The Evolution and Extratropical Transition of Tropical Cyclones from a GPM, ISS LIS and GLM Perspective

Not much is known about the evolution of lightning within extra-tropical cyclones traversing the mid-latitudes, especially its oceans. To facilitate such studies we combine a recently constructed precipitation features (PF) database obtained from the Global Precipitation Measurement (GPM) mission constellation of satellites with lightning observations from the Geostationary Lightning Mapper (GLM) onboard GOES-16 and the Lightning Imaging Sensor (LIS) onboard the International Space Station (ISS). The goal of this study is to provide a new observationally-based view of the tropical to extra-tropical transition and its impact on lightning production. Such data fusion approaches, as presented here, will also be important in future satellite studies of convective precipitation

Global statistics of lightning in anvil and stratiform regions over tropics and subtropics observed by TRMM

[1] The statistics of lighting in the anvil and stratiform regions of convective systems are summarized from Tropical Rainfall Measuring Mission (TRMM) satellite observations from 1998 to 2009. The locations of lightning flashes in convective systems are determined by combining three-dimensional precipitation radar (PR) observations with lightning flash center locations from lightning imaging sensor observations. The geographical distributions of flashes in the anvil and stratiform regions of thunderstorms over the tropics and subtropics are presented. Flashes in stratiform regions are found to account for 5.6% of all lightning flashes observed within the TRMM PR swath, while flashes in nonraining anvil regions made up another 5.5% of the sample. Diurnally, flashes in anvil regions peak earlier than flashes in stratiform regions (15:30 LT as opposed to 17:30 LT). Seasonal and regional variations of these flashes are discussed. Features in PR observations that likely contribute to charge separation are identified as contiguous areas with 6 km echoes exceeding 30 dbZ. Lightning flashes are then assigned to one of these features by the nearest neighbor method. Convective properties of features linked with lightning in stratiform and nonraining anvil regions are then analyzed. We find that features associated with lightning flashes in anvil regions are relatively weak and occur in small systems composed of a single convective region, while flashes in the stratiform regions are also relatively weak but more likely occur in multicell systems. About 15% of features with lightning are associated with at least one stratiform or anvil flash. Citation: Peterson, M., and C. Liu (2011), Global statistics of lightning in anvil and stratiform regions over the tropics and subtropics observed by the Tropical Rainfall Measuring Mission

Rain Characteristics and Large-Scale Environments of Precipitation Objects with Extreme Rain Volumes from TRMM Observations

This study adopts a "precipitation object" approach by using 14 years of Tropical Rainfall Measuring Mission (TRMM) Precipitation Feature (PF) and National Centers for Environmental Prediction (NCEP) reanalysis data to study rainfall structure and environmental factors associated with extreme heavy rain events. Characteristics of instantaneous extreme volumetric PFs are examined and compared to those of intermediate and small systems. It is found that instantaneous PFs exhibit a much wider scale range compared to the daily gridded precipitation accumulation range. The top 1% of the rainiest PFs contribute over 55% of total rainfall and have 2 orders of rain volume magnitude greater than those of the median PFs. We find a threshold near the top 10% beyond which the PFs grow exponentially into larger, deeper, and colder rain systems. NCEP reanalyses show that midlevel relative humidity and total precipitable water increase steadily with increasingly larger PFs, along with a rapid increase of 500 hPa upward vertical velocity beyond the top 10%. This provides the necessary moisture convergence to amplify and sustain the extreme events. The rapid increase in vertical motion is associated with the release of convective available potential energy (CAPE) in mature systems, as is evident in the increase in CAPE of PFs up to 10% and the subsequent dropoff. The study illustrates distinct stages in the development of an extreme rainfall event including: (1) a systematic buildup in large-scale temperature and moisture, (2) a rapid change in rain structure, (3) explosive growth of the PF size, and (4) a release of CAPE before the demise of the event

Properties of Hail Storms over China and the United States from the Tropical Rainfall Measuring Mission

A 16-yr record of hail reports over the southeast US and from weather stations in China are collocated with Precipitation Features (PF) derived from the Tropical Rainfall Measurement Mission (TRMM) radar and passive microwave observations. While U.S. hail reports are dominated by cases with hail size greater than 19 mm, hail reports in China mostly include diameters of 1-10 nm and mostly occur over the Tibetan Plateau. The fraction of PFs collocated with hail reports (hail PFs) reaches 3% in the plains of the U.S. In China, the fraction is higher in high elevation regions than low elevation regions. Hail PFs in the U.S. show lower brightness temperatures, higher lightning flash rates, stronger maximum reflectivity, and higher echo tops than those in China, consistent with the larger hail diameters in the U.S. reports. The average near surface maximum reflectivity of hail PFs at higher elevations (greater than or equal to 2000 m) in China is about 5 dB smaller than those at low elevations. Larger hail is reported with PFs having stronger maximum reflectivity above 6 km, though the median of maximum reflectivity values at levels below 5 km is close among the storms with large and small hail sizes

