Farmers in the indigenous Andean community of Cañar, Ecuador rely on an abundant wet season each growing year and are concerned that their wet seasons are becoming less rainy. The normal seasonal rainfall pattern in this region, the Andes of southern Ecuador, is driven primarily by the seasonal migration of the Intertropical Convergence Zone (ITCZ). Existing scientific literature suggests that the ITCZ’s seasonal migration pattern could be affected by anthropogenic climate change, thereby impacting the seasonal precipitation in the region. This study explores the possibility that the ITCZ’s migration pattern has already changed, which would validate the concerns of the Cañari people. This is accomplished by tracking the movement of the ITCZ over the past few decades using Outgoing Longwave Radiation (OLR) data. No obvious trend in the seasonal mean position of the ITCZ has been detected. However, OLR maps indicate an abnormal ITCZ signature during strong warm phases of the El Niño-Southern Oscillation (ENSO), consistent with previous studies. The interannual variability in the region’s seasonal precipitation is also associated with varying phases of ENSO. An additional component of this study is the development of a statistical model using ENSO indices as input, among other atmospheric indices, to provide seasonal precipitation forecasts for the tropical Andean wet season each year. Besides ENSO, another potentially useful index for seasonal prediction is the phase of the Quasi-Biennial Oscillation, which has been linked to precipitation variability in the tropics. The seasonal forecasting model is expected to help Ecuadorian highland farmers decide which of their crops to plant each year, based on the water needs of each crop.

Superparameterized (SP) global climate models have been shown to better simulate—as compared to conventional models—various features of precipitation, including diurnal timing as well as extreme events. While various studies have looked at the effect of differing microphysics parameterizations on precipitation within limited-area cloud-resolving models, we examine here the effect on continental-US extremes in a global SP model. We vary the number of predicted moments for hydrometeor distributions, the character of the rimed ice species, and the representation of raindrop self-collection and breakup. Using a likelihood ratio test and accounting for the effects of multiple-hypothesis testing, we find that there are some regional differences, both in the current climate and in a warmer climate with uniformly increased sea-surface temperatures. These differences are most statistically significant and widespread when the number of moments is changed. To determine whether these results are due to (fast) local effects of the different microphysics or the (slower) ensuing feedback on the large-scale atmospheric circulation, we run a series of short, 5-day simulations initialized from reanalysis data. We find that the differences largely disappear in these runs and therefore infer that the different parameterizations impact precipitation extremes indirectly via the large-scale circulation. Finally, we compare the present-day results with hourly rain-gauge data and find that, for the model configuration and resolution used, SP underestimates extremes relative to observations regardless of which microphysics scheme is used.

In this presentation, we seek to understand the altitudinal response of the auroral E-region neutral wind to substorms using observations from the Poker Flat Incoherent Scatter Radar (PFISR). Zou et al. (2009) presented different nighttime ion drift pattern associated with three different types of substorm events whose onset locations were at, to the east and to the west of PFISR. In addition, Zou et al. (2021) presented different types of latitudinal responses of the F-region neutral wind to substorm events and suggested that the response is highly local time dependent. While these two studies give much insight on the F region ion and neutral responses during substorm events, the E region neutral wind response is not well-understood. Previous studies showed that during disturbed conditions E-region winds, in particular below 110 km, are larger than what tidal theory predicts, while the winds in the upper E-region shows strong impacts from the convection flow. We select events whose onset locations are over the PFISR radar site, but in different MLT sectors using the SuperMag data product during 2010-2019. We present a superimposed epoch analysis of three different types of events after subtracting the quiet background neutral winds. This study will further our understanding of the contribution in a statistical view from forces that are associated with the E-region wind variation during substorm events during different MLT sectors and spanning the altitude range from 90-130 km.

In this talk, I will draw distinction between linear plasma waves and strong turbulent fluctuations and argue general characteristics of 3He rich solar energetic particle events favor the scenario that 3He ions are mostly energized via cyclotron resonance with proton cyclotron waves. These waves can be produced via magnetic reconnection at the ion diffusion scale and/or via cascade of turbulence energy from low to high frequencies. Both PIC and hybrid simulations can be used to verify these scenarios.

