Intensity Anomalies Research Articles

Analysis of Changes and Factors Influencing Air Pollutants in the Beijing-Tianjin-Hebei Region During the COVID-19 Pandemic

A series of strict control measures were imposed in the Beijing-Tianjin-Hebei region in early 2020 to control the spread of COVID-19. These measures have led to a reduction of anthropogenic air pollutants, providing an opportunity to observe the contribution of human activities to local air pollution. In this study, the control period was divided into four stages:the before, early, middle, and later stages. Based on a variety of data including meteorological, traffic, and industrial manufacturing datasets, statistical methods were combined with spatial analysis to evaluate changes in air pollution and associated human impacts during each stage. In addition, suggestions are made for further regional air pollution control in the Beijing-Tianjin-Hebei area. Key results are as follows:① Overall, the AQI and the concentrations of six air pollutants, especially SO2, PM10, and NO2, were lower during control period than during the equivalent period in 2019 (reductions of 26.5%, 24.3%, and 16.9%, respectively). From the before to later stages, pollutants (except O3) showed a downward trend while O3 increased significantly during the before stage (by 76.2%) and the growth rate slowed during the middle and later stages; ②During the prior stage, Beijing experienced two periods with heavy air pollution days as a result of the local accumulation of pollutants, secondary transformation, and regional transport. The concentration of PM2.5 in February was nearly 60% lower than in February 2014 under similar meteorological conditions in Beijing; ③ Following an increase in traffic volume and industrial activity, changes in air pollutants tended to be stable or slightly increase during the middle and later stages of the control period. The grey relation coefficients between thermal radiation intensity anomalies and the main pollutants in heavy industrial cities were greater than 0.6, which means that the control of industrial emissions remains key to controlling air pollution.

Long-lived cold blobs in the Northeast Pacific linked with the tropical La Niña

This study explores the counterpart of marine heatwave, known as the cold blob, in the Northeast Pacific (NEP) by selecting the long-lived events with the normalized sea surface temperature (SST) anomalies averaged over the blob area (160°–135° W, 40°–50° N) smaller than − 0.75 for at least 5 months. There are 10 summer-peak events with a stronger intensity and 7 winter-peak events. The summer-peak cold blob events are mostly attributed to the vertical entrainment when the mixed layer depth is shoaling. For the winter-peak group, the greater heat loss at surface is the principal factor to stimulate the cold blob, associated with the intense westerly anomalies around the blob area. However, the vertical entrainment generally hinders the amplification of winter-peak cold blobs. Moreover, the advection of colder-than-normal water to the blob area contributes much less for both two groups. We conjecture that the NEP cold blob and tropical La Nina-like state are potentially linked. The summer-peak cold blob event is often followed by a La Nina event in the ensuing winter. On the other hand, the equatorial La Nina-like SST cooling in late summer and autumn in turn enhances the winter-peak cold blobs. We find the subtropical region, particularly near the Baja California, may act as the oceanic bridge to connect the NEP cold blob and equatorial La Nina.

On the Development and Demise of the Fall 2019 Southeast U.S. Flash Drought: Links to an Extreme Positive IOD

AbstractMuch of the southeast United States experienced record dry conditions during September of 2019, with the area in abnormally dry to exceptional drought conditions growing from 25% at the beginning of the month to 80% by the end of the month. The drought ended just as abruptly due to above-normal rain that fell during the second half of October. In this study we employed MERRA-2 and the GEOS-5 AGCM to diagnose the underlying causes of the drought’s onset, maintenance, and demise. The basic approach involves performing a series of AGCM simulations in which the model is constrained to remain close to MERRA-2 over prespecified areas that are external to the drought region. The start of the drought appears to have been forced by anomalous heating in the central/western tropical Pacific that resulted in low-level anticyclonic flow and a tendency for descending motion over much of the Southeast. An anomalous ridge associated with a Rossby wave train (emanating from the Indian Ocean region) is found to be the main source of the most intense temperature and precipitation anomalies that develop over the Southeast during the last week of September. A second Rossby wave train (emanating from the same region) is responsible for the substantial rain that fell during the second half of October to end the drought. The links to the Indian Ocean dipole (with record positive values) as well as a waning El Niño allow some speculation as to the likelihood of similar events occurring in the future.

