Event type: Seminar
Date: 9 March 2022
Time: 13:00 – 16:00 Jakarta Time (15:00 – 18:00 JST)
Location: Online via ZOOM (link and ZOOM ID will be sent to registered emails)
Registration link (FREE): http://bit.ly/registrationESC
Program: Special guest lecture
Presenter: Professor Tetsuya Takemi
Affiliation: Disaster Prevention Research Institute, Kyoto University
Title: Effects of environmental stability conditions on the intensity of linear-shaped mesoscale convective systems
Abstract: The development and intensity of mesoscale convective systems (MCSs) are affected by environmental conditions such as the vertical profiles of temperature, humidity, and winds. The vertical profile of temperature, i.e., stability condition, depends on the season, geographical location, and climate of the area of interest. For example, the stability condition is quite different between the tropical and the midlatitude regions. This study investigates how the stability conditions influence the evolution and strength of MCSs by using a non-hydrostatic meteorological model, the Weather Research and Forecasting (WRF) model. The simulated MCSs become stronger in environments with higher temperature lapse rate in terms of updraft strength and system-total rainfall. On the other hand, hourly rainfall (i.e., rain intensity) becomes stronger in environments with a lower temperature lapse rate, if a certain amount of convective available potential energy exits. The dependence of the MCS intensity on stability conditions found in these numerical experiments is useful in diagnosing the intensity of observed precipitating systems and also the intensity of convective rainfall under climate change.
Program: Presentation by four students
(1) Yesi Ratnasari (22420035)
Title: A Study of Low-Level Wind Shear (LLWS) at Soekarno-Hatta International Airport
Abstract: Low-level wind shear (LLWS) is a wind shear that occurs between surfaces up to 1600 feet. This phenomenon is hazardous for flight, especially during take-off and landing. However, LLWS predictions are still challenging because of natural phenomena (small scale, high variability, and short duration). As a result, understanding trigger factors and LLWS characteristics became crucial in publishing early warnings. During 2015-2019, the pilot has reported 146 LLWS cases in Soekarno-Hatta International Airport. However, the trigger factor of every case is barely recognized. So, the dominant cause and characteristic of frequency events have not been found. This objective of the research is to analyze the main trigger factor and characteristics frequency (spatial and temporal) of LLWS in Soekarno-Hatta International Airport, which focuses on convective cloud, sea breeze front (SBF), and land breeze front (LBF). Data used are Pilot Report (PIREP), Doppler weather radar, and Automated Weather Observing System (AWOS). The analysis shows that the dominant cause of LLWS is convective cloud (single and multicell), especially accompanied by gust front and microburst, with a relative frequency of 53,44%. This convective cloud is dominated from the south of the airport caused by strong convection during daylight and the result of propagation from mountainous terrain and highland. This finding is supported by the pattern of frequency LLWS, which as seasonal maximum on Dec-Jan-Feb (DJF) and as diurnal, forming a semidiurnal pattern with two peaks (07.00-08.59 UTC and 14.00-15.59 UTC). As spatial, LLWS often occur on runway 25L (52%) with an average speed of 19,95 knots.
(2) Trinah Wati (32418301)
Title: Statistical Performance of Gridded Rainfall Data over Indonesia
Abstract: Gridded precipitation datasets have been used as alternatives to rain gauge observations, but their applicability for a specific region should be thoroughly evaluated. The study aims at finding the most appropriate one for climatological and hydrological applications in Indonesia, by evaluating the statistics of the performance of eight different datasets (research products) having horizontal resolutions between 0.1◦ and 0.25◦ and with a time span of data availability from 2003 to 2015. The datasets are compared against the observed daily rainfall at 133 stations using 13 statistical metrics that can be classified into three groups with different characteristics of measurements, namely, distribution, time sequence, and extreme value representations. By applying Summation of Rank (SR), it is found that MSWEP is the best precipitation by overall SR, combining 13 statistical metrics that cover performance indices of daily, monthly, seasonal, and annual time scales. Nevertheless, the GPM-IMERG (final-run) and GSMaP_NRL perform better than MSWEP in capturing extreme events with thresholds of 200 mm/day. Results of this study suggest that MSWEP (v2) are presently the best gridded precipitation datasets available for climatological and hydrological applications in Indonesia.
(3) Andika (22419011)
Title: Equatorial waves activity and its impact on MJO propagation over the Maritime Continent
Abstract: The eastward propagation of the Madden-Julian Oscillation (MJO) from the Indian Ocean to the Pacific Ocean in some cases is blocked over the Indonesian Maritime Continent (BMI), called MJO-B (inversely called MJO-C). A previous study (Feng et al., 2015) found a dry anomalous feature called transient dry precursor (TDP) that propagates westward from the Pacific Ocean for the case of MJO-B which appears to attenuate the wet anomaly of the MJO, presumably as the equatorial Rossby wave. In this work, it will be proven whether TDP is an equatorial Rossby wave or not. Wave filter, spatial composite analysis on outgoing longwave radiation (OLR) and specific humidity data, and divergence analysis on moisture transport were carried out on 21 MJO-C events and 12 MJO-B events from 1998 to 2015 to prove TDP as equatorial Rossby wave. It was found that the TDP that appeared in the MJO-B case was indeed equatorial Rossby waves.
(4) Femmy Marsitha B (22420043 )
Title: MJO, IOD, and ENSO Signatures on Daily Precipitation over Maritime Continent in The Global Climate Models: CMIP5 and CMIP6
Abstract: As primary tools used in climate change projection, the Global Climate Model (GCMs) in the Climate Model Intercomparison Project (CMIP) has improved resolution and physical parameterization from CMIP5 to CMIP6. However, those improvements do not always guarantee climate representation, including over the Maritime Continent (MC). This study examines Madden Julian Oscillation (MJO), Indian Ocean Dipole (IOD), and El Niño-Southern Oscillation (ENSO) signatures in the historical run of twelve models from each CMIP5 and CMIP6. Daily precipitation of ERA-5 is used as a reference for 1981-2005. Multiple Linear Regression (MLR) is applied to assess the contribution of those phenomena on daily precipitation anomalies over the MC. We perform the cosine similarity to quantify the spatial similarity between models and reference, then rank the values to obtain the best model. Result shows that only half of 12 models in CMIP6 experienced an improvement from the models in CMIP5. MIROC5 (CMIP5) is the best model while NorESM1-M (CMIP5) is the worst at representing the signature of those phenomena relative to 24 models. Therefore, this study recommends the best models for climate projection analysis and adaptation strategy over the MC.