The Extratropical Transition of Tropical Storm Cindy From a GLM, ISS LIS and GPM Perspective

The distribution of lightning with respect to tropical convective precipitation systems has been well established in previous studies and more recently by the successful Tropical Rainfall Measuring Mission (TRMM). However, TRMM did not provide information about precipitation features poleward of +/-38 deg latitude. Hence we focus on the evolution of lightning within extra-tropical cyclones traversing the mid-latitudes, especially its oceans. To facilitate such studies, lightning data from the Geostationary Lightning Mapper (GLM) onboard GOES-16 was combined with precipitation features obtained from the Global Precipitation Measurement (GPM) mission constellation of satellites

Improving a Spectral Bin Microphysical Scheme Using TRMM Satellite Observations

Comparisons between cloud model simulations and observations are crucial in validating model performance and improving physical processes represented in the mod Tel.hese modeled physical processes are idealized representations and almost always have large rooms for improvements. In this study, we use data from two different sensors onboard TRMM (Tropical Rainfall Measurement Mission) satellite to improve the microphysical scheme in the Goddard Cumulus Ensemble (GCE) model. TRMM observed mature-stage squall lines during late spring, early summer in central US over a 9-year period are compiled and compared with a case simulation by GCE model. A unique aspect of the GCE model is that it has a state-of-the-art spectral bin microphysical scheme, which uses 33 different bins to represent particle size distribution of each of the seven hydrometeor species. A forward radiative transfer model calculates TRMM Precipitation Radar (PR) reflectivity and TRMM Microwave Imager (TMI) 85 GHz brightness temperatures from simulated particle size distributions. Comparisons between model outputs and observations reveal that the model overestimates sizes of snow/aggregates in the stratiform region of the squall line. After adjusting temperature-dependent collection coefficients among ice-phase particles, PR comparisons become good while TMI comparisons worsen. Further investigations show that the partitioning between graupel (a high-density form of aggregate), and snow (a low-density form of aggregate) needs to be adjusted in order to have good comparisons in both PR reflectivity and TMI brightness temperature. This study shows that long-term satellite observations, especially those with multiple sensors, can be very useful in constraining model microphysics. It is also the first study in validating and improving a sophisticated spectral bin microphysical scheme according to long-term satellite observations

Vulnerability assessment of the fishery system in China’s coastal provinces since 2000

Coastal fishery systems are vital for both the environment and the economy, and at present, they face heightened vulnerability due to global climate change and natural disasters. A clearer understanding of the challenges that the system presents can be obtained by examining the vulnerabilities of fishery systems. This study employed a vulnerability scoping diagram framework and a multi-indicator approach combined with the entropy weight method for assigning weights to systematically evaluate the vulnerabilities of fishery systems in China’s coastal provinces. The spatiotemporal variation characteristics of vulnerability were analyzed and characterized, and the primary obstacles that affect vulnerability are discussed. The findings suggest that China’s coastal provinces’ fishery systems display vulnerability in terms of both time and space. From a temporal perspective, Liaoning, Hebei, and Shandong provinces exhibited an increasing trend in vulnerability, while Tianjin, Jiangsu, Zhejiang, Shanghai, Fujian, Guangdong, Guangxi, and Hainan showed decreasing trends. From a spatial perspective, Hainan and Liaoning’s fishery systems exhibited extremely high vulnerability in most years. In contrast, Tianjin consistently experienced extremely low vulnerability in most years. From the perspective of obstacles, the main factor was the funding for the extension of aquaculture technology, and this remained the primary obstacle factor across all years. The findings are significant for enhancing our understanding of vulnerability in fishery systems and for strengthening disaster prevention and mitigation measures. The results provide robust support for the improvement of management and the protection of fishery systems

On the Variability of Wilson Currents by Storm Type and Phase

Storm total conduction currents from electrified clouds are thought to play a major role in maintaining the potential difference between the earth's surface and the upper atmosphere within the Global Electric Circuit (GEC). However, it is not entirely known how the contributions of these currents vary by cloud type and phase of the clouds life cycle. Estimates of storm total conduction currents were obtained from data collected over two decades during multiple field campaigns involving the NASA ER-2 aircraft. In this study the variability of these currents by cloud type and lifecycle is investigated. We also compared radar derived microphysical storm properties with total storm currents to investigate whether these storm properties can be used to describe the current variability of different electrified clouds. The ultimate goal is to help improve modeling of the GEC via quantification and improved parameterization of the conduction current contribution of different cloud types