Phys.org September 18, 2023 Due to the lack of long homogenous climate data and methodological frameworks, it is challenging to estimate how extreme precipitation could get and what the physical drivers are. Researchers in Switzerland developed two complementary strategies to extrapolate beyond the precipitation records: (a) statistical estimates based on fitting generalized extreme value distributions, providing their probabilistic information on return periods and, (b) ensemble boosting, a model-based re-initialization of heavy precipitation in large ensembles, providing a physical coherent storyline in space and time, however, with no direct quantification of its probability. Both show that 3-day accumulated precipitation maxima can […]
Category Archives: Atmospheric science
In dust and clouds over Africa, scientists find clues to how hurricanes form
Phys.org May 25, 2023 When the dust that wafts off the Sahel and Sahara regions of Africa mixes with tropical clouds, it creates rainy “disturbance” in the eastern Atlantic which are hurricanes in their youngest form. To study these infant storms, a group of NASA scientists spent a month flying off the northwestern coast of Africa aboard NASA’s research plane logging roughly 100 hours. The campaign encountered and measured one of the largest dust events the Airborne Laboratory capturing data with its instruments. Onboard remote sensing instruments captured detailed profiles of Saharan dust, wind speed and direction, temperature, moisture, and […]
Extended-range forecasts to be recast in next model upgrade
Phys.org May 18, 2023 In the next upgrade of European Centre for ECMWF’s (Medium-Range Weather Forecasts) Integrated Forecasting System (IFS), extended-range forecasts will have 101 instead of 51 ensemble members and will run more frequently than before, at a consistent horizontal resolution of 36 km. The upgrade will lead to improvements in forecast performance across all parameters. The extended-range forecasts provide predictions up to 46 days ahead. The 51‑member ensemble in the current configuration cannot always properly capture small shifts in forecast probabilities. Doubling the ensemble size to 101 ensemble members will provide a more accurate representation of the forecast […]
Initial wind field structure: A crucial factor in determining tropical cyclone size and intensity
Phys.org May 15, 2023 Researchers in China conducted experiments by varying the radius of maximum wind (RMW) and shape parameter b of the initial vortices. The size–intensity relationship was quantified by the linear regression coefficient of the azimuthally-averaged gale-force wind radius against the maximum wind during the development stage, reflecting the degree of size expansion at the same intensity increment. The regression coefficient increased with increased RMW and decreased b, with the RMW being the primary constraint. Enlarging the RMW led to a secondary circulation with a horizontally elongated structure, which retards the intensification while expanding the size. Broadening the […]
Scientists develop Earth system models with clouds and ocean submesoscale eddies
Phys.org April 26, 2023 Researchers in China developed a series of high-resolution coupled Earth system models (SW-HRESMs) with up to 5 km of atmosphere and 3 km of ocean which can meet the needs of multiscale interaction studies with different computational costs. They described the progress of SW-HRESMs development, with an overview of the major advancements made by the international Earth science community in HR-ESMs. They showed the preliminary results of SW-HRESMs regarding capturing major weather-climate extremes in the atmosphere and ocean, stressing the importance of permitted clouds and ocean submesoscale eddies in modeling tropical cyclones and eddy-mean flow interactions, […]
Lightning Bolt Deposits a Strange Mineral Never Seen on Earth Before
Science Alert April 15, 2023 Phosphate minerals such as those in the apatite group tend to be the dominant forms of phosphorus in minerals on the Earth’s surface. Phosphate can be reduced to phosphides during high-energy events, such as lightning and impacts. An international team of researchers (Italy, USA – University of South Florida) has shown that, in addition to formation of metal phosphides, a new compound was formed by lightning in a fulgurite from New Port Richey, Florida.. A calcium phosphite material, ideally CaHPO3, was found in spherules mainly consisting of iron silicides that formed by lightning-induced fusion of […]
Scientists discover a way Earth’s atmosphere cleans itself
Phys.org April 7, 2023 Hydroxyl radical (OH) is a key oxidant that triggers atmospheric oxidation chemistry in both gas and aqueous phases. The current understanding of its aqueous sources is mainly based on known bulk (photo) chemical processes, uptake from gaseous OH, or related to interfacial O3 and NO3 radical-driven chemistry. An international team of researchers (France, USA – UC Irvine, Israel) has provided experimental evidence that OH radicals are spontaneously produced at the air–water interface of aqueous droplets in the dark and the absence of known precursors, possibly due to the strong electric field that forms at such interfaces. […]
Dust lifted into the air by cyclones provides anchor points for cloud-forming ice
Phys.org March 14, 2023 Researchers in China examined dust-infused baroclinic storm (DIBS) over East Asia in May 2017 to study the dust effects on cirrus clouds. The data indicated that the 2017 storm produced extremely high ice particle concentrations of 1 to 10 particles per cubic centimeter, with particle sizes in the range of 10 to 30 micrometers. They found that the more sophisticated parameterization matched cloud observations more closely than the simple model: The new, more complex model yielded ice particle concentrations that were 10 to 100 times higher and particle sizes that were 2 to 3 times smaller. […]
Researchers advance insights into cause of ripples on icicles
Science Daily December 5, 2022 Icicles that have grown from slightly impure water develop ripples around their circumference. The ripples have a near-universal wavelength and are thought to be the result of a morphological instability. Researchers in Canada used laboratory-grown icicles and various species of impurities, including fluorescent dye, to show that a certain fraction of the impurities remains trapped inside the icicle, forming inclusions within the ice. The inclusions were organized into chevron patterns aligned with the peaks of the ripples. Within the chevrons, there was a substructure of crescent-shaped structures. They also examined the crystal grain structure of […]
Insect Swarms Can Electrify The Air as Much as a Thunderstorm
Science Alert October 25, 2022 The atmosphere hosts multiple sources of electric charge that influence critical processes such as the aggregation of droplets and the removal of dust and aerosols. Whereas these electric fields are known to respond to physical and geological processes, the effect of biotic sources of charge has not hitherto been considered. Researchers in the UK combined theoretical and empirical evidence to demonstrate that honeybee swarms directly contribute to atmospheric electricity, in proportion to the swarm density. They provided a quantitative assessment of this finding, by comparing the electrical contribution of various swarming insect species with common […]