nasa-gesdisc/es-publications-researchareas huggingface dataset:
Comparison of polarization at two lunar eclipse events (2019)

We present the results of imaging polarimetry of the eclipsed Moon on 2014 October 8. The observed polarization degree was less than 1% in both the V and R bands, which contrasts with the reported 2%3% polarization during the eclipse of 2015 April 4. We examined the Earths atmospheric data on the two dates and found that the high (7 km) cloud distribution was more inhomogeneous for the 2015 eclipse than it was for the 2014 eclipse. The polarization position angle observed during the 2015 eclipse can be explained if the major polarizing source was high clouds with an intermediate horizontal optical thickness. We suggest a possible dependence of the lunar eclipse polarization on the Earths high cloud distribution.

Research areas: Validation
Aerosol solar radiative forcing near the Taklimakan Desert based on radiative transfer and regional meteorological simulations during the Dust Aerosol … (2020)

Abstract. The Taklimakan Desert is a main and continuous source of Asian dust particles causing significant direct radiative effects, which are commonly quantified by the aerosol solar radiative forcing (ASRF). To improve the accuracy of estimates of dust ASRF, the Dust Aerosol Observation-Kashi (DAO-K) campaign was carried out near the Taklimakan Desert in April 2019. The objective of the DAO-K campaign is to provide crucial parameters needed for the calculation of ASRF, such as dust optical and microphysical properties, vertical distribution, and surface albedo. The ASRF was calculated using radiative transfer (RT) simulations based on the observed aerosol parameters, additionally considering the measured atmospheric profiles and diurnal variations of surface albedo. As a result, daily average values of ASRF of 19 W m2 at the top of the atmosphere and 36 W m2 at the bottom of the atmosphere were derived from the simulations conducted during the DAO-K campaign. Furthermore, the Weather Research and Forecasting model with Chemistry (WRF-Chem), with assimilation of measurements of the aerosol optical depth and particulate matter (PM) mass concentrations of particles with aerodynamic diameter smaller than 2.5 m (PM2.5) and 10 m (PM10), is employed to estimate the dust ASRF for comparison. The results of the ASRF simulations (RT and WRF-Chem) were evaluated using ground-based downward solar irradiance measurements, which have confirmed that the RT simulations are in good agreement with simultaneous observations, whereas the WRF-Chem estimations reveal obvious discrepancies with the solar irradiance measurements.

Research areas: Sun-Earth Interactions
Changes in the surface broadband shortwave radiation budget during the (2020)

Abstract. While solar eclipses are known to greatly diminish the visible radiation reaching the surface of the Earth, less is known about the
magnitude of the impact. We explore both the observed and modeled levels of change in surface radiation during the eclipse of 2017. We deployed a pyranometer and Pandora spectrometer instrument to Casper, Wyoming, and Columbia, Missouri, to measure surface broadband shortwave (SW) flux and
atmospheric properties during the 21 August 2017 solar eclipse event. We
performed detailed radiative transfer simulations to understand the role of
clouds in spectral and broadband solar radiation transfer in the Earth's
atmosphere for the normal (non-eclipse) spectrum and red-shift solar spectra
for eclipse conditions. The theoretical calculations showed that the
non-eclipse-to-eclipse surface flux ratio depends strongly on the
obscuration of the solar disk and slightly on the cloud optical depth. These findings allowed us to estimate what the surface broadband SW flux would be
for hypothetical non-eclipse conditions from observations during the eclipse
and further to quantify the impact of the eclipse on the surface broadband
SW radiation budget. We found that the eclipse caused local reductions of
time-averaged surface flux of about 379 W m2 (50 %) and 329 W m2 (46 %) during the 3 h course of the eclipse
at the Casper and Columbia sites, respectively. We estimated that the Moon's
shadow caused a reduction of approximately 7 %8 % in global average surface
broadband SW radiation. The eclipse has a smaller impact on the absolute
value of surface flux reduction for cloudy conditions than a clear
atmosphere; the impact decreases with the increase in cloud optical depth. However, the relative time-averaged reduction of local surface SW flux
during a solar eclipse is approximately 45 %, and it is not sensitive to cloud optical depth. The reduction of global average SW flux relative to
climatology is proportional to the non-eclipse and eclipse flux difference
in the penumbra area and depends on cloud optical depth in the Moon's shadow
and geolocation due to the change in solar zenith angle. We also discuss the influence of cloud inhomogeneity on the observed SW flux. Our results not
only quantify the reduction of the surface solar radiation budget, but also advance the understanding of broadband SW radiative transfer under solar
eclipse conditions.

