scholarly journals On the analysis of a summertime convective event in a hyperarid environment

2020 ◽  
Author(s):  
Diana Francis ◽  
Marouane Temimi ◽  
Ricardo Fonseca ◽  
Narendra R. Nelli ◽  
Rachid Abida ◽  
...  
Keyword(s):  
Convective Event

Verification of modeling of convective events based on radar reflectivity

2021 ◽  
Author(s):  
Ekaterina Svechnikova ◽  
Nikolay Ilin ◽  
Evgeny Mareev
Keyword(s):  
General Pattern ◽  
Measurement Data ◽  
Quantitative Agreement ◽  
Convective Event ◽  
Simulation Results ◽  
Verification Process ◽  
Using Data ◽  
Wrf Modeling ◽  
Probabilistic Nature

<p>The use of numerical modeling for atmospheric research is complicated by the problem of verification by a limited set of measurement data. Comparison with radar measurements is widely used for assessing the quality of the simulation. The probabilistic nature of the development of convective phenomena determines the complexity of the verification process: the reproduction of the pattern of the convective event is prior to the quantitative agreement of the values at a particular point at a particular moment.</p><p>We propose a method for verifying the simulation results based on comparing areas with the same reflectivity. The method is applied for verification of WRF-modeling of convective events in the Aragats highland massif in Armenia. It is shown that numerical simulation demonstrates approximately the same form of distribution of areas of equal reflectivity as for radar-measured reflectivity. In this case, the model tends to overestimate on average reflectivity, while enabling us to obtain the qualitatively correct description of the convective phenomenon.</p><p>The proposed technique can be used to verify the simulation results using data on reflectivity obtained by a satellite or a meteoradar. The technique allows one to avoid subjectivity in the interpretation of simulation results and estimate the quality of reproducing the “general pattern” of the convective event.</p>

Mixing of boundary layer and upper tropospheric ozone during a deep convective event over Western Europe

2002 ◽  
Vol 36 (28) ◽  
pp. 4491-4501 ◽  
Author(s):  
P Tulet ◽  
K Suhre ◽  
C Mari ◽  
F Solmon ◽  
R Rosset
Keyword(s):  
Boundary Layer ◽  
Tropospheric Ozone ◽  
Western Europe ◽  
Convective Event

Response of Humidity and Clouds to Tropical Deep Convection

2009 ◽  
Vol 22 (9) ◽  
pp. 2389-2404 ◽  
Author(s):  
Mark D. Zelinka ◽  
Dennis L. Hartmann
Keyword(s):  
Large Scale ◽  
Deep Convection ◽  
Lower Troposphere ◽  
Upward Motion ◽  
Temporal Separation ◽  
Convective Event ◽  
Clear Sky ◽  
Intense Precipitation ◽  
Upper Level ◽  
Precipitation Events

Abstract Currently available satellite data can be used to track the response of clouds and humidity to intense precipitation events. A compositing technique centered in space and time on locations experiencing high rain rates is used to detail the characteristic evolution of several quantities measured from a suite of satellite instruments. Intense precipitation events in the convective tropics are preceded by an increase in low-level humidity. Optically thick cold clouds accompany the precipitation burst, which is followed by the development of spreading upper-level anvil clouds and an increase in upper-tropospheric humidity over a broader region than that occupied by the precipitation anomalies. The temporal separation between the convective event and the development of anvil clouds is about 3 h. The humidity increase at upper levels and the associated decrease in clear-sky longwave emission persist for many hours after the convective event. Large-scale vertical motions from reanalysis show a coherent evolution associated with precipitation events identified in an independent dataset: precipitation events begin with stronger upward motion anomalies in the lower troposphere, which then evolve toward stronger upward motion anomalies in the upper troposphere, in conjunction with the development of anvil clouds. Greater upper-tropospheric moistening and cloudiness are associated with larger-scale and better-organized convective systems, but even weaker, more isolated systems produce sustained upper-level humidity and clear-sky outgoing longwave radiation anomalies.

scholarly journals Impact of MPEX Upsonde Observations on Ensemble Analyses and Forecasts of the 31 May 2013 Convective Event over Oklahoma

2016 ◽  
Vol 144 (8) ◽  
pp. 2889-2913 ◽  
Author(s):  
Stacey M. Hitchcock ◽  
Michael C. Coniglio ◽  
Kent H. Knopfmeier
Keyword(s):  
Kalman Filter ◽  
Ensemble Kalman Filter ◽  
Mobile Systems ◽  
Observation Error ◽  
Ensemble Spread ◽  
Convective Event ◽  
Localization Radius ◽  
Standard Value ◽  
The Impact ◽  
Vertical Localization

