scholarly journals A Lightning Parameterization for the ECMWF Integrated Forecasting System

2016 ◽  
Vol 144 (9) ◽  
pp. 3057-3075 ◽  
Author(s):  
Philippe Lopez
Keyword(s):  
Atmospheric Chemistry ◽  
Convective Available Potential Energy ◽  
Horizontal Resolution ◽  
Cloud Base ◽  
Lightning Flash ◽  
Severe Convection ◽  
Forecasting System ◽  
Total Lightning ◽  
Optical Transient ◽  
Cloud Base Height

A new parameterization able to diagnose lightning flash densities is proposed for the ECMWF Integrated Forecasting System, including its tangent-linear and adjoint versions. Total lightning densities are expressed as a function of hydrometeors contents, convective available potential energy, and cloud-base height output by the convective parameterization. Potential future applications range from the computation of NOx emissions by lightning in atmospheric chemistry models, severe convection forecasting, and data assimilation. In this study, a decade-long experiment is used to calibrate the simulated global annual mean flash density against the LIS/Optical Transient Detector (OTD) climatological value. On the seasonal and continental scales, the new parameterization is shown to agree well with the LIS/OTD observations. In forecast mode, output lightning densities are found to be almost independent of the horizontal resolution used in the model. Decade-long experiments also show that the new parameterization gives better results overall than the main existing lightning parameterizations designed for global models. Sensitivity experiments using its adjoint version are also performed to assess its potential for the future assimilation of lightning observations in the ECMWF 4D-Var system.

scholarly journals Modeling of Lightning Events using WRF-derived Microphysical Parameters

2021 ◽  
Vol 8 (2) ◽  
pp. 41-50
Author(s):  
Md Ashraful Islam ◽  
Javed Meandad ◽  
Saurav Dey Shuvo ◽  
Alamgir Kabir
Keyword(s):  
Model Simulation ◽  
Convective Available Potential Energy ◽  
Temporal Variations ◽  
Horizontal Resolution ◽  
Cumulus Parameterization ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Lightning Flash ◽  
Microphysical Parameters ◽  
Pbl Scheme

Numerical simulation of lightning events in Bangladesh has been carried out by using Weather Research and Forecasting Model with Advanced Research Dynamic solver (WRF-ARW). Three major lightning events have been considered for the case study; Case_1, lightning occurrence in Netrokona district in March 24 2017, Case_2, lightning event in Barishal district in April 23 2017, and case_3, lightning event in Sherpur district in April 29, 2018. The model simulation was run in 9 km and 3 km of horizontal resolution using six hourly NCEP-FNL datasets. Yonsei University (YSU) PBL scheme, Rapid Radiative Transfer Model (RRTM) long-wave scheme for radiation, and Kain-Fritsch cumulus parameterization scheme is used for this study. The obtained results from the simulation could reasonably capture the lightning condition of the atmosphere for all the three cases. The WRF simulation give reasonable agreement with the available observational data with some spatial and temporal variations, for example the Convective Available Potential Energy (CAPE) values observed are 1299 J/Kg, 3150 J/kg, 1221 J/kg and CAPE values simulated are 1618 J/kg, 3275 J/kg and 1023 J/kg for case_1, case_2 and case_3 respectively. The regression analysis of the flash count with the microphysical parameters is also studied. It is found that there is strong correlation between the lightning flash counts with the microphysical parameters. This study will help to understand the lightning better and will help to design a better lightning forecasting system. The Dhaka University Journal of Earth and Environmental Sciences, Vol. 8(2), 2019, P 41-50

Thermodynamic Contribution to Lightning Activity in the Fourth Chimney

2021 ◽  
Author(s):  
Earle Williams ◽  
Diego Enore ◽  
Enrique Mattos ◽  
Yen-Jung Joanne Wu
Keyword(s):  
Convective Available Potential Energy ◽  
Lightning Activity ◽  
South Pacific Convergence Zone ◽  
Convergence Zone ◽  
Lightning Flash ◽  
Schumann Resonance ◽  
Flash Rate ◽  
Zonal Wavenumber ◽  
Usual Behavior ◽  
Total Lightning

