Session 7

The first satellite in the Meteosat Third Generation (MTG) series was launched on 13 December 2022. It carries the state-of-the-art Flexible Combined Imager (FCI) and Lightning Imager (LI) which will provide significant improvements to geostationary observations over Europe, Africa, and surrounding regions. The FCI has 16 spectral channels, collects full disk images every 10 minutes, and provides up to 500 m spatial resolution, all notable upgrades over the imager aboard the previous Meteosat Second Generation series. And the LI will provide the first continuous optical lightning detection capability from geostationary orbit over Europe. The National Oceanic and Atmospheric Administration (NOAA) has been operating its Advanced Baseline Imager and Geostationary Lightning Mapper as part of the GOES-R satellites series over the western hemisphere since 2016. These instruments have many similarities to MTG’s and provide ideal proxy data for understanding how the new satellite observations will benefit severe storm analysis and short-term forecasting in Europe and Africa.

This presentation will highlight the various ways that NOAA’s GOES-R satellites have improved severe storm analysis over the U.S. These include better detection of boundaries prior to convective initiation (CI), improved monitoring of cumulus fields and low-level moisture in anticipation of CI, the ability to track lightning activity, improved depiction of severe storm top features such as above anvil cirrus plumes and overshooting tops, and the ability to occasionally detect storm-scale rotation from space. In The potential of all of these will be discussed in the context of severe storm nowcasting over MTG’s domain.

How to cite: Lindsey, D.: What will Meteosat Third Generation Bring to the Table for Severe Storm Analysis?, 11th European Conference on Severe Storms, Bucharest, Romania, 8–12 May 2023, ECSS2023-10, https://doi.org/10.5194/ecss2023-10, 2023.

Satellite observations provide a unique way of observing the Earth and the weather that we are experiencing on the surface, as they have the potential of providing data over a large spatial area at a high temporal resolution. With new satellite technologies, the ability to better predict, detect and monitor severe weather is improving, allowing for more precise weather forecasting, now-casting and analysis.

With the Flexible Combined Imager (FCI), EUMETSAT is following along this path, with the first instrument recently launched on-board the first Meteosat Third Generation satellite on December 13th, 2022. FCI is a multi-spectral imager with 16 spectral channels that will continuously monitor the evolution of weather over Europe, Africa and the Atlantic Ocean with a spatial resolution up to 500 meter and a temporal resolution up to 2.5 minutes in rapid scanning mode.

These new and novel data will be a leap forward for the observation of deep convection and severe weather and in this presentation we will give an overview of the FCI instrument and its data and products. In addition to Level-1 data, FCI will provide a suite of geophysical Level-2 products useful for detecting and monitoring deep convection and severe storms, including cloud macro- and microphysical properties, atmospheric instability indices and atmospheric motion vectors. With the new FCI data we also have the ability for the first time to derive geostationary true colour imagery over Europe and Africa, offering a good reference for the human eye when observing and now-casting severe storms. With several months into the commissioning phase, we finally hope to conclude the presentation by demonstrating some of the major improvements of this new instrument by showing the first actual measurement data.

How to cite: Strandgren, J., Burini, A., Meraner, A., and Grandell, J.: Meteosat Third Generation Flexible Combined Imager for the continuous monitoring of severe storms from space, 11th European Conference on Severe Storms, Bucharest, Romania, 8–12 May 2023, ECSS2023-137, https://doi.org/10.5194/ecss2023-137, 2023.

The Meteosat Third Generation (MTG) Lightning Imager (LI) is the first geostationary optical lightning detector imaging Europe, Africa, and a large fraction of the Atlantic Ocean. Launched on board of the MTG-I1 satellite on 13 December 2022, LI will perform the detection from space of optical pulses produced by lightning. Optical pulses at cloud tops are produced by the photons emitted by lightning electric discharges within or below clouds that reach cloud tops after multiple scattering. The LI senses this cloud-top light within a 1.9 nm wide band centred on 777 nm, with a 4.5 km resolution at sub-satellite point, and 1 kHz acquisition frequency.

The LI instrument consists of four cameras (optical channels), covering a total of 84% of visible disk with continuous lightning data. The field of view of the LI fully covers Europe and Africa. In addition, the eastern and southern parts of the Atlantic Ocean, eastern part of South America and north western part of the Indian Ocean are also covered.

