Dry Microburst Research Articles

Assessment of Dry Microburst Index over India derived from INSAT-3DR satellite

Dry microbursts can generate severe meteorological conditions including turbulence and strong winds even in the absence of precipitation. Present study evaluate the performance of Indian geostationary satellite, INSAT-3DR in capturing Dry Microburst Index (DMI) and validated against the radiosonde dataset. Data is validated across 14 selected stations across the India for 3 year (2020–2022). However, radiosonde data is very limited but spatial and temporal resolution of INSAT-3DR is good to analyse and predict the atmospheric phenomena. Different statistics have been used to validate INSAT-3DR against radiosonde observation. A Taylor plot confirm strong correlation and low RMSE between INSAT-3DR and radiosonde data. Spatial distribution depicts annual mean DMI values, it is influence by diurnal variation, regional weather pattern, and seasonal factors. Seasonal analysis indicates lower DMI during winter (5–45) due to reduced instability and moisture, while post-monsoon season witness increased DMI owing to warmer, humid conditions. The pre-monsoon season shows rising DMI as temperature increase. Study also analyses the co-occurrence of thunderstorm during DMI events, revealing a Probability of Detection (POD) of 0.75 for the INSAT-3DR DMI product, indicating 75% correct identification of thunderstorms. However, the False Alarm Rate (FAR) suggest false alarms occurred in approximately 55.2% of cases. Overall, study underscores the importance of considering local factors and conditions in interpreting INSAT-3DR satellite-based DMI data. Understanding and accurately predicting dry microbursts are crucial for enhancing aviation safety and improving the resilience of infrastructure in regions prone to these phenomena.

Analysis of the Causes and Wind Field Structure of a Dry Microburst in a Weak Weather Background

Dry microbursts in weak weather backgrounds, due to their small scale and general lack of precipitation, are often difficult to observe using weather radar. On the night of 26 April 2023, a dry microburst occurred at the Yinchuan Airport. Based on conventional meteorological observations, Automated Weather Observing System (AWOS) data, and the Doppler Wind Lidar data, an analysis was conducted on the causes and wind field structure of this microburst. It was found that (1) the sounding data indicated a DCAPE value of 880 J·kg−1, which is important for forecasting the potential for dry microburst events; (2) the foehn from the Helan Mountains contributed to the occurrence of microburst weather at the Yinchuan Airport; (3) the Doppler Wind Lidar wind data showed distinct characteristics of the wind field during this microburst event, including a symmetric horizontal wind field structure, significant vertical downdraft velocities (reaching −5.76 m·s−1), and low-level wind shear over the airport runway and its vicinity; and (4) effective monitoring of such microburst weather events with the Doppler Wind Lidar wind measurements is crucial for ensuring aviation safety.

Convective Density Current Circulations That Modulated Meso-γ Surface Winds near the Yarnell Hill Fire

On 30 June 2013, 19 Granite Mountain Hotshots firefighters were killed fighting a wildfire near Yarnell in the mountains of Central Arizona. They succumbed when the wildfire, driven by erratic winds, blocked their escape route and overran their location. A previous study is extended to simulate and analyze the downscale organization of convective circulations that redirected the wildfire, which started from the scale of the Rossby Wave Breaking over North America to a convective gust front that redirected the wildfire, trapping the firefighters. Five stages are found: Stage I, the initial deep prolonged gust front; Stage II, a front-to-rear jet and its ascending motions that organized high-based convection; Stage III, high-based dry microburst-induced downdrafts organized initially by ascending flow in Stage II that transported mass and entropy to the surface; Stage IV; multiple meso-γ-scale high centers and confluence zones formed that encompassed the firefighters’ location, which established a favorable environment leading to Stage V, canyon-scale circulations formed surrounding the fire. The atmosphere thus transitioned from supporting a deep and long-lived convective density current to elevated dry microbursts with mass and wind outflow into a canyon, redirecting the ongoing wildfire.

