Cb Cloud Research Articles

Pemanfaatan Data Satelit Himawari-8 dalam Analisis Kejadian Hujan Lebat di Jombang

On February 2, 2021, flooding struck Jombang, damaging 38 houses and public facilities due to heavy rainfall from cumulonimbus clouds. The analysis of convective cloud development using Himawari-8 Satellite with RGB Day Convective Storm, 24H-Microphysics, Airmass, and Cloud Convective Overlay methods revealed that the microphysics phase occurred in two different phases on February 1 and 2. The peak temperature of the Cb cloud during the development phase ranged from -20 to -60°C. Convective cloud clusters originated from the Java Sea and the Southern Sea. The peak cloud formation occurred at 12:00 UTC on February 1 and 2. Increased updraft and thickness intensity strengthened convective cloud formation. During the decay phase, downdraft increased with a decrease in cloud distribution, as observed in the Day Convective Storm and 24H-Microphysics images.

Analysis of Cloud Growth Phases When Nocturnal Hail Occurs (Case Study: Sekadau, 22 August 2020)

On August 22 2020, hail was reported in Sekadau, West Kalimantan at 21:23 WIB. The phenomenon of hail does not usually occur at night. So, further research is needed to find out how the cloud growth phase and Cumulonimbus (Cb) cloud structure are in this phenomenon. This research utilizes remote sensing instruments in the form of a C-Band type weather radar for the Supadio Meteorological Station and the Himawari 8 Satellite, as well as a radiosonde instrument that is closest to the time and location of the hail events. The results of satellite imagery show that nocturnal hail occurs before the clouds reach the mature phase, with the cloud top temperature at the time of hail less than -60 ºC. The maximum reflectivity detected by the radar using CMAX products shows a less significant value with an intensity of up to 52 dBZ. The VCUT product shows the maximum intensity altitude is at an altitude of 5 – 8 km. This shows that there is a process of ice condensation on the freezing level layer. The ZHAIL product image shows that there is a potential for hail in the Sekadau area with a probability of more than 80%. The occurrence of ice rain at Sekadau at night is caused by the presence of Cumulonimbus clouds with very cold peak temperatures and the mixing process above the freezing level which supports the formation of ice condensation in Cb clouds.

Analysis of Atmospheric Conditions during the Occurrence of Mesoscale Convective Complex (MCC) in East Kalimantan and Surrounding Area (Case Study: December 26, 2021)

Mesoscale Convective Complex (MCC) was first introduced in 1980 through research on infrared (IR) satellite images by Maddox. The MCC phenomenon can caused rain with a long period of time. This study aims to determine the atmospheric conditions when MCC occurred in East Kalimantan and surroundings area on December 26, 2021. The research data used in this study is Himawari-8 satellite data to display cloud top temperatures and convective cloud distribution using the CCO method and image interpretation using RGB method. Analysis of atmospheric conditions was also carried out on air humidity, vertical velocity, and reflectivity in the atmosphere obtained from weather radar data from the Stasiun Meteorologi Sultan Aji Muhammad Sulaiman - Sepinggan. Based on the results of the analysis, MCC was identified as a mature phase on December 26, 2021 at 12.00 UTC. Airmass RGB analysis shows the presence of clouds which are known as Cb clouds through CCO analysis as well as warm air masses with high humidity in East Kalimantan. Negative value of vertical velocity also indicates an updraft of moist air masses and the maximum reflectivity value of the CMAX product, which is 53 dBz, indicates strong convection activity.

Rainfall Characteristics In Medan City With Pearson Correlation Analysis (Case Study Of February 27, 2022)

February is climatologically the first peak of the dry season in the North Sumatra region, but floods can still occur. This study analyzes the characteristics of rainfall patterns that occur during extreme rainfall that occurred in the Medan area on February 27, 2022 which resulted in flooding in several areas in Medan with Pearson correlation. The data used are rainfall data, satellite data, radar and other atmospheric dynamics analysis data. Based on dynamic analysis on February 27, 2022, the growth of CB clouds began at 14.00 WIB reaching its peak at 17.00 WIB where the peak temperature of the cloud reached 82.4 ° C and cloud growth lasted until 21.00 WIB, where the rain lasted long enough to cause hydrometeorological disasters (floods) to occur. The Pearson correlation coefficient method (r) used to analyze the relationship between rainfall and DMI, ENSO, SST Anomalies and SOI conditions can be seen that the dominant influence is SST Anomalies and SOI, where in February conditions that affect rainfall are ENSO with a correlation value of 0.36272 and SST Anomalies with a correlation value of 0.37548.