The operationally disseminated LI data (expected in early 2024) will consist of point data and accumulated data. The most important point data products for severe storm monitoring and tracking are the lightning groups (LGR) and lightning flashes (LFL), containing the times, latitudes, longitudes and optical radiance information of observed lightning groups and flashes. The lightning group product is similar to strokes/pulses produced by ground-based lightning location systems while the LI flash product is similar to flashes produced by ground-based systems.

In addition to point data, three accumulated data products, Accumulated Flashes (AF), Accumulated Flash Area (AFA) and Accumulated Flash Radiance (AFR) will be disseminated. All accumulated products provide users with information about the full accumulated spatial extent of the observed optical pulses. This is achieved by integrating over 30 sec pixels-based lightning detections composing the Level 2 flashes (also available in LFL as point data). This type of data will allow users to monitor features like long horizontal lightning channels in the stratiform regions of Mesoscale Convective Systems. Finally, all accumulated products are provided to users on the Flexible Combined Imager (FCI) 2 km grid, making it easy to combine LI and FCI products for more advanced severe weather monitoring products.

The presentation will give a brief overview of the LI System to introduce examples of LI data complemented by some early Commissioning results.  

How to cite: Enno, S.-E., Viticchiè, B., and Grandell, J.: Meteosat Third Generation Lightning Imager for the continuous monitoring of lighting from space, 11th European Conference on Severe Storms, Bucharest, Romania, 8–12 May 2023, ECSS2023-135, https://doi.org/10.5194/ecss2023-135, 2023.

With Meteosat Third Generation geostationary satellite being in orbit, users will receive the data that will highly upgrade the abilities of monitoring convective clouds over Europe.

Two main sensors on MTG-I1, FCI – Flexible Combined Imager and LI - Lightning imager, provide imagery from geostationary orbit with unprecedented spatial resolution and improved spectral resolution with 16 spectral channels, half of them being in solar part of spectrum. Spatial resolution of 500m with VIS0.6 channel doubles the SEVIRI’s High resolution visible channel resolution and reveals even smaller details on top of convective clouds. New channel VIS2.25 offers new capabilities for analysing cloud microphysics and cloud phase. VIS0.9 μm channel is a great benefit to convection nowcasting providing insight into low-level humidity content.

The new channels enable production of RGBs and derived products for different application areas. This information is amended by the data from Lightning Imager, indicating the lightning activity in the storms.

Depending on the availability, the examples of the new images, RGB combinations and products will be shown, with a special focus to storm nowcasting applications. Different stages of convection as well as features occurring during storm development will be presented through the MTG FCI and LI data, emphasizing the benefits of the newest European geostationary satellite. 

How to cite: Strelec Mahović, N., Smiljanić, I., Bojinski, S., and Nietosvaara, V.: Seeing convection with the new eyes - An overview of the first EUMETSAT MTG-I RGB products, 11th European Conference on Severe Storms, Bucharest, Romania, 8–12 May 2023, ECSS2023-134, https://doi.org/10.5194/ecss2023-134, 2023.

Up until the introduction of Meteosat Third Generation FCI instrument, the concept of low-level moisture estimation using solely data from imagers on board GEO satellites was to a high degree limited to so-called split window difference, i.e. difference in the brightness temperatures (BT) between two IR channels in ‘atmospheric WV window’ spectral region. Perhaps the biggest down side of this approach is the fact that BT difference relies heavily on the vertical temperature profiles of the atmosphere (the temperature of moisture level), also few other factors like aerosol presence play role.

Introduction of water-vapour absorption channel in the near infra-red (NIR) spectral region avoids the dependency on any temperature profiles, plus it provides even higher spatial sampling on the full disc domain. Hence the novel NIR0.91 FCI channels is seen as one of the crucial tools for nowcasting of severe storms, i.e. assessment of pre-conditions and moisture feeding dynamics of convective systems. The concept of NIR low-level moisture estimate and recent findings through a proxy data will be discussed.

It is worth adding that this is the first time that NIR0.9 channel is introduced with one of the major meteorological GEO satellite imagers, globally. Hence the importance for early discussions on potential capabilities.