We propose a new approach to unambiguous determination of parameters of positive and negative electric streamer discharges (streamers). We derive several relations between streamer parameters which allow us to express them in terms of the streamer length L and the external electric field E_e, as functions of streamer radius a. In particular, we find that the streamer velocity V(a) has a maximum at a certain value of radius a_s. We interpret the streamer as a nonlinear instability, whose behavior is determined by maximizing its growth rate, proportional to V. The radius of the streamer is therefore hypothesized to be equal to a_s, which fixes all streamer parameters. Thus, for the first time (to our knowledge) we prove that the streamer parameters are completely determined by E_e and L and suggest a simple way to calculate them that does not require hydrodynamic simulations. The parameters of streamers in air at sea level conditions, calculated in the proposed way, are compared and found to be compatible with experimental data [e.g., velocities obtained by Allen and Mikropoulos, 1999, doi:10.1088/0022-3727/32/8/012 and radii seen on the photographic images of Kochkin et al, 2016, doi:10.1088/0022-3727/49/42/425203], as well as with results of hydrodynamic simulations [Lehtinen and Østgaard, 2018, doi:10.1029/2018JD028646]. We also reproduce the correct values of streamer threshold fields of ~0.45 MV/m for positive streamers and ~0.75-1.25 MV/m for negative streamers.

Every year, the area of the Arctic sea-ice decreases in the boreal spring and summer and reaches its yearly minimum in the early autumn. The continuous satellite-based time series shows that the September area has decreased from 4.5*10^6 km^2 in 1979, to 2.8*10^6 km^2 in 2020. The decline has been approximately linear in global mean surface temperature, with a rate of loss of 2.7*10^6 km^2 per degree C of global warming. In the CMIP6 ensemble, however, we find that the majority of the models that reach an Arctic sea-ice free state in the SSP585 runs shows an accelerated loss of sea-ice for the last degree of warming compared to the second last degree of warming, which implies an increased sensitivity of the sea-ice to temperature changes. Both in the observational and CMIP6 data, we find that the decline in September sea-ice area is approximately proportional to the area north of which the zonal average temperature in spring and summer is lower than a critical threshold Tc. The Arctic amplification implies that the zonally averaged temperatures increase relative to the global temperatures, and with rates increasing with latitude. Linear extrapolation of the zonally averaged temperatures predicts that, with further warming, the September sea-ice area will depend non-linearly on global temperature, the sensitivity will increase and the September sea-ice area may become less that 1*10^6 km^2 for global warming between 0.9 and 1.6 degrees C above the current temperature. As a result of accelerated sea-ice loss, the average evolution of the sea-ice area among the CMIP6 models before the loss of the summer sea-ice shows an increase in the year-to-year fluctuations in minimum ice cover in the next decade. This implies exceptional accumulation of extreme events with very low or no sea-ice at all even before the final loss of the sea-ice. Likewise, an apparent short-term recovery of the sea-ice loss might be observable due to the increasing fluctuations.

The Khumbu Icefall lies at an approximate altitude of 5,500 meters on the Nepali side of Mt. Everest and is one of the most dangerous stages of the major South Col route to the summit. In the Khumbu Icefall, seracs, or ridges on the surface of a glacier, are known to collapse unexpectedly, displacing massive volumes of ice down the Khumbu Glacier, estimated to advance 0.9 to 1.2 m down the mountain every day. Satellite Synthetic Aperture Radar (SAR) uniquely enables a next generation of remote sensing capabilities that offer a persistent, all-weather, day/night, complete characterization of the Earth and its dynamic surface changes. Using open C-band SAR data from the Sentinel-1 satellite constellation, ice dynamics can be reliably tracked at an approximately bi-monthly cadence over the past five years. The C-band instrument is nearly unaffected by cloud cover as it is not significantly attenuated by water vapor, making it incredibly useful for time-sensitive and temporal analysis such as tracking ice volumes, especially in regions under heavy cloud cover for roughly half of the year. Also, the Radar signal can be unwrapped to create phase history data to unlock information about the movement of objects in the scene. We demonstrate the use of this complex data to perform very accurate measurements of 3D change across the glacier and to extract two dimensional (azimuth and range directions) glacier surface velocities through the use of SAR speckle tracking. By enhancing 3D static geospatial data in the form of 3D high-resolution surface models with dynamic SAR information in 4D (3D + time) we additionally demonstrate a unique approach for more effective multi-temporal analysis and 3D change detection. We fuse the enhanced SAR open data with commercial 3D surface models to build a temporal stack of imagery over the Khumbu region and track changes in volume over time and their corresponding velocities. We showcase our analysis using 3D renderings of SAR fused data and SAR derived analytics for enhanced interpretability of the results. This data-driven time series coupled with geophysics principles can lead to significant research advances in studying glacier loss or retreat, ice thinning, or forecasting probabilistic ice motion to better prepare expeditions.

