Impact Of Storms Research Articles

Resolution of the equatorial spread F problem: Revisited

An overview of recent advances made in understanding the phenomenon of equatorial spread F (ESF) is presented and a discussion of unresolved issues that need to be addressed. The focus is on research that has occurred in the last decade. The topics include satellite observations, theory, and modeling. The suggested areas that require further exploration are a unified theory of turbulence extending from 100 s m to 10 s cm, the impact of geomagnetic storms on the development of equatorial spread F, the need for accurate thermospheric wind measurements and models, and identifying the underlying physics of ESF in the post-midnight sector during solar minimum.

The impact of sand and dust storms on agriculture in Iraq

ABSTRACT Sand and dust storms are a common natural hazard in arid and dry areas of the Middle East and North Africa severely affecting human life and economic sectors, including agriculture production. In this paper, I explore the potential impact of sand and dust storms (SDS) on agricultural sub-sectors in Iraq by combining the household-level production and socioeconomic data with the climate dataset to allow the empirical assessment of agricultural impacts due to dust storms. I find compelling evidence that exposure of crops and livestock to dust storms significantly diminish agricultural productivity, vegetation cover and have significant bearings on the household welfare. Our analysis reveals a 1.1% reduction in the value of crop production as a result of an additional SDS event. This corresponds to about 0.045% losses in the GDP of Iraq, an amount equivalent to about $0.1 billion. Crop yields are reduced significantly ranging from 0.9% to 3% for an additional day of sand and dust storms.

Weathering the Storm: the impact of the Vaia storm on tourism flow

Weathering the Storm: the impact of the Vaia storm on tourism flow

Impact of the 2021 north american winter storms on children with epilepsy.

In February 2021 a series of winter storms caused power outages for nearly 10 million people in the United States, Northern Mexico and Canada. In Texas,the storms caused the worst energy infrastructure failure in state history, leading to shortages of water, food and heat for nearly a week. Impacts on health and well-being from natural disasters are greater in vulnerable populations such as individuals with chronic illnesses, for example due to supply chain disruptions. We aimed to determine the impact of the winter storm on our patient population of children with epilepsy (CWE). We conducted a survey of families with CWE that are being followed at Dell Children's Medical Center in Austin, Texas. Of the 101 families who completed the survey, 62% were negatively affected by the storm. Twenty-five percent had to refill antiseizure medications during the week of disruptions, and of those needing refills, 68% had difficulties obtaining the medications, leading to nine patients-or 36% of those needing a refill-running out of medications and two emergency room visits because of seizures and lack of medications. Our results demonstrate that close to 10% of all patients included in the survey completely ran out of antiseizure medications, and many more were affected by lack of water, heat, power and food. This infrastructure failure emphasizes the need for adequate disaster preparation for vulnerable populations such as children with epilepsy for the future.

Impact of desert dust storms, PM10 levels and daily temperature on mortality and emergency department visits due to stroke.

It is known that the inhalation of air pollutants adversely affects human health. These air pollutants originated from natural sources such as desert storms or human activities including traffic, power generating, domestic heating, etc. This study aimed to investigate the impacts of desert dust storms, particulate matter ≤10 μm (PM10) and daily maximum temperature (MT) on mortality and emergency department (ED) visits due to stroke in the city of Gaziantep, Southeast Turkey. The data on mortality and ED visits due to stroke were retrospectively recruited from January 1, 2009, to March 31, 2014, in Gaziantep City Centre. PM10 levels did not affect ED visits or mortality due to stroke; however, MT increased both ED visits [adjusted odds ratio (OR) = 1.002, 95% confidence interval (CI) = 1.001-1.003] and mortality (OR = 1.006, 95% CI = 0.997-1.014) due to stroke in women. The presence of desert storms increased ED visits due to stroke in the total population (OR = 1.219, 95% CI = 1.199-1.240), and all subgroups. It was observed that desert dust storms did not have an increasing effect on mortality. Our findings suggest that MT and desert dust storms can induce morbidity and mortality due to stroke.

