Examination of the contribution from O.A. Troshichev, S. Dolgacheva, N.A. Stepanov, and D.A. Sormakov: “The PC index variations during 23/24 solar cycles: relation to solar wind parameters and magnetic disturbances. https://doi.org/10.1029/2020JA028491 ” has disclosed inconsistencies in the applied methods and serious errors in the calculated values. Some of the discrepancies reported in the present commentary affect directly the illustrations presented in their contribution while other possible errors may not be apparent since the use of relative values in their presentation makes thorough assessments difficult.

The Middle East is one of the world’s most vulnerable areas to climate change, which has exacerbated environmental, agricultural, water conflict, and public health issues in the region. Here we analyze the latest climate model projections of precipitation and temperature for the very high emissions scenario, SSP5-8.5, to detect potential future changes in this region. A baseline period (1981-2010) is compared with the middle (2040-2069) and end (2070-2099) of the 21st century. The results, representing the worst-case scenario, identify the Tigris-Euphrates headwaters as the hotspot of future compounding effects of climate change in the Middle East. Those effects result from the coincidence of elevated temperature, reduced precipitation, and enhanced interannual variability of precipitation. The hotspot overlays the location of the Southeastern Anatolia Project (in Turkish, GAP) irrigation initiative. In this climate context, risks to GAP viability and downstream water security, and associated potential for water-related conflicts and migration are considerable and demand a reconsideration of the risk-benefit assessment of GAP. This need has become more urgent after the recent widespread and deadly climate-related conflicts and wildfires in summer 2021 across the Middle East that further underlined vulnerability of the region to climate extremes.

While hotspot tracks beneath thin oceanic lithosphere are visible as volcanic island chains, the plume-lithosphere interaction for thick continental or cratonic lithosphere often remains hidden due to the lack of volcanism. To identify plume tracks with missing volcanism, we characterize the amplitude and timing of surface heat flux anomalies following a plume-lithosphere interaction using mantle convection models. Our numerical results confirm an analytical relationship in which surface heat flux increases with the extent of lithosphere thinning, which is primarily controlled by on the viscosity structure of the lower lithosphere and the asthenosphere. We find that lithosphere thinning is greatest when the plate is above the plume conduit, while the maximum heat flux anomaly occurs about 40-140\,Myr later. Therefore, younger continental and cratonic plume tracks can be identified by observed lithosphere thinning, and older tracks by an increased surface heat flux, even if they lack extrusive magmatism.

Numerical Weather Prediction models (NWP) have been used extensively since the ’40-’50s. Despite the advances in the field, the representation and forecast of the magnitude and variability of tropical processes in models is still a challenge. One of the steps to improve the precipitation forecasts using limited-area models is to evaluate which set of physical schemes and model domain configurations represent in a better way the actual behavior observed in the tropics. We implemented, as a part of a regional risk management strategy, two different operational weather forecast strategies for a complex terrain region in the Andes mountain range in northern South America. Both strategies, together, generate a total of eleven different forecasts every day, using the Weather Research and Forecasting model (WRF) with initial and boundary conditions from the Global Forecast System (GFS). The first configuration, implemented over five years ago and referred to as SYNAPSIS, includes three nested domains (18, 6 and 2 km) and is carried out every day using the 12 UTC GFS run and three different microphysics parametrizations: Eta Ferrier scheme, Purdue Lin Scheme and Thompson Scheme. The forecast lead-time of the latter strategy is 120 hours, and it does not use data assimilation. Since December of 2017, we implemented a second configuration termed RDFS, with two nested domains (12 and 2.4 Km), which carried out four times a day using the 00, 06, 12 and 18 UTC GFS runs. This configuration has a 30-hours lead time with the Thompson microphysics scheme. In RDFS, two WRF forecast runs are performed for each start hour, one assimilating weather radar reflectivity and the other without assimilation as control run, for a total of eight forecast runs daily. In this study, we assess the rainfall and temperature forecasts for all the different configurations using precipitation derived from reflectivity from weather radar, and air temperature at 2m from a network of automatic weather stations. We use 6 hourly and monthly skill scores (RMSE, BIAS, and Correlation coefficient) to quantify the precipitation differences between the SYNAPSIS and the RDFS configurations. To evaluate the impact of data assimilation in the precipitation forecast, we aggregate the results in a region within the inner domain, and then we calculate the average precipitation forecast between 0 and 36 predicted hours for RDFS with and without data assimilation. The results suggest a strong relationship between the forecast start time and the improve of precipitation forecast accuracy using data assimilation. The diurnal cycle of precipitation in the study region has a minimum in the morning (12 UTC) and a maximum in the afternoon (00 UTC) and during the night (09 UTC). The correspondence between the forecast improvement using data assimilation and the diurnal cycle of precipitation is likely due to the amount of assimilated data. In order to quantify the precipitation differences between the diffe