Numeracy is the ability to understand and interpret numbers. The numeracy skills are required and relevant across all disciplines and especially in STEM majors. The diverse group of underrepresented students from two-year community college was assessed on the knowledge of basic units of measurement and unit conversions in this study. The student performance was assessed in a lesson plan administered during The Numeracy Infusion for College Educators (NICE) Program at Bronx Community College. The students were assessed to identify different units; to be able to perform basic unit conversions; to recognize the scale of bigger and smaller units; and associated vocabulary. The learning goals aimed at developing thinking skills in reading graphs, trends or patterns and develop a habit of comparing the values of measurement in one unit system to another system of units. The students were provided tools to remember the increasing and decreasing trends in the scale of units. The real-life examples were incorporated into the learning process. The assessment was administered at different stages of learning in this lesson plan. This study will present the assessment results of lesson plan administered to a diverse group of underrepresented students from various majors in community college education. The student performance assessment in this lesson plan highlights the urgency to incorporate tools and techniques for numeracy skills across the curriculum in various disciplines of higher education.

Gas hydrates have been reported to exist in marine sediments from various parts of the world ocean. The hydrates start decomposing soon after recovery of the sediments through coring operations due to changes in ambient pressure and temperature. This decomposition leads to changes in sedimentary structures, and thus complicates physical property related measurements of the sediments by conventional methods. In this study, we used a medical X-ray CT scanner to quickly scan the recovered cores, and then used raw data from the CT, and thus avoided image processing steps, to estimate porosity and density of the sediments. The raw data were in terms of CT numbers, which were obtained by drawing a circular region of interest (ROI) to cover most of the sediments visible in a cross section XCT image of the sediments. The data were weighted for relative contribution of liquid and solid in sediments before estimating porosity. On the other hand, density was estimated by using an average CT number that was automatically calculated by the Osirix software used for drawing the ROI on an XCT image, and by using a calibration equation based on a set of standards. Although some uncertainty in estimation of relative volumes of solid, liquid and gas could not be avoided, the results obtained by this new procedure were in good agreement with those obtained by conventional methods. Since porosity and density estimates by the new procedure can be made in a matter of minutes after core recovery, it can guide progress of coring operation and further processing of hydrate-bearing sediments.

Satellite-based radar measurement are increasingly important for the detection of avalanche activity and the characterization of the snow cover properties on a regional scale. However, they operate with a temporal resolution of several days, which can detect major avalanche cycles, but changes induced by melt-freeze cycles, rain-on-snow events, snow fall, avalanche events and alike are more challenging to deduce. We present a ground-based radar system that measured the snow cover of a complete mountain slope during the winter season 2020-2021 with an hourly resolution and records flowing avalanches with 50Hz sampling. The observed mountain in Austria is a steep slope of southern aspect with avalanche control measures and corresponding artificial avalanche releases after every significant snow fall. We observe significant changes in the radar backscatter signal on different time scales: The rapid avalanche movement is analyzed by means of moving target identification filtering which suppresses the background signal from the resting snow cover, but enhances the rapid signal variations of the flow. Avalanche activity and their deposits can be identified by comparing the radar signal before and after avalanche events. And longer variations like diurnal changes in the backscatter signal are associated with meteorological influences, such as absorption of solar radiation and warming of the snow cover. We analyze the backscatter signal in terms of the flowing avalanches, immediate changes from fresh avalanche deposits and put these into relation to the magnitude of backscatter changes caused by the meteorological factors. We find that the backscatter signal of avalanche deposits can fluctuate significantly across the runout area, which is in accordance with satellite-based avalanche detection procedures that cluster deposits as regions with large radar signal variation. In the future, the developed radar may be used as ground-truth to support snow cover characterization with satellite-based radar missions.

