Phys.org February 12, 2024 Clouds affected by solar eclipses could influence the reflection of sunlight back into space and might change local precipitation patterns. Satellite cloud retrievals have so far not taken into account the lunar shadow, hindering a reliable spaceborne assessment of the eclipse-induced cloud evolution. Researchers in the Netherlands used satellite cloud measurements during three solar eclipses between 2005 and 2016 that have been corrected for the partial lunar shadow together with large-eddy simulations to analyze the eclipse-induced cloud evolution. The corrected data revealed that, over cooling land surfaces, shallow cumulus clouds start to disappear at very small […]
Tag Archives: Atmospheric science
Detecting atmospheric rivers with satellite observations
Phys.org February 19, 2024 Atmospheric rivers (ARs) are filaments of enhanced horizontal moisture transport in the atmosphere. They play a prominent role in the meridional moisture transport and regional weather extremes. But the representations of ARs and their associated precipitation on a global scale remains largely unknown. A team of researchers in the US (UCLA, NCAR, Caltech) developed an AR detection algorithm specifically for satellite observations using moisture and the geostrophic winds derived from 3D geopotential height field from the combined retrievals of the Atmospheric Infrared Sounder and the Advanced Microwave Sounding Unit on NASA Aqua satellite. The algorithm enabled […]
Earth’s ‘third pole’ and its role in global climate
Phys.org August 25, 2023 Researchers in China reviewed recent advances in research regarding land–atmosphere coupling processes over the Tibetan Plate (TP) and concluded that climate warming has caused glacier retreat, permafrost degradation, and a general increase in vegetation density, while climate wetting has led to a significant increase in the number of major lakes, primarily through increased precipitation. The TP drives surface pollutants to the upper troposphere in an Asian summer monsoon (ASM) anticyclone circulation before spreading to the lower stratosphere. The thermal forcing of the TP plays an essential role in the ASM. TP forcing can modulate hemispheric-scale atmospheric […]
Scientists improve the accuracy of weather and climate models
Phys.org March 1, 2023 Researchers in Switzerland have developed a new modelling framework for atmospheric flow simulations for cryospheric regions called CRYOWRF. CRYOWRF couples the state-of-the-art and used atmospheric model WRF (the Weather Research and Forecasting model) with the detailed snow cover model SNOWPACK. CRYOWRF makes it feasible to simulate the dynamics of a large number of snow layers governed by grain-scale prognostic variables with online coupling to the atmosphere for multiscale simulations from the synoptic to the turbulent scales. They also introduced a scheme for blowing snow in CRYOWRF. They described the technical design goals, model capabilities and the […]
Scientists can now map lightning in 3D
Phys.org February 15, 2023 A team of researchers in the US (Los Alamos National Laboratory, New Mexico Institute of Mining and Technology) developed and deployed a new 3-dimensional broadband radio frequency interferometric mapping and polarization system (BIMAP-3D) which provides an unprecedented capability in high-resolution, time-evolving 3D lightning source mapping and 3D source polarization detection for detailed study of lightning discharge physics. In this article they described the BIMAP-3D system design, a generalized and analytical 2D interferometry technique for noncoplanar antenna array, a two-stage 3D mapping technique based on geometric triangulation and baseline-based differential time of arrival, and a technique to […]
Deflecting lightning with a laser lightning rod
Phys.org January 16, 2023 An international team of researchers (France, Switzerland, Germany, USA – New Mexico Institute of Mining and Technology, Sweden) conducted the first field-result that experimentally demonstrated lightning guided by lasers. They conducted an experimental campaign on the Säntis mountain in north-eastern Switzerland during the summer of 2021 with a high-repetition-rate terawatt laser. The guiding of an upward negative lightning leader over a distance of 50 m was recorded by two separate high-speed cameras. It was corroborated in three other instances by very-high-frequency interferometric measurements, and the number of X-ray bursts detected during guided lightning events greatly increased. According […]
What drives the recent decline of East Asian dust activity?
Phys.org December 21, 2022 Dust entrained into the atmosphere serves as a major aerosol type, exerting effects on weather and climate system via aerosol-radiation-cloud interactions and delivering nutrients from continents to other continents and oceans. Using a physically-based dust emission model, an international team of researchers (China, Germany, USA – Texas A&M University) has shown that the weakening of surface wind and the increasing of vegetation cover and soil moisture have all contributed to the decline in dust activity during 2001 to 2017. The relative contributions of these three factors to the dust emission reduction during 2010–2017 relative to 2001 […]
New kind of tropical cyclone identified in the Indian Ocean
Phys.org November 28, 2022 Researchers in Australia focused on the regional wind variability that controls the intensity of cold-water upwelling off Sumatra – a key feature of the Indian Ocean Dipole (IOD). Their analysis of daily atmospheric data revealed the existence of convectively triggered synoptic-scale atmospheric cyclones in the South-East Tropical Indian Ocean (SETIO). The northern branch of the cyclones corresponded to westerly equatorial wind events, whereas the eastern branch involved north-westerly winds that operate to suppress cold-water upwelling off Sumatra’s west coast. Data for the period 1988–2022 showed that 5–9 SETIO cyclones normally form each year during the boreal […]
Unabated Carbon Is Shrinking Earth’s Upper Atmosphere, Scientists Warn
Science Alert November 22, 2022 A team of researchers in the US (NASA Langley Research Center, industry, NCAR, University of Colorado, Catholic University of America, NASA Langley Research Center, Hampton University) examined the thermal structure of the mesosphere and lower thermosphere (MLT) using observations from 2002 through 2021 from the NASA satellite. They showed that the MLT has significantly cooled and contracted between the years 2002 and 2019 due to a combination of a decline in the intensity of the 11-year solar cycle and increasing CO2. During this time the thickness of atmosphere between approximately 48 and 105 km has […]
The lightness of water vapor adds heft to global climate models
Science Daily October 24, 2022 The molar mass of water vapour is less than that of dry air, making humid air lighter than dry air at the same temperature and pressure. This effect is known as vapour buoyancy and has been considered negligibly small in large-scale climate dynamics. Using theory, reanalysis data and a hierarchy of climate models a team of researchers in the US (UC Davis, Lawrence Livermore National Laboratory, Pacific Northwest National Laboratory) showed that vapour buoyancy has a similar magnitude to thermal buoyancy in the tropical free troposphere. They also showed that vapour buoyancy makes cold air […]