Conservation and Sustainability of Coastal City Tourism In the Advent of Seal Level Rise in Durban, South Africa

Given the socioeconomic significance of oceans in South Africa and the threat of climate change, it is vital to understand the effects on coastlines and tourism. With very little known about the implications of sea level rise in Southern Africa, this study investigates its impact on tourism and conservation of coastlines in Durban, South Africa. The study conducted in 2021 used primary data collected through key informant interviews ( n = 10), an online questionnaire (303), direct field observations, and archival data from the National Oceanic and Atmospheric Administration. Trend analysis for climate data was done using Mann Kendal Trend Analysis, while the content and thematic analysis were used to assess qualitative data. The study found that the compounded effect of sea level rise of 1.49 mm/year in Durban between 1971 and 2018 poses a threat to the beach and coastal tourism. The compounded impact of sea level rise, sea surges, coastal storms, and high tides often results in high levels of beach erosion and coastal flooding, threatening tourism infrastructure. The municipality has embarked on a beach nourishment program, dune restoration, and coastal defense mechanisms to preserve and conserve the beachfront to ensure coastal tourism sustainability.

The impact of the pandemic policy storm on the stock price of Taiwan property insurance industry

<p>本文採用事件研究法來檢驗防疫保單之亂對產物保險業股價的影響。本文定義兩個重要事件，一為2022年4月7日疫情指揮中心首次提出「從清零走向與病毒共存」的政策宣告，二為現金增資宣告。實證結果發現從清零走向與病毒共存之宣告存在正向效果，隱含經濟活動即將復甦，投資人已提前反應並持續看好至事件發生後第四天才收斂。收斂原因係事件發生後第五天投資人明確接收到「理賠從寬認定」的訊號並反應在股價上產生顯著超常負報酬。第二現金增資宣告效果對於擁有產物保險子公司之金控公司不存在，未引起恐慌。但對於專營再保險的公司以及大股東為汽車製造業的公司而言，現金增資宣告存在負向效果，但很快收斂。本文實證結果將有助分析未來類防疫保單出現時防疫政策改變對股價的影響，及作為未來投資決策參考方向。</p> <p> </p><p>This paper uses the event study to test the impact of the pandemic policy storm on the stock price of Taiwan property insurance industry. This study defines two important events, one is the policy announcement that the Epidemic Command Center first proposed “from zero to coexist with the virus” on April 7, 2022, and the second is the announcement of seasoned equity offerings. Empirical results found that there is a positive effect from the declaration of clearing to coexistence with the virus, implying that economic activities are about to recover, and investors have reacted in advance and continued to be optimistic until the fourth day after the event. The reason for the convergence is that on the fifth day after the event, the investor clearly received the signal of "claims leniency determination" and reflected a significant abnormal negative return on the stock price. The effect of the second seasoned equity offerings announcement does not exist for the financial holding company that owns a product insurance subsidiary, which does not cause panic. However, for companies specializing in reinsurance and companies whose major shareholders are in the automobile manufacturing industry, the seasoned equity offerings announced that there is a negative effect exists, but it will soon subside. The empirical results of this paper will help analyze the impact of changes in pandemic policies on stock prices when future pandemic policies appear, and serve as a reference direction for future investment decisions.</p> <p> </p>

Monitoring Short-Term Morphobathymetric Change of Nearshore Seafloor Using Drone-Based Multispectral Imagery

Short-term changes in shallow bathymetry affect the coastal zone, and therefore their monitoring is an essential task in coastal planning projects. This study provides a novel approach for monitoring shallow bathymetry changes based on drone multispectral imagery. Particularly, we apply a shallow water inversion algorithm on two composite multispectral datasets, being acquired five months apart in a small Mediterranean sandy embayment (Chania, Greece). Initially, we perform radiometric corrections using proprietary software, and following that we combine the bands from standard and multispectral cameras, resulting in a six-band composite image suitable for applying the shallow water inversion algorithm. Bathymetry inversion results showed good correlation and low errors (<0.3 m) with sonar measurements collected with an uncrewed surface vehicle (USV). Bathymetry maps and true-color orthomosaics assist in identifying morphobathymetric features representing crescentic bars with rip channel systems. The temporal bathymetry and true-color data reveal important erosional and depositional patterns, which were developed under the impact of winter storms. Furthermore, bathymetric profiles show that the crescentic bar appears to migrate across and along-shore over the 5-months period. Drone-based multispectral imagery proves to be an important and cost-effective tool for shallow seafloor mapping and monitoring when it is combined with shallow water analytical models.