The early Eocene (~56-48 million years ago) is characterised by high CO2 estimates (1200-2500 ppmv) and elevated global temperatures (~10 to 16°C higher than modern). However, the response of the hydrological cycle during the early Eocene is poorly constrained, especially in regions with sparse data coverage (e.g. Africa). Here we present a study of African hydroclimate during the early Eocene, as simulated by an ensemble of state-of-the-art climate models in the Deep-time Model Intercomparison Project (DeepMIP). A comparison between the DeepMIP pre-industrial simulations and modern observations suggests that model biases are model- and geographically dependent, however these biases are reduced in the model ensemble mean. A comparison between the Eocene simulations and the pre-industrial suggests that there is no obvious wetting or drying trend as the CO2 increases. The results suggest that changes to the land sea mask (relative to modern) in the models may be responsible for the simulated increases in precipitation to the north of Eocene Africa, whereas it is likely that changes in vegetation in the models are responsible for the simulated region of drying over equatorial Eocene Africa. There is an increase in precipitation over equatorial and West Africa and associated drying over northern Africa as CO2 rises. There are also important dynamical changes, with evidence that anticyclonic low-level circulation is replaced by increased south-westerly flow at high CO2 levels. Lastly, a model-data comparison using newly-compiled quantitative climate estimates from palaeobotanical proxy data suggests a marginally better fit with the reconstructions at lower levels of CO2.

Polar Cap PC) indices, PCN North based on magnetic observations from Qaanaaq (THL) in Greenland and PCS South based on magnetic data from Vostok in Antarctica, are very useful indices for studies of solar wind-magnetosphere interactions and for space weather monitoring and forecasts. PCN indices are issued from the Danish Space Research Institute (DTU Space) while PCS indices are issued from the Arctic and Antarctic Research Institute (AARI) in St Petersburg. Unfortunately, series of invalid PCS values have been provided from AARI and used in a number of publications issued since the PC index concept was endorsed by the International Association of Geomagnetism and Aeronomy (IAGA) in 2013. The present contribution defines the invalidating features of the PCS indices in question, conveys examples, and discusses the applications in peer-reviewed publications.

The iris hypothesis suggests a cloud feedback mechanism that a reduction in the tropical anvil cloud fraction (CF) in a warmer climate may act to mitigate the warming by enhanced outgoing longwave radiation. Two different physical processes, one involving precipitation efficiency and the other focusing on upper-tropospheric stability, have been argued in the literature to be responsible for the iris effect. In this study, A-Train observations and reanalysis data are analyzed to assess these two processes. Major findings are as follows: (1) the anvil CF changes evidently with upper-tropospheric stability as expected from the stability iris theory, (2) precipitation efficiency is unlikely to have control on the anvil CF but is related to mid- and low-level CFs, and (3) the day and nighttime cloud radiative effects are expected to largely cancel out when integrated over a diurnal cycle, suggesting a neutral cloud feedback.

Data collected by space probes and Earth-based observations allow to investigate multiple aspects of planetary bodies in the Solar System. Typical spatial data utilized for geological and geophysical global scale investigations include imagery basemaps, digital elevation models, feature density maps, geochemical, magnetic and gravity anomaly maps. Different datasets often present local correlations, and their simultaneous use can help unveil the wide diversity of geological and geophysical processes that contribute to the planetary evolution. A geostatistical approach can be applied to quantify the level of correlation and anticorrelation between the different datasets. We developed a method based on a linear regression analysis of multiple planetary data, producing georeferenced maps that can be imported into a Geographic Information System (GIS) environment. We show how this geostatistical method can be used to quantify the level of correlation between different spatial data, and to investigate the geological and geophysical processes of planetary bodies. We present the results of the geostatistical method for the Mercury science case, using datasets returned by the MESSENGER mission.