Abstract This study examines the impact of assimilating three radiosonde profiles obtained from ground-based mobile systems during the Mesoscale Predictability Experiment (MPEX) on analyses and convection-permitting model forecasts of the 31 May 2013 convective event over Oklahoma. These radiosonde profiles (in addition to standard observations) are assimilated into a 36-member mesoscale ensemble using an ensemble Kalman filter (EnKF) before embedding a convection-permitting (3 km) grid and running a full ensemble of 9-h forecasts. This set of 3-km forecasts is compared to a control run that does not assimilate the MPEX soundings. The analysis of low- to midlevel moisture is impacted the most by the assimilation, but coherent mesoscale differences in temperature and wind are also seen, primarily downstream of the location of the soundings. The ensemble of forecasts of convection on the 3-km grid are improved the most in the first three hours of the forecast in a region where the analyzed position of low-level frontal convergence and midlevel moisture was improved on the mesoscale grid. Later forecasts of the upscale growth of intense convection over central Oklahoma are improved somewhat, but larger ensemble spread lowers confidence in the significance of the improvements. Changes in the horizontal localization radius from the standard value applied to the MPEX sounding assimilation alters the specific times that the forecasts are improved in the first three hours of the forecasts, while changes to the vertical localization radius and specified temperature and wind observation error result in little to no improvements in the forecasts.

scholarly journals Stochastic Rain Generator Based on Disaggregation of Precipitation into Convective and Stratiform for Climate Change Studies

2021 ◽  
Author(s):  
Marta Martinkova
Keyword(s):  
Climate Change ◽  
Observational Data ◽  
Control Period ◽  
Convective Precipitation ◽  
Western Region ◽  
Convective Event ◽  
Change Factors ◽  
The Future ◽  
The Western Region ◽  
And Control

<p>The outputs from regional climate models (RCMs) have to be further downscaled. This is usually done via a bias correction method.  This study presents a novel approach to statistical downscaling of outputs from RCMs. The novelty lies primarily in distinguishing the convective and stratiform precipitation by rain generator operating in 6-hour time step. For this purpose, the technique based on determination of threshold rainfall intensity is used, built on the observation that the convective precipitation amounts follow exponential distribution.</p><p>The resulting rain generator operates in the following steps: disaggregation of 6-hour cumulative precipitation into convective and stratiform types, fitting of the first order 3-state discrete time Markov chain to the data, and simulation of long time series of precipitation. Then the mixture of log-normal and Generalized Pareto distribution is fitted to stratiform events and the Generalized extreme value distribution to convective events.</p><p>The impact of climate change on precipitation is represented by change factors that are identified for precipitation occurrence (by comparing the transition matrices for the future and control period) and for precipitation amounts (by comparing the scale and location parameters of distributions fitted for the future and control period). The observational data are then altered with the obtained change factors.</p><p>From evaluation of observational data it stems that the average volume of a convective event is higher for the western region than the eastern region of the Czech Republic. Additionally, statistically significant trends in the number and volume of convective events were identified for the western region. The analysis of the RCM simulations shows that even though the overall precipitation is projected to be lower in future, the proportion of convective events (versus stratiform ones) would be higher. In a future climate, the number of convective events is projected to be lower while the mean volume of a convective event to be larger.</p>

scholarly journals Characterisation and predictability of a strong and a weak forcing severe convective event – a multi-data approach

2015 ◽  
Vol 24 (4) ◽  
pp. 393-410 ◽  
Author(s):  
Kathrin Wapler ◽  
Florian Harnisch ◽  
Tobias Pardowitz ◽  
Fabian Senf
Keyword(s):  
Convective Event

scholarly journals Convective uplift of pollution from the Sichuan basin into the Asian monsoon anticyclone during the StratoClim aircraft campaign

2020 ◽  
Author(s):  
Keun-Ok Lee ◽  
Brice Barret ◽  
Eric L. Flochmoën ◽  
Pierre Tulet ◽  
Silvia Bucci ◽  
...  
Keyword(s):  
Sichuan Basin ◽  
Asian Monsoon ◽  
Aerosol Layer ◽  
Transport Pathway ◽  
Break Phase ◽  
Convective Event ◽  
Convective Clouds ◽  
Co Concentration ◽  
The Sichuan Basin ◽  
The Impact