The backprojection algorithm for synthetic aperture radar (SAR) has the ability of focusing raw data and forming an image without requiring simplifying assumptions for the azimuth-direction phase response of the recorded signal (Zebker et al., 2010). In fact, the usual quadratic phase assumption is not accurate when the recording platform is affected by turbulent motion or when wide variations in incidence angle across the range swath are present in the acquired data (Duersh, 2013). In addition, as we show here the backprojection algorithm is easily extendable to create SAR images of the subsurface in addition to the surface. These reasons make backprojection a well-suited method to create 3D subsurface SAR volume images from spaceborne acquisitions. The ability to form 3D SAR volumes using spaceborne data allows the study of larger areas than those available using to airborne acquisitions (Hélière et al., 2007). In this work, we create volume images by applying a 3D backprojection method to Advanced Land Observing Satellite (ALOS) data recorded over an icy area in Greenland previously studied by Banda et at. (2016). The 3D SAR image volumes created using different acquisition times enables the study of the evolution of the ice structure and properties. To decrease the processing time, we implement our algorithm using graphics processing units (GPUs) by taking advantage of the embarrassingly parallel nature of the backprojection algorithm (Fasih and Hartley, 2010).

The present space-based solar observing facilities, such as the Helioseismic and Magnetic Imager (HMI) instrument aboard the Solar Dynamics Observatory (SDO) satellite, can obtain time series photospheric vector magnetograms of solar active regions with high spatial and temporal resolution. The time evolution of the photospheric vector magnetic fields can be traced continuously for nearly all active regions appearing on the solar disk except for the marginal area near the solar limb. This facilitating condition is a huge benefit to the solar flare forecasting. By numerical modeling of the coronal magnetic fields based on the sophisticated nonlinear force-free field model from the observed photospheric vector magnetograms, the time series data of the coronal magnetic fields corresponding to the time series photospheric vector magnetograms can also be obtained. Then, the numerical analysis can be performed on the coronal magnetic field data, and the time evolution of the internal coronal magnetic structures as well as the evolution of the nonpotentiality in solar active regions can be revealed. The deduced quantitative measures of the coronal magnetic fields from the numerical analysis, such as the electric current density, the force-free factor, and the magnetic energy density, can be utilized in the solar flare forecasting and for establishing the solar flare prediction model. Samples of electric current analysis are presented. Through the numerical analysis of the time series magnetic fields in solar active regions, it is expected to predict flare locations, flare classes, and timing of flares.

It has been long known that the preferred crack alignments and fractures in rock cause seismic anisotropy and corresponding S-wave birefringence. Here the S-wave birefringence caused by the preferred alignment of cracks due to subcritical stress in the granitic basement of north central Oklahoma is examined. The data used for this study was collected during the IRIS Community Wavefields Experiment (CWE) in June and July of 2016, where more than 300 3-component (3-C) short-period seismographs were deployed in dense arrays with station spacings of 100m or less. These arrays were also in an area where many small earthquakes were occurring on a monthly basis, so that many were recorded by these arrays. The seismic data were cut from the original 30-day field records to produce short 3-C SEG-Y records of local earthquakes and explosions at a variety of back azimuths from the CWE array. Each 3-C record was rotated to the back azimuth of the source, such that the components become vertical, radial, and transverse with respect to the source. Vertical components are dominated by P arrivals, while radial components are dominated by SV arrivals and transverse components are dominated by SH arrivals. Seismic sections of the radial components of the array are then plotted in one color and overlain by the corresponding transverse components from the same array in another color. S-wave birefringence can then be directly observed as the time difference between arrivals, particularly first arrivals. S-wave birefringence is proof of seismic anisotropy and some characteristics of that anisotropy can be observed in record sections. For instance, birefringence is high along some azimuths and absent along other azimuths. Where birefringence is absent arrivals coincide, this could be either due to arrivals crossing or arrivals meeting but do not crossing. The latter case is important because it is the direction of an axis of symmetry for the anisotropic medium where the arrivals are propagating. This is also the case is observed in the record sections. The axis of symmetry observed in the record sections has an azimuth of 335 +/- 5 degrees. The fact that an axis of symmetry with no birefringence exists in the horizontal plane indicates that the anisotropic medium exhibits hexagonal symmetry, also known as horizontal transverse isotropy (HTI). It indicates that cracks and fractures are open perpendicular to the axis of symmetry and closed in other directions. Because of the large number of earthquakes occurring in this area a number of studies have been conducted on the in-situ stress orientations. In the sedimentary section overlaying the basement close to the CWE seismic array, borehole image logs indicate that the azimuth of drilling induced tensile fractures is 59 +/- 12 degrees. This is interpreted as the orientation of the maximum horizontal stress in the borehole. The axis of seismic anisotropy, which indicates the direction of minimum horizontal stress.

