Article
Geosciences, Multidisciplinary
Maximilien Bolot, Stephan Fueglistaler
Summary: A recent study found that convective ice flux near the tropical tropopause plays a crucial role in moisture transport, but due to challenging observation conditions and computational limitations, the quantification of these storms' effects remains limited.
GEOPHYSICAL RESEARCH LETTERS
(2021)
Article
Geosciences, Multidisciplinary
Cameron R. Homeyer, Jessica B. Smith, Kristopher M. Bedka, Kenneth P. Bowman, David M. Wilmouth, Rei Ueyama, Jonathan M. Dean-Day, Jason M. St. Clair, Reem Hannun, Jennifer Hare, Apoorva Pandey, David S. Sayres, Thomas F. Hanisco, Andrea E. Gordon, Emily N. Tinney
Summary: The concentration of water vapor in the lower stratosphere is the most sensitive factor contributing to Earth's radiative forcing. Rapid increases in stratospheric water vapor are often caused by tropopause-overshooting convection. This study focuses on obtaining in situ observations of stratospheric air affected by recent convection over the United States. The findings show that convective hydration routinely affects the stratosphere, with records of previous heights of convective hydration being exceeded during the DCOTSS flights. The most extreme event observed indicates a 26% increase in stratospheric water vapor at an altitude of 19.25 km, a potential temperature of 463 K, and an ozone mixing ratio >1500 ppbv.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Environmental Sciences
Ling Zou, Lars Hoffmann, Sabine Griessbach, Reinhold Spang, Lunche Wang
Summary: Ice clouds in the lowermost stratosphere affect stratospheric water vapour and the Earth's radiation budget. The knowledge of its occurrence and driving forces is limited. To assess the distribution and possible formation mechanisms of stratospheric ice clouds (SICs) over North America, we analysed SIC occurrence frequencies observed by the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) instrument during the years 2006 to 2018. Possible driving forces such as deep convection are assessed based on Atmospheric Infrared Sounder (AIRS) observations during the same time. Results show that at nighttime, SICs are most frequently observed during the thunderstorm season over the Great Plains from May to August (MJJA) with a maximum occurrence frequency of 6.2 %. During the months from November to February (NDJF), the highest SICs occurrence frequencies are 5.5% over the north-eastern Pacific and western Canada and 4.4% over the western North Atlantic. Occurrence frequencies of deep convection from AIRS, which includes storm systems, fronts, mesoscale convective systems, and mesoscale convective complexes at midlatitude and high latitude, show similar hotspots like the SICs, with highest occurrence frequencies being observed over the Great Plains in MJJA (4.4 %) and over the north-eastern Pacific, western Canada, and the western North Atlantic in NDJF (similar to 2.5 %). Both, seasonal patterns and daily time series of SICs and deep convection show a high degree of spatial and temporal relation. Further analysis indicates that the maximum fraction of SICs related to deep convection is 74% over the Great Plains in MJJA and about 50% over the western North Atlantic, the north-eastern Pacific, and western Canada in NDJF. We conclude that, locally and regionally, deep convection is the leading factor related to the occurrence of SICs over North America. In this study, we also analysed the impact of gravity waves as another important factor related to the occurrence of SICs, as the Great Plains is a well-known hotspot for stratospheric gravity waves. In the cases where SICs are not directly linked to deep convection, we found that stratospheric gravity wave observations correlate with SICs with as much as 30% of the cases over the Great Plains in MJJA, about 50% over the north-eastern Pacific and western Canada, and up to 90% over eastern Canada and the north-west Atlantic in NDJF. Our results provide a better understanding of the physical processes and climate variability related to SICs and will be of interest for modellers as SIC sources such as deep convection and gravity waves are small-scale processes that are difficult to represent in global general circulation models.