Research areas: Sun-Earth Interactions
Do modelled or satellite-based estimates of surface solar irradiance accurately describe its temporal variability? (2017)

Abstract. This study investigates the characteristic time-scales of variability found in long-term time-series of daily means of estimates of surface solar irradiance (SSI). The study is performed at various levels to better understand the causes of variability in the SSI. First, the variability of the solar irradiance at the top of the atmosphere is scrutinized. Then, estimates of the SSI in cloud-free conditions as provided by the McClear model are dealt with, in order to reveal the influence of the clear atmosphere (aerosols, water vapour, etc.). Lastly, the role of clouds on variability is inferred by the analysis of in-situ measurements. A description of how the atmosphere affects SSI variability is thus obtained on a time-scale basis. The analysis is also performed with estimates of the SSI provided by the satellite-derived HelioClim-3 database and by two numerical weather re-analyses: ERA-Interim and MERRA2. It is found that HelioClim-3 estimates render an accurate picture of the variability found in ground measurements, not only globally, but also with respect to individual characteristic time-scales. On the contrary, the variability found in re-analyses correlates poorly with all scales of ground measurements variability.

Research areas: Sun-Earth Interactions
Datasets on hub-height wind speed comparisons for wind farms in California (2018)

This article includes the description of data information related to the research article entitled The future of wind energy in California: Future projections with the Variable-Resolution CESM[1], with reference number RENE_RENE-D-1703392. Datasets from the Variable-Resolution CESM, Det Norske Veritas Germanischer Lloyd Virtual Met, MERRA-2, CFSR, NARR, ISD surface observations, and upper air sounding observations were used for calculating and comparing hub-height wind speed at multiple major wind farms across California. Information on hub-height wind speed interpolation and power curves at each wind farm sites are also presented. All datasets, except Det Norske Veritas Germanischer Lloyd Virtual Met, are publicly available for future analysis.

Research areas: Energy Production/Use
Assessing temporal complementarity between three variable energy sources through correlation and compromise programming (2020)

Renewable energies are deployed worldwide to mitigate climate change and push power systems towards sustainability. Nevertheless, the weather-dependent nature and variability of renewable energy sources often hinders their integration to national grids. The combination of different sources to profit from their beneficial complementarity has often been proposed as a partial solution to overcome these issues. This paper introduces a novel method for quantifying total temporal energetic complementarity between three different variable renewable sources, based on well-known mathematical techniques: correlation coefficients and compromise programming. It has the major advantage of allowing the simultaneous assessment of partial and total complementarity, as well as allowing for a linear assessment of complementarity. The method is employed to study the complementarity of wind, solar and hydropower generation on different temporal scales in a region of Poland. Results show that timescale selection has a determinant impact on the estimated value of the total temporal complementarity index.

Research areas: Energy Production/Use
The quest for the optimum angular-tilt of terrestrial solar panels or their angle-resolved annual insolation (2020)

Although solar energy is the fastest growing power technology, terrestrial solar panels typically fall behind their performance ratings established under standardised test-conditions. In particular, the angular-tilt of a panel can greatly affect its overall performance. Many studies thus aim to find the optimum tilt that maximises the annual insolation level. However, no widespread consensus has so far been found, partly because of different model assumptions applied. Here, a technique is proposed to use actual, historical solar spectra for the rigorous assessment of a panels tilt at a specific site. By combining multiple, free-accessible satellite-retrieved data products, the total all-sky insolation levels are tracked with a minutely changing global (hemispherical) solar spectrum over many years. While time-resolved annual insolation profiles can considerably vary among each other, the solar angle-resolved profile turns out to be robust to climatic conditions and is even site-independent for latitude-tilted panels. These findings can potentially unlock innovative yield optimisation methods.

