PEMANFAATAN CITRA SATELITE HIMAWARI-8 DALAM KEJADIAN HUJAN LEBAT DI KABUPATEN CIANJUR (Studi Kasus Cianjur 11, April 2021)

Latar Belakang: Indonesia merupakan negara kepulauan yang memiliki iklim tropis. Di wilayah Benua Maritim Indonesia (BMI) terdapat tiga tipe hujan dinataranya adalah tipe monsunal, ekuatorial, dan lokal. Tipe hujan monsunal dicirikan dengan distribusi hujan bulanan yang memiliki satu kali hujan minimum sehingga membentuk huruf “V” dalam grafiknya bulanannya. Sementara tipe hujan ekuatorial memiliki pola hujan bulanan yang mengalami dua kali hujan maksimum selama setahunnya. Sedangkan tipe hujan lokal adalalah tipe hujan yang lebih banyak dipengaruhi sifat-sifat lokal seperti topografi setempat, ataupun angin lokal. Distribusi hujan bulanan dari jenis ini mengalami satu kali hujan maksimum selama setahunnya. (Sipayung, 2007).Metode: Penelitian dilakukan dengan memanfaatkan data citra satelit Himawari-8 dengan menggunakan metode RGB (Red-Green-Blue), CCO (Cloud Convective Overlays), CST (Convective Stratiform Technique) dan mCST (Modified Convective Stratiform Technique).Hasil: Berdasarkan peta sebaran awan konvektif dengan menggunakan metode SWA pada gambar 9, awan konvektif sedang tumbuh dan berkembang diatas wilayah Kabupaten Cianjur.Kesimpulan: Berdasarkan hasil analisis peristiwa hujan lebat di Kabupaten Cianjur pada tanggal 11 April 2021 yang menimbulkan dua orang korban jiwa dan bangunan rusak disebabkan oleh aktivitas awan konvektif yaitu awan Cumulunnimbus (CB

Study of second-order turbulence closure technique and its application to