Phys.org January 18, 2022 Intense atmospheric rivers (ARs), eddy transports of moisture over the middle latitudes, contributed significantly to the extremely heavy rainfall events over the last decade in parts of East Asia. The extent to which ARs produce extreme rainfall over East Asia in a warmer climate remains unclear. An international team of researchers (Japan, USA – University of North Carolina) evaluated changes in the frequency and intensity of AR-related extreme heavy rainfall under global warming using a set of high-resolution global and regional atmospheric simulations. They found that both the AR-related water vapor transport and rainfall intensify over […]
Tag Archives: Atmospheric science
Weather balloon data shows troposphere getting thicker, pushing tropopause higher over past 40 years
Phys.org November 8, 2021 Tropopause height (H) is a sensitive diagnostic for anthropogenic climate change. Previous studies showed increases in H over 1980–2000 but were inconsistent in projecting H trends after 2000. While H generally responds to temperature changes in the troposphere and stratosphere, the relative importance of these two contributions is uncertain. An international team of researchers (China, Canada, USA – NCAR, Boulder CO, Austria) used radiosonde balloon observations in the Northern Hemisphere (NH) over 20°N to 80°N to reveal a continuous rise of H over 1980–2020. Over 2001–2020, H increases at 50 to 60 m/decade, which is comparable […]
Global satellite data shows clouds will amplify global heating
Phys.org July 19, 2021 Researchers in the UK used data from Earth observations and climate model simulations to develop a statistical learning analysis of how clouds respond to changes in the environment. They showed that global cloud feedback is dominated by the sensitivity of clouds to surface temperature and tropospheric stability. Considering changes in just these two factors, they were able to constrain global cloud feedback to 0.43 ± 0.35 W⋅m−2⋅K−1 (90% confidence), implying a robustly amplifying effect of clouds on global warming and only a 0.5% chance of Equilibrium Climate Sensitivity below 2 K. The “cloud feedback” is the […]
Understanding of invisible but mighty particles in Earth’s radiation belts
Science Daily May 26, 2021 In recent years, however, a growing body of experimental evidence has shown that EMIC waves can cause the scattering loss of electrons down to sub-MeV energies. Using measurements of trapped electron flux from the GPS satellite constellation, an international team of researchers (New Zealand, UK, USA – Los Alamos National Laboratory) investigated the ability of EMIC waves to cause significant depletions of radiation belt electron populations. They presented statistical evidence demonstrating global decreases in sub-MeV trapped electron flux in response to EMIC wave activity. Although they found that electron losses extend down to sub-MeV energies, […]
Lightning and subvisible discharges produce molecules that clean the atmosphere
Phy.org April 29, 2021 Lightning increases the atmosphere’s ability to cleanse itself by producing nitric oxide (NO), leading to atmospheric chemistry that forms ozone (O3) and the atmosphere’s primary oxidant, the hydroxyl radical (OH). A team of researchers (Pennsylvania State University, Texas Tech University, NOAA, University of Oklahoma, University of Maryland, University of Alaska, University of Colorado) analyzed data from their 2012 airborne study of deep convection and chemistry which showed that lightning also directly generates the oxidants OH and the hydroperoxyl radical (HO2). Extreme amounts of OH and HO2 were discovered and linked to visible flashes occurring in front […]
Aerosol formation in clouds
Science Daily March 24, 2021 Cloud processing is potentially important for secondary organic aerosol (SOA) formation, a major aerosol component: however, laboratory experiments fail to mimic this process under atmospherically relevant conditions. An international team of researchers (Switzerland, UK, USA – Carnegie Mellon University, industry) developed a wetted-wall flow reactor to simulate aqueous-phase processing of isoprene oxidation products (iOP) in cloud droplets. They found that 50 to 70% (in moles) of iOP partition into the aqueous cloud phase, where they rapidly react with OH radicals, producing SOA. Integrating their experimental results into a global model, they showed that clouds effectively […]
Researchers explore using light to levitate discs in the mesosphere
Phys.org February 15, 2021 To improve weather prediction sensors need to be sent to mesosphere. The satellites and rockets currently used have problems as the air is too thick and friction and heat would make long-duration flights impractical. Researchers at the University of Pennsylvania constructed and demonstrated light-driven levitation of macroscopic polymer films with nanostructured surface as candidates for long-duration near-space flight. The disks were made of 0.5-micron-thick mylar film coated with carbon nanotubes on one side. When illuminated with light intensity comparable to natural sunlight, the polymer disk heats up and interacts with incident gas molecules differently on the […]
Scientists Detect ‘Superbolts’ 1,000 Times Brighter Than Typical Lightning Strikes
Science Alert November 24, 2020 Researchers at the Los Alamos National Laboratory used Fast On-Orbit Detection of Transient Events (FORTE) satellite observations to identify superbolt-class optical lightning events and evaluate their origins. Superbolts have been defined as lightning pulses whose peak optical power exceeds 1011 W. However, it has been unclear whether superbolts resulted from particular types of high-energy lightning process or whether they were the result of measurement bias. According to their 12-year analysis of FORTE superbolt detections indicates that the lower optical superbolt energy range (~100 GW) is dominated by normal lightning, but brighter cases are predominantly strong […]
Shift in atmospheric rivers could affect Antarctic sea ice, glaciers
Science Daily November 23, 2020 Researchers at UCLA investigated the atmospheric river (AR) frequency trends over the Southern Hemisphere using three reanalyses and two Community Earth System Model (CESM) ensembles. Their results show that AR frequency has been increasing over the Southern Ocean and decreasing over lower latitudes in the past four decades and that ARs have been shifting poleward. While the observed trends are mostly driven by the poleward shift of the westerly jet, the experiments indicate anthropogenic forcing would result in positive AR frequency trends over the Southern Ocean due mostly to moisture changes. They conclude that the […]
Atlantic hurricanes linked to weather system in East Asia
Science Daily August 7, 2020 A team of researchers in the US (University of Iowa, Princeton University) has identified an association between the East Asian Subtropical Jet Stream (EASJ) during July–October and the frequency of Atlantic tropical cyclones during August–November based on observations for 1980–2018. According to the researchers the Rossby waves hitch a ride on the EASJ to the North Atlantic when tropical cyclones in the Atlantic are most likely to form. The waves affect wind shear, a key element in the formation of tropical storms. Rossby waves form within the Earth’s oceans and atmosphere because of the planet’s […]