Research areas: Energy Production/Use
Comparisons of radiative transfer schemes for infrared spectra and the region with solar and infrared spectra overlap in RRTMG (2020)

Five radiative transfer schemes are compared in infrared spectra using the Rapid Radiative Transfer Model for General Circulation Models Applications (RRTMG). By calculating the root mean squared error of net flux (referred as RMSE(NF)) in various atmosphere, the general accuracy of these schemes ranked from low to high are: non-scattering simplification (NS), the adding method of -two-stream discrete ordinate approximation (-2DDA), -two-stream variational iteration method (-2VIM), the adding method of -four-stream discrete ordinate approximation (-4DDA) and -four-stream variational iteration method (-4VIM). And their sensitivities to cloud fraction are decreased in the same order. Furthermore, the accuracy and efficiency of these schemes other than NS are studied under the contexts of using two different methods for dealing with the region where the solar and infrared spectra overlap. As one of the two overlap methods, One Band method (OB), which is used by RRTMG, has no advantage in model efficiency and is about 0.34 (0.41) W/m2 higher in mean column RMSE(NF) of the -two-stream (-four-stream) schemes than Whole Bands method (WB). Moreover, a new scheme, which is simple but adequate to handle the overlap region, is derived to solve the solar energy in longwave spectra.

Research areas: Sun-Earth Interactions
Predictability of characteristics of temporal variation in surface solar irradiance using cloud properties derived from satellite observations (2018)

Abstract Understanding of the characteristics of variation in surface solar irradiance on time scales shorter than several hours has been limited because ground-based observation stations are located coarsely. However, satellite observation data can be used to bridge this gap. We propose an approach for predicting characteristics of a time series of surface solar irradiance in a 121-min time window for areas without ground-based measurement systems. Time series featuresmean, standard deviation, and sample entropyare used to represent the characteristics of variation in surface solar irradiance quantitatively. We examine cloud properties over the area to design prediction models of these time series features. Cloud properties averaged over the defined domain and texture features that represent characteristics of the spatial distribution of clouds are used as measures of cloud features. Predictors for time series features, where explanatory variables are cloud features, are constructed employing the random-forest regression method. The performance test for predictions indicates that the mean and standard deviation can be predicted with higher prediction skill, whereas the predictor for sample entropy has lower prediction skill. The importance of cloud features for predictors and partial dependence of the predictors on explanatory variables are also analyzed. Cloud optical thickness (COT) and cloud fraction (CFR) were important for predicting the mean. Two texture featurescontrast and local homogeneity (LHM)and COT were important for predicting the standard deviation, and COT, LHM, and CFR were important for predicting the sample entropy. These results indicate which satellite-derived cloud field properties are useful for predicting time series features of surface solar irradiance.

Research areas: Sun-Earth Interactions
The impact of weathering upon the roughness characteristics of a splay of the active fault system responsible for the massive 2016 seismic sequence of the Central … (2021)