Abstract. The StratoClim airborne campaign took place in Nepal from 27 July to 10 August 2017 to document the physical and chemical properties of the South Asian Upper Troposphere Lower Stratosphere (UTLS) during the Asian Summer Monsoon (ASM). In the present paper, simulations with the Meso-NH cloud-chemistry model at a horizontal resolution of 15 km are performed over the Asian region to characterize the impact of monsoon deep convection on the composition of Asian Monsoon Anticyclone (AMA) and on the formation of the Asian Tropopause Aerosol Layer (ATAL) during the StratoClim campaign. StratoClim took place during a break phase of the monsoon with an intense convective activity over south China and Sichuan. Comparisons between Brightness Temperature (BT) at 10.8 microns observed by satellite sensors and simulated by Meso-NH highlight the ability of the model to correctly reproduce the life cycle of deep convective clouds. Comparison between CO and O3 concentrations from Meso-NH and airborne observations (StratoClim and IAGOS) demonstrates that the model captures most of the observed variabilities. Nevertheless, for both gases, the model tends to overestimate the concentrations and misses some thin CO plumes related to local convective events probably because of a too coarse resolution, but the convective uplift of pollution is very well captured by the model. We have therefore focused on the impact of Sichuan convection on the AMA composition. A dedicated sensitivity simulation showed that the 7 August convective event brought large amounts of CO deep into the AMA and even across the 380 K isentropic level located at 17.8 km. This Sichuan contribution enhanced the CO concentration by ~ 15 % to reach more than 180 ppbv over a large area around 15 km height. Noteworthy, Meso-NH captures the impact of the diluted Sichuan plume on the CO concentration during a StratoClim flight south of Kathmandu highlighting its ability to reproduce the transport pathway of Sichuan pollution. According to the model, primary organic aerosol and black carbon particles originating from Sichuan are transported following the same pathway as CO. The large particles are heavily scavenged within the precipitating part of the convective clouds but remain the most important contributor to the particle mass in the AMA. Over the whole AMA region, the 7 August convective event resulted in a 0.5 % increase of CO over the 10–20 km range that lasted about 2 days. The impact of pollution uplift from three regions (India, China and Sichuan) averaged over the first 10 days of August has also been evaluated with sensitivity simulations. Even during this monsoon break phase, the results confirm the predominant role of India relative to China with respective contributions of 11 and 7 % to CO in the 10–15 km layer. Moreover, during this period a large part (35 %) of the Chinese contribution comes from the Sichuan basin alone.

Assessment of Radar Reflectivity-Rainfall Rate, Z-R Relationships for a Convective Event in Malaysia

2013 ◽  
Vol 1 (4) ◽  
pp. 239-243 ◽  
Author(s):  
Nuurul Hudaa Mohd Sobli ◽  
Ahmad Fadzil Ismail ◽  
Farah Nadia Md. Isa ◽  
Hasmah Mansor
Keyword(s):  
Radar Reflectivity ◽  
Rainfall Rate ◽  
Convective Event

scholarly journals Hydrometeorological Ensemble Forecast of a Highly Localized Convective Event in the Mediterranean

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1545
Author(s):  
Luca Furnari ◽  
Giuseppe Mendicino ◽  
Alfonso Senatore
Keyword(s):  
Ensemble Prediction ◽  
Lead Times ◽  
Forecast Uncertainty ◽  
Ensemble Prediction System ◽  
Distributed Information ◽  
Convective Event ◽  
Spatially Distributed ◽  
Accumulated Rainfall ◽  
Clear Information

The uncertainties that affect hydrometeorological modelling chains can be addressed through ensemble approaches. In this paper, a convection-permitting ensemble system was assessed based on the downscaling of all members of the ECMWF ensemble prediction system through the coupled atmospheric-hydrological WRF-Hydro modelling system. An exemplary highly localized convective event that occurred in a morphologically complex area of the southern Italian coast was selected as a case study, evaluating the performance of the system for two consecutive lead times up to the hydrological forecast on a very small (11.4 km2) catchment. The proposed approach accurately downscales the signal provided by the global model, improving up to almost 200% the quantitative forecast of the accumulated rainfall peak in the area affected by the event and supplying clear information about the forecast uncertainty. Some members of the ensemble simulations provide accurate results up to the hydrological scale over the catchment, with unit peak discharge forecasts up to 3 m3∙s−1∙km−2. Overall, the study highlights that for highly localized convective events in coastal Mediterranean catchments, ensemble approaches should be preferred to a classic single-based simulation approach, because they improve the forecast skills and provide spatially distributed information about the forecast uncertainty, which can be particularly useful for operational purposes.

Sign in / Sign up

Export Citation Format

Share Document