Relationship between geomagnetic storms and occurrence of ionospheric irregularities in the west sector of Africa during the peak of the 24th solar cycle

The study of ionospheric irregularities is important since many technological systems might be influenced by the ionosphere. In this work, we use data from the Global Navigation Satellite Systems (GNSS) receiver installed in Abuja, Nigeria, GPS Scintillation Network Decision Aid (SCINDA) TEC data from the Air Force Research Laboratory (AFRL) data archive, and the geomagnetic data from the World Data Center (WDC) in Kyoto, Japan, to investigate the relationship between geomagnetic storm and ionospheric irregularity occurrences using the rate of change of total electron content (TEC) index (ROTI), with a validation using the S4 indices, during the peak of the 24th solar cycle. The occurrences of irregularities were investigated on day-to-day and seasonal bases. The nighttime ionospheric irregularities, which are attributed to ionospheric plasma irregularities in the equatorial ionospheric F-region, were found to be prevalent. To investigate the relationship between the strength of ionospheric irregularities (ROTI) and the geomagnetic storm (Dst), the periodogram power spectral density (PSD) and regression analysis were used. The results showed that there was no correlation, cc = 0.073, between the Dst and ROTI, implying that the strengths of ionospheric irregularities occurring during geomagnetic storms are not strictly decided by the magnitudes of the storms; this was also confirmed using the S4 index. The impact of geomagnetic storms caused enhanced development or inhibition of ionospheric irregularities. We observed that the bulk of the storms occurring during the period of this study is not associated with ionospheric irregularities. Finally, the investigation showed that the correlation between the ROTI and Dst observed during the coronal mass ejection (CME)-driven geomagnetic storms was higher than that during the corotating interaction region (CIR)-driven geomagnetic storms, during the peak of the 24th solar cycle. The results of this work confirm the findings by other researchers.

Bradykinin and Galectin-3 in Survived and Deceased Patients with COVID-19 Pneumonia: An Increasingly Promising Biochemical Target.

There are still no definite curative or preventive strategies for COVID-19 disease. It is crucial to fully comprehend the pathogenesis of COVID-19 infection so that we can develop expedient pharmacological protocols. While the impact of cytokine storm on COVID-19 severity has been one of the most tested hypotheses, the role of bradykinin and various other oxidative stress markers has been relatively under-researched. Their levels can be determined immediately after a hospital admission so they could be used as early predictors of the further development of the disease. The study aims at evaluating the possibility of using bradykinin and galectin-3 levels as early predictors that COVID-19 disease will progress into a severe case. Material and methods. The study was conducted as a prospective cross-sectional study. It included 47 consecutive adult patients with confirmed SARS-CoV-2 infection and COVID-19 pneumonia. All study subjects were admitted for a hospital treatment to the tertiary Clinical Hospital Center Bezanijska kosa, Belgrade, Serbia on June 2021. The blood samples were collected at the patients' admission. The analyses of demographic, radiological, and clinical data were later conducted for both groups (the deceased patients and those who survived). In addition, we analyzed the potential relations between the outcome and the levels of bradykinin and galectin-3 measured immediately after the patients were admitted to the hospital. The patients who passed away were predominantly older men with comorbidities. We recorded higher CT scores in the deceased patients and the significantly higher levels of urea, creatinine, CK, troponine, CRP, and other laboratory markers. They stayed at the ICU unit longer and required mechanical ventilation more frequently than the patients who survived. On the other hand, no differences were recorded in the time periods passing from the onset of the systems to the hospital admissions. Finally, we can highlight several independent predictors of mortality in patients with COVID-19 pneumonia, including the following: (1) patients who are 50 or more years old, (2) with in-hospital stays are longer that 4 days, (3) bradykinin levels surpass 220000 pg/ml, (4) D-dimer, creatinine, and CRP are elevated, and (5) comorbidities were present (such as hypertension and diabetes). The present study strongly supports the bradykinin storm hypothesis. Since elevated bradykinin levels have been found in most COVID-19 cases with fatal outcomes, the future therapeutical strategies for COVID-19 have to be focused on reducing bradykinin serum concentrations.

