Causes of Landslide and its Socio-economic Effects: a study on Chattogram City and Surrounding Areas, Bangladesh

Landslide is a regular hazard in Bangladesh especially in Chattogram, the South-Eastern part of the Country. In 2007 and 2008 there happened two massive landslides in Chattogram. As a result, a huge number of people (130 and 11 respectively) died with heavy loss of properties affecting thousands of people in the region. Most of the landslides happened after torrential rain. Combined effect of rainfall and hill cutting induced slope instability adding Earthquake-triggered landslide in Chattogram. Some influential people are involved in hill cutting and developing hilly settlements in Chattogram. In some places, Government and non-Government authorities are developing settlements by razing hills there. A detailed area planning, landslide vulnerability zoning, landslide database development, geophysical analysis, and strictly implementation of Government’s existing rules are recommended to ensure avoiding further tragedy in Chattogram like 2007 and 2008.

The characteristics of the equatorial waves caused a record torrential rain event over western Sumatra

This study examined the cause of a record torrential rain event over the western coast of Sumatra Island in March 2016. The influence of atmospheric equatorial waves (EWs) and the characteristics of the EWs were investigated. Analysis of the Japanese 55-year Reanalysis data (JRA-55) and precipitation data from the Global Precipitation Measurement (GPM) satellite showed that the event was caused by the combined effects of Kelvin waves, equatorial Rossby waves, and westward inertio-gravity (WIG) waves. An examination of the characteristics of the EWs revealed that the Kelvin waves had longitudinal scales of ~6,000 km, with a period of ~6 days and phase speed of ~12 m s-1, which was typical of the convectively coupled Kelvin waves in this region. The WIG waves had a scale of ~2,500 km, with a period of 2.5 days and a relatively fast phase speed of 12~13 m s-1. Heavy precipitation occurred when an eastward Kelvin wave from the Indian Ocean encountered a westward inertio-gravity (WIG) over Sumatra Island. It was concluded that along with the Kelvin and equatorial Rossby waves, the WIG waves might have played a major role in the formation of the extreme precipitation event.

Synoptic Causes of Torrential Rainfall in the Balearic Islands (1941–2010)

This article determines the atmospheric situation for the 53 days where any weather station in the Balearic Islands detected torrential rain (equal to or above 200 mm in a single day) during the period 1941–2010. To do this, the synoptic charts for each day were analysed, classifying them in accordance with the types established by Martín Vide (1984) and, in addition, through the automatic synoptic classifications from Jenkinson and Collison (1977). The analysis results demonstrate the importance of cyclonic situations over the Western Mediterranean Basin linked to favourable altitude configurations (earlier presence of cut-off lows—DANA—or troughs). These atmospheric conditions contrast with those that predominate in nearby Mediterranean areas, such as the south-eastern coast of the Iberian Peninsula. Days with torrential rain on the Iberian coastline tend to coincide with easterly advections—a less common occurrence in the Balearics.

Effect of natural rainfall on the migration characteristics of runoff and sediment on purple soil sloping cropland during different planting stages

Due to the difficulty in monitoring subsurface runoff and sediment migration, their loss loads are still not clear and need further study. This study monitored water and soil loss occurring within experimental field plots for two calendar years under natural rainfall events. The sediment loss load was quantified by considering the corresponding water flow flux and its sediment concentration. The results showed that 60.04% of the runoff and 2.83% of the sediment were lost underground. The annual underground sediment loss reached up to 54.6 kg*ha−1*yr−1. A total of 69.68% of the runoff yield and 67.25% of the sediment yield were produced during the corn planting stage (CPS: March–July). Heavy rain and torrential rain events produced 94.45%, 65.46% of the annual runoff and 94.45%, 76.21% of the sediment yields during the corn-planting stage and summer fallow period (SFP: August–September). The rain frequency, rainfall, and rainfall duration of each planting stage significantly affected the resulting runoff and sediment yield. Measures aimed at the prevention and control of water-soil loss from purple soil sloping land should heavily focus on torrential rain and heavy rain events during the CPS and SFP. This paper aims to provide a practical reference for quantifying the water and soil loss from purple soil sloping cropland.

