160 research outputs found
Moisture source identification for precipitation associated with tropical cyclone development over the Indian Ocean: a Lagrangian approach
Financiado para publicación en acceso aberto: Universidade de Vigo/CISUGIn this study, we investigated the moisture sources for precipitation through a Lagrangian approach during the genesis, intensification, and dissipation phases of all tropical cyclones (TCs) that occurred over the two hemispheric sub-basins of the Indian Ocean (IO) from 1980 to 2018. In the North IO (NIO), TCs formed and reached their maximum intensity on both sides of the Indian Peninsula, to the east in the Bay of Bengal (BoB), and to the west in the Arabian Sea (AS). The oceanic areas where TCs occurred were their main moisture sources for precipitation associated with TCs. Additionally, for TCs over the BoB, continental sources from the Ganges River basin and the South China Sea also played a notable role; for TCs over the AS, the Somali Low-Level jet (along the African coast in a northerly direction) also acted as an essential moisture transport. In the South IO (SIO), the western, central, and eastern basins were identified as the preferred areas for the genesis and development of TCs. During TC activity, the central IO and the Wharton and Perth basins mostly supplied atmospheric moisture. The Mascarene High circulation was the main moisture transport mechanism for the precipitation of TCs formed in the SIO basin. In both basins, during their intensification process, TCs gained more moisture (even more intensely when reaching the hurricane category) than during the genesis or dissipation stages. Additionally, the modulation during monsoonal seasons of the moisture contribution to the TCs was more noticeable over the NIO basin than for the SIO. Overall, the moisture uptake for precipitation from the sources for TCs occurred slightly faster in the NIO basin than in the SIO basin.Xunta de Galicia | Ref. ED481B 2019/070Xunta de Galicia | Ref. ED481A-2020/193Xunta de Galicia | Ref. ED431C 2021/44Agencia Estatal de Investigación | Ref. RTI2018-095772-B-I00Agencia Estatal de Investigación | Ref. PID2021-122314OB-I0
Estimation of mean water vapour residence time during tropical cyclones using a Lagrangian approach
Tropical cyclone (TC)-related rainfall mostly depends on the atmospheric moisture uptake from local and remote sources. In this study, the mean water vapour residence time (MWVRT) was computed for precipitation related to TCs in each basin and on a global scale by applying a Lagrangian moisture source diagnostic method. According to our results, the highest MWVRT was found for the TCs over the South Indian Ocean and South Pacific Ocean basins (∼3.08 days), followed by the Western North Pacific Ocean, Central and East North Pacific Ocean, North Indian Ocean, and North Atlantic Ocean basins (which exhibited values of 2.98, 2.94, 2.85, and 2.72 days, respectively). We also found a statistically significant (p < 0.05) decrease in MWVRT, at a rate of ∼2.4 h/decade in the North Indian Ocean and ∼1.0 h/decade in the remaining basins. On average, the MWVRT decreased during the 24 h before TCs made landfall, and the atmospheric parcels precipitated faster after evaporation when TCs moved over land than over the ocean. Further research should focus on the relationship between global warming and MWVRT of atmospheric parcels that precipitate over TC positionsMinisterio de Ciencia, Innovación y Universidades | Ref. RTI2018-095772-B-I00Ministerio de Ciencia, Innovación y Universidades | Ref. PID2021-122314OB-I00Xunta de Galicia | Ref. ED431C2021/44Xunta de Galicia | Ref. ED481A-2020/19
Predicting Benzene Concentration Using Machine Learning and Time Series Algorithms
[EN] Benzene is a pollutant which is very harmful to our health, so models are necessary to predict its concentration and relationship with other air pollutants. The data collected by eight stations in Madrid (Spain) over nine years were analyzed using the following regression-based machine learning models: multivariate linear regression (MLR), multivariate adaptive regression splines (MARS), multilayer perceptron neural network (MLP), support vector machines (SVM), autoregressive integrated moving-average (ARIMA) and vector autoregressive moving-average (VARMA) models. Benzene concentration predictions were made from the concentration of four environmental pollutants: nitrogen dioxide (NO2), nitrogen oxides (NOx), particulate matter (PM10) and toluene (C7H8), and the performance measures of the model were studied from the proposed models. In general, regression-based machine learning models are more effective at predicting than time series models.S
Dynamic downscaling of wind speed over the North Atlantic Ocean using CMIP6 projections: implications for offshore wind power density
