Innovatory rainfall simulator design – A concept of moving storm automation

We developed an advanced design programmable rainfall simulator (RS) to simulate a moving storm rainfall condition. The RS consists of an automated nozzle control system coupled with a pressure regulator mechanism for an operating range of 50 kPa to 180 kPa at a drop height of 2000 mm above the soil flume surface. Additionally, a programmable mobile application was developed to regulate all RS valves. Near natural rainfall conditions were simulated at varying spatial and temporal resolutions in a controlled environment. A soil flume of 2500 mm × 1400 mm × 500 mm was fabricated to conduct different hydrological experiments. The flume was designed to record overland, subsurface, and base flows simultaneously. This study focused on a detailed analysis of moving storms and their impact on hydrograph characteristics. Experimental results showed a considerable difference in terms of time to peak (tp), peak discharge (Qp), and hydrograph recession for two different storm movement directions (upstream and downstream). Two multiple regression models indicate a statistically significant relationship between the dependent variable (tp or Qp) and the independent variables (i.e. storm movement direction, storm velocity, and bed slope gradient) at a 5 % level of significance. Further, the impact of these moving storm phenomena reduces with the increase in the storm movement velocity.

Motivation, Satisfaction, and Risks of Operational Forces and Helpers Regarding the 2021 and 2013 Flood Operations in Germany

Pluvial floods claimed more than 180 lives in Germany in July 2021, when a large and slow-moving storm system affected Germany and many neighbouring countries. The death tolls and damages were the highest since 1962 in Germany, and soon after, the crisis management was under public critique. This study has undertaken an online survey to understand crisis management better and identify lessons to learn. It has received a positive interest among operational relief forces and other helpers (n = 2264). The findings reveal an overall satisfaction with the operation in general as well as personal lessons learned. It also reveals shortcomings in many areas, ranging from information distribution, coordination, parallel ongoing COVID-19 pandemic, infrastructure resilience, and other factors. Just as well, areas for improvement of the crisis management system are suggested by the respondents. Cooperation and support by the affected population are perceived as positive. This helps to inform other areas of research that are necessary, such as studies on the perception by the affected people. The gaps in assessments of operational forces and some methodological constraints are discussed to advance future follow-up studies.

Convectively Induced Stabilizations and Subsequent Recovery with Supercell Thunderstorms during the Mesoscale Predictability Experiment (MPEX)

The adiabatic and diabatic processes inherent to midlatitude deep convective storms are well known to modify the atmospheric temperature, moisture, and winds especially within horizontal scales equivalent to a Rossby radius of deformation. Such modifications, or “feedbacks,” induced by supercell thunderstorms were a particular focus of the Mesoscale Predictability Experiment (MPEX), owing to the unique supercell dynamics and associated supercell intensity and longevity. During the MPEX field phase, which was conducted 15 May–15 June 2013 within the Great Plains region of the United States, radiosonde observations collected in immediate supercell wakes exhibited temperature lapse rates that were qualitatively and quantitatively similar to preconvective lapse rates above the boundary layer. Complementary idealized model simulations were used to confirm that there was little residual effect of the supercell in the wake of the moving storm except within the area occupied by the surface cold pool, and where stabilizations were induced adiabatically by transient gravity wave disturbances. The persistency of the (i) cold pool, and its inhibition to surface-based convection, depended on the evolving cold pool strength and environmental winds; and (ii) gravity wave effects depended on the Doppler-shifted phase speed relative to the moving storm. Otherwise, recovery of the wake environment to its preconvective state occurred approximately over a time scale defined by the updraft length scale and horizontal advective velocity scale.

Impact of environmental moisture on tropical cyclone intensification

The impacts of environmental moisture on the intensification of a tropical cyclone (TC) are investigated in the Weather Research and Forecasting (WRF) model, with a focus on the azimuthal asymmetry of the moisture impacts relative to the storm path. A series of sensitivity experiments with varying moisture perturbations in the environment are conducted and the Marsupial Paradigm framework is employed to understand the different moisture impacts. We find that modification of environmental moisture has insignificant impacts on the storm in this case unless it leads to convective activity that deforms the quasi-Lagrangian boundary of the storm and changes the moisture transport into the storm. By facilitating convection and precipitation outside the storm, enhanced environmental moisture ahead of the northwestward-moving storm induces a dry air intrusion to the inner core and limits TC intensification. In contrast, increased moisture in the rear quadrants favors intensification by providing more moisture to the inner core and promoting storm symmetry, with primary contributions coming from moisture increase in the boundary layer. The different impacts of environmental moisture on TC intensification are governed by the relative locations of moisture perturbations and their interactions with the storm Lagrangian structure.

Impact of environmental moisture on tropical cyclone intensification

The impacts of environmental moisture on the intensification of a tropical cyclone (TC) are investigated in the Weather Research and Forecasting (WRF) model, with a focus on the azimuthal asymmetry of the moisture impacts. A series of sensitivity experiments with varying moisture perturbations in the environment are conducted and the Marsupial Paradigm framework is employed to understand the different moisture impacts. We find that modification of environmental moisture has insignificant impacts on the storm in this case unless it leads to convective activity in the environment, which deforms the quasi-Lagrangian boundary of the storm. By facilitating convection and precipitation outside the storm, enhanced environmental moisture ahead of the northwestward-moving storm induces a dry air intrusion to the inner core and limits TC intensification. However, increased moisture in the rear quadrants favors intensification by providing more moisture to the inner core and promoting storm symmetry, with primary contributions coming from moisture increase in the boundary layer. The different impacts of environmental moisture on TC intensification are governed by the relative locations of moisture perturbations and their interactions with the storm Lagrangian structure.