Evolution of Global Lightning in the Transition From Cold to Warm Phase Preceding Two Super El Niño Events

AbstractMultistation observations of Schumann resonance (SR) intensity document common behavior in the evolution of continental‐scale lightning activity in two super El Niño events, occurring in 1997/98 and 2015/16. The vertical electric field component of SR at Nagycenk, Hungary and the two horizontal magnetic field components in Rhode Island, USA in 1997, and in 2014–2015, the two horizontal magnetic field components at Hornsund, Svalbard and Eskdalemuir, United Kingdom as well as in Boulder Creek, California and Alberta, Canada exhibit considerable increases in SR intensity from some tens of percent up to a few hundred percents in the transition months preceding the two super El Niño events. The UT time distribution of anomalies in SR intensity indicates that in 1997 the lightning activity increases mainly in Southeast Asia, the Maritime Continent and India, i.e. the Asian chimney region. On the other hand, a global response in lightning is indicated by the anomalies in SR intensity in 2014 and 2015. SR‐based results are strengthened by comparison to independent lightning observations from the Optical Transient Detector and the World Wide Lightning Location Network, which also exhibit increased lightning activity in the transition months. The increased lightning is attributable to increased instability due to thermodynamic disequilibrium between the surface and the midtroposphere during the transition. The main conclusion is that variations in SR intensity may act as a precursor for the occurrence and magnitude of these extreme climate events, and in keeping with earlier findings, as a precursor to maxima in global surface air temperature.

Two types of warm blobs in the Northeast Pacific and their potential effect on the El Niño

AbstractIn recent years, the predominant marine heatwaves in Northeast Pacific, the so‐called warm blobs, have exerted substantial environmental and socioeconomic influences on North America and its coastal waters. We select the historical warm blob events from 1951 to 2018 and divide them into double‐peak and single‐peak categories by their seasonal evolutions. The heat budget analyses attribute the leading contributor of double‐peak warm blobs to the surface heat flux at the first wintertime maximum while the vertical entrainment and diffusion take responsibility for the second peak 5 months later. The positive net heat flux anomalies indicate less heat loss from ocean to the atmosphere due to an exceptionally anomalous high as the northern lobe of the North Pacific Oscillation and intensive easterly anomalies, which counteract with the climatological westerlies. For the single‐peak category, the vertical entrainment and diffusion primarily trigger the warm blob and also lead to its termination. Moreover, the single‐peak warm blob induces positive sea surface temperature (SST) anomalies near the Baja California and establishes the Pacific Meridional Mode as the oceanic bridge to convey its influence onto the tropics and trigger the following El Niño around 10 months after the peak. In addition, the subsurface processes, such as the trade wind charging mechanism, also play an essential part by bringing warmer water upwards to the surface and hence cause the positive SST anomalies in equatorial central‐eastern Pacific. However, the interim connection between the double‐peak warm blob and El Niño is not very clear although their intensities appear to be stronger.

Structure of the Upper Crust beneath the Klyuchevskoy Group of Volcanoes Revealed from Ambient Noise Tomography