Launched in October 2018, the ESA/JAXA BepiColombo mission is currently in cruise to reach Mercury in late 2025. The Mercury Orbiter Radioscience Experiment (MORE) is one of the 16 instruments hosted on board the spacecraft. Testing general relativity is among the primary objectives of MORE. Superior conjunction experiments (SCE) will be performed during the interplanetary trajectory, with the aim of obtaining an accurate estimate of the post-Newtonian parameter γ. This is allowed by MORE advanced radio tracking system which provides precise range and Doppler data almost at all solar elongation angles, thus enabling an accurate measure of the relativistic time delay and frequency shift undergone by the signal when the spacecraft is in a superior solar conjunction (SSC). The rst BepiColombo SCE will take place in March 2021, and others will follow during the cruise phase. The nal objective is to place new limits to the accuracy of the general relativity as a theory of gravity in the weak eld limit, improving previous result from the Cassini SCE (Bertotti et al. 2003), which was able to determine that γ-1=(2.1±2.3)×10-5. Because of the proximity to the Sun, the spacecraft will undergo severe solar radiation pressure acceleration, and the effect of the random uctuations of the solar irradiance may become a major concern. We address the problem of a realistic estimate of the outcome of the SCE of BepiColombo, by including the effects of solar irradiance random variations in the dynamical model. We analyzed the experiment under different assumptions on the ranging system performances, observation coverage and solar activity showing their impact on the attainable result. We propose a numerical method to mitigate the impact of the variable solar radiation pressure on the scienti c result. Our simulations show that, exploiting data from multiple SSCs, the accuracy obtainable in the relativistic time delay measurement is 13×10-6 for a strong solar activity, and 6×10-6 for weak irradiance uctuations. We found that the latter result can be obtained by the rst SSC alone if the plasma noise calibration works until the impact parameter reaches 6 solar radii.

We perform physics-based simulations of earthquake rupture propagation on geometrically complex strike-slip faults. We consider many different realization of the fault roughness and obtain heterogeneous stress fields by performing dynamic rupture simulation of large earthquakes. We calculate the Coulomb failure function (CFF) for all these realizations so that we can quantify zones of stress increase/shadows surrounding the main fault and compare our results to seismic catalogs. To do this comparison, we use relocated earthquake catalogs from Northern and Southern California. We specify the range of fault roughness parameters based on past observational studies. The Hurst exponent (H) varies in range from 0.5 to 1 and RMS height to wavelength ratio ( RMS deviation of a fault profile from planarity) has values between 10-2 to 10-3. For any realization of fault roughness, the Probability density function (PDF) values relative to the mean CFF change show a wider spread near the fault and this spread squeezes into a narrow band as we move away from fault. For lower value of RMS ratio ( 10-3), we see bigger zones of stress change near the hypocenter and for higher value of RMS ratio ( 10-2), we see alternate zones of stress increase/decrease surrounding the fault to have comparable lengths. We also couple short-term dynamic rupture simulation with long-term tectonic modelling. We do this by giving the stress output from one of the dynamic rupture simulation (of a single realization of fault roughness) to long term tectonic model (LTM) as initial condition and then run LTM over duration of seismic cycle. This short term and long term coupling enables us to understand how heterogeneous stresses due to fault geometry influence the dynamics of strain accumulation in the post-seismic and inter-seismic phase of seismic cycle.

