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Forests absorb carbon by capturing carbon dioxide from the atmosphere, making forest carbon stocks an important resource against climate change. In research published in Ecology and Evolution, investigators examined existing tree regeneration patterns to develop an indicator of potential changes to future carbon stocks across forests in the northeastern and midwestern United States.

A 3D-Var assimilation scheme for vertical velocity with CMA-MESO v5.0
Hong Li, Yi Yang, Jian Sun, Yuan Jiang, Ruhui Gan, and Qian Xie
Geosci. Model Dev., 17, 5883–5896, https://doi.org/10.5194/gmd-17-5883-2024, 2024
Vertical atmospheric motions play a vital role in convective-scale precipitation forecasts by connecting atmospheric dynamics with cloud development. A three-dimensional variational vertical velocity assimilation scheme is developed within the high-resolution CMA-MESO model, utilizing the adiabatic Richardson equation as the observation operator. A 10 d continuous run and an individual case study demonstrate improved forecasts, confirming the scheme's effectiveness.

IITM High-Resolution Global Forecast Model Version 1: An attempt to resolve monsoon prediction deadlock
R. Phani Murali Krishna, Siddharth Kumar, Athippatta Gopinathan Prajeesh, Peter Bechtold, Nils Wedi, Kumar Roy, Malay Ganai, B. Revanth Reddy, Snehlata Tirkey, Tanmoy Goswami, Radhika Kanase, and Parthasarathi Mukhopadhyay
Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2024-89,2024
Preprint under review for GMD (discussion: open, 0 comments)
The newly developed HGFM is an advanced iteration of the operational GFS model. The HGFM can produce forecasts at a spatial scale (~6 km in tropics). It demonstrates improved accuracy in short to medium-range weather prediction over Indian summer monsoon regions, as well as notable success in predicting extreme rainfall events. Following validation and testing, the model will be entrusted to operational forecasting agencies. Forecasts from this model could significantly affect billions of lives.

Abstract

The resolution and above all the stability of the geodetic reference frames is crucially important when global change, such as the sea level rise is observed. In this context systematic errors are still presenting a significant challenge to the measurement techniques of space geodesy. In order to overcome this unfortunate situation for the satellite laser ranging technique, we have utilized the injection of a mode-locked laser to provide a stable low-noise link between the optical domain, where the measurements are carried out, and the microwave regime in which the station clock is defined. We obtained a considerably enhanced measurement delay stability by 10–20 ps over several days, albeit with some experimental challenges. The implementation of waveform scans required us to revisit the issue of target structure and intensity variation in satellite laser ranging.

Abstract

The Inter-Satellite Link (ISL) technology plays a vital role in BeiDou Navigation Satellite System (BDS), and it’s a developmental trend of the future GNSS. However, ISL is insensitive to both the Earth’s rotation and the constellation’s overall rotation, which has resulted in persistent overall constellation drift issues for autonomous navigation. Due to technical limitations, the current method for autonomous navigation requires adding ground anchor stations in order to connect the satellite constellation to Earth’s surface, thereby minimizing the drift of constellation. Nevertheless, this approach is not a fully autonomous navigation as we expected. This paper proposes an autonomous navigation scheme based on ISL utilizing a lunar satellite as a spatial anchor point and leveraging lunar gravity to establish an inertial space direction reference for the satellite constellation. The feasibility and effectiveness of this scheme are validated through theoretical analysis and simulation experiments. After 120 days of precise orbit determination simulation, the accuracy of result is improved from 408.56 m to 7.78 m, which shows a 98% improvement for all GNSS orbit by adding a lunar satellite into ISL net. This improvement is primarily observed in terms of tangent and normal directions, which experience enhancements of 89.6% and 98.6%, respectively. Specifically, we achieve an improvement of approximately 89% in the accuracy of the inclination angle, around 99% in the right ascension of ascending node, and about 89% in the sum of the argument of perigee and mean anomaly.