Coastal barrier morphogenic categories in Mississippi Delta plain development

Coastal barriers are defined as shore-parallel, aggraded-prograded supratidal beach ridge sets and individual single ridge-landforms, composed of sand and/or gravel. Island, spit, and mainland barriers represent the three major topographic subdivisions. In terms of bathymetric and hydrographic characteristics, bottom sediment types and associated habitats, barriers separate the marine offshore from inshore facies. This definition is not uniformly accepted and applied in the literature. Barriers impose reduced salinities inshore, diminish storm impact and moderate inland inundation, protect critical habitats and may mark ancient longshore transport directions, shore and sea-level positions. A wide range of dimensions, topography, and other factors characterize mainland strandplains. Shoal aggradation appears to be the prime island-forming mechanism, followed by accretion around semi-consolidated, elevated cores. Smaller islands may also form by barrier spit fragmentation. Detachment of dune ridges from the mainland shore is an often cited but at best unlikely mode of island genesis. Review of the literature and remote-sensed images created new insights, utilized barrier definitions and genetic theories, as applied in the Mississippi Delta Complex. A three-stage concept, involving dune ridge or barrier spit-detachment by marine encroachment and landward shift of fragmented transgressive islands forms the basis of a recent invited Marine Geology research article. That model assumes spit-growth from delta headlands, followed by splintering into landward-migrating islands. Submerged, they become permanent shoals. For several reasons, this “island-cycle” hypothesis is questionable and a reassessment of the geomorphic and stratigraphic context of this delta coast is required.Contradicting the geomorphic setting of assumed Stage 1, key component of the cycle-model, evidence is lacking for subrecent delta lobes and erosional headland in spawning barrier islands. In addition, the delta headland-flanking islands reveal only progradational (regressive) development and in situ disintegration,. Transgressive landward migrations is known only from the Chandeleur chain's prehistory. Sand from decaying Terrebonne-Lafourche 6 Subdelta headland was the dominant source for the Caminada Strandplain and for the shoal /or island predecessor of Grand Isle. Wave refraction around an inferred Lafourche delta lobe (dated provisionally between ∼2900 - ∼ 2300 yrs. BP) and its decayed erosional headland remnant resulted in diametric reversal of littoral sand transport. An earlier proferred ∼750–300 yrs. BP Caminada Strandplain age range is now replaced by a loosely defined ∼2200- to- ∼800 yrs. BP value, based on ages of Grand Isle and reworked delta hinterland sediments incorporated into the Strandplain.

Bloom of Trichogloeopsis pedicellata (Rhodophyta, Nemaliales) following hurricane Iota in San Andrés, Southwestern Caribbean Sea

Hurricanes and tropical storms are major climatic disturbances with potentially catastrophic effects on coastal and marine ecosystems. The impact of these climatic events on coastal communities may vary greatly and depends on the hurricane’s severity, trajectory, and duration. Furthermore, the impact of hurricanes can be patchy, causing extensive damage in some locations, while leaving other subjacent areas intact. In coral reef areas, breakage, dislodgement, and sandblasting may cause extensive coral mortality, and loss of coral cover may increase due to sedimentation and freshwater runoff. After the impact of the climatic event, successional stages in the reef community have been observed, where blooms of ephemeral algae may occupy space made available by the storm impact. We report a bloom of the red alga Trichogloeopsis pedicellata on the west coast of the island of San Andrés, following Hurricane Iota. The survey was carried out in seven locations at different depths: shallow (2–5 m) and deep (8–15 m). Three video transects were recorded at each sampling site, and 15 photo quadrats were analyzed for benthic cover. For the biomass estimate, three to five quadrats of 25 × 25 cm were laid on the substrate, all the algae inside were collected, and their wet biomass was determined. The algal cover reached 100% in some locations, with wet biomass up to 5,264 g/m2, and persisted for several weeks. The bloom was more severe at shallow depths. Apparently, the availability of the substrate due to the detachment of foliose algae triggered the bloom. After a few months, the bloom receded naturally.

Bayesian networks to predict storm impact using data from both monitoring networks and statistical learning methods

Bayesian networks to predict storm impact using data from both monitoring networks and statistical learning methods

Performance Analysis of GPS/BDS Broadcast Ionospheric Models in Standard Point Positioning during 2021 Strong Geomagnetic Storms