Offshore wind energy is an important agent to fight climate change. However, it is simultaneously very sensitive to climate change. This study analyzes the future changes in wind speed of 10 m above sea surface (V10) in the North Atlantic Ocean and how these variations may affect offshore wind energy resources for three potential subregions (the United States (US) East Coast, western Iberian Peninsula, and the Caribbean Sea). Dynamic downscaling of three different future scenarios of the CESM2 global climate model (CMIP6 project) was performed using the WRF-ARW atmospheric model. V10 is expected to decrease in the winter and spring seasons but increase in summer and autumn, mainly in tropical regions up to 30 °N. Annually, it shows the maximum increase in the tropical region. For the Iberian Peninsula subregion, significant increases in summer are expected for wind power density (WPD) along the 21st century, but there is uncertainty for the other seasons. A WPD decrease in winter and increases in summer and autumn are expected along the 21st century for the US subregion. No significant changes were observed at annual scale. Finally, for the Caribbean Sea, a decrease is projected in the Yucatan Basin and considerable increases are foreseen for the Colombia and Venezuela basins.Xunta de Galicia | Ref. ED481A-2020/193Xunta de Galicia | Ref. ED431C 2021/44Agencia Estatal de Investigación | Ref. JC2020-043745-IAgencia Estatal de Investigación | Ref. PID2021-22314OB-I00Universidade de Vigo/CISU
Evaluating changes in the moisture sources for tropical cyclones precipitation in the North Atlantic that underwent extratropical transition
In this study, we investigated the changes in the origin of moisture for the precipitation associated with tropical cyclones (TCs) after extratropical transition (ET) over the North Atlantic Ocean basin from 1980 to 2018. We analyzed the 24 hr before and after the occurrence of ET events. By applying a TC-centric methodology we found that the moisture uptake (MU) occurred predominantly in the south and southwest sectors within ∼2,000 km of TC center before ET and from the southwest and west sectors after ET. In addition, the development of the cold front and the warm conveyor belt after ET induces changes in the moisture transport pattern. Overall, the secondary circulation of TCs favored the moisture flux inward for TCs precipitation, while the large-scale baroclinic environment controlled the MU after ET.Xunta de Galicia | Ref. ED481A‐2020/193Xunta de Galicia | Ref. ED431C 2021/44Agencia Estatal de Investigación | Ref. PID2021‐122314OB‐I0
Climatological variations of moisture sources for precipitation of North Atlantic tropical cyclones linked to their tracks
Financiado para publicación en acceso aberto: Universidade de Vigo/CISUGThe tropical cyclones (TCs) trajectories are mainly controlled by the large-scale parameters related with the steering flow. We used the HURDAT2 database from 1980 to 2018 for grouping the tracks of TCs formed in the North Atlantic (NATL) main development region into straight moving (SM), recurving landfall (RCL) and recurving ocean (RCO). Based on this classification, we investigated the changes in the moisture sources' contributions to the precipitation along the TCs trajectories for each track category by applying a Lagrangian moisture source diagnostic method to the air parcels pathways from the FLEXPART model. The highest moisture contribution occurred within 3-5° from the average TCs trajectories. The moisture supplied from the Gulf of Mexico represented 19.1% of humidity gained by SM but was negligible for recurving TCs. Likewise, the Caribbean Sea contributed 31.8% for SM, and its humidity support notably decreased for recurving storms to 0.9–8.3%. In addition, the moisture uptake from the tropical NATL was similar for all track types. The western NATL increased the moisture supply from 15.3% for SM to 31.1% for RCO and 42.6% for RCL, while the eastern subtropical NATL provided 3.1% of moisture to SM, 12.5% to RCL and 45.4% to RCO. It was also notable the moisture support from the terrestrial source southeastern United States (5.3%) for RCL tracks. Furthermore, we found that El Niño–Southern Oscillation, the North Atlantic Oscillation, the Atlantic Multidecadal Oscillation and the Atlantic Meridional Mode influence the moisture contributions variability from sources for each track typeXunta de Galicia | Ref. ED481A2020/193Ministerio de Ciencia, Innovación y Universidades | Ref. PID2021-122314OB-I00Xunta de Galicia | Ref. ED431C 2021/44Xunta de Galicia | Ref. ED481A2022/12
The rare case of Hurricane Catarina (2004) over the South Atlantic Ocean: The origin of its precipitation through a Lagrangian approach
Tropical cyclones (TCs) are extremely rare over the South Atlantic Ocean (SATL)
due to predominantly unfavourable conditions, that is, cool sea-surface temperature and strong vertical wind shear. Nevertheless, unusual conditions over
SATL associated with a blocking system promoted the formation of Hurricane
Catarina from an extratropical precursor in late March 2004, which produced
heavy rainfall over the states of Santa Catarina and the Rio Grande do Sul
in south Brazil. This work identifies the moisture sources for the precipitation produced by Catarina along its 6-hourly trajectory, through a Lagrangian
moisture-tracking method. We extracted the pathways of precipitating air
parcels within the cyclone’s outer radius from the global outputs of the FLEXPART model forced with the ERA-Interim reanalysis. Our findings revealed the