Abstract ––The Klyuchevskoy group of volcanoes (KGV) located in the central part of Kamchatka is a unique complex that demonstrates exceptional variety and intensity of volcanic manifestations. These features of the eruptive activity of the KGV are determined by a complex system of magmatic sources in the crust and mantle. While the structure of deep anomalies is quite reliably determined by tomography techniques based on body waves, the structure of the upper crust can only be determined using ambient noise tomography. We present the results of processing data from the KISS temporary network. This network consisted of more than 100 seismic stations that were installed from 2015 to 2016 over a large area covering the Klyuchevskoy group of volcanoes and its surroundings. To retrieve Rayleigh surface waves, cross-correlation of continuous seismic noise records from pairs of stations was used. We obtained the dispersion curves of the group velocities of these Rayleigh surface waves using frequency–time analysis (FTAN) of the calculated correlograms. These curves served as input data for performing ambient noise tomography. Tomography was performed in two stages: (1) computation of two-dimensional group velocity maps for different frequencies and (2) calculation of a three-dimensional model of the shear wave velocity to a depth of about 8 km based on the inversion of local dispersion curves obtained from these maps. The resulting models revealed the structural features of individual volcanic systems of the KGV. High velocities were observed at shallow depths beneath the large basaltic edifices of the Ushkovsky and Tolbachik volcanoes. At greater depths, while the velocity structure beneath Ushkovsky remained unchanged, we detected low velocities beneath Tolbachik. This fact illustrates the difference between dormant and active magmatic systems. Velocity anomalies of a complex shape are observed beneath the Klyuchevskoy, Kamen, and Bezymianny volcanoes, varying both laterally and with depth. Absolute velocities in vertical sections show that the edifices of these volcanoes are relatively low-velocity bodies located on a horizontal high-velocity basement. A low-velocity anomaly was discovered under the Bezymianny Volcano at a depth of 6 km, which is presumably associated with a shallow magma reservoir. An intense low-velocity anomaly was found beneath the Udina Volcano. It was interpreted as an image of a magma reservoir experiencing strong seismic unrest that began in December 2017 and continues to this day.

Thermal Waters Circulation During the Formation of Ore Deposits

The paper analyzes processes leading to the formation of gold-bearing sulphide deposits. The study was based on the data available for the territory of Ukraine and other regions. The deposits in question are shown to be associated with post-geosynclinal activation as postulated by concepts of the advection-polymorphism hypothesis. The nature of ore-bearing fluids is analyzed. Even on the ocean bottom helium isotopy points to the presence of mantle components in the fluid. Metamorphogenic and magmatic fluids are obviously involved in the process. An abnormally fast growth of permeability in fault zones during the activation period is shown to have contributed to the formation of deposits. The existence of metalliferous and barren phases of hydrothermal activity is explained. Thermal models of deposits are constructed and diagnostic criteria for their identification determined. The main features of the deposits are associated with faults through which mineralized deep waters circulate. In young deposits, these are: 1. Increased content of metals in soil and plants. 2. Intense heat flow anomalies. 3. High helium isotope ratios, indicating an active process in the Earth's mantle. 4. Zones of high electrical conductivity in the crust and upper mantle. 5. Near the faults, positive anomalies of the gravity field are formed, associated with the transformation of rocks under the influence of heating. The search for gold-bearing sulphide deposits should be continued, considering that the reserves already explored in Ukraine guarantee commercially viable production of over 10 tons of gold per year.

Temperature Structure of the Pipe Nebula Studied by the Intensity Anomaly of the OH 18 cm Transition

Abstract We present observations of the four hyperfine structure components of the OH 18 cm transition (1612, 1665, 1667, and 1720 MHz) toward a filamentary dark cloud, the Pipe nebula, with the Green Bank Telescope. A statistical equilibrium analysis is applied to the spectra, and the kinetic temperature of a diffuse molecular gas surrounding dense cores is determined accurately; the derived temperature ranges from 40 to 75 K. From this result, we assess the heating effect on the filamentary structure of the nebula’s “stem” region due to UV photons from a nearby star θ-Ophiuchi and a possible filament–filament collision in the interface of the “stem” and “bowl” regions. In the stem region, the gas kinetic temperature is found to be almost independent of the apparent distance from θ-Ophiuchi: the UV-heating effect by the star is not visible. On the other hand, the gas kinetic temperature is raised, as high as ∼75 K, at the interface of the two filamentary structures. This result provides us with additional support for the filament–filament collision scenario in the Pipe nebula.