The most important parameter driving the solar wind-magnetosphere interaction is the southward (Bz) component of the interplanetary magnetic field (IMF). While the dawn-dusk (By) component of the IMF is also known to play an important role, its effects are usually assumed to be independent of its sign. Here we demonstrate for the first time a seasonally varying, explicit IMF By-dependence of the ring current and Dst index. Using satellite observations and a global magnetohydrodynamic (MHD) model coupled with a ring current model, we show that for a fixed level of solar wind driving the flux of energetic magnetospheric protons and the growth-rate of the ring current are greater for By<0 (By>0) than for By>0 (By<0) in Northern Hemisphere summer (winter). While the physical mechanism of this explicit By-effect is not yet fully understood, our results suggest that IMF By modulates magnetospheric convection and plasma transport in the inner magnetosphere.

MAJOR POINTS: 1) The Barents and GIN basins are warming rapidly and exhibiting strong strong interannual variability. 2) While interannual variability of heat content in the GIN Seas is controlled by Atlantic water transport, we show interannual variability of heat content in the Barents is controlled by surface flux (see also Schlichtholtz et al 2011). 3) Interannual variations in surface flux are the result of variations in wintertime latent heat loss resulting from intrusions of warm moist air from the south. 4) (not shown) these variations also control winter sea ice cover.

Accelerating demand for energy storage has led to increasing development of brine resources in the “Lithium Triangle”, estimated to hold about 75% of the planet’s Li reserves but persistent and fundamental questions regarding the source and transit time of groundwater have confounded efforts to manage these resources effectively. The basins containing these brines lie within the massive Altiplano-Puna Plateau, home to people whose ancestors have inhabited this land for thousands of years and fragile ecosystems that exist nowhere else on Earth. This region is very dry, bordering Earth’s driest non-polar desert and as such, groundwater is the predominant and, in many areas the only source of water. Fundamental questions about the spatiotemporal dimensions of these groundwater systems have only begun to be addressed. In much of this extreme and remote region, there is a severe lack of quality baseline understanding of the regional hydrological system and connections between surface and groundwater bodies. To address these questions, we utilize an exhaustive set (~2,500 individual analyses) of environmental tracer data (δ18O, δ2H, 3H, 87Sr/86Sr), and dissolved major and minor elements in waters collected from over a dozen field campaigns in the Salar de Atacama and Altiplano of Chile and on the Puna Plateau of Argentina. Our integrated analysis pairs these data with rigorous geochemical modelling and physical hydrological measurements from the field and remote sensing products. 3H data show much of the groundwater currently discharging into these basins is non-modern (>60 yrs. old), stable isotope and geochemical data show strong connectivity but also a marked disconnect between some recharge and discharge areas. We show that “fossil” groundwater, 100-10,000 yrs. or older is widespread and fundamental to the system, sharp disconnects exist between the modern hydrological system, the water bodies it sustains, and those sustained by paleo-recharge water. By defining these connections in spatial detail and within a regional integrated framework, we greatly improve the fundamental mechanistic understanding of this and other groundwater-sustained systems. This will greatly improve the ability of communities, governments and industry to manage of these water resources in a way that is genuinely sustainable.

The National Antarctic Data Center (NADC) is the ICT infrastructure designed to gather, handle, publish and provide access to the large amount of scientific data collected by several projects in the framework of the Italian Antarctic National Research Program (PRNA). Aim of the infrastructure is to provide a single integrated system that allows the final users to easily access and share data wherever they are stored. The architecture is based on a System-of-Systems (SoS) concept: a set of systems (functional nodes) interconnected together with each other by means of mediation and adaptation services running on a central infrastructure (common node). The common node is managed by the five Organizations (CNR, INGV, ENEA, OGS, MNA) that contribute to the NADC and is devoted to a regular harvesting of the metadata. Each functional node consists of an existing metadata and data management system implemented by each Organization. Istituto Nazionale di Geofisica e Vulcanologia (INGV) hosts one of those functional nodes and it is managing, among others, data/metadata produced by the permanent geomagnetic and ionospheric observatories installed in Antarctica since 1985. The functional nodes are interconnected and federated together by means of interfaces and standard data/metadata models. This distributed architecture allows to interconnect heterogeneous systems and digital infrastructures in a flexible, scalable and sustainable way. This paper describes the general infrastructure and, as an example of functional node, the contribution of the data management related to the Antarctic Ionospheric and Geomagnetic Observatories managed by INGV at Mario Zucchelli station (74°41′42″S, 164°06′50.4″E) and Concordia base (75°05′59.91″S, 123°19′57.38″E).