Atmosphere Condition Analysis on Hail Event (Case Study : Pelalawan on September 23rd, 2019)

<p align="justify">Hail in Pulau Muda Village, Pelalawan Regency, Riau Province, occured on September 23rd 2019 when the entire Riau area was covered by smoke due to forest and land fires phenomenon. The hail was not accompanied by extreme rain and did not cause material harm. However, a study of atmospheric conditions before, during, and after the hail occurred is needed to reference for early warning of future events. The result was analyzed descriptively on the radar products, satellite images and observation parameters. CMAX and VCUT of radar product generated from RainbowV5.9 showed that at 06.02 UTC there was a single CB cloud, which its maximum reflectivity core was 60 dBZ at 5 km height. Both the core reflectivity and its height decreased by the time as the cloud dissipated. Himawari-8 RGB images and cloud top temperature time series processed by SATAID showed a significant decrease of cloud top temperature reached -75<sup>o</sup>C at 06.00 UTC where the cloud had large ice particles with strong updraft and dissipated within 1 hour into thin cirrus and medium-low clouds. ECMWF ERA5 Reanalysis data processed by GrADS showed that surface air temperature, RH, and CAPE index has a different value from h-1 to h+1 of hail occurrence. Vertical profile showed the single CB cloud had much amount of ice particles and also strong updrafts that the maximum value of updraft was 0,202 m/s at the development stage. In contrast, the maximum value of downdraft was 0,032 m/s in the dissipation stage of the cloud.</p>

PREDICTION OF CUMULONIMBUS (CB) CLOUD BASED ON INTEGRATED FORECAST SYSTEM (IFS) OF EUROPEAN MEDIUM-RANGE WEATHER FORECAST (ECMWF) IN THE FLIGHT INFORMATION REGION (FIR) OF JAKARTA AND UJUNG PANDANG

This study was focused on cumulonimbus (Cb) cloud prediction based on Integrated Forecast System (IFS) European Medium-Range Weather Forecast (ECMWF) model in the Flight Information Region (FIRs) Jakarta and Ujung Pandang. The Cb cloud prediction was calculated using convective cloud cover (CC) of the precipitation product. The model predictability was examined through categorical verification. The Cb cloud observation was based on brightness temperature (BT) IR1 and brightness temperature difference (BTD) IR1-IR2. The results showed that CC 50%' predictor was the best predictor to estimate the Cb cloud. The study in the period other than 2019 is suggested for the next research because Indian Ocean Dipole (IOD) is extreme that may affect the Cb cloud growth in the study area.

Connected Variations of Meteorological and Electrical Quantities of Surface Atmosphere under the Influence of Heavy Rain

The electrical state of the surface atmosphere changes significantly under the influence of cloudiness and atmospheric phenomena, including atmospheric precipitation. These features can be used for possible diagnostics of precipitation and improvement of their characteristics based on variations of atmospheric-electrical quantities in the surface layer. Studies of variations of meteorological and atmospheric-electrical quantities in the surface layer were carried out during the heavy rainfall associated with the cumulonimbus (Cb) clouds passage. Meteorological and atmospheric-electrical observations in the Geophysical Observatory of the Institute of Monitoring of Climatic and Ecological Systems are presented in this paper. Precipitation data are used to identify periods of heavy rainfall ≥ 5 mm/h. Information of weather stations and satellites is used to separate the heavy rainfall events by synoptic conditions like thunderstorms and showers of frontal or internal air masses. We find that rains associated with the frontal Cb clouds produce more abrupt changes in negative electrical conductivity in comparison with the Cb clouds in internal air masses. The significant increase in negative electrical conductivity (more than two times vs. normal values) occurs typically during the passage of frontal Cb and heavy rain with droplet size greater than 4 mm.