Biogeochemical response of Pinus brutia and Olea europaea to lithological variations and Cu mineralisation in Cyprus

Regional geochemical mapping programs are predominantly based on regolith materials as the sampling media. The use of plant organs has been more limited, despite potential advantages demonstrated in more localised studies that have examined biogeochemical responses to various types of mineralisation or contamination, or sought to identify species with phytoremediation potential. This study investigated the effects of variations in lithology and mining wastes on the multielement chemistry of Pinus brutia (pine) needles and O. europaea (olive) leaves, obtained from low-density traverses across Cyprus and detailed sampling around two Cyprus-style VHMS Cu-deposits. A total of 476 samples were analysed by a combination of inductively-coupled plasma mass spectrometry (ICP-MS) and portable X-ray fluorescence spectrometry (pXRF). At the regional scale there are substantial differences in the composition of the pine needles, especially for Ni, Ba, Sr, Mn and Zn, between the major lithological groups that range from the ultramafic and mafic units of the Troodos Ophiolite to the mineralised pillow basalts and various marine carbonate units. Both pine needles and olive leaves display intense Re anomalies in areas with mine wastes and consistently low concentrations in background areas. The response for Cu and other macro- or micronutrient elements to contamination is less pronounced and may reflect barriers to uptake by the plants. The relative magnitude of variations between the different lithologies in median plant metal concentrations is equivalent to that displayed in soils of the Geochemical Atlas of Cyprus (e.g. REE, Zn and Sr), but for some elements the patterns differ substantially. There is close correlation between the ICP-MS and pXRF data for elements where most values are above pXRF detection limits. The study further demonstrates the potential of plants in regional geochemical mapping for a range of applications, in combination with or as an alternative to conventional regolith media.

Formation of Abnormal Gas-Geochemical Fields of Methane, Helium, and Hydrogen in Northern Vietnam, Its Coastal and Adjacent Water Areas

Gas-geochemical studies of the methane, helium, and hydrogen concentrations in the water of thermal and mineral springs, as well as the subsurface atmosphere, of northern Vietnam showed that the region is in the hypabyssal degassing zone of hydrogen and helium flowing to the surface through a fault system in the Earth’s crust. A joint transit of these gases through the fault structures was established. Distribution pattern of hydrogen and helium concentrations in the Red River Rift area (northern Vietnam) was obtained from the extensive gas and water sample data. Intense linear anomalies are associated with the Red River Rift and the Dien Bien regional rift. Seismic events are associated with the fault, and earthquake epicenters are located in the Dien Bien Province.

Survey of the Yel’chevskii Settling Pond Soil Dam by the Method of Frequency Dispersion of Electrical Resistivity

From the results of studies of the frequency variance of the electrical resistivity of backfilling a dam and rocks in its foundation, local anomalies of polarization parameters in the body of the dam that are associated with filtration of atmospheric precipitation and water from the pond were discovered. An intense anomaly of induced polarization was discovered in the eastern part of the dam, where the spread to underground waters of the solid chemical substances that contain silt of the settlement pond is possible.

Possible Relationships Between the Interannual Anomalies of the South-North Positions of the Northeastern China Cold Vortexes and the Sea Surface Temperatures (SSTs) During the Early Summer Periods

The Northeastern China Cold Vortex (NCCV) processes during the early summer periods (June) from 1979 to 2018 were objectively identified in this study by using the daily precipitation data in Northeastern China (NEC), along with the six-hourly atmospheric circulation fields of ERA Interim/ECMWF, and the temperature field data and monthly mean sea surface temperature field data reconstructed by NOAA. Then, the NCCV processes from the objective identifications were divided into the Southern Cold Vortex (SCV) and the Northern Cold Vortex (NCV) according to the positions of their activity trajectories in the NEC geographical range. Next, an index was defined which could better represent the frequencies and intensities of the SCV and NCV. Relationships between the indices of the SCV and NCV and atmospheric circulation fields during the early summer months and the early SST fields were analyzed. Finally, the results of the sensitivity test of the AM2.1 model were used to verify the statistical analysis results. It was found that the SST factor impacting the intensity of the SCV was the North Atlantic Tripole (NAT) in early April. The anomalies of the NAT in April forced the formation of the “high-low pressure cooperation types” in early summer, which resulted in the intensity anomalies of the SCV. The SST factors impacting the intensity of the NCV were the south-north inverse SSTs of the Northwest Pacific (March) and the SSTs of the tropical Southeast Pacific (May). During the two examined periods of 1979 to 1999 and 2000 to 2018, the south-north inverse SST anomalies in the Northwest Pacific in March, as well as the SST anomalies in the tropical Southeast Pacific in May, were observed to have forced the formations of “double blocking low vortex types” and EAP teleconnection types during the early summer months, which resulted in anomalies in the NCV intensities. AM2.1 model was found to have good simulation effects regarding the observed impact results of the SSTs on the early circulation types during the early summer months, which further supported the conclusions achieved from the statistical analysis results.