Evolution and Structure of a Dry Microburst Line Observed by Multiple Remote Sensors in a Plateau Airport

The civilian airplane is a common transportation mode for the local people in the Qinghai-Tibet Plateau (QTP). Due to the profound dynamic and thermal effects, the QTP can trigger strong windstorms during the warm season, during which downbursts can cause severe low-level wind shear and threaten aviation safety. However, the study of downbursts over QTP has not been given much attention. This study analyzes and interprets a typical traveling dry microburst line that happened at the Xining Caojiapu International Airport (ZLXN) on 14 May 2020, intending to show a better understanding of the dry downbursts over QTP and explore the synergetic usage of different remote sensing technologies for downburst detection and warning in plateau airports. Specifically, the characteristics of synoptic conditions, the convective system formation process, and the structure and evolution of downbursts and relevant low-level winds are comprehensively investigated. The results show that, under the control of an upstream shallow trough, features of the local atmosphere state, including a dry-adiabatic stratification, a shallow temperature inversion, increases in solar radiation heating, and strong vertical shears of horizontal winds, can be favorable atmospheric prerequisites for the formation and development of dry storms and downbursts. Low-reflectivity storm cells of the Mesoscale Convective System (MCS) organize to form narrow bow echoes, and downbursts show features of radial wind convergences and rapid descending reflectivity cores with hanging virga as observed by a Doppler weather radar. Moreover, details of gales, gust fronts, convergences, turbulences, wind collisions, and outflow interactions triggered by the downburst line are also detected and interpreted by a scanning Doppler wind lidar from different perspectives. In addition, the findings in this work have been compared with the results observed in Denver, U.S., and some simulation studies. Finally, a few conceptual models of low-level wind evolutions influenced by the dry downburst line are given.

Numerical study of unmanned aerial vehicle (UAV) in dry microburst environment using large eddy simulation (LES) model

PurposeIn a microburst wind, the profiles and characteristics are significantly different from those of normal boundary layer winds. The objective of this work is to study the microburst effect on the performance of aircraft for providing guidelines to frame escape strategies.Design/methodology/approachLarge eddy simulation model is used to study the effect of microburst by simulating the actual physical process of microburst-generated downdraft environment over the unmanned aerial vehicle. In this work, an attempt has been made to simulate the dry microburst (microburst not accompanied by rain) numerically using the impinging jet model to explore the effect of microburst at 12° angle of attack for flight take-off condition with a Mach number 0.04.FindingsThe numerical results revealed the aerodynamic performance loss of an aircraft in the microburst-generated downdraft during take-off condition quantitatively. This could be a more valuable information to the aviation industry. The authors believe that the results shown in this paper will be useful for the designers of aircraft. This will also help train the pilots to control the airplanes in a microburst environment.Practical implicationsSevere thunderstorms are significant weather phenomena that have a significant impact on various facets of national activity, including civil and defence operations, specifically aviation, space vehicle launch and agriculture, in addition to their potential to cause damage to life and property.Originality/valueThe maximum percentage of pressure increases on the upper surface of the aircraft between 2 and 7 s is 99.86% under the microburst-generated downdraft condition. The flight escape maneuver could be initiated, before increasing the pressure on the upper surface of the aircraft. The aircraft flies with high airspeed through the microburst environment, where the microburst-generated downdraft is most severe.

ANALYSIS ON THE PULSE STORM EVENT IN THE SOUTH BANDUNG WEST JAVA BASED ON THE TRANSPORTABLE X-BAND DOPLLER RADAR CAMPAIGN, (CASE STUDY : MARCH 16, 2017)

Pulse storm is a term to mention the occurrence of storms that have a short duration with the nature of its weak updraft. The results of the Transportable X-band radar campaign were able to capture a pulse storm at a location 25 km southwest from a radar position. Convective core with echo value > 50 dbz is detected at 4 km altitude but has a weak updraft so that it dissipated in the next 40 minutes. This convective activity is also showed by convective index value as well as Tbb value from Himawari Satellite data in those area. The microburst effect showed from the surface wind shear that expand along + 6.6 km with the edge of the area experiencing high wind with maximum speed from combine shear showed up to 14.5 m/s. The microburst category is dry microburst based on the increase in precipitation value from AWS surface data

The Great Basin Derecho of 31 May 1994

AbstractA significant, convectively induced windstorm known as a derecho occurred over parts of Utah, Wyoming, Idaho, and Colorado on 31 May 1994. The event was unusual in that it occurred not only in an environment of relatively limited moisture, but also one with a thermodynamic profile favorable for dry microbursts in the presence of moderate midtropospheric flow. The development and evolution of the severe wind-producing convective system is described, with emphasis on the synoptic and mesoscale features that may have contributed to its strength and maintenance. A very similar derecho that affected much the same region on 1 June 2002 is more briefly introduced. Questions are raised regarding the unique nature of these events and their potential utility in achieving an increased understanding of the mechanics of derecho-producing convective systems in more moisture-rich environments.