ATMOSPHERIC CHEMISTRY AND PHYSICS
(2021)
Article
Meteorology & Atmospheric Sciences
Zhenquan Wang, Jinming Ge, Jialin Yan, Wenxue Li, Xuan Yang, Meihua Wang, Xiaoyu Hu
Summary: This research focuses on the diurnal cycles and radiative effects of tropical oceanic high clouds above the 300 hPa level. The study finds that the diurnal cycle of these clouds significantly impacts their radiative effects, with the shifting of the diurnal centroid from midnight towards noon correlating with a decrease in net cloud radiative effects. The strength of convection and cold point temperature are identified as major factors influencing the diurnal-cycle centroid of these clouds. Additionally, observations show a correlation between the diurnal-cycle centroid of these clouds and the global mean temperature, with a 2-hour shift towards noon for every 1 degree Celsius increase in global mean temperature.
Article
Geosciences, Multidisciplinary
M. K. Sporre, J. Friberg, C. Svenhag, O. Sourdeval, T. Storelvmo
Summary: This study investigates the impact of downwelling sulphate aerosol on midlatitude cirrus clouds during springtime using three satellite data sets. The results show that cirrus clouds in the northern hemisphere have lower ice water content, ice crystal number concentrations, and cloud fraction when the aerosol load in the lowermost stratosphere is elevated by volcanism. However, the cirrus clouds in the southern hemisphere show no significant changes with downwelling aerosol levels. The reduction in cirrus ice water content and cloud fraction in the northern hemisphere implies that volcanic aerosol can cool the climate through reduced warming from cirrus clouds.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Geosciences, Multidisciplinary
Jacqueline M. Nugent, Christopher S. Bretherton
Summary: Tropical convection that overshoots the cold point tropopause can directly impact the climate by affecting water vapor, temperatures, and thin cirrus in the upper troposphere-lower stratosphere region. The distribution of these overshoots between land and ocean can determine their influence in a changing climate. Cold point-overshooting convection occurs more frequently over convectively active land areas than over warm oceans. This proxy method can evaluate the accuracy of simulated cold point overshoots. Cold point overshoots have an influence on the temperature structure and water vapor in the lower stratosphere.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Geosciences, Multidisciplinary
Ling Zou, Lars Hoffmann, Rolf Mueller, Reinhold Spang
Summary: This study analyzes the characteristics of the tropical tropopause using ERA5 reanalysis data from 1980 to 2021 and finds a general rise and cooling of the tropopause during this period. However, from 2006 to 2021, the tropical tropopause shows a warming trend with a slower rise. The study also reveals large uncertainties in the variability of the tropical belt width.
FRONTIERS IN EARTH SCIENCE
(2023)
Article
Environmental Sciences
Andries Jan de Vries, Franziska Aemisegger, Stephan Pfahl, Heini Wernli
Summary: The study investigates the formation of tropical ice clouds related to deep convection in the West African monsoon using stable water isotopes as tracers. The findings demonstrate that isotopes can be useful in understanding the processes involved in the formation of ice clouds and their impact on climate.
ATMOSPHERIC CHEMISTRY AND PHYSICS
(2022)
Article
Environmental Sciences
Jing Feng, Yi Huang
Summary: The study found that tropical cyclone events significantly increase the occurrence frequency of TTL clouds, mainly contributed by overshooting deep convection. Using a synergistic method with satellite observations, a vertically oscillating pattern of temperature anomalies above tropical cyclones was discovered.
ATMOSPHERIC CHEMISTRY AND PHYSICS
(2021)
Article
Environmental Sciences
Jinpeng Lu, Fei Xie, Hongying Tian, Jiali Luo
Summary: The study highlights the significant impacts of tropopause layer ozone changes on global climate change, especially on LSWV. A depletion of tropopause layer ozone at mid-low latitudes leads to cooling of the tropical cold-point tropopause and a reduction in LSWV, whereas the effect of polar ozone changes is opposite and weaker. The joint effect of tropopause layer ozone depletion causes negative cold-point tropopause temperature and decreased tropical LSWV.
Article
Environmental Sciences
Ling Zou, Sabine Griessbach, Lars Hoffmann, Reinhold Spang
Summary: This study investigates the occurrence and variability of stratospheric ice clouds (SICs) in the tropics and at midlatitudes by analyzing their relationships with tropopause temperature, double tropopauses, UTLS clouds, gravity waves, and stratospheric aerosols. The results show that SICs mainly occur in the tropics and are strongly associated with double tropopauses and UTLS clouds.