Seismo ionospheric anomalies possibly associated with the 2018 Mw 8.2 Fiji earthquake detected with GNSS TEC

The detection of earthquake (EQ) related ionospheric anomalies using Global Navigation Satellite System (GNSS) has emerged as a convincing approach and new field in the search for seismic precursors. Total Electron Content (TEC) from International GNSS Services (IGS) network may help to distinguish seismo ionospheric anomalies from geomagnetic storm induced anomalies. In this paper, spatial and temporal TEC anomalies are investigated in 1 s resolution data from GNSS stations around the epicenter of the August 19, 2018, Fiji EQ (Mw 8.2). Moreover, median and standard deviation based anomaly detection techniques are implemented on TEC and the variations are quantified on the basis of z-test at α = 0.05 significance level. We find evidence of significant ionospheric anomalies of low intensity within 5–10 days before and 5 days after the main shock by estimating TEC from four GNSS stations within the EQ preparation period. On the other hand, a significant ionospheric anomaly of high intensity arises after the main shock beyond 5 days (+7 day and onward) after the EQ, which is associated with an intense geomagnetic storm (Dst <-150 nT and Kp ≥ 7). More analysis reveals that EQ induced TEC anomalies are significant during Local Time (LT) = 08:00−16:00 (for Fiji, LT= UT+12) and similarly the storm (Dst =-150 nT and Kp ≥ 7) induced TEC anomaly prevails in all GNSS stations during LT= 08:00−18:00. The TEC intensity of the storm anomaly is more substantial in all four GNSS stations compared to the EQ induced TEC anomaly. All these anomalies before and after the main shock during the EQ preparation period are advantageous towards differentiating seismic versus geomagnetic storm anomalies. Furthermore, this analysis aids in the developing hypothesis of lithosphere ionosphere coupling through TEC monitoring.

Southern Ocean convection amplified past Antarctic warming and atmospheric CO2 rise during Heinrich Stadial 4

The record of past climate highlights recurrent and intense millennial anomalies, characterised by a distinct pattern of inter-polar temperature change, termed the ‘thermal bipolar seesaw’, which is widely believed to arise from rapid changes in the Atlantic overturning circulation. By forcing a suppression of North Atlantic convection, models have been able to reproduce many of the general features of the thermal bipolar seesaw; however, they typically fail to capture the full magnitude of temperature change reconstructed using polar ice cores from both hemispheres. Here we use deep-water temperature reconstructions, combined with parallel oxygenation and radiocarbon ventilation records, to demonstrate the occurrence of enhanced deep convection in the Southern Ocean across the particularly intense millennial climate anomaly, Heinrich Stadial 4. Our results underline the important role of Southern Ocean convection as a potential amplifier of Antarctic warming, and atmospheric CO2 rise, that is responsive to triggers originating in the North Atlantic.

DELINEATION OF GEOMETRY AND SPATIAL DISTRIBUTION OF BASIC BODIES USING MAGNETIC AND RESISTIVITY METHODS IN SOHAGPUR COAL FIELD AREA, MADHYA PRADESH

