reduced maritime ozone, counteracting the impact of the growing Southeast Asia's emissions. Our results fill the gap in the long‐term ozone trend in Asia and highlight the complex interaction of weather and emissions in driving the ozone change. Plain Language Summary: Tropospheric ozone has great influence on environmental issues ranging from air quality, to ecosystem productivity and to climate warming. Assessing the ozone impacts in fast‐developing Asia has been hindered by lacking long‐term measurements. We present here the longest continuous record of surface ozone in nonurban areas of tropical Asia. Using comprehensive tools, we reveal that the measurements on the south China's coast detected different ozone trends in air masses from eastern China (increasing in early years but stabilizing lately) and from Southeast Asia (continuously rising and at the largest rate). The latter finding is particularly striking, and we show that the recent weather patterns counteracted the expected increase of ozone due to emissions increases from Southeast Asia. Our results fill the gap in the long‐term ozone trends in Asia and highlight the complex interaction of weather and emission in driving the ozone trend. Key Points: We present the first long‐term record of ozone and CO in tropical East Asia, which shows that ozone has increased at the rate of 0.35 ppbv/yearThe ozone increase occurred during the first half of the 25‐year period and appears to have leveled off during recent years in the outflow from ChinaOzone shows the largest increase in maritime air mass, and weather change has counteracted the ozone increase associated with Southeast Asia's growing emissions [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.