How to cite: Smiljanić, I. and Nietosvaara, V.: Applications of FCI near-IR 0.91µm channel for detection of low-level humidity, 11th European Conference on Severe Storms, Bucharest, Romania, 8–12 May 2023, ECSS2023-139, https://doi.org/10.5194/ecss2023-139, 2023.

EUMETSAT generates operational water-vapour and temperature ‘all-sky’ products from the infrared (IASI) and microwave (AMSU, MHS) sounders onboard EPS/Metop satellites (EUMETSAT Polar System). The atmospheric profiles are available to the regional users within 15 to 30 minutes from sensing, via EUMETSAT EARS-IASI L2 service¹.

The potential for the prediction and monitoring of severe storms of such satellite–based thermodynamic profiles -and their derived nowcasting-relevant parameters, e.g. CAPE- complementary to numerical forecasts has been established in dedicated severe storm test beds² and nowcasting studies³. The operational baseline of the future sounding missions –IASI-NG and MTG-IRS- directly builds on the experience made with IASI, implementing the same machine-learning all-sky retrieval approach, namely the piece-wise linear regression (PWLR)⁴.

It is essential to characterise and document the precision of the satellite products in particular in severe weather precursor conditions. The quality of the satellite sounding products is routinely assessed against radiosondes for validation and long-term monitoring purposes⁵. Unfortunately, the satellite overpass times rarely match the in situ measurements from the synoptic sondes. The 3h difference tolerated in building the validation match-ups (satellite-sonde) can incur large collocation uncertainties especially in the boundary layer. This and the fact that radiosonde sites are relatively scarce, makes it difficult to evaluate the satellite products in pre-convective situations with large statistical significance.

To circumvent this and evaluate satellite products specifically in pre-convective environments, we studied the potential of routine in situ measurements acquired from commercial airlines. These are coordinated under WMO auspices in the AMDAR (Aircraft Meteorological Data Relay) programme. The AMDAR data have the decisive advantage of higher spatio-temporal density than radiosondes, which ensures numerous and more representative collocations to satellite products.

We present here the preliminary results, confirming that satellite sounders are capable of quantifying atmospheric instability. These results also tend to quantitatively identify a dry bias in unstable situations, which was previously suspected, while confirming the relative robustness and accuracy of temperature soundings in the free and lower troposhere. The next generation of EUMETSAT imagers, e.g. MTG-FCI and EPS-SG/METimage, will operate channels around 0.9 µm. This near-infrared channel has unique sensitivity to atmospheric moisture in the boundary layer while infrared sounders have their maximum sensitivity in the mid-troposphere. We will also present the status and plans to retrieve atmospheric humidity from the optical imagers (TCWV first, and then study in the boundary layer) and their complementarity with passive sounders, which will provide key information for storm prediction.

¹ https://www.eumetsat.int/ears-iasi

² https://www.eumetsat.int/severe-storm-forecasting-lab

³ https://www.eumetsat.int/hyperspectral-instability-monitoring-using-iasi

⁴ https://www.eumetsat.int/IASI-PWLR

⁵ https://www.eumetsat.int/iasi-level-2-geophysical-products-monitoring-reports

How to cite: August, T., Wagner, T., Spezzi, L., Hultberg, T., Bozzo, A., and Crapeau, M.: Operational water-vapour products at EUMETSAT, latest evaluation in pre-convective situations and future plans, 11th European Conference on Severe Storms, Bucharest, Romania, 8–12 May 2023, ECSS2023-131, https://doi.org/10.5194/ecss2023-131, 2023.

It is a well-established that the Tropical Cyclones (TC) often fuel from the thermal energy stored in the ocean top layer. As the ocean mixed layer temperature is able to modulate the air-sea interactions between ocean and tropical cyclones, the identified changes/dominant processes in mixed layer heat budget could have notable impact on the cyclone intensity and propagation. The present study examines the role of distinct oceanic mixed layer processes over warm and cold core eddies in impacting the tropical cyclones. Three severe cyclones are studied. We have examined the relationship between mixed layer heat budget terms and the cyclone genesis potential parameters, with a focus on cyclones approaching and sustained time over warm-core eddy regions. To further examine the role of different Ocean variables on atmospheric counterparts of cyclones, we have computed the area-averaged values of these Ocean variables and the Genesis Potential Parameter (GPP) index for warm-core eddy region. The temperature tendency shows highest magnitude of negative correlation with GPP. Among all the parameters that determines net heat flux, the net latent heat flux showing high response/influence on GPP. The relatively moderate correlation values between latent heat flux and GPP is evident during the active period of cyclones. The findings found in the present study has vital future scope in the area or studies related to air-sea interactions particularly for the case of tropical cyclones and adaptation of such knowledge in forecast models could enhance the predictions.