ЕФЕКТИВНИЙ РАДІУС КРАПЕЛЬ В ХМАРАХ РІЗНИХ ФОРМ ТА ФРОНТАЛЬНИХ ХМАРНИХ СИСТЕМАХ ЗА ДАНИМИ СУПУТНИКОВИХ СПОСТЕРЕЖЕНЬ У ТЕПЛИЙ ПЕРІОД РОКУ

The distribution of drop effective radius on cloud upper level was defined and analyzed for main cloud forms over Ukraine during two years (2014-2015) using satellite observations. The effective radius values of isolated cumulonimbus on cloud top and its dependency on optical thickness was estimated in measurements during April-September 2014 over Kyiv area. For cumulonimbus clouds with precipitation the dependence of effective radius on the type, precipitation intensity and liquid water path was defined. The distribution of drop effective radius on cloud top in the strength frontal systems with heavy showers area over all territory of Ukraine was defined for two systems and it dependence on the cloud height and the precipitation type, their intensity and the liquid water path was estimated. For all types of clouds the size of effective radius of the droplets was 6 μm. In St and As cloud system droplets with this size of effective radius were observed in 100%, in Sc and As cloud system – 91-92%. The values of effective radius in Ns and Cb cloud system was close to 6 μm (71 and 89% respectively). Larger droplets (8 μm) in Ns were observed in 29% and in Cb in 9%. However, in Cb, accompanied by rainfalls and powerful thunderstorms, the values of effective radius were 10-15 μm (1.5%) and 25-45 μm (0.5%). In 75% of moderate precipitation cases were formed by drops with an effective radius of 6 μm and in 25% with an effective radius of 8 μm. For the heavy precipitated clouds, the drops with an effective radius of 8 μm (62%) had the highest frequency, in 33% the effective radius of 6 μm were observed. The larger droplets (≥10 μm) had a small frequency (5%). The drop effective radius for cases of heavy rainfalls was 8 μm in 75%, in 25% larger droplets were observed (10, 15 and 30 μm). More intense rainfall was accompanied by greater values of cloud water content and, accordingly, greater effective radius values. The cases with large values of microphysical parameters and precipitation were observed as streaks in frontal cloud systems.

KAJIAN PERTUMBUHAN AWAN HUJAN PADA SAAT BANJIR BANDANG BERBASIS CITRA SATELIT DAN CITRA RADAR (STUDI KASUS : PADANG, 2 NOVEMBER 2018)

Banjir besar kembali melanda enam kecamatan di kota Padang, Sumatera Barat pada tanggal 2 November 2018. Banjir terjadi disebabkan oleh debit sungai yang meluap akibat hujan sangat lebat yang terjadi di bagian hulu dan hilir. Dampak banjir bandang tersebut mengakibatkan 600 rumah terendam banjir, 3 jembatan putus dan menelan korban jiwa. Karena dampak tersebut maka penelitian ini dilakukan untuk meninjau kondisi suhu permukaan laut, mean sea level pressure, nilai transport uap air, streamline, data citra satelit Himawari-8 dan data citra radar cuaca C-Band. Data diolah dalam bentuk grafik dan peta spasial kemudian dilakukan analisis deskriptif yang meliputi analisis temporal dan analisis spasial. Berdasarkan hasil analisis hujan sangat lebat yang terjadi di wilayah Padang dipicu oleh gangguan cuaca skala regional berupa adanya pola shearline atau komponen zona arah lintasan angin yang mengalami perubahan secara tiba-tiba yang sejajar dengan angin horizontal dan daerah tekanan rendah yang menimbulkan konvergensi di pesisir kota Padang, kemudian nilai transport uap air yang cukup tinggi yaitu kisaran antara 700-1100 Kg/ms-1 pada lapisan 1000-300 mb. Terjadinya hujan lebat seringkali terkait dengan keberadaan awan Cumulonimbus (Cb). Hal ini dikarenakan karakteristik awan Cb dengan dimensi yang besar serta mengandung banyak partikel presipitasi seperti air dan kristal es. Kondisi ini didukung dengan keberadaan awan Cb berdasarkan analisis time series citra satelit Himawari-8 dan nilai reflektifitas radar berada pada nilai 45-60 dBz. Pada tanggal 2 November 2018, hampir seluruh awan hujan yang muncul mempunyai ketebalan lebih dari 7 km, dimana suhu puncak awan terendah mencapai nilai -72.5°C.