<p>Lightning activity over oceans is normally greatly suppressed in comparison with continents.  The most conspicuous region of enhanced lightning activity over open ocean is found in the equatorial Pacific (150 W) in many global lightning climatologies (OTD, LIS, WWLLN, GLD360, RHESSI, Schumann resonance Q-bursts) and is associated with the South Pacific Convergence Zone (SPCZ).  This oceanic lightning anomaly completes the zonal wavenumber-4 structure of continent-based lightning maxima (with nominal 90-degree longitudinal separation between sources), and so is appropriately named “the fourth chimney”.  This region is now under continuous surveillance by the Geostationary Lightning Mapper (GLM) on the GOES-17 satellite (at 137 W).  This total lightning activity is compared with Convective Available Potential Energy (CAPE) from ERA-5 reanalysis.  These CAPE values are correlated with values extracted from thermodynamic soundings at proximal stations Atuona, Rikitea and Tahiti.  The shape of the regional climatology of CAPE resembles that of the SPCZ and is oblique to the equator.  The total lightning flash rate is positively correlated with CAPE, and lightning locations are found preferentially in regions of elevated CAPE on individual days.  The diurnal variation of total lightning for January exceeds a factor-of-two and shows a phase at odds with the usual behavior of oceanic lightning near continents.</p>

scholarly journals Cloud base height retrieval from multi-angle satellite data

2019 ◽  
Vol 12 (3) ◽  
pp. 1841-1860 ◽  
Author(s):  
Christoph Böhm ◽  
Odran Sourdeval ◽  
Johannes Mülmenstädt ◽  
Johannes Quaas ◽  
Susanne Crewell
Keyword(s):  
Reanalysis Data ◽  
Horizontal Resolution ◽  
Cloud Base ◽  
Height Distribution ◽  
Cloud Properties ◽  
Scene Structure ◽  
Global Coverage ◽  
Terra Satellite ◽  
High Clouds ◽  
Cloud Base Height

Abstract. Clouds are a key modulator of the Earth energy budget at the top of the atmosphere and at the surface. While the cloud top height is operationally retrieved with global coverage, only few methods have been proposed to determine cloud base height (zbase) from satellite measurements. This study presents a new approach to retrieve cloud base heights using the Multi-angle Imaging SpectroRadiometer (MISR) on the Terra satellite. It can be applied if some cloud gaps occur within the chosen distance of typically 10 km. The MISR cloud base height (MIBase) algorithm then determines zbase from the ensemble of all MISR cloud top heights retrieved at a 1.1 km horizontal resolution in this area. MIBase is first calibrated using 1 year of ceilometer data from more than 1500 sites within the continental United States of America. The 15th percentile of the cloud top height distribution within a circular area of 10 km radius provides the best agreement with the ground-based data. The thorough evaluation of the MIBase product zbase with further ceilometer data yields a correlation coefficient of about 0.66, demonstrating the feasibility of this approach to retrieve zbase. The impacts of the cloud scene structure and macrophysical cloud properties are discussed. For a 3-year period, the median zbase is generated globally on a 0.25∘ × 0.25∘ grid. Even though overcast cloud scenes and high clouds are excluded from the statistics, the median zbase retrievals yield plausible results, in particular over ocean as well as for seasonal differences. The potential of the full 16 years of MISR data is demonstrated for the southeast Pacific, revealing interannual variability in zbase in accordance with reanalysis data. The global cloud base data for the 3-year period (2007–2009) are available at https://doi.org/10.5880/CRC1211DB.19.

scholarly journals Storm-Scale Ensemble Kalman Filter Assimilation of Total Lightning Flash-Extent Data

2014 ◽  
Vol 142 (10) ◽  
pp. 3683-3695 ◽  
Author(s):  
Edward R. Mansell
Keyword(s):  
Kalman Filter ◽  
Ensemble Kalman Filter ◽  
Deep Convection ◽  
Spatial Location ◽  
Horizontal Resolution ◽  
Lightning Flash ◽  
Simulation Experiments ◽  
Linear Relationships ◽  
Single Moment ◽  
Total Lightning

Abstract A set of observing system simulation experiments (OSSEs) demonstrates the potential benefit from ensemble Kalman filter (EnKF) assimilation of total lightning flash mapping data. Synthetic lightning data were generated to mimic the Geostationary Lightning Mapper (GLM) instrument that is planned for the Geostationary Operational Environmental Satellite-R series (GOES-R) platform. The truth simulation was conducted using multimoment bulk microphysics, explicit electrification mechanisms, and a branched lightning parameterization to produce 2-min-averaged synthetic pseudo-GLM observations at 8-km GLM resolution and at a hypothetical 1-km resolution. The OSSEs use either perfect (two-moment bulk) or imperfect (single-moment, graupel only) microphysics. One OSSE with perfect microphysics included the same electrification physics as the truth simulation to generate lightning flash rates and flash-extent densities (FED). The other OSSEs used linear relationships between flash rate and graupel echo volume as the observation operator. The assimilation of FED at 8-km horizontal resolution can effectively modulate the convection simulated at 1-km horizontal resolution by sharpening the location of reflectivity echoes and the spatial location probability of convective updrafts. Tests with zero flash rates show that the lightning assimilation can help to limit spurious deep convection, as well. Pseudo-GLM observations at 1 km further sharpen the analyses of location (updraft and reflectivity) of the relatively simple storm structure.