The state of Madhya Pradesh in Central India is known to bear ‘A’ grade coal seams within Gondwana basin. An alluvium-covered area to the north-east of Shahdol was considered to be prospective for the exploration of coal. A number of basic intrusive are encountered in the area and these appear to have played an important role for enhancement of the rank of coal seams. Delineation of the geometry and spatial distribution of these basic bodies has therefore become necessary for exploration of high rank coal seams. Magnetic and resistivity surveys were mainly carried out. Geologically, the alluvium covered area was known to be composed of rocks of different ages such as Precambrian, Gondwana Triassic, Cretaceous (trap) and older alluvium in succession. Gondwana basins are formed over basement depressions or in the downthrown side of the faulted Precambrian. Gondwana sediments lying over such basement sub-basins are prospective areas for the exploration of coal. The magnetic map was vitiated through the presence of high amplitude and small wavelength anomalies due to a thick blanket of basic bodies lying above the Gondwana sediments. Fluctuations in magnetic responses are observed at a few locations which may be due to the presence of basement faults? Low intensity but distinct anomaly patterns are observed in the south-western part of the area possibly indicating subsurface basic intrusive. 2D modeling of the magnetic data has effectively brought out the basement depth varying between 680 m to 1460 m an increasing trend from west to east. Selected resistivity soundings confirm that the overlying high resistivity layer (107-390 Ohm-m) and of thickness (0.7-386.3 m) may possibly indicate the geometry of basic bodies from the surface to depth of 547.5 m. The basement could not be picked up.

NH3 (1,1) hyperfine intensity anomalies in the Orion A molecular cloud

Ammonia (NH3) inversion lines, with their numerous hyperfine components, are a common tracer used in studies of molecular clouds (MCs). In local thermodynamical equilibrium, the two inner satellite lines (ISLs) and the two outer satellite lines (OSLs) of the NH3(J, K) = (1,1) transition are each predicted to have equal intensities. However, hyperfine intensity anomalies (HIAs) are observed to be omnipresent in star formation regions, a characteristic which is still not fully understood. In addressing this issue, we find that the computation method of the HIA by the ratio of the peak intensities may have defects, especially when used to process the spectra with low-velocity dispersions. Therefore, we defined the integrated HIAs of the ISLs (HIAIS) and OSLs (HIAOS) by the ratio of their redshifted to blueshifted integrated intensities (unity implies no anomaly) and developed a procedure to calculate them. Based on this procedure, we present a systematic study of the integrated HIAs in the northern part of the Orion A MC. We find that integrated HIAIS and HIAOS are commonly present in the Orion A MC and no clear distinction is found at different locations of the MC. The medians of the integrated HIAIS and HIAOS are 0.921 ± 0.003 and 1.422 ± 0.009, respectively, which is consistent with the HIA core model and inconsistent with the collapse or expansion (CE) model. In the selection of those 170 positions, where both integrated HIAs deviate by more than 3σ from unity, most (166) are characterized by HIAIS &lt; 1 and HIAOS &gt; 1, which suggests that the HIA core model plays a more significant role than the CE model. The remaining four positions are consistent with the CE model. We compare the integrated HIAs with the para-NH3 column density (N(para-NH3)), kinetic temperature (TK), total velocity dispersion (σv), non-thermal velocity dispersion (σNT), and the total opacity of the NH3(J, K) = (1,1) line (τ0). The integrated HIAIS and HIAOS are almost independent of N(para-NH3). The integrated HIAIS decreases slightly from unity (no anomaly) to about 0.7 with increasing TK, σv, and σNT. The integrated HIAOS is independent of TK and reaches values close to unity with increasing σv and σNT. The integrated HIAIS is almost independent of τ0, while the integrated HIAOS rises with τ0, thus showing higher anomalies. These correlations cannot be fully explained by either the HIA core nor the CE model.

