ALBERT

Description: Evidence for ungauged large freshwater palaeofloods in valley-confined landscapes frequently includes giant flow-eddy bars, deposited in alcoves along the floodway margins. Elevations of the bar tops commonly are used to define the minimum water level for computational flood simulations. Field study has shown that giant bar stratigraphy and sedimentology can be distinctive; identifying the alluvial signature of large palaeofloods where the morphological evidence may be less clear. However, whether the shape and stratigraphy of eddy bars provide indicators as to the nature of the floodwaves has not been considered widely. Flood hydrographs might be dam-break surge waves, gradually varied, or steady flows, for example. Yet, if bar form and stratigraphy vary systematically with the nature of the flood wave, then bars have additional value in defining the style of unrecorded floodwaves for environmental interpretation and flood modelling purposes. An experimental water flume was used to reproduce three styles of scaled floodwave that might be associated with sudden and more protracted releases of water from upstream reservoirs. Discharge was through a channel consisting of a series of contractions and expansions. Eddy bars were deposited within the flow separation zones that formed at each flow expansion. The basic hydraulic characteristics of the floodwaves were recorded and the form of the bars and the stratigraphy were examined. The results indicate that each style of flood deposited a distinctive barform and related stratigraphy. In this manner, we demonstrate that the examination of the form and stratification of giant bars in the natural environment can provide information on the style of the palaeoflood – sudden release or protracted flow – that was responsible for the deposition of the bars. Such information assists with the identification and interpretation of the nature and source of the floodwater as well as informing attempts to model hydrograph shapes.

Description: Abstract: In order to analyze the influence of K-band and LRI inter-satellite range-rate observation from GRACE-FO on gravity field recovery. Incorporating both K-Band and LRI inter-satellite range-rate data from GRACE-FO into gravity field recovery, we derive a new time series of monthly solutions entitled Tongji-Grace2022 complete to degrees and orders 60, 96, and 120 over the period Apr. 2002 to Sept.2022. During deriving Tongji-Grace2022, the[S1] low-degree coefficients up to d/o 6 were co-estimated with the high-degree coefficients to account for the temporal variations within one month. Analyses of Tongji-Grace2022 allow us to draw the following conclusions: (1) In the time domain, the RMS of LRI post-fit residuals is about 50% less than that of KBR; (2) In the frequency domain, the LRI shows significant noise reduction as compared to K-band data at high frequencies; (2) The comparison of Tongji-Grace2022 to CSR RL06, JPL RL06, GFZ RL06, and ITSG‐Grace2018 in terms of geoid degree variances suggests that Tongji-Grace2022 agrees well with other GRACE models at the low degrees (below degree 30), while the high-frequency noise in Tongji-Grace2022 is significantly reduced; (3) Less striping noise over oceans can be observed in Tongji-Grace2022 even only using decorrelation filtering (P4M6); (4) Over the selected river basins (i.e., Amazon, Mississippi, and Ganges) and Greenland, the correlation coefficient of the mass changes between Tongji-Grace2022 and others (i.e., CSR RL06, JFZ RL06, ITSG‐ Grace2018) are all over 92%.

Description: We present results from a study of three SEP events that occurred on July 12, 2012, April 3, 2010, and March 15, 2013 to understand effects of the heliospheric current sheet (HCS) on the propagation of SEPs. The three SEP events are associated with coronal mass ejections (CMEs), which share a number of similar properties: all CMEs (1) were of halo type and were originated near the Sun-Earth line, (2) were fast (〉 ~1000 km/s initially), with similar Sun-to-Earth transit time, (4) were accompanied with shocks observed at 1 AU, and (4) induced large geomagnetic storms. However, the onset time and intensity of the SEP (~ 3–41 MeV/nuc. He) at 1 AU were quite different. Our magnetohydrodynamic simulations suggest that delays of SEP flux for the studied events are due to the presence of the HCS between the CME source and the observer. It is also shown that elevated SEP fluxes can occur after part of the CME expands into the same magnetic sector as the observer or the observer moved across the HCS. This study suggests that the HCS can limit the propagation of energetic particles, at least in the energy range studied here, in the heliosphere. * This work was supported partially by the Chief of Naval Research, NASA HSR & HTMS programs.

Description: We have developed a new three-dimensional (3D) MHD simulation model of the propagation of coronal mass ejections (CMEs) through the upper corona and inner solar wind region. We implement a characteristics-based boundary conditions in an existing solar wind simulation model. The new model allows us to obtain the steady-state solar wind in the trans-magnetosonic regions subject to synoptic magnetogram data and simulate CME propagation from the low corona. Specifically, we define an inner boundary surface at 2.5 solar radii (Rs) and use a physics-based erupting flux rope model of CMEs to calculate the 3D CME dynamics from the initial expansion and to 2.5Rs. The passage of the model CME through this spherical surface is numerically implemented by using the values of magnetic field vector, plasma density, and plasma velocity vector on the cross-sectional intersection of the expanding model flux rope and the spherical surface at 2.5 Rs. Here, the initial flux rope is chosen so that the calculated height-time trajectory and synthetic coronagraph images fit the observed CME data in the initial phases. We discuss the simulated propagation of the model CME and its self-consistent interaction with the ambient solar wind beyond the 2.5-Rs boundary surface.

Description: Western Iran is an important dust source region in the Middle East, with strong dust activities occurring in the spring and summer seasons. Based on the station observation data, the interannual and decadal variations of dust activities during 1979-2015 have been investigated. It is found that the interannual variability of dust day frequency (DDF) in western Iran is largely regulated by wind speed, precipitation, and soil moisture in the region, with a strong negative correlation of -0.5 between spring DDF and precipitation, and -0.6 between spring DDF and soil moisture. Strong positive correlations between spring DDF and surface wind are around 0.4-0.6. However, the summer DDF is mainly associated with surface wind. A remarkable decadal change in spring dust frequency is found in the west and southwest of Iran, with fewer dust activities during 1992–2005 and more frequent dust activities occurring during 2006–2015. The decadal change signal in dust activities is closely associated with the corresponding decadal difference in precipitation and atmospheric moisture transportation in the region. Furthermore, negative SST anomalies in the central and western North Pacific and positive SST anomalies in the eastern North Pacific can be found from 1992–2005, which is corresponding to the positive phase of the Pacific Decadal Oscillation (PDO). Conversely, a negative phase of PDO can be found during 2006–2015. This suggests that PDO is the key influential factor for the decadal change of spring dust activities in western Iran.

Description: In considering the changing world, the authors of the Integrated Science: Science without Borders were asked how you would see the future of your field 30 years later. The present chapter publishes authors’ views on this subject in 2050. Authors have integrated science into the person, thinking of complex problems, artificial intelligence, management under changing conditions, and a sustainable future.