ALBERT

Description: In the Northwestern Pacific, the meridionally propagating Rossby waves known as the Pacific-Japan (PJ) pattern is the dominant teleconnection pattern in the vicinity in East Asia, and it often accompanies heatwaves. In this study, the circulation and thermodynamic characteristics of the pattern was investigated based on a daily timescale to better understand their relationship with the likelihood of heatwaves/marine heatwaves in East Asia. According to thermodynamic budget calculations, horizontal heat advection crossing the climatological flow pattern is the key factor for the observed surface air warming. For the ocean warming, the increased solar radiation due to anti-cyclonic circulation is the most impact factor over the East Asia. The CESM2 simulation results show that the heat forcing in the tropical western Pacific and atmospheric/marine heatwaves over East Asia is closely relevant the meridionally propagating Rossby waves.

Description: The high-precision X-ray diffraction setup for work with diamond anvil cells (DACs) in interaction chamber 2 (IC2) of the High Energy Density instrument of the European X-ray Free-Electron Laser is described. This includes beamline optics, sample positioning and detector systems located in the multipurpose vacuum chamber. Concepts for pump-probe X-ray diffraction experiments in the DAC are described and their implementation demonstrated during the First User Community Assisted Commissioning experiment. X-ray heating and diffraction of Bi under pressure, obtained using 20 fs X-ray pulses at 17.8 keV and 2.2 MHz repetition, is illustrated through splitting of diffraction peaks, and interpreted employing finite element modeling of the sample chamber in the DAC.

Description: Despite the importance of high-latitude surface energy budgets (SEBs) for land-climate interactions in the rapidly changing Arctic, uncertainties in their prediction persist. Here, we harmonize SEB observations across a network of vegetated and glaciated sites at circumpolar scale (1994–2021). Our variance-partitioning analysis identifies vegetation type as an important predictor for SEB-components during Arctic summer (June-August), compared to other SEB-drivers including climate, latitude and permafrost characteristics. Differences among vegetation types can be of similar magnitude as between vegetation and glacier surfaces and are especially high for summer sensible and latent heat fluxes. The timing of SEB-flux summer-regimes (when daily mean values exceed 0 Wm−2) relative to snow-free and -onset dates varies substantially depending on vegetation type, implying vegetation controls on snow-cover and SEB-flux seasonality. Our results indicate complex shifts in surface energy fluxes with land-cover transitions and a lengthening summer season, and highlight the potential for improving future Earth system models via a refined representation of Arctic vegetation types.

Description: Despite the importance of surface energy budgets (SEBs) for land-climate interactions in the Arctic, uncertainties in their prediction persist. In situ observational data of SEB components - useful for research and model validation - are collected at relatively few sites across the terrestrial Arctic, and not all available datasets are readily interoperable. Furthermore, the terrestrial Arctic consists of a diversity of vegetation types, which are generally not well represented in land surface schemes of current Earth system models. This dataset describes the data generated in a literature synthesis, covering 358 study sites on vegetation or glacier (〉=60°N latitude), which contained surface energy budget observations. The literature synthesis comprised 148 publications searched on the ISI Web of Science Core Collection.

Description: The ultrafast synthesis of ε-Fe3N1+x in a diamond-anvil cell (DAC) from Fe and N2 under pressure was observed using serial exposures of an X-ray free electron laser (XFEL). When the sample at 5 GPa was irradiated by a pulse train separated by 443 ns, the estimated sample temperature at the delay time was above 1400 K, confirmed by in situ transformation of α- to γ-iron. Ultimately, the Fe and N2 reacted uniformly throughout the beam path to form Fe3N1.33, as deduced from its established equation of state (EOS). We thus demonstrate that the activation energy provided by intense X-ray exposures in an XFEL can be coupled with the source time structure to enable exploration of the time-dependence of reactions under high-pressure conditions.

Description: Morphological variables (e.g., maximum dimension D〈sub〉max〈/sub〉, projected area, perimeter, width, and roundness) of ice crystals are fundamental information to represent microphysical and radiative properties of ice clouds in numerical models, which can be derived via in-situ aircraft measurements. Conventional airborne cloud probes are limited to a single observation angle to measure morphological variables. Non-spherical ice crystals may have different measured morphological variables depending on the observation angle, which causes uncertainties in the calculation of the microphysical and radiative properties of ice clouds. Thus, it is necessary to quantify uncertainties that depend on observation angles for determining the morphological variables of ice crystals. In this study, differences in determining the morphological variables of the ice crystals depending on observation angles were quantified using measurements of Particle Habit Imaging and Polar Scattering (PHIPS) probe that were acquired during the Arctic CLoud Observation Using airborne measurements during polar Day field campaign and the Southern Ocean Clouds Radiation Aerosol Transport Experimental Study field campaign. The PHIPS is a probe that provides stereo images of the sampled ice crystal from two different observation angles that are 120° apart. Morphological variables and habits of ice crystals were determined based on PHIPS stereo images. The uncertainties in determining morphological variables of ice crystals were quantified by calculating relative differences in morphological variables of ice crystals depending on observation angles. The nonsphericity of ice crystals sampled during ACLOUD and SOCRATES caused an average 14.69% (22.75%; 14.57%; 16.67%; 18.76%) uncertainty in determining Dmax (projected area; perimeter; width; roundness).