INVESTIGATION OF SUBSURFACE STRUCTURES WITHIN PARTS OF NIGER DELTA, NIGERIA, VIA AEROMAGNETIC DATA

Geophysical study involving aeromagnetic method was carried out to investigate parts of Niger Delta in Nigeria, aimed at investigating the cause and nature of anomalous bodies within the study area. Spectral analysis technique was employed in quantitative interpretation to determine depth/thickness of the sedimentary basin, basement topography, structural trends, curie point depth, thermal gradient and heat flow in the area. The total magnetic intensity (TMI) anomalies had values of between -53.7nT and 119.5nT while the residual magnetic intensity ranged from -52.5 to 58.0nT. The spectral analysis revealed the depth to magnetic sources varying from 2.5 to 5.5km while the shallow magnetic sources varied from 0.89 to 1.47km. The geothermal analysis revealed the curie point depth between 11.782 and 18.048km while the calculated geothermal gradient ranged lie between 32.137 and 49.231o𝐶𝑘𝑚−1. The heat flow values ranged from 80.343 to 123.080𝑚𝑊𝑚−2. The results from this study have thrown more light to the understanding of the variation of subsurface structures in the study area. These will enhance the development of the resources and will be of economic benefit to the country if well harnessed. However, possible future research work on this active area is proposed for more robust results.

Identifying Local-Scale Weather Forcing Conditions Favorable to Generating Iberia’s Largest Fires

The Mediterranean region is characterized by the frequent occurrence of summer wildfires, representing an environmental and socioeconomic burden. Some Mediterranean countries (or provinces) are particularly prone to large fires, namely Portugal, Galicia (Spain), Greece, and southern France. Additionally, the Mediterranean basin corresponds to a major hotspot of climate change, and anthropogenic warming is expected to increase the total burned area due to fires in Mediterranean Europe. Here, we propose to classify summer large fires for fifty-four provinces of the Iberian Peninsula according to their local-scale weather conditions and fire danger weather conditions. A composite analysis was used to investigate the impact of local and regional climate drivers at different timescales, and to identify distinct climatologies associated with the occurrence of large fires. Cluster analysis was also used to identify a limited set of fire weather types, each characterized by a combination of meteorological conditions. For each of the provinces, two significant fire weather types were identified—one dominated by high positive temperature anomalies and negative humidity anomalies, and the other by intense zonal wind anomalies with two distinct subtypes in the Iberian Peninsula., allowing for the identification of three distinct regions.

Characterizing the source of a prominent magnetic anomaly in the southwestern part of the Cuddapah basin

The total magnetic intensity anomaly (TMI) map of the Proterozoic intracratonic Cuddapah basin shows the presence of a prominent high–low–high anomaly of about 600 nT amplitude at its southern end. The source of this anomaly is inferred to be a mafic intrusive body due to a thermal plume that might have initiated the basin evolution. Though some quantitative studies have been carried out over this anomaly, the magnetic body remains ambiguous as only a part of this anomaly was modelled along the E–W direction. In present study, we model this anomaly by a 2.5D algorithm and analytical signal of the vertical integral (ASVI) of the TMI approach. A near circular outline of the causative body has been delineated by the analysis of ASVI, which also revealed three characteristic zones of the near surface irregularities. The 2.5D modelling along a SW–NE profile across the anomaly yielded the main body of about 10 km wide top at 3.5 km depth and 40 km wide at 25 km depth. The Curie temperature depth in this region is 30–40 km and this allows the source to be magnetic at this depth. It is inferred from both ASVI and modelling that the main body is bifurcated into two in its south-western part between Parnapalle and Muddanuru while it attains a lopolithic shape over the remaining part. Existing regional aeromagnetic data elucidates shape of the mafic intrusive both laterally and vertically.

Large-scale environmental controls on the seasonal statistics of rapidly intensifying North Atlantic tropical cyclones

This study is concerned with the connections between the large-scale environment and the seasonal occurrence of rapid intensification (RI) of North Atlantic tropical cyclones. Physically-motivated statistical analysis using observations and reanalysis products suggests that for tropical cyclones over the open tropical North Atlantic, the interannual variability of the probability of storms undergoing RI is influenced by seasonal large-scale atmospheric and oceanic variables, but not so for storms over the Gulf of Mexico and western Caribbean Sea. We suggest that this differentiated response is due to the former region exhibiting a strong negative correlation between the seasonal anomalies of vertical wind shear and potential intensity. Differences in the mean climatology and subseasonal variations of the large-scale environment in these regions appear to play an insignificant role in the distinctive seasonal environmental controls on RI. We suggest that the interannual correlation of vertical wind shear and potential intensity is an indicator of seasonal predictability of tropical cyclone activity (including RI) across the tropics .