How to cite: Barbosa, H., Buriti, C., and Buriti, C.: The effects of warm and cold core eddy processes on cyclone activity, 11th European Conference on Severe Storms, Bucharest, Romania, 8–12 May 2023, ECSS2023-46, https://doi.org/10.5194/ecss2023-46, 2023.

Geostationary satellite imagers, such as those of the Geostationary Operational Environmental Satellite (GOES) and Meteosat series, provide both historical and near-real-time observations of cloud top patterns that are commonly associated with severe convection. Environmental conditions favorable for severe weather are thought to be represented well by reanalyses. Predicting exactly where convection and costly storm hazards like hail will occur using models or satellite imagery alone, however, is extremely challenging. The multivariate combination of satellite-observed cloud patterns with reanalysis environmental parameters, linked to United States Next Generation Weather Radar- (NEXRAD-) estimated Maximum Expected Size of Hail (MESH) using a deep neural network (DNN), enables estimation of potentially severe hail likelihood for any observed storm cell. These estimates are specifically designed to make hail likelihood distinctions based on satellite-indicated points of deep convection within environments favorable for storm development. We seek an approach that can be used to estimate climatological hailstorm frequency and risk throughout the historical satellite data record.

This presentation demonstrates that statistical distributions of convective parameters from satellite and reanalysis show separation between non-severe/severe hailstorm classes for predictors including overshooting cloud top temperature and area characteristics, convective available potential energy, vertical wind shear, 500 hPa temperature, mid-level lapse rate, precipitable water, and convective inhibition. These complex, multivariate predictor relationships are exploited within a DNN to produce a hail likelihood metric with a critical success index of 0.504 and Heidke skill score of 0.403, which is exceptional among recent analogous hail studies. Furthermore, applications of the DNN to select case studies demonstrate good qualitative agreement between hail likelihood and MESH. These hail classifications are aggregated across an 11-year GOES-12/13 image database to derive a hail frequency and severity climatology, which denotes the Central Plains, the Midwest, and northwestern Mexico as being the most hail-prone regions within the domain studied. Opportunities for training and applying DNN-based hailstorm predictions to recently developed GOES-8/10/12/13/16 and Meteosat Second Generation convective storm detection and characterization climatologies over South America and South Africa, respectively, will also be presented.

How to cite: Bedka, K., Scarino, B., Itterly, K., Spangenberg, D., Homeyer, C., Allen, J., Bang, S., and Cecil, D.: Toward The Development of Hailstorm Climatologies Derived From Reanalyses and Infared/Passive Microwave Satellite Imagers, 11th European Conference on Severe Storms, Bucharest, Romania, 8–12 May 2023, ECSS2023-174, https://doi.org/10.5194/ecss2023-174, 2023.

In addition to their tremendous power display and serious damages they often cause, convective storms also play important roles in the global atmospheric transport processes. In this presentation, I would like to discuss two aspects of these processes: (1) the cross-tropopause transport of matter and (2) the transport of momentum and energy to the upper atmosphere. The cross-tropopause transport of matter is manifested by the phenomenon of the above-anvil cirrus plumes (AACP) discovered more than two decades ago by Martin Setvak and others via satellite data. I will review both satellite observations and theoretical modeling of this and related storm top phenomena. The transport of momentum and energy to the upper atmosphere by convective storms is manifested by the presence of concentric airglow patterns at the mesopause whose centers are collocated with storm activities in the troposphere. The wave-like airglow patterns have been observed by Suomi/NPP VIIRs imageries and we have performed numerical simulations to show that they form such patterns due to the propagation of storm-generated gravity waves from the lower atmosphere to the mesopause level.

How to cite: Wang, P. K.: The Impact of Convective Storms on Global Atmospheric Transport Processes, 11th European Conference on Severe Storms, Bucharest, Romania, 8–12 May 2023, ECSS2023-172, https://doi.org/10.5194/ecss2023-172, 2023.