ATMOSPHERIC CHEMISTRY AND PHYSICS
(2022)
Article
Meteorology & Atmospheric Sciences
Aodhan Sweeney, Qiang Fu, Hamid A. Pahlavan, Peter Haynes
Summary: This study uses satellite data to investigate the impact of the Quasi-Biennial Oscillation (QBO) on equatorial clouds. The results show that the QBO has a strong seasonality in its effects on cloud coverage, with the strongest response occurring in spring and early summer in the northern hemisphere.
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES
(2023)
Article
Geosciences, Multidisciplinary
Samuel Bartusek, Yutian Wu, Mingfang Ting, Cheng Zheng, Arlene Fiore, Michael Sprenger, Johannes Flemming
Summary: Understanding the transport of ozone from the stratosphere to the troposphere is crucial, and a systematic analysis of the relationship between tropopause folding and tropospheric ozone is limited. Comparing high-resolution reanalysis ERA5 and low-resolution chemical reanalysis CAMSRA, it is found that high-resolution folding is more frequent and better correlated with tropospheric ozone. It suggests that tropopause folding is more responsible for stratosphere-to-troposphere ozone transport.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Meteorology & Atmospheric Sciences
Blaz Gasparini, Adam B. Sokol, Casey J. Wall, Dennis L. Hartmann, Peter N. Blossey
Summary: Satellite observations show that tropical maritime convection exhibits a peak in anvil cloud fraction in the afternoon, which cannot be explained by the diurnal cycle of deep convection peaking at night. Idealized cloud-resolving model simulations reveal that anvil clouds formed during the day are more widespread and longer lasting due to the influence of shortwave radiative heating, which leads to lofting and spreading of the clouds through a mesoscale circulation. In contrast, a different, longwave-driven circulation dominates at night and leads to erosion of the cloud top and shorter lifetimes for anvil clouds.
JOURNAL OF CLIMATE
(2022)
Article
Geosciences, Multidisciplinary
Aaron Match, Edwin P. Gerber
Summary: In response to global warming, ozone reductions in the tropical lower stratosphere are caused by both strengthening upwelling and tropospheric expansion, making it challenging to determine their relative contributions.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Meteorology & Atmospheric Sciences
Rei Ueyama, Eric J. Jensen, Leonhard Pfister, Ji-Eun Kim
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES
(2015)
Article
Geosciences, Multidisciplinary
Eric J. Jensen, Rei Ueyama, Leonhard Pfister, Theopaul V. Bui, M. Joan Alexander, Aurelien Podglajen, Albert Hertzog, Sarah Woods, R. Paul Lawson, Ji-Eun Kim, Mark R. Schoeberl
GEOPHYSICAL RESEARCH LETTERS
(2016)
Article
Geosciences, Multidisciplinary
Ji-Eun Kim, M. Joan Alexander, T. Paul Bui, Jonathan M. Dean-Day, R. Paul Lawson, Sarah Woods, Dennis Hlavka, Leonhard Pfister, Eric J. Jensen
GEOPHYSICAL RESEARCH LETTERS
(2016)
Article
Meteorology & Atmospheric Sciences
M. Joan Alexander, David A. Ortland, Alison W. Grimsdell, Ji-Eun Kim
JOURNAL OF THE ATMOSPHERIC SCIENCES
(2017)
Article
Meteorology & Atmospheric Sciences
Ji-Eun Kim, Chidong Zhang, George N. Kiladis, Peter Bechtold
JOURNAL OF THE ATMOSPHERIC SCIENCES
(2018)
Article
Geosciences, Multidisciplinary
Ji-Eun Kim, M. Joan Alexander
GEOPHYSICAL RESEARCH LETTERS
(2013)
Article
Meteorology & Atmospheric Sciences
Ji-Eun Kim, M. Joan Alexander
JOURNAL OF CLIMATE
(2013)
Article
Meteorology & Atmospheric Sciences
Ji-Eun Kim, Chidong Zhang
Summary: The study found a solution to the linear equatorial shallow-water equations resembling a harmonic oscillator, showcasing key characteristics of the observed MJO. Unlike existing theories interpreting the MJO as a new mode of variability arising from moisture evolution, this solution emphasizes the core dynamics of the MJO without explicit fluctuations in moisture.