Estimation of the Precipitable Water and Water Vapor Fluxes in the Coastal and Inland Cities of China Using MAX-DOAS

Water vapor transport affects regional precipitation and climate change. The measurement of precipitable water (PW) and water vapor flux (WVF) is of great importance for the study of precipitation and water vapor transport. This study presented a new method of computing PW and estimating WVF using the water vapor vertical column density (VCD) and profile retrieved from multi-axis differential optical absorption spectroscopy (MAX-DOAS), combined with the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA5 wind profiles. We applied our method to MAX-DOAS observations in the coastal (Qingdao) and inland (Xi’an) cities of China from June 2019 to May 2020 and compared the results to the ERA5 reanalysis datasets. Good agreement with ERA5 datasets was found; the correlation coefficient (r) of the PW and the zonal and meridional WVFs were r ≥ 0.92, r = 0.77, and r ≥ 0.89, respectively. The comparison results showed the feasibility and reliability of estimating PW and WVF using MAX-DOAS. Then, we analyzed the seasonal and diurnal climatology of the PW and WVFs in Qingdao and Xi’an. The results indicated that the seasonal and diurnal variations of the PW in the two cities were similar. The zonal water vapor transport of the two cities mainly involved eastward transport, Qingdao’s meridional water vapor mainly involved southward transport, and that of Xi’an mainly involved northward transport. The WVFs of the two cities were higher in the afternoon than in the morning, which may be related to wind speed. The results also indicated that the WVF transmitting belts appeared at around 2 and 1.4 km above the surface in Qingdao and around 2.8, 2.6, 1.6, and 1.0 km above the surface in Xi’an. Before precipitation, the WVF transmitting belt moved from near the ground to a high level, reaching its maximum at about 2 km, and the PW and meridional vertically integrated WVF increased. Finally, the sources and transports of water vapor during continuous precipitation and torrential rain were analyzed according to a 24 h backward trajectory. The air mass from the southeast accounted for more than 84% during continuous precipitation in Xi’an, while the air mass from the ocean accounted for more than 75% during torrential rain in Qingdao and was accompanied by a high-level ocean jet stream. As an optical remote sensing instrument, MAX-DOAS has the advantages of high spatiotemporal resolution, low cost, and easy maintenance. The application of MAX-DOAS to meteorological remote sensing provides a better method for evaluating the PW and WVF.

The role of aerosol spatial inhomogeneity in mixed-phase deep convective clouds and torrential rain in urban areas

<p>This study examines the role played by aerosol in mixed-phase deep convective clouds and torrential rain that occurred in the Seoul area, which is a conurbation area where urbanization has been rapid in the last few decades, using cloud-system resolving model (CSRM) simulations. The model results show that the spatial variability of aerosol concentrations causes the inhomogeneity of the spatial distribution of evaporative cooling and the intensity of associated outflow around the surface. This inhomogeneity generates a strong convergence field and the associated spatial inhomogeneity of condensation, deposition and associated cloud mass, leading to the formation of torrential rain.  With the increases in the variability of aerosol concentrations, the occurrence of torrential rain increases. This study finds that the effects of the increases in the variability play a much more important role in the increases in the intensity of mixed-phase clouds and torrential rain than the much-studied effects of the increases in aerosol loading. Results in this study demonstrate that for a better understanding of extreme weather events such as torrential rain in urban areas, not only changing aerosol loading but also changing aerosol spatial distribution since industrialization should be considered in aerosol-precipitation interactions. </p>

Arcade

“Let’s try to do something educational for the kids,” Sarah’s message read. Sarah Milken and her husband David were from the United States and had been traveling for several months with their eight-year-old son, Colin. We happened to be in Buenos Aires, Argentina at the same time, and I was trying to set up a research interview that could double as a playdate for Colin and Elliot. I suggested a children’s science museum, but it turned out to be closed for renovations. Maybe a park where the kids could play outside? The forecast promised torrential rain. We finally agreed on the Abasto shopping center. The building, at least, had some historical significance....