The broadcast ionospheric model is one of the main methods for eliminating ionospheric delay errors for the Global Navigation Satellite Systems (GNSS) single-frequency users. GPS Klobuchar model (GPSK8) is the widely used broadcast ionospheric model for GPS, while BDS usually implements the BDS Klobuchar model (BDSK8) and BeiDou Global Broadcast Ionospheric Delay Correction Model (BDGIM). Geomagnetic storms may cause interference within the ionosphere and near-Earth space, compromising the accuracy of ionospheric models and adversely affecting the navigation satellite systems. This paper analyzes the static Standard Point Positioning (SPP) accuracy of GPS and BDS by implementing the broadcast ionospheric models and then investigates the impact of strong geomagnetic storms occurring in 2021 on positioning accuracy. The results show that the global 3D positioning accuracy (95%) of GPS + GPSK8, BDS + BDSK8, and BDS + BDGIM are 3.92 m, 4.63 m, and 3.50 m respectively. BDS has a better positioning accuracy in the northern hemisphere than that of the southern hemisphere, while the opposite is valid for GPS. In the mid-latitude region of the northern hemisphere, BDS + BDSK8 and BDS + BDGIM have similar positioning accuracy and are both better than GPS + GPSK8. The positioning accuracy after applying those three broadcast ionospheric models shows the superior performances of winter and summer over spring and autumn (based on the northern hemisphere seasons). With the exception of during winter, nighttime accuracy is better than that of daytime. The strong geomagnetic storm that occurred on the day of year (DOY) 132, 2021 has an impact on the positioning accuracy for only a small number of stations; however, the global average positioning accuracy is not significantly affected. The strong geomagnetic storms that occurred in DOY 307 and DOY 308 have a significant impact on the positioning accuracy of dozens of stations, and the global average positioning accuracy is affected to a certain extent, with some stations experiencing a serious loss of accuracy. Decreased degrees in positioning accuracy is proportional to the intensity of the geomagnetic storm. Of the 33 IGS Multi-GNSS Experiment (MGEX) stations worldwide, those located in the low and mid-latitudes are more significantly affected by the geomagnetic storms compared with higher latitudes. Evident fluctuations of the positioning errors existed during the strong geomagnetic storms, with an increase in extreme values, particularly in the up direction.

Quantifying Coastal Storm Impacts Using a New Cumulative Storm Impact Index (CSII) Model: Application Along the Virginia Coast, USA

AbstractThis paper presents a new empirical model, called the cumulative storm impact index (CSII), that quantifies the impact of coastal storms on sandy beaches. The new model utilizes user‐defined storm data to incorporate both individual storm magnitude and the cumulative effect of successive storms into an index, which is a proxy for beach erosion at a given time. Applying this model to long‐term water‐level data from a Virginia tide gauge showed that the greatest storm impact resulted not from the larger individual storms, such as the Ash Wednesday nor'easter of 1962, the “Perfect Storm” of 1991, or Hurricane Sandy of 2012, but rather from especially stormy winter seasons that occurred during the twenty‐first century. Additionally, the CSII model uncovered a trend—not detectable by single storm impact analyses—toward greater storm impacts, which began c. 1980 and continued to the present day. Finally, comparative analyses using wave power as a storm index shows CSII can capture decadal or seasonal scale storminess. We expect this model to have utility in many areas of the coastal sciences and engineering, including developing holistic response models, quantifying erosion potential at other locations, and managing coastal ecosystems.

Proposal of Parameter Range that Offered Optimal Performance in the Coastal Morphodynamic Model (XBeach) Through GLUE

The process-based XBeach model has numerous empirical parameters because of insufficient understanding of hydrodynamics and sediment transport on the nearshore; hence, it is necessary to calibrate parameters to apply to various study areas and wave conditions. Therefore, the calibration process of parameters is essential for the improvement of model performance. Generally, the trial-and-error method is widely used; however, this method is passive and limited to various and comprehensive parameter ranges. In this study, the Generalized Likelihood Uncertainty Estimation (GLUE) method was used to estimate the optimal range of three parameters (gamma, facua, and gamma2) using morphological field data collected in Maengbang beach during the four typhoons that struck from September to October 2019. The model performance and optimal range of empirical parameters were evaluated using Brier Skill Score (BSS) along with the baseline profiles, sensitivity, and likelihood density analysis of BSS in the GLUE tools. Accordingly, the optimal parameter combinations were derived when facua was less than 0.15 and simulated well the shifting shape, from crescentic sand bar to alongshore uniform sand bars in the surf zone of Maengbang beach after storm impact. However, the erosion and accretion patterns nearby in the surf zone and shoreline remain challenges in the XBeach model.