Rapid Arctic warming and sea ice decline in recent decades might have profound impacts on midlatitude weather and climate. This study uses a high-top atmospheric general circulation model - Whole Atmosphere Community Climate Model version 6 (WACCM6) - to investigate the atmospheric responses to the Arctic sea ice reduction, including impacts on mid-latitude blocking and cyclones. The high-top configuration (top layer at about 100 km or 0.001 hPa) together with the finer vertical resolution (70 layers) in WACCM6 allow more realistic representation of stratosphere-troposphere interactions. The sea ice impact during 1979-2015 is obtained by comparing ensemble simulations forced by daily observational sea ice concentration (SIC) and sea surface temperature (SST) to simulations where the time-varying SIC is replaced by a daily SIC climatology. A series of SIC-SST adjustments are performed to minimize unrealistic SIC and SST forcings used in the simulations. Each ensemble consists of 30 members with slightly different atmospheric initial conditions in order to separate forced atmospheric responses from internal model spread.

The Dobi graben is a NW-trending, Quaternary continental rift found within the East-Central Block (ECB) of the Afar Depression (AD) in northeastern Ethiopia. Extension occurs on steeply dipping faults, where the ratio of maximum displacement to traced fault length extends to four orders of magnitude. We conducted fault population analysis in the Dobi graben using a 30 m resolution Shuttle Rader Topography Mission (SRTM) Digital Elevation Model (DEM). We traced a total of 953 faults. We used the fault displacement length profiles’ tapering directions and the different types of fault propagations’ termination styles to characterize the fault kinematics pattern. Our population analysis results show that ~45% of the normal faults in the Dobi graben are tapering towards the southeast in a manner similar to the Red Sea Rift (RSR) regional strain gradient. On the other hand, our analysis showed that ~40% of the faults in the Dobi graben are tapering towards the northwest direction in a manner similar to the Gulf of Aden Rift (GAR) regional strain gradient. We found the statistical regression correlation coefficients (R-square value) for both the southeast and the northwest tapering faults to be ~0.7. Therefore, we suggest that ~85% of the lateral propagation of the 953 faults in the Dobi graben is highly influenced by the regional strain transfer of the RSR and GAR. Additionally, based on the fault propagation termination styles, our faults population analysis shows that faults which exhibit the half-restricted termination style account for 85% of the 953 faults. The maximum displacement over the maximum length (Dmax/Lmax) ratio of these faults is 0.03, which is in accord with the constant displacement length fault growth model.

Tropical convective systems that grow larger than 100,000km2 sizes play a significant role in the water cycle and energy budget of the Earth system. Previously, we developed hybrid tropical cloud-precipitation regimes (TCPRs) derived from Moderate Resolution Imaging Spectroradiometer (MODIS) cloud observations and Integrated Multi-satellitE Retrievals for GPM (IMERG) precipitation data at a 1° scale, and demonstrated that TCPRs enabled a simple but effective identification of convective systems at the synoptic scale. The Madden-Julian Oscillation (MJO) is the dominant mode of tropical intraseasonal variability, which is characterized as a planetary-scale envelop of convective clouds that propagates eastward over the Indo-Pacific warm pool. Recent studies showed a statistically robust correlation between the MJO and the quasi-biennial oscillation (QBO); MJO-related convective activities are enhanced and suppressed during an easterly and westerly phase of QBO, respectively. While the underlying mechanism of the MJO-QBO relationship has remained elusive, one of the most popular hypotheses is that the weakened stability in the upper troposphere and lower stratosphere during easterly QBO years provides a preferrable condition for deep convection to develop deeper and persist longer. To test the stability hypothesis for the QBO control on the MJO, we examine properties of the convective aggregates of TCPRs in the southern Maritime Continent region, in which the contrast in MJO activities between easterly and westerly QBO years is most pronounced. By taking advantage of TCPRs, we composite the total size, fractions of stratiform clouds to core area, and top height of core for different phases of MJO and QBO, and the results are compared to find any systematic difference in the characteristics of convective aggregates. Our results show that, as consistent to previous studies, bigger convective aggregates tend to occur when the stability weakens. Further insight will be obtained by examining cloud radiative effects and atmospheric energy budget per convective aggregates.