SummaryThe Korean infrasound catalog (KIC) covers 1999 to 2022 and characterizes a rich variety of source types as well as document the effects of the time-varying atmosphere on event detection and location across the Korean Peninsula. The KIC is produced using data from six South Korean infrasound arrays that are cooperatively operated by Southern Methodist University and Korea Institute of Geoscience and Mineral Resources. Signal detection relies on an Adaptive F-Detector (Arrowsmith et al., 2009) that estimates arrival time and backazimuth, which draws a distinction between detection and parameter estimation. Detections and associated parameters are input into a Bayesian Infrasonic Source Location procedure (Modrak et al., 2010). The resulting KIC contains 38,455 infrasound events and documents repeated events from several locations. The catalog includes many anthropogenic sources such as an industrial chemical explosion, explosions at limestone open-pit mines and quarries, North Korean underground nuclear explosions, and other atmospheric or underwater events of unknown origin. Most events in the KIC occur during working hours and days, suggesting a dominance of human-related signals. The expansion of infrasound arrays over the years in South Korea and the inclusion of data from the International Monitoring System infrasound stations in Russia and Japan increase the number of infrasound events and improve location accuracy because of the increase in azimuthal station coverage. A review of selected events and associated signals at multiple arrays provides a location quality assessment. We quantify infrasound events that have accompanying seismic arrivals (seismoacoustic events) to support the source type assessment. Ray tracing using the Ground-to-Space (G2S) atmospheric model generally predicts observed arrivals when strong stratospheric winds exist, although the predicted arrival times have significant discrepancies. In some cases, local atmospheric data better captures small-scale variations in the wind velocity of the shallow atmosphere and can improve arrival time predictions that are not well matched by the G2S model. The analysis of selected events also illustrates the importance of topographic effects on tropospheric infrasound propagation at local distances. The KIC is the first infrasound catalog compiled in this region, and it can serve as a valuable dataset in developing more robust infrasound source localization and characterization methods.

SummaryGlobally, there is now a growing evidence for a low velocity layer in the deeper parts of the upper mantle, above the 410 km discontinuity (hereafter called LVL-410). The origin of this layer is primarily attributed to interaction of slabs or plumes with a hydrous mantle transition zone (MTZ) that results in dehydration melting induced by water transport upward out of the MTZ. However, the ubiquitous nature of this layer and its causative remain contentious. In this study, we use high quality receiver functions (RFs) sampling diverse tectonic units of the Indian sub-continent to identify Ps conversions from the LVL-410. Bootstrap and differential slowness stacking of RFs migrated to depth using a 3D velocity model reveal unequivocal presence of a deep low velocity layer at depths varying from 290 to 400 km. This layer appears more pervasive and deeper beneath the Himalaya, where detached subducted slabs in the MTZ have been previously reported. Interestingly, the layer is shallower in plume affected regions like the Deccan Volcanic Province and Southern Granulite Terrane. Even though a common explanation does not appear currently feasible, our observations reaffirm deep low velocity layers in the bottom part of the upper mantle and add to the list of regions that show strong presence of such layers above the 410 km discontinuity.

Various stress-releasing phenomena, such as episodic tremor and slip (ETS) and low-frequency earthquakes, occur at the downdip seismogenic zone in southwest Japan. However, it is unclear how much net stress an...

Abstract

The topography in the Maritime Continent (MC) has significant impact on climate anomalies in the Asian-Australian monsoons region. In the present study, the Regional Climate Model Version 4.6 (RegCM4.6) is applied for the simulation of climate over the Asian-Australian monsoon region during the boreal summer. Results demonstrate that the RegcM4.6 is able to well reproduce precipitation, temperature and low-level and upper-level circulation patterns over the Asian-Australian monsoons region. A sensitivity experiment with zero topographic height in the MC region shows that the intensity of western Pacific subtropical high (WPSH) and Australian cold high both weaken simultaneously, while the cross-equatorial flows also decline and the East Asian-Australian monsoons become weaker. Meanwhile, the anomalous cyclonic circulation with significant convergence prevails in lower levels over the western Pacific, leading to more precipitation and higher temperature. In the MC region, there are more precipitation and high temperature in the north while there are less precipitation and low temperature in the south. Temperature increases over a large area from the Yunnan-Guizhou Plateau to the Loess Plateau but decreases in the southeastern coast of China and eastern India. These results have important implications for better understanding the topographic impact of the MC region on the interaction between the east Asian-Australian monsoons.