Internal waves and vortical mode are ubiquitous in the ocean, providing a conduit for energy transfer from tides and wind-driven circulation to fine- and micro-scale turbulence associated with internal-wave breaking and dissipation. Numerical simulations of a Garrett-Munk internal-wave field are used to study the interactions between internal waves and vortical mode, and the generation of turbulent mixing events and semi-permanent finestructure (vortical mode). Regions of reduced stratification are found to occupy between ~5% and 25% of the model domain, depending on the strength of the anomalies. Decomposition of 3-dimensional model fields into linear internal-wave and vortical-mode components shows that both influence stratification, with ~88% of the anomalies due to linear internal waves and ~40% due to vortical mode, the overlap in percentiles representing regions that are a combination of the two. The time evolution of anomalies is examined, from the initial generation to eventual dissipation. Results further describe the preconditions of these regions, including their relation to a subcritical Richardson number and overturning / mixing events as quantified via Thorpe scales and turbulent dissipation rate.

Continuous Structural Parameterization (CSP) is a method for approximating different numerical model parameterizations of the same process as functions of the same gridscale variables. This allows systematic comparison of parameterizations with each other and observations or resolved simulations of the same process. Using the example of two convection schemes running in the Met Office Unified Model (UM), we show that a CSP is able to capture concisely the broad behavior of the two schemes, and differences between the parameterizations and resolved convection simulated by a high resolution simulation. When the original convection schemes are replaced with their CSP emulators within the UM, basic features of the original model climate and some features of climate change are reproduced, demonstrating that CSP can capture much of the important behavior of the schemes. Our results open the possibility that future work will estimate uncertainty in model projections of climate change from estimates of uncertainty in simulation of the relevant physical processes.

Moisture quasi-equilibrium theory postulates that the instability index, a measure of low to mid-tropospheric moist convective instability, is inversely proportional to saturation fraction, a good proxy for precipitation. We looked at thermodynamic properties for 16 convective events from dropsonde data collected during the field project Organization of Tropical East Pacific Convection (OTREC). OTREC2019 performed 22 flights in the Eastern Pacific and Southwest Caribbean out of Costa Rica using the NSF/NCAR Gulfstream V aircraft. Convective available potential energy and saturation fraction show weak anti-correlation, while the instability index and saturation fraction are more strongly anti-correlated. This supports the moisture quasi-equilibrium hypothesis. Vertical mass flux profiles are calculated for all 16 convective events (8 convective cases in the tropical Eastern Pacific, 5 off the Pacific coast of Colombia and 3 in the Southwest Caribbean). Every developing convective case has a bottom-heavy vertical mass flux profile and every decaying case has top-heavy profile.

We report high technical quality absolute paleointensity determinations from a Pliocene sequence of 20 consecutive lava flows sampled in South Georgia named Apnia, which record either the Gilbert-Gauss polarity reversal or a composite transition from chron C2Ar to subchron C2An-2n. Paleointensity determinations with the multispecimen (MSP) technique were performed on 12 samples with both the original method (MSP-DB) and the extended protocol with corrections (MSP-DSC). Six MSP-DB and eight MSP-DSC determinations passed the proposed quality criteria. MSP-DB yielded higher intensity values than MSP-DSC. In order to provide additional reliability to the results, we have carried out a consistency test by means of a multi-method approach. We have compared the MSP intensities with Thellier-type intensities obtained from the reinterpretation of determinations performed in previous study. The match of both types of paleointensity determinations gives the results an added reliability. Paleointensity results have been obtained in all 20 flows, 11 of which were supported on different methods. At the reverse polarity lower section, low-VADM values between 2.1 and 4.2 x 10 Am were obtained. The single transitional flow displayed 4.3 x 10 Am, and the normal polarity upper section showed higher values between 5.1 and 7.1 x 10 Am. The lower section results might be a pre-reversal stage record and the upper section may reflect the intensity recovery after the complete reversal. Furthermore, the results comparison from both methods will allow the evaluation of the quality parameters proposed to MSP method, which are controversial given the novelty of the technique.