Physical simulation of dry microburst using impinging jet model with swirl

Severe thunderstorm is an important weather phenomena, which impact on aviation, space vehicle launching, agriculture in addition to its damage potential to life and properties. One of the most important event in the thunderstorms is the “Downburst”. It consists of slow rotating column of air, which burst violently after reaching the ground. It is believed that a downburst is generated when the upward moving moist buoyant air can no longer be sustained above and subsided into downdraft. The flow due to downburst impacts on the ground and spreads outward in different directions. Downbursts are classified as either microburst or macroburst depending on their horizontal extent of damage. In this work, an attempt has been made to simulate the dry microburst (microburst not accompanied by rain) experimentally using the impinging jet model for investigating the macroflow dynamics and scale (Reynolds number) dependency of the downburst flow. Flow visualization is done using a smoke generator for understanding the flow dynamics.

Retrieval of Microscale Flow Structures from High-Resolution Doppler Lidar Data Using an Adjoint Model

Radial velocity data measured by high-resolution Doppler lidar (HRDL) are assimilated with a four-dimensional variational data assimilation (4DVAR) method to retrieve microscale flow structures in an atmospheric boundary layer. The control variables of 4DVAR consist of initial three-dimensional velocity and temperature fields, as well as profiles of eddy viscosity and thermal diffusivity. The effects of lateral boundary conditions and buffer zones on the retrieval quality are evaluated using identical twin experiments with synthetic observational data prior to HRDL data retrieval. It is found that use of inflow/outflow boundary conditions in conjunction with buffer zones yields good results. HRDL field observations are then assimilated with 4DVAR, together with the above treatment of boundaries to recover microscale flow structures in a convective boundary layer. The uncertainty of the retrieved data is assessed by conducting a grid sensitivity test. A large-scale flow structure resembling a dry microburst is observed in the retrieved wind field. Characteristics of this structure are discussed and compared with those of a typical microburst.

Recent Improvements to the GOES Microburst Products

Abstract The downburst is defined as a strong downdraft produced by a deep convective storm that induces strong or damaging winds on or near the earth's surface. Because of the intense wind shear they produce, downbursts are a hazard to aircraft in flight, especially during takeoff and landing phases. Retrieved profiles of temperature and moisture obtained from the Geostationary Operational Environmental Satellite (GOES) sounders have been shown to be useful in assessing the potential for convective downbursts. Sounder-derived parameters examined in this paper include the wind index (WINDEX), used to estimate maximum wind gusts; a dry microburst index (DMI), used to estimate dry microburst potential; and maximum theta-e deficit (TeD), used to estimate wet microburst potential. Currently under development is a new wet microburst index that will summarize the physical processes of convective storm development and downburst generation to quantify the potential severity of convective wind gusts. The experimen...

Experimental GOES Sounder Products for the Assessment of Downburst Potential

Abstract Several experimental products derived from Geostationary Operational Environmental Satellite (GOES) Sounder retrievals (vertical profiles of temperature and moisture) have been developed to assist weather forecasters in assessing the potential for convective downbursts. The product suite currently includes the wind index (WINDEX), a dry microburst index, and the maximum difference in equivalent potential temperature (θe) from the surface to 300 hPa. The products are displayed as color-coded boxes or numerical values, superimposed on GOES visible, infrared, or water vapor imagery, and are available hourly, day and night, via the Internet. After two full summers of evaluation, the products have been shown to be useful in the assessment of atmospheric conditions that may lead to strong, gusty surface winds from thunderstorms. Two case studies are presented: 1) a severe downburst storm in southern Arizona that produced historic surface wind speeds and damage, and 2) multiple dry and wet downbursts in...