terrestrial source in south-southeastern Brazil (SEB) and the oceanic source
limited by the box between 20-40◦S and 30–50◦W over SATL (WSATL) as the
principal moisture sources, with the overall support of ∼27% and ∼66%, respectively. However, their contribution varied according to the development phase
of Catarina. While the moisture uptake from SEB decreased from ∼75% during
the extratropical phase to ∼8% during the hybrid stage, the moisture contribution from WSATL notable increased from ∼20% to 87%, respectively. Likewise,
the contributions from SEB and WSATL during the tropical phase of the cyclone
accounted for ∼13% and ∼85%, respectively. The tracked air parcels achieved
the high water content in a short period before the precipitation, leading to a
reduction of the mean water vapour residence time to ∼3.1 days. Additionally,
the precipitating moisture uptake along the Catarina trajectory was noticeably
higher than the climatological value.Xunta de Galicia | Ref. ED481A2020/193Xunta de Galicia | Ref. ED481A2022/128Xunta de Galicia | Ref. ED431C 2021/44Ministerio de Ciencia, Innovación y Universidades | Ref. PID2021‐122314OB‐I00Fundação para a Ciência e a Tecnologia | Ref. JPIOCEANS/0001/201
Oceanic and terrestrial origin of precipitation over 50 major world river basins: Implications for the occurrence of drought
The terrestrial and oceanic origins of precipitation over 50 major river basins worldwide were investigated for the period 1980–2018. For this purpose, we used a Lagrangian approximation that calculates the humidity that results in precipitation from the entire ocean area (ocean component of the precipitation, PLO) and the entire land area (land component, PLT) as well as the sum of both components (Lagrangian precipitation, PL). PL and its components were highly correlated with precipitation over the basins, where PLT accounted for >50 % of the PL in most of them. This confirmed the importance assigned by previous studies to terrestrial recycling of precipitation and moisture transport within the continents. However, the amount of PLO in almost all North American river basins was highlighted. The assessment of drought conditions through the Standardized Precipitation Index (SPI) at a temporal scale of 1- and 3-months revealed the number of drought episodes that affected each river basin, especially the Amazon, Congo, and Nile, because of the lower number of episodes but higher average severity and duration. A direct relationship between the severity of drought episodes and the respective severity computed on the oceanic and terrestrial SPI series was also found for the majority of basins. This highlights the influence of the severity of the SPI of oceanic origin for most basins in North America. However, for certain basins, we found an inverse relationship between the severity of drought and the associated severity according to the SPI of oceanic or terrestrial origin, thus highlighting the principal drought attribution. Additionally, a copula analysis provided new information that illustrates the estimated conditional probability of drought for each river basin in relation to the occurrence of drought conditions of oceanic or terrestrial origin, which revealed the possible main driver of drought severity in each river basin.Xunta de Galicia | Ref. ED481B-2019/070Xunta de Galicia | Ref. ED481B-2021/134Xunta de Galicia | Ref. ED481A-2020/193Agencia Estatal de Investigación | Ref. RTI2018-095772-B-I00Agencia Estatal de Investigación | Ref. PID2021-122314OB-I00Xunta de Galicia | Ref. ED431C 2021/44Financiado para publicación en acceso aberto: Universidade de Vigo/CISU
Changes in moisture sources of atmospheric rivers landfalling the Iberian Peninsula with WRF-FLEXPART
This paper makes use of a combination of FLEXPART-WRF simulations forced with ERA5 and the CESM2 model—incorporated in the CMIP6 project—to infer a series of changes over the present century in the behavior of the landfalling atmospheric rivers (ARs) arriving to the Iberian Peninsula. In addition, future changes in the intensity and position of their main moisture sources are studied. In overall terms, there is a noticeable increase in the amount of moisture transported by ARs in the study region, particularly accentuated by the end of the century. However, no significant changes in the number of events are observed. A northward shift of both the mean position of the ARs as well as their main sources of moisture is also detected, particularly for the end of the century, and in the summer and fall months. In relation to the latter, an increase in the contribution of moisture contribution is also observed, quantitatively compatible with Clausius-Clapeyron amplification.Agencia Estatal de Investigación | Ref. PID2021-122314OB-I00Xunta de Galicia | Ref. ED481A‐2020/193Xunta de Galicia | Ref. ED431C 2021/44Universidade de Vigo/CISU
How much of precipitation over the Euroregion Galicia - Northern Portugal is due to tropical-origin cyclones?: A Lagrangian approach
Xunta de Galicia | Ref. ED431C 2021/44Agencia Estatal de Investigación | Ref. PID2021-122314OB-I00Universidade de Vigo/CISU
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