Cold Pool and Precipitation Responses to Aerosol Loading: Modulation by Dry Layers

The relative sensitivity of midlatitude deep convective precipitation to aerosols and midlevel dry layers has been investigated in this study using high-resolution cloud-resolving model simulations. Nine simulations, including combinations of three moisture profiles and three aerosol number concentration profiles, were performed. Because of the veering wind profile of the initial sounding, the convection splits into a left-moving storm that is multicellular in nature and a right-moving storm, a supercell, which are analyzed separately. The results demonstrate that while changes to the moisture profile always induce larger changes in precipitation than do variations in aerosol concentrations, multicells are sensitive to aerosol perturbations whereas supercells are less so. The multicellular precipitation sensitivity arises through aerosol impacts on the cold pool forcing. It is shown that the altitude of the dry layer influences whether cold pools are stronger or weaker and hence whether precipitation increases or decreases with increasing aerosol concentrations. When the dry-layer altitude is located near cloud base, cloud droplet evaporation rates and hence latent cooling rates are greater with higher aerosol loading, which results in stronger low-level downdrafts and cold pools. However, when the dry-layer altitude is located higher above cloud base, the low-level downdrafts and cold pools are weaker with higher aerosol loading because of reduced raindrop evaporation rates. The changes to the cold pool strength initiate positive feedbacks that further modify the cold pool strength and subsequent precipitation totals. Aerosol impacts on deep convection are therefore found to be modulated by the altitude of the dry layer and to vary inversely with the storm organization.

Hurricane Isaac Post-Storm Response1

ABSTRACT Hurricane Isaac made landfall on August 29, 2012 over Louisiana, lingering overhead for more than 60 hours. While most were concerned with surviving the 80+ mph winds and ensuing storm surge and floods, Coast Guard members statewide knew there would be no calm after the storm; instead it would be a grueling fight to restore the port to normalcy. The slow moving storm caused grounded deep draft vessels and barges, spilled oil, releases of hazardous materials (HAZMAT), and damage to various buildings and infrastructures. U.S. Coast Guard Sector New Orleans integrated local, states, and federal agencies into a Unified Command structure to coordinate limited resources post-storm. Within Sector New Orleans, the Incident Management Division (IMD) made it their primary mission to mitigate any substantial threats of oil discharges or HAZMAT releases and ensure proper cleanup. On September 2, 2012, IMD utilized the Incident Command System (ICS) to establish a Marine Environmental Response (MER) Incident Management Team (IMT) to achieve their post storm mission. The MER IMT consisted of 200 personnel, of which 60 were Coast Guard members, and included representatives from the National Strike Force, U.S. Environmental Protection Agency (EPA), U.S. Fish and Wildlife Service (USFWS), National Oceanic and Atmospheric Administration (NOAA), Louisiana Department of Environmental Quality (LDEQ), Louisiana Oil Spill Coordinator's Office (LOSCO), Louisiana Department of Wildlife and Fisheries (LDWF), and three Oil Spill Removal Organizations (OSROs); together the team collected 4500 barrels of oily water and 1200 HAZMAT containers, deployed over 11,000 feet of containment boom, and federalized three pollution projects. The MER IMT was disestablished on September 28, 2012 leaving Sector New Orleans IMD to maintain complete management of the ongoing federalized projects, “Fantome”, “Map Drilling”, and “Gulf South”. The projects included oil discharges in adjacent waterways of two oil production/storage facilities, oil discharges from fixed facility barges, and oil discharges from a storage platform along the marsh shoreline. Sector New Orleans executed $9.5 million in Oil Spill Liability Trust Funds towards emergency response efforts and successfully restored safety to the public health, welfare, environment, and maritime community.

THE MARCH 1962 STORM ON THE ATLANTIC COAST OF THE UNITED STATES

As far back as 1635, records show that the East Coast of the United States has repeatedly suffered from severe storm damage (McAleer , 1962). Most of these storms appear to have been of the hurricane type. Such storms generally form in the Atlantic to the east of the Bahama Islands and move eastward and then turn northward to sweep along the Atlantic Coast line (Fig. 1). Along the southern part of the Atlantic Coast the hurricanes move relatively slowly; damage results principally from flooding caused by direct wind action. North of Cape Hatteras the hurricanes move more rapidly (speeds of 40 to 50 miles per hour) and damage is largely due to sudden flooding from a rapidly moving storm surge (Simpson, 1962). The combination of storm surge, wind-driven water, and storm waves inundating large areas along the coast has on numerous occasions caused great damage and loss of life. The great Atlantic Coast storm of March 1962, however, differed in character from the usual hurricane. It proved to be the most disastrous winter coastal storm on record, causing damage from southern New England to Florida. This storm, of relatively large diameter and having gale force winds, remained nearly stationary off the Coast for almost 36 hours . The size and location of the storm, as further discussed below, was such that persistent strong northeasterly winds blowing over a relatively long fetch raised the spring tides (maximum range) to near-record levels. The tidal flooding which attended this storm was in many ways more disastrous than that which accompanies hurricanes (Cooperman and Rosendal, 1962). The storm surge in tropical cyclones generally recedes rapidly after one or two high tides, but the surge accompanying this storm occurred in many locations on four and five successive high tides .' The great destruction was caused by high waves and breakers superimposed on these high tides.