Description: Korea has been frequently exposed to aerosol cloud precipitation interactions specifically in the polluted season such that the enhanced aerosols might slow down coalescence and accretion, and thus delay the conversion of cloud water to precipitation drop. This inadvertent weather modification was identified as a couple of possible evidence, which as a result would make weather forecast incorrect in terms of precipitation intensity and timing in the mid-Korean peninsula (Eun et al., 2016; 2021). Meanwhile, the advertent weather modification campaign has been made during the past decade in the eastern mountainous region (Yeongdong) where cloud active aerosols are relatively fewer than the metropolitan region. This ongoing campaign largely focuses on winter and early spring in order to secure water supply and further prevent wildfire in dry season. The previous experiments showed a significant response in precipitation of the target (downwind) domain in comparison with the control zone after AgI burning at a fixed site for the several events. In addition, using a multi-angle snowflake camera, a decrease in snow crystal size and an increase in riming degree were demonstrated after the seeding on 14 March 2017, that was also identified with smartphone photographs on 9 March 2016 and 21 March 2018. In Korea, the advertent seeding experiment has been ongoing in the eastern mountainous (relatively clean) region whereas some inadvertent weather modification events occurred largely in the west (urban) region probably through the similar mechanism in the different environments.

Description: Explosive volcanic eruptions are one of the major natural hazards in East Asia. The study of eruptive history and volcanic ash dispersal are the key to understand eruption frequency and to identify the level of risk from different volcanoes. Here we use cryptotephra extraction techniques to examine a marine core from the southwestern Sea of Japan. The results reveal that six tephra layers are preserved in the Holocene core section, four of which are cryptotephra layers. Glass compositions of tephra shards indicate that these ashes are the B-Tm from Changbaishan volcano (China/N Korea), the K-Ah from Kikai caldera (Japan) and four tephras (U-1 to U-4) from the Ulleungdo volcano (S Korea). Except for the U-1 tephra whose age is previously unknown, terrestrially-based ages of the other tephras are used to constrain the marine reservoir effect and the age-depth model of the record. Through 〈sup〉14〈/sup〉C dating of marine sediment and reservoir correction, we report for the first time, a precise eruptive age for the Ulleungdo U-1 eruption (3354-3080 cal yr BP, 95.4%). The Holocene eruptive history of the volcano is now fully revealed, with four eruptions occurred at ca. 10.2, 8.4, 5.6 and 3.2 cal ka BP. Using the identified ash layers, we can now synchronize the marine record with sedimentary archives from in and around the Sea of Japan, to as far as the Arctic and the tropical regions. Our cryptotephra study shows the potential of this approach for future studies in the region.

Description: La Niña events, characterized by extended periods of cooling in the Pacific Ocean, are no longer limited to one year. In this talk, we'll delve into observational data and simulations to uncover the underlying mechanisms behind multi-year La Niña events. The evidence suggests that these events can be generated through both the tropical and subtropical components of ENSO dynamics. While a strong El Niño is necessary for the formation of multi-year La Niña events through the tropical dynamics, the subtropical dynamics can trigger the phenomenon without a preceding El Niño, instead relying on a positive feedback loop between La Niña and the subtropical Pacific. Additionally, we'll highlight the distinct impacts that multi-year La Niña events have on the climate of the northern and southern hemispheres.

Description: Geostationary Environment Monitoring Spectrometer (GEMS) have provided hourly observations of air quality (AQ) over Asia for the first time from a geostationary Earth orbit (GEO) since its launch in February 2020. After 8-month in-orbit tests, GEMS has observed column amounts of atmospheric pollutants (O3, NO2, SO2, HCHO, CHOCHO, and aerosols) to capture their diurnal variations with the UV–visible spectrometer at 0.6 nm spectral resolution and sophisticated retrieval algorithms. Details of the GEMS mission are presented, including calibrations, results, validations, and case studies including volcanic eruption, dusts, and urban pollution. L2 algorithms have been updated for version 2 and the products were released on November 30, 2022. In version 2, there are noticible improvements in trace gases from updated AMF and the separation of stratospheric/tropospheric components. Ongoing calibration/validation activities including the 2022 GMAP/SIJAQ campaign and international CAL/VAL team works are critical to diagnose and improve the overall data quality. The GEMS retrievals indicate good agreements from the validation campaign, but still require further improvement in L1 processing. We start testing improvements for L1 processing including BTDF correction. Faster sampling rates at higher spatial resolution increase the probability of finding cloud-free pixels, leading to more observations of aerosols and trace gases than has been possible from LEO. GEMS will be joined by NASA’s Tropospheric Emissions: Monitoring of Pollution (TEMPO) this year and ESA’s Sentinel-4 to form a GEO AQ satellite constellation in late 2024, respectively, as recognized by the Committee on Earth Observation Satellites (CEOS).