scholarly journals Cloud base height retrieval from multi-angle satellite data

2018 ◽  
Author(s):  
Christoph Böhm ◽  
Odran Sourdeval ◽  
Johannes Mülmenstädt ◽  
Johannes Quaas ◽  
Susanne Crewell
Keyword(s):  
Reanalysis Data ◽  
Horizontal Resolution ◽  
Cloud Base ◽  
Height Distribution ◽  
Satellite Measurements ◽  
New Approach ◽  
Global Coverage ◽  
One Year ◽  
Terra Satellite ◽  
Cloud Base Height

Abstract. Clouds are a key modulator of the Earth energy budget at the top of the atmosphere and at the surface. While the cloud top height is operationally retrieved with global coverage, only few methods have been proposed to determine cloud base heights (zbase) from satellite measurements. This study presents a new approach to retrieve cloud base heights using the Multi-angle Imaging SpectroRadiometer (MISR) on the Terra satellite. It can be applied if some cloud gaps occur within the chosen distance of typically 10 km. The MISR cloud base height (MIBase) algorithm then determines zbase from the ensemble of all MISR cloud top heights retrieved at a 1.1-km horizontal resolution in this area. MIBase is first calibrated using one year of ceilometer data from more than 1500 sites within the continental United States of America. The 15th percentile of the cloud top height distribution within a circular area of 10 km radius provides the best agreement with the ground-based data. The thorough evaluation of the MIBase product zbase with further ceilometer data yields a correlation coefficient of about 0.66. For a three year period, the median zbase is generated globally on a 0.25° × 0.25° grid. It shows plausible results in particular over sea as well as for seasonal differences. The potential of the full 16 years of MISR data is demonstrated for the southeast Pacific revealing inter-annual variability in zbase in accordance with reanalysis data.

A 42 year inference of cloud base height trends in the Luquillo Mountains of northeastern Puerto Rico

2018 ◽  
Vol 76 (1) ◽  
pp. 87-94 ◽  
Author(s):  
PW Miller ◽  
TL Mote ◽  
CA Ramseyer ◽  
AE Van Beusekom ◽  
M Scholl ◽  
...  
Keyword(s):  
Puerto Rico ◽  
Cloud Base ◽  
Luquillo Mountains ◽  
Cloud Base Height

scholarly journals A Unified Convection Scheme (UNICON). Part I: Formulation

2014 ◽  
Vol 71 (11) ◽  
pp. 3902-3930 ◽  
Author(s):  
Sungsu Park
Keyword(s):  
Deep Convection ◽  
Convective Available Potential Energy ◽  
Horizontal Resolution ◽  
Vertical Transport ◽  
Convective Precipitation ◽  
Cold Pool ◽  
Quasi Equilibrium ◽  
Convection Scheme ◽  
Time Step ◽  
Turbulent Eddies

Abstract The author develops a unified convection scheme (UNICON) that parameterizes relative (i.e., with respect to the grid-mean vertical flow) subgrid vertical transport by nonlocal asymmetric turbulent eddies. UNICON is a process-based model of subgrid convective plumes and mesoscale organized flow without relying on any quasi-equilibrium assumptions such as convective available potential energy (CAPE) or convective inhibition (CIN) closures. In combination with a relative subgrid vertical transport scheme by local symmetric turbulent eddies and a grid-scale advection scheme, UNICON simulates vertical transport of water species and conservative scalars without double counting at any horizontal resolution. UNICON simulates all dry–moist, forced–free, and shallow–deep convection within a single framework in a seamless, consistent, and unified way. It diagnoses the vertical profiles of the macrophysics (fractional area, plume radius, and number density) as well as the microphysics (production and evaporation rates of convective precipitation) and the dynamics (mass flux and vertical velocity) of multiple convective updraft and downdraft plumes. UNICON also prognoses subgrid cold pool and mesoscale organized flow within the planetary boundary layer (PBL) that is forced by evaporation of convective precipitation and accompanying convective downdrafts but damped by surface flux and entrainment at the PBL top. The combined subgrid parameterization of diagnostic convective updraft and downdraft plumes, prognostic subgrid mesoscale organized flow, and the feedback among them remedies the weakness of conventional quasi-steady diagnostic plume models—the lack of plume memory across the time step—allowing UNICON to successfully simulate various transitional phenomena associated with convection (e.g., the diurnal cycle of precipitation and the Madden–Julian oscillation).

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