Extreme Poleward Expanding Super Plasma Bubbles Over Asia‐Pacific Region Triggered by Tonga Volcano Eruption During the Recovery‐Phase of Geomagnetic Storm

AbstractThe Tonga volcano eruption of 15 January 2022 unleashed a variety of atmospheric perturbations, coinciding with the recovery‐phase of a geomagnetic storm. The ensuing thermospheric variations created rare display of extreme poleward‐expanding conjugate plasma bubbles seen in the rate of total electron content index over 100–150°E, reaching ∼40°N geographic latitude. This is associated with fluctuations in FORMOSAT‐7/COSMIC‐2 (F7/C2) ion‐density measurements and spread‐F in ionograms. Preceding to this, an unusually strong pre‐reversal enhancement (PRE) occurred in the global ionospheric specification (GIS) electron density profiles derived from F7/C2 observations. The GIS also revealed a decrease of equatorial ionization anomaly (EIA) crest density due to the storm impact. Reduced E‐region conductivity by volcano‐induced waves and enhanced F‐region wind, further accelerated by reduced ion‐drag over the EIA, apparently intensified the PRE. Accompanied with the strong PRE, volcano‐induced seed perturbations triggered the super plasma bubble activity.

Assessing the Role of Extreme Mediterranean Events on Coastal River Outlet Dynamics

River mouths are highly dynamic environments responding very rapidly to changes in wave energy or river floods. While the morphological response during floods or during marine storm events has been widely documented in the literature, little is known about the mechanisms acting during the co-occurrence of fluvial and marine hazards. This concomitance of river flood and marine storm is quite common in the western Mediterranean Sea, and was the case for the Gloria event, considered to be the most extreme event in recent decades. During this event, monitoring of hydrodynamics and morphological evolution was implemented, making it possible to better understand the impact of concomitant marine storm and fluvial flood during an extreme meteorological event on spit breaching of a small Mediterranean river mouth. Monitoring using a combination of high-resolution hydrodynamic measurements, topographic and bathymetric surveys, and sediment cores was used before, during, and after the storm “Gloria”. The results suggest an amplification of the morphological impact of the events and a different morphogenic response than if each of the events had acted independently on the system. The marine storm, occurring first, weakened the spit and initiated its breaching, which was continued by the extreme fluvial flood, thus leading to the complete destruction of the mouth. The destruction of the spit acted as a sediment source for subaqueous large delta deposition amounting to 50% of the total volume. The contribution of the river, estimated at 30%, was quite low for an exceptional event, showing the importance of locating rainfall in a catchment area controlled by a dam. For this event, extreme morphological evolution was observed, as well as the importance of water levels in the river mouth, which probably increased flood hazards, demonstrating the importance of including the compounding effect of extreme coastal water levels in river flood risk management.

New Approach for Reducing Impact of Sand Storm and Subsequent Deposition on Solar Panel in Desert Area

New Approach for Reducing Impact of Sand Storm and Subsequent Deposition on Solar Panel in Desert Area

Effect of survey parameters on unmanned aerial vehicles-derived topography for coastal dune monitoring

Coastal dunes are fragile ecosystems emerging at the interface between marine and continental environments. They provide multiple services, among which are the protection against the impact of storms and the hosting of diverse and unique species of fauna and flora. However, changes in the topography or biological component of these systems may endanger the perpetuation of service provision. Topographic changes within dunes can significantly differ in magnitude depending on the type of process (i.e., marine or aeolian) and the temporal scale of analysis (event to annual scale), making their monitoring a challenging task. In recent years, unmanned aerial vehicles (UAVs) have been increasingly used to monitor coastal dunes, proving to be a cost-efficient methodology for the collection of topographic data. Yet, the application of UAVs in combination with the structure from motion approach to obtain digital surface models (DSMs) presents some limitations related to the level of accuracy provided for the evaluation of topographical changes in dunes with low sedimentation rates. This work explores different survey configurations using UAVs flying at low altitudes with the aim of obtaining high-quality DSMs with vertical accuracies preferably around or lower than 0.04 m. Several tests were performed to evaluate the influence of different parameters on the accuracy of the DSM, including flight altitude and orientation, density and spatial distribution of ground control points (GCPs), terrain slope, vegetation cover, and sun-related parameters. The results indicate that the intended accuracies can be obtained by combining overlapped perpendicular flights, GCPs distributed regularly following a diamond grid, with densities of at least 6 GCPs per hectare, sun altitudes between 30 and 40 deg, and a total solar radiation per hour between 1750 and 2250 KJ / m2. In addition, better results were obtained across gentle slope areas, suggesting the eventual need to adapt to the particularities of each site to ensure the accuracy.