An approach to radiated testing of installed airborne Doppler radar with weather/windshear detection capability

Low altitude windshear phenomena has been causally linked to numerous civil transport aircraft incidents with fatalities and injuries exceeding 800, covering a period of more than 25 years. The crash of a USAir DC-9 at Charlotte, NC on July 2,1994 has caused an increased focus on windshear and microburst activity. FAA, NASA, the airline industry and equipment manufacturers have been working with the problem since the 1980's, to define, design and test predictive sensor systems that would provide adequate and dependable advance warning to pilots that would allow safely executed evasive actions during take off's and landings. Three sensor systems were investigated: radar, laser radar (lidar), and infrared imaging, with the pulsed Doppler radar consistently detecting both wet and dry microbursts indicative of hazardous windshear conditions at longer ranges than the other two. Numerous documents were reviewed, including the NASA Airborne Doppler Radar together with meetings held with AlliedSignal, Rockwell Collins and Westinghouse to verify radar parameters needed to analyze and present the tester concept described herein. The weather and windshear models defined use the identical criteria established for the Doppler radar in terms of F-factor. The basic concept of the tester is to transmit coherent simulated radar returns in response to the airborne radar's transmission while mounted on a tripod in the far field of the radar when parked on the ramp. The varying amplitude of the received radar pulses are analyzed and put into memory as the tester antenna is illuminated by the scanning main beam and side lobes of the radar's antenna patterns. The tester controls the power of its outputted simulated radar returns in inverse relation to the power of the received radar pulses. These simulated radar returns, outputted into the main beam and/or side lobes of the scanning radar antenna, are interpreted by the radar system as received in the main lobe. The tester transmissions, incorporating microburst, storm and gust front models, previously defined, can thereby test the aircraft radar system performance in various hazard environments. The tester is designed to: verify operational performance of the radar; demonstrate installed radar performance; verify crew reports and minimize radar or LRU's removal for maintenance; test before and after a repair; and verify radome effects on radar performance.

Downbursts from Innocuous Clouds: An Example

Abstract A microburst occurred at Goodland, Kansas, on 4 March 1990. This event was unique in the sense that it occurred at 0348 AM MST (1048 UTC) and produced 14°F (7.8°C) of warming. The environment along the High Plains exhibited characteristics similar to those associated with dry microbursts documented in the literature. Examination of an interpolated sounding for Goodland implied that evaporational cooling would need to occur throughout most of the dry sub-cloud layer to support the observed surface temperature.

The 700–500 mb Lapse Rate as an Index of Microburst Probability: An Application for Thermodynamic Profilers

Abstract This study validates the predicted association between frequency of dry microburst occurrence and large temperature lapse rate. In applying lapse rate trend data and high time resolution data from remote sensors, we first compared lapse rates from the Denver rawinsonde with the thermodynamic profiler and obtained linear correlation coefficients ranging from .63 to .94. Continuous 20-minute radiometer samples of lapse rate were available throughout the experiment period. The data indicate a critical value of 700–500 mb lapse rate ≥8°C km−1 for dry microburst occurrence. Also, we found dry microburst occurrence in the Denver area better correlated with late afternoon lapse rates than with early morning lapse rates: 67% of dry microbursts occurred with 1200 UTC lapse rates ≥8°C km−1, while 89% of dry microbursts occurred with 2200 UTC lapse rates ≥8°C km−1. We recommend that remote sensor temperature retrievals such as with Radio Acoustic Sounding Systems (RASS) extend to at least 3 km AGL to aid dr...

A Decision Tree Method of Forecasting Thunderstorms, Severe Thunderstorms and Tornadoes

Abstract A decision tree approach to forecasting thunderstorms, severe thunderstorms and tornadoes is described which uses only meteorological parameters considered essential for these phenomena to develop. The physical relevance of the parameters is explained in terms of thunderstorm and severe thunderstorm structures and dynamics. Forecast output also includes dry microbursts, wet microbursts and downbursts, and local floods. The decision tree has had only limited subjective evaluation.

An Early Morning Dry Microburst in the Great Basin

An Early Morning Dry Microburst in the Great Basin

Forecasting Dry Microburst Activity over the High Plains

Abstract The active dry microburst days during the 1982 JAWS (Joint Airport Weather Studies) Project in Colorado are examined for common characteristics. The environments on these days are shown to have similar thermodynamic structures in the vertical. In the morning, a shallow radiation inversion is capped by a deep, dry-adiabatic boundary layer. Moisture is present at midlevels. By evening the radiation inversion has been replaced by a superadiabatic layer at the surface. Solar heating of the boundary layer is shown to be important for producing an environment favorable for dry microbursts. A model is proposed that can be used by forecasters to issue a “wind shear watch” to the general public and aviation community. Peak downdraft speeds associated with dry microbursts appear to be a result of negative buoyancy, owing to the evaporation of precipitation during the descent below cloud base. These downward velocities are of the same magnitude as the horizontal wind speeds. Entrainment of subcloud air into...