Abstract

Deep atmospheric convection is often observed over the Kuroshio in the East China Sea (ECSK). However, the mechanisms by which warm oceanic currents fuel transient deep convection are not fully understood. This study investigates an atmospheric cold front that brought heavy precipitation as it traversed the ECSK in April 2004. The southwesterlies ahead of the cold front advected moist and warm air, creating a zone with high convective available potential energy (CAPE) values. As the cold front approached the ECSK, the pre-frontal high CAPE values coalesced with those over the warm current that substantially strengthened the deep convection, with precipitation rate increasing from 3 mm hr−1 to 10 mm hr−1. A numerical model well simulated the marked increase in precipitation over the ECSK, permitting the isolation of the ECSK's influence by contrasting the control (CTRL) run with an experiment with smoothed sea surface temperatures (SMTH run). Results show the ECSK contributed to 46% of the precipitation over the warm current. The ECSK was found to amplify ascending motion and elevate neutral buoyancy levels, extending its effect up to the tropopause. Furthermore, the strengthened deep convection significantly lowered the sea level pressure (SLP) over the ECSK and impressed upon the time-mean SLP field. An additional experiment with lowered SST underscored the high SST's critical role in deep convection. This case study suggests a novel pathway by which the effects of warm oceanic currents influence the upper troposphere under extreme conditions with strong baroclinic instability.

Abstract

With urbanization, anthropogenic water vapor emissions have become a significant component of the urban atmosphere. Fossil fuel combustion-derived vapor (CDV) is a primary source of these emissions. Owing to the notably low CDV d-excess, stable hydrogen and oxygen isotopes are promising for distinguishing CDV from natural sources. Considering the limitations of in situ observations, this study aims to explore the feasibility of using IsoRSM, an isotopically enabled regional atmospheric model, to simulate CDV emissions in urban areas in winter. Two experiments were conducted: one in Salt Lake City (SLC) in January 2017 and another in Beijing in January 2007. The simulation results showed that the CDV addition significantly reduced the water vapor d-excess, particularly when the boundary layer was stable. The simulation with CDV emissions aligned better with the time series of in situ observations in SLC. The modification led to a more pronounced positive correlation between vapor d-excess and specific humidity, which was similar to the observation of SLC. The CDV inclusion significantly increased the vapor d-excess variability with varying wind directions in both sites. However, in Beijing, the underestimation of d-excess variation from natural sources caused a bigger discrepancy between the observed and simulated d-excess and CDV fraction. Thus, though there were still biases, the inclusion of CDV could improve the accuracy of isotopic simulation in the urban regions where CDV was one of the controlling factors of vapor d-excess.

Abstract

The Tibetan Plateau (TP) provides vital water resources for downstream regions, with spring precipitation contributing considerably to the annual totals over the southeastern TP. The added value of convection-permitting modeling in simulating the spring climate over the TP is uncertain. Here, we conducted and compared decade-long regional convection-permitting (3.3 km) and convection-parameterized (13.2 km) Icosahedral Nonhydrostatic Weather and Climate Model (ICON) simulations to reproduce the atmospheric water cycle in spring over the TP. Results indicated that 3.3 km mesh ICON (ICON_3.3 km) exhibited notable added value in simulating the spring atmospheric water cycle over the TP. ICON_3.3 km reduced the wet biases of precipitation in the ERA5 reanalysis and 13.2 km mesh ICON (ICON_13.2 km) simulations, and improved the simulation of surface evaporation over the central and eastern TP. The reduction in the simulated precipitation in ICON_3.3 km was primarily followed by a decrease in surface evaporation from March to May, second by a reduction in water vapor flux convergence in May due to decreased water vapor inflow from the southeastern TP. Furthermore, compared to ICON_13.2 km, ICON_3.3 km alleviated the “drizzling” bias, leading to drier surface soils and decreased evaporation, and lead to 3% decrease in the fraction of evaporation converted into precipitation. Sensitivity experiments conducted at resolution of 13.2 km but turning off the convection parameterization demonstrated that both explicit representation of convection and enhanced horizontal resolution were crucial for accurately representing the spring atmospheric water cycle over the TP. Our results highlighted the need to develop kilometer-scale models for successfully reproducing the climate characteristics across the TP.