Validation of Automatic Cb Observations for METAR Messages without Ground Truth

AbstractIn aviation meteorology, METAR messages are used to disseminate the existence of cumulonimbus (Cb) clouds. METAR messages are traditionally constructed manually from human observations, but there is a growing trend toward automation of this process. At the Finnish Meteorological Institute (FMI), METAR messages incorporate an operational automatic detection of Cb based solely on weather radar data, when manual observations are not available. However, the verification of this automatic Cb detection is challenging, as good ground truth data are not often available; even human observations are not perfect as Cb clouds can be obscured by other clouds, for example. Therefore, statistical estimation of the relevant verification measures from imperfect observations using latent class analysis (LCA) was explored. In addition to radar-based products and human observations, the convective rainfall rate from EUMETSAT’s Nowcasting Satellite Application Facility and lightning products from the Finnish lightning network were used for determining the existence of Cb clouds. Results suggest that LCA gives reasonable estimates of verification measures and, based on these estimates, the Cb detection system at FMI gives results comparable to human observations.

Analysis and Application of the Relationship between Cumulonimbus (Cb) Cloud Features and Precipitation Based on FY-2C Image

Although cumulonimbus (Cb) clouds are the main source of precipitation in south China, the relationship between Cb cloud characteristics and precipitation remains unclear. Accordingly, the primary objective of this study was to thoroughly analyze the relationship between Cb cloud features and precipitation both at the pixel and cloud patch scale, and then to apply it in precipitation estimation in the Huaihe River Basin using China’s first operational geostationary meteorological satellite, FengYun-2C (FY-2C), and the hourly precipitation data of 286 gauges from 2007. First, 31 Cb parameters (14 parameters of three pixel features and 17 parameters of four cloud patch features) were extracted based on a Cb tracking method using an artificial neural network (ANN) cloud classification as a pre-processing procedure to identify homogeneous Cb patches. Then, the relationship between Cb cloud properties and precipitation was analyzed and applied in a look-up table algorithm to estimate precipitation. The results were as follows: (1) Precipitation increases first and then declines with increasing values for cold cloud and time evolution parameters, and heavy precipitation may occur not only near the convective center, but also on the front of the Cb clouds on the pixel scale. (2) As for the cloud patch scale, precipitation is typically associated with cold cloud and rough cloud surfaces, whereas the coldest and roughest cloud surfaces do not correspond to the strongest rain. Moreover, rainfall has no obvious relationship with the cloud motion features and varies significantly over different life stages. The involvement of mergers and splits of minor Cb patches is crucial for precipitation processes. (3) The correlation coefficients of the estimated rain rate and gauge rain can reach 0.62 in the cross-validation period and 0.51 in the testing period, which indicates the feasibility of the further application of the relationship in precipitation estimation.

Automatic Tracking and Characterization of Cumulonimbus Clouds from FY-2C Geostationary Meteorological Satellite Images

This paper presents an automated method to track cumulonimbus (Cb) clouds based on cloud classification and characterizes Cb behavior from FengYun-2C (FY-2C). First, a seeded region growing (SRG) algorithm is used with artificial neural network (ANN) cloud classification as preprocessing to identify consistent homogeneous Cb patches from infrared images. Second, a cross-correlation-based approach is used to track Cb patches within an image sequence. Third, 7 pixel parameters and 19 cloud patch parameters of Cb are derived. To assess the performance of the proposed method, 8 cases exhibiting different life stages and the temporal evolution of a single case are analyzed. The results show that (1) the proposed method is capable of locating and tracking Cb until dissipation and can account for the eventual splitting or merging of clouds; (2) compared to traditional brightness temperature (TB) thresholds-based cloud tracking methods, the proposed method reduces the uncertainty stemming from TB thresholds by classifying clouds with multichannel data in an advanced manner; and (3) the configuration and developmental stages of Cb that the method identifies are close to reality, suggesting that the characterization of Cb can provide detailed insight into the study of the motion and development of thunderstorms.