Fault roughness constitutes a key element in the understanding of earthquake nucleation, and surficial asperities on the fault plane play a critical role in slip dynamics and frictional behavior during the seismic cycle. Since it is not generally feasible to recover fault roughness profiles or maps directly at the seismogenic sources, faults at the Earths surface are typically used as analogues. However, these analogue fault surfaces are often subjected to weathering and erosion, which in turn, reduces their representativeness as seismogenic faults. Rupture along active faults episodically exposes fresh fault planes at the Earths surface, which represent the best available targets for the evaluation of fault roughness generated at seismogenic depths.Here we present a study conducted on a splay of the Mt. Vettore fault system in the Central Apennines, Italy, along a vertical transect that includes both a weathered and freshly exposed portion of the fault. The latter was exposed after the dramatic Mw 6.5 shock that hit the area on 30 October 2016. We have produced a highly detailed model (i.e., point cloud) of a section of the fault using structure from motion-multiview stereo photogrammetry to assess its roughness parameters (i.e., the Hurst fractal parameter) and to determine the extent to which these parameters are affected by weathering assuming that they had similar fractal characteristics when reaching the surface.Our results show that weathering can modify the value of the fractal parameters. In particular, by independently analyzing different patches of the fault, we have observed that the smoother and recently exposed portions have an average Hurst exponent of 0.52 while the average Hurst exponent of zones with more prolonged exposure times is 0.64. Accordingly, we conclude that by using high-resolution point clouds, it is possible to recognize patches of faults having a similar intensity of deterioration attributable to weathering.

Research areas: Earthquakes
Seismic Energy Release from Intra-Basin Sources along the Dead Sea Transform and Its Influence on Regional Ground Motions (2020)

The Dead Sea Transform (DST) dominates the seismicity of Israel and neighboring countries. Whereas the instrumental catalog of Israel (19862017) contains mainly M<5 events, the preinstrumental catalog lists 14 M 7 or stronger events on the DST, during the past two millennia. Global Positioning System measurements show that the slip deficit in northern Israel today is equivalent to M>7 earthquake. This situation highlights the possibility that a strong earthquake may strike north Israel in the near future, raising the importance of groundmotion prediction.Deep and narrow strikeslip basins accompany the DST. Here, we study ground motions produced by intrabasin seismic sources, to understand the basin effect on regional ground motions. We model seismicwave propagation in 3D, focusing on scenarios of Mw 6 earthquakes, rupturing different active branches of the DST. The geological model includes the major structures in northern Israel: the strikeslip basins along the DST, the sedimentary basins accompanying the Carmel fault zone, and the densely populated and industrialized Zevulun Valley (Haifa Bay area).We show that regional ground motions are determined by sourcepath coupling effects in the strikeslip basins, before waves propagate into the surrounding areas. In particular, ground motions are determined by the location of the rupture nucleation within the basin, the nearrupture lithology, and the basins local structure. When the rupture is located in the crystalline basement or along material bridges connecting opposite sides of the fault, ground motions behave predictably, decaying due to geometrical spreading and locally amplified atop sedimentary basins. By contrast, if rupture nucleates or propagates into shallow sedimentary units of the DST strikeslip basins, ground motions are amplified within, before propagating outside. Repeated reflections from the basin walls result in a resonant chamber effect, leading to stronger regional ground motions with prolonged durations.

Research areas: Earthquakes
Multi-objective optimization for enhancing hospital network resilience under earthquakes (2022)

The catastrophic earthquakes will cause numerous casualties requiring medical treatment, resulting in overcrowding in hospitals. To maintain the functionality of the hospital network, ambulance diversion (AD) between hospitals is required to relieve the stress of crowded hospitals. This research proposes a multi-objective optimization (MOO)-based emergency response model to enhance the resilience of the regional-level hospital network following earthquakes. The proposed model determines the optimal AD plan between hospitals for a given earthquake scenario. The average waiting time in the emergency department (ED) and the shortage of inpatient beds are selected as the objectives to measure the functionality of the hospital network, where the optimal solution is obtained by the Non-dominated Sorting Genetic Algorithm II (NSGA-II). The hospital network of Chengdu, China with the earthquake scenario of the Wenchuan earthquake is selected as the case study to demonstrate the validity of the proposed model. Important findings are: (1) in the optimal response plan, 66.2% of medical demands is transported to other hospitals by AD, (2) compared with the baseline situation, the average waiting time and the shortage of inpatient beds improve by 99.4% and 94.2% with the optimal emergency plan, (3) the high medical demand, low transportation efficiency, and the lack of ambulances have significant adverse impacts on the functionality of the hospital network, and (4) the proposed model is composed of high-effective coordination and a comprehensive hospital network, which avoids the waste of medical resources.