JOURNAL OF THE ATMOSPHERIC SCIENCES
(2021)
Article
Geosciences, Multidisciplinary
Doo Young Lee, June-Yi Lee, Young-Min Yang, Pang-Chi Hsu, Ji-Eun Kim
Summary: During El Nino developing summers, BSISO-related convections are stronger and more organized with northward propagation compared to decaying summers. The easterly vertical shear in the developing phase remarkably increases due to enhanced upper-level easterly anomaly, leading to stronger air-sea interaction and amplifying northward propagation.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Geosciences, Multidisciplinary
Hien X. Bui, Axel Timmermann, June-Yi Lee, Eric D. Maloney, Yi-Xian Li, Ji-Eun Kim, Jacquelyn Shuman, Sun-Seon Lee, William R. Wieder
Summary: This study investigates the relationship between atmospheric stationary waves and wildfire occurrences, and finds that a zonal wavenumber 5-6 stationary wave pattern tends to synchronize wildfires in the Northern Hemisphere midlatitudes. The presence of upper-troposphere ridges and troughs creates alternating hot/dry and cold/wet conditions, affecting wildfire occurrence. More persistent high-pressure systems increase the likelihood of wildfires. While the dynamics of stationary waves do not change significantly with global warming, the variability of midlatitude wildfires is projected to intensify due to changes in climate conditions.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Meteorology & Atmospheric Sciences
Hien X. X. Bui, Yi-Xian Li, Eric D. D. Maloney, Ji-Eun Kim, Sun-Seon Lee, Jia-Yuh Yu
Summary: The Madden-Julian oscillation (MJO) has significant impacts on weather and climate phenomena. This study investigates the timing of the emergence of MJO change signals from natural variability under human-induced global climate change. Using simulations of the Community Earth System Model, it is found that MJO precipitation amplitude increases earlier than MJO wind amplitude. The findings provide valuable information for predicting MJO variability and associated extreme events.
NPJ CLIMATE AND ATMOSPHERIC SCIENCE
(2023)
Article
Geosciences, Multidisciplinary
Keith B. Rodgers, Sun-Seon Lee, Nan Rosenbloom, Axel Timmermann, Gokhan Danabasoglu, Clara Deser, Jim Edwards, Ji-Eun Kim, Isla R. Simpson, Karl Stein, Malte F. Stuecker, Ryohei Yamaguchi, Tamas Bodai, Eui-Seok Chung, Lei Huang, Who M. Kim, Jean-Francois Lamarque, Danica L. Lombardozzi, William R. Wieder, Stephen G. Yeager
Summary: Climate variability plays a crucial role in climate adaptation efforts, and greenhouse warming alters variance spectra of Earth system variables, leading to a wide range of changes. The modeling results have important implications for climate adaptation, resource management, seasonal predictions, and assessing stressors on terrestrial and marine ecosystems.
EARTH SYSTEM DYNAMICS
(2021)
Article
Meteorology & Atmospheric Sciences
Eric J. Jensen, Leonhard Pfister, David E. Jordan, Thaopaul V. Bui, Rei Ueyama, Hanwant B. Singh, Troy D. Thornberry, Andrew W. Rollins, Ru-Shan Gao, David W. Fahey, Karen H. Rosenlof, James W. Elkins, Glenn S. Diskin, Joshua P. DiGangi, R. Paul Lawson, Sarah Woods, Elliot L. Atlas, Maria A. Navarro Rodriguez, Steven C. Wofsy, Jasna Pittman, Charles G. Bardeen, Owen B. Toon, Bruce C. Kindel, Paul A. Newman, Matthew J. McGill, Dennis L. Hlavka, Leslie R. Lait, Mark R. Schoeberl, John W. Bergman, Henry B. Selkirk, M. Joan Alexander, Ji-Eun Kim, Boon H. Lim, Jochen Stutz, Klaus Pfeilsticker
BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY
(2017)
Article
Environmental Sciences
T. Wang, A. E. Dessler, M. R. Schoeberl, W. J. Randel, J. -E. Kim
ATMOSPHERIC CHEMISTRY AND PHYSICS
(2015)