The Role of GPS Precipitable Water Vapor and Atmosphere Stability Index in the Statistically Based Rainfall Estimation Using MTSAT Data

Abstract A rainfall estimation method was developed based on the statistical relationships between cloud-top temperature and rainfall rates acquired by both the 10.8-μm channel of the Multi-Functional Transport Satellite (MTSAT) series and the Automated Meteorological Data Acquisition System (AMeDAS) C-band radar, respectively. The method focused on cumulonimbus (Cb) clouds and was developed in the period of June–September 2010 and 2011 over the landmass of Japan and its surrounding area. Total precipitable water vapor (PWV) and atmospheric vertical instability were considered to represent the atmospheric environmental conditions during the development of statistical models. Validations were performed by comparing the estimated values with the observed rainfall derived from the AMeDAS rain gauge network and the Tropical Rainfall Measuring Mission (TRMM) 3B42 rainfall estimation product. The results demonstrated that the models that considered the combination of total PWV and atmospheric vertical instability were relatively more sensitive to heavy rainfall than were the models that considered no atmospheric environmental conditions. The use of such combined information indicated a reasonable improvement, especially in terms of the correlation between estimated and observed rainfall. Intercomparison results with the TRMM 3B42 confirmed that MTSAT-based rainfall estimations made by considering atmospheric environmental conditions were more accurate for estimating rainfall generated by Cb cloud.

MTSATによる輝度温度情報から作成した東南アジアにおける雲の気候特性

There are many extreme hydrometeorological phenomena such as heavy rain and drought events in the world. A considerable shortage of observing stations was motivated us to utilize the remote sensing for observing water resources and related information from space. In this study we used MTSAT (Multi-functional Transport Satellite) to acquire cloud type characteristics. The observation target was the western pacific region. The spatial distribution between MTSAT and JMA(Japan Meteorological Agency) cloud classification showed reasonably good agreement while our result estimated many Cb(Cumulonimbus) focusing on June to September 2010. The Cb cloud was estimated 20 to 60% larger than the 15-year climatology(1996-2010) over northern part of Thailand in 2011.

Cloud Seeding with the TG-10 Rockets

Efficiency of a hail suppression (HS) system is strongly affected technical devices in use, and the way they are used. In case of antihail actions, it is necessary to inject the meteorological reagent into the proper seeding area, as soon as possible. A technical description for the rocket TG-IO is given, together with theomethodology whichoi s base~ upon investigations of rocket operating in beams 25 wide, between -5 to -10 C isotherms on the front part of the Cb clouds.

Cumulonimbus cloud with anvil over India : Synoptic cloud type observations 1970-2000

The features of observational aspects of frequencies of occurrence of Cb clouds with anvil over India have been presented. Synoptic cloud type observations for 101 uniformly distributed Class I surface observatories of India Meteorological Department for pre-monsoon months for period 1970-2000 is taken.
 The results reveal that the formation of Cb clouds with anvil exhibit the diurnal tendency of growth of cloud areas and show drastic decrease in the early morning hours. The temporal evolution of Cb clouds with anvil show that during the period from 0900 UTC to 2100 UTC, the maximum peak of convective cloud activity occur at 1200 UTC. This study has brought forth five prominent belts of Cb clouds prevalence showing both temporal and spatial characteristics during the month of May which is the month of peak thunderstorm activity. The first belt extends from South peninsula along West Coast of India covering regions of Kerala, Tamil Nadu and Puducherry, South Interior Karnataka, Coastal Karnataka, parts of North Interior Karnataka, Konkan and Goa, Madhya Maharashtra and West Madhya Pradesh (3 to 10 days). The region South Interior Karnataka and adjoining Kerala and Tamil Nadu has reported Cb clouds with anvil to be about 10 days. The second belt comprises Himachal Pradesh and adjoining Jammu & Kashmir, Uttarakhand and adjoining West UP. The third belt covers spatial areas of Chhattisgarh and adjoining Vidharbha, Orissa, Gangetic West Bengal and adjoining areas of Jharkhand and Bihar. The fourth belt is SHWB, Assam and Meghalaya covering Guwahati and Shillong. The fifth belt comprises regions of Tripura and adjoining Mizoram. The rest of Northeast India report Cb clouds with anvil on the average of 1 to 3 days. The region South Bihar and adjoining Jharkhand and Gangetic West Bengal report Cb clouds with anvil on the average of 5 to 7 days.