Research areas: Earthquakes
Icequake-Magnitude Scaling Relationship Along a Rift Within the Ross Ice (2022)

Fractures within ice shelves are zones of weakness, which can deform on timescales from seconds to decades. Icequakes produced during the fracturing process show a higher b-value in the Gutenberg-Richter scaling relationship than continental earthquakes. We investigate icequakes on the east side of rift WR4 in the Ross Ice Shelf, Antarctica. Our model suggests a maximum icequake slip depth that is ∼7.8 m below the rift mélange, where the slip area can only grow laterally along the fracture planes. We propose ductile deformation below this depth, potentially due to the saturation of unfrozen water. We use remote sensing and geodetic tools to quantify surface movement on different timescales and find that the majority of icequakes occur during falling tides. The total seismic moment is &lt;1% of the estimated geodetic moment during a tidal cycle. This study demonstrates the feasibility of using seismology and geodesy to investigate ice rift zone rheology.

Research areas: Earthquakes, Cryospheric Indicators
Analytical solution for time-dependent shoreline position response to the tectonic recovery process in the Sendai Plain, Japan, after the 2011 Great East Japan … (2021)

The 2011 Great East Japan Earthquake on March 11, 2011 triggered not only giant tsunami waves, but also caused significant land subsidence followed by land rise in the Sendai Coastal Plain areas. These impacts resulted in severe damages to the coastal infrastructure and induced coastal morphology changes along Japan's northeast coast. It was observed that the maximum downward deformation in the Sendai Coastal Plain was initially about - 0.3 m. Immediately after the earthquake, the land started to rise and it has already recovered back to its original position at some locations after 10 years. Thus, the high-quality measured beach profile data sets after the 2011 Tohoku Earthquake are valuable for exploring the impact of sea level rise (SLR) on shoreline position evolution, since the bed level change is inversely related to the sea level rise process. The data also provide a unique opportunity to evaluate the Equilibrium Beach Profile (EBP) theory and validate the Bruun concept. In the present study, a new simple analytical solution for time-dependent shoreline position response to the tectonic recovery process is developed based on the convolution method. The model results are able to predict the time-dependent shoreline evolution, including the maximum potential response and the characteristic erosion time scale at which the profile evolves towards a new equilibrium state.

Research areas: Earthquakes
Forecasting seismic risk within the context of the Sendai framework: An application to the Dominican Republic (2022)

The Sendai Framework proposes recording disaster losses from hazard events between 2015 and 2030 to monitor the progress towards reduction targets to curtail risk worldwide. In the case of earthquakes, relying on losses over 15 years is unlikely to yield sufficient evidence to support risk mitigation strategies. In this study we propose a general methodology to monitor and forecast Sendai indicators. We apply our approach to explore trajectories of probabilistic indicators of mortality (A1) and economic loss (C1) in the form of custom Sendai Indicators for the Dominican Republic. Risk reduction targets, at national and subnational level, are established and tested along with two mitigation strategies: nationwide retrofitting campaign and stronger code-enforcement. The baseline projection indicates that earthquake risk is expected to increase at a national level, with indicators A1 and C1 increasing over 17% and 27%, respectively, in a period of 35 years. At that scale, code enforcement is more effective in meeting the targets of reduced mortality by 2030 and 2050. At the sub-national level, results depend on the risk drivers in each municipality. We provide two cases: in Santiago de los Caballeros, the baseline risk projection suggests that indicators A1 and C1 will increase by more than 18% and 26% by 2050, respectively, while in Distrito Nacional they decrease by almost 5% and 3%, respectively. In the former region, code-enforcement is the most effective measure to meet the risk reduction targets, while for the latter it was found to be the retrofit campaign.

Research areas: Earthquakes