Abstract

As a crucial element in the Earth's system, development of convective clouds is still insufficiently understood and simulated in both weather and climate models, particularly for small-scale regional convective clouds. In this study, a series of convective clouds cases with relatively small scales are selected over south China, and the evolution characteristics of those convective clouds are investigated using high spatiotemporal resolution geostationary satellite data. Statistical results show that the shorter the life cycle or the smaller the area, the higher the proportion of convective clouds. Notably, approximately 79.23% of convective clouds have a life cycle of less than 3 hr, and 63.81% have an area of less than 500 km2 for selected cases. In addition, there are significant differences in the cloud characteristics and meteorological parameters during various convective cloud stages and durations. Nevertheless, the relative proportions of convective clouds at three identified stages remain relatively constant with almost no dependence on duration of convective clouds, which are 33.50%, 23.92%, and 42.58% for the developing, mature, and dissipation stages, respectively. In addition, we find that the cloud-top cooling rate during the developing stage also affects the characteristics of the later stage of convective clouds. Quantitatively, the average cloud area and duration changed by 157.03 km2 and 0.17 hr when the cloud-top cooling rate varies by 15 K/h.

Abstract

The strip-like bulge is a storm-time conjugate ionospheric plasma density enhancement, constituted by the plasmaspheric H+/He+, that extends widely (over 150° in longitude) in the zonal dimension but occupies only 1°–5° in latitude. Based on in-situ measurements of 11 low earth orbit satellites, this study statistically investigates the bulge structures of geomagnetic storms driven by 136 interplanetary coronal mass ejections during 2000–2021. The statistical results show that the strip-like bulges are observed at the end of the storm main phase and can persist for more than 60 hr. The spatial and temporal coverage of the strip-like bulge varies from storm to storm. However, the bulges do exhibit occurrence preferences: stronger storms (for the ICME-driven) during solar minimum periods, the Asian-Pacific sector (with eastward magnetic declination), and the nightside of the dawn-dusk terminator. A quiet time density enhancement called mid-latitude enhancement could be recognized as a precursor of the strip-like bulge. The evolution features of the plasmapause height exhibit similarities with the strip-like bulge, indicating a field-aligned downward and cross-L inward intrusion of the plasmaspheric ions. The local net ion drifts partly support this scenario with downward/inward being the most dominant but not unique pattern, the other diverse net ion drift configurations exist but their impact on the strip-like bulges remains unclear.

Abstract

By utilizing the close orbital separation between Swarm A and C during the Counter Rotation Orbit phase, we check the agreement and stationarity between the FAC-associated magnetic signatures at the two spacecraft through cross-correlation analysis. When the agreement and stationarity are passed, the magnetic signature is considered suitable for small and meso-scale Field-aligned currents (FAC) estimates with dual-spacecraft technique. It is found that at low and middle latitudes the dayside wave structure with apparent periods of about 10–60s can be observed around 90% of the time during all seasons. From those 90% can be identified as quasi-static current structures. On the nightside, the shorter period signatures dominate the apparent period spectrum. At about 30% of the time structures with 1–7s periods are observed. For the longer period signals the proportion is reduced greatly. About 80% of these signatures with periods longer than 3s are identified as quasi-static current structures. By taking advantage of the constantly changing longitudinal orbit separation during the considered time intervals, we can determine the mean separation at which the correlation breaks down. This provides FAC scale sizes in east-west direction separately for FACs of various latitudinal wavelengths. The result shows that typical east-west scale sizes of FAC structures with latitudinal wavelength of 10–400 km range from 10 to 60 km, respectively. FAC-related structures on the nightside have been associated with medium-scale traveling ionospheric disturbances and structures on the dayside primarily with FACs driven by atmospheric gravity waves.

Publication date: Available online 26 July 2024

Source: Advances in Space Research

Author(s): Ziyang Qu, Xiaolong Xu, Qile Zhao, Jing Guo

Publication date: Available online 26 July 2024

Source: Advances in Space Research

Author(s): Cheng Jia, Zhongjie Meng, Xincheng Guo

Publication date: Available online 26 July 2024

Source: Advances in Space Research

Author(s): Bruno S. Zossi, Franco D. Medina, Trinidad Duran, Ana G. Elias

Publication date: Available online 26 July 2024

Source: Advances in Space Research

Author(s): Y.P. Singh, B. Badruddin, S. Agarwal

Publication date: Available online 25 July 2024

Source: Advances in Space Research

Author(s): Chengbiao Fu, Yuheng Jiang, Anhong Tian