Garnet-bearing volcanic rocks are extremely rare at convergent margins, with few known occurrences worldwide [ref 1-2]; however, such rocks are common within the late Miocene volcanic rock suite of the Northern Andean block (NAB) along the Central Cordillera, Colombia [ref 3-5]. They have been linked to pre-existing zones of crustal weakness that channeled magmas to the upper crust in a short period of time [ref 5-6]. Here we present new geochronological and petrographic data to constrain the timing and petrogenesis of these unusual rocks. We obtained mineral chemical analyses from 7 porphyritic-andesite samples from the eastern flank of the Central Cordillera and the Cauca-Patia Basin, Colombia. Garnet phenocrysts are almandine in composition, ranging from 23 to 29 wt.% FeO, 6 to 8 wt.% CaO, and 1 to 4 wt.% MnO. In some samples, garnets are homogeneous with no reaction rims and lacking inclusions; however, in other samples, garnets show re-absorption rims and inclusion assemblages similar to the rock matrix (plag, amph, ± bt) as well as rare plagioclase coronas. The high Ca and low Mn contents of the NAB garnet cores are consistent with crystallization at ~1.2GPa, based on phase equilibrium experiments of [ref 7], while garnet rim assemblages are congruent with a second stage of crystallization at ~0.8GPa under water-undersaturated conditions. Finally, a pre-eruption dehydration stage is evidenced by the presence of breakdown rims in amphibole crystals. Our new U-Pb in zircon ages reveal that NAB garnet-bearing volcanic rocks formed between 9 and 8 Ma. Taken together, our data suggest a rapid ascent of the NAB magmas associated with the onset of regional volcanism and extension, and possibly the development of the Caldas Tear, a slab window within the Nazca Plate. [1] Green & Ringwood (1968) CMP. [2] Harangi et al. (2001) Journal of Petrology. [3] Orrego (1975) UNAL Colombia. [4] García (1983) UNAL Colombia. [5] Bissig et al. (2017) EG. [6] Weber et al. (2018) SGC (in press). [7] Alonso-Pérez et al. (2006) CMP.

Conventional tidal prediction models typically combine constituent lunisolar forcing factors harmonically fit to sets of collected tidal gauge data. A harmonics analysis is favored over a precise orbital ephemeris-based gravitational forcing model, as tides are localized in scope and sensitive to a particular volume geometry. But what happens when the dynamic behavior is much larger in scale? As we have demonstrated previously [1], lunisolar tidal constituents forced by a strong biennial-modulated annual signal will provide a high-quality fit to ENSO – albeit subject to over-fitting of the numerous constituent factors available. Yet as ENSO is a large-scale phenomenon, it should be more amenable to applying a precise set of ephemeris data as the forcing to a Laplace’s tidal equation formulation. This should reflect the underlying physics governing the dynamics more realistically, while severely constraining the degrees of freedom (DOF) in factors which lead to the possibility of over-fitting. We used the NASA JPL Horizons (https://ssd.jpl.nasa.gov/horizons.cgi) ephemeris data for the Sun and Moon as a parametric input to the well-known 1/R^3 gravitational forcing function and verify as good a quality fit as that available from a high-DOF harmonics approach. This extends over the modern-day instrumental record of ENSO but also covers the coral proxy records that span the years from 1650 to 1880. The approach works effectively because the extra DOF (including phases and elliptical nonlinearities in the orbits) needed to precisely define the gravitational forcing are accurately tracked by the Horizons ephemeris algorithm. Importantly, the results are highly sensitive to the relative forcing amplitudes, which is not surprising, since the fast lunisolar cycles are projected over spans of hundreds of years. The challenge is equivalent to attempting to perform a conventional tidal analysis over a similarly lengthy time span, while also dealing with noise and a limited resolution time-series. [1] Pukite, P.R. “Biennial-Aligned Lunisolar-Forcing of ENSO: Implications for Simplified Climate Models.” AGU Fall Meeting, 2017.