Investigation of the impact of dynamic factors on Cb cloud development in Saudi Arabia

Changes are analyzed of a Cb cloud characteristics due to its merging with feeder clouds, on the data on a long-living Cb cloud in Saudi Arabia on July 4, 2008. Continuous radar and satellite observations of the cloud are carried out during 6 h. The Cb cloud development is also numerically simulated using a nonstationary 1½ model. It is found that the processes of Cb cloud merging with feeder clouds developing in its vicinities affect significantly the Cb cloud development. This impact demonstrates itself in longer duration of the Cb cloud life span, increasing top height, reflectivity, precipitation duration and intensity. Modification of the feeder clouds can accelerate their development, which eventually can affect notably the Cb cloud.

Atmospheric circulations associated to the interannual variability of cumulonimbus cloud frequency in the southern part of Romania

AbstractEspecially in summer time, Romania is affected by deep convections associated with severe weather phenomena (hail, wind gusts, flash floods, frequent thunder).The interannual variability of the Cb (cumulonimbus) cloud frequency recorded at 20 weather stations from the southern part of Romania in the 1961–2007 interval was investigated in connection with the atmospheric circulation variability.Using the Canonical Correlation Analysis (CCA) three types of atmospheric circulations have been identified that control about 60% of the interannual variability of the Cb cloud frequency.The three types of identified circulations facilitate warm and moist air advection from the Mediterranean, and cold air advection from northern Europe towards the south of Romania, creating conditions for Cb clouds to occur. Copyright © 2011 Royal Meteorological Society

Complex study of characteristics of a Cb cloud developing over the arabian peninsula under conditions of high dew point deficit in the atmosphere. Part 2. Analysis of the meteosat data

Development of a long-living Cb cloud in the desert part of Saudi Arabia on April 10, 2008 is analyzed. Continuous satellite and radar observations of the cloud are carried out during five hours. Numerical modeling of the cloud is performed using a nonstationary 1.5-dimensional model. Data on the Cb cloud and its anvil development dynamics are obtained. It is shown that the anvil characteristics differ significantly in the zone of its formation directly over the cloud and when moving away from it. It is pointed out that the radar underestimates the anvil sizes. Estimation of precipitation rate from the cloud under study by means of satellite and radar measurements is compared against the results of numerical modeling. It is found that precipitation rate could reach 100 mm/h. The radar estimates of the precipitation rate are significantly overstated, which is, in this case, due to presence of large hail particles.

Complex study of characteristics of a Cb cloud developing over the Arabian Peninsula under high dew point deficit in the atmosphere. Part 1. Field observations and numerical modeling

Basing on airmass motion trajectory calculations over the Arabian Peninsula on April 10, 2008, it can be assumed that in the lower and middle troposphere, zones with increased air moisture exist due to air inflow from the Red Sea. As a result, mesoscale volumes of dry and moist air are neighboring, though large-scale field is comparatively homogeneous with low humidity. In the mesoscale zones, intense thunderstorm and hailstorm Cb clouds developed, whose characteristics and evolution are studied in the paper. Continuous radar observations of the clouds are carried out during 5 hours. Numerical simulation of the cloud evolution is performed with nonstationary 1.5-dimensional model. It is noted that under the mentioned atmospheric conditions, in the area under consideration, heavy rain and hail from the Cb clouds are observed. The main factors of their origination are high thermal instability of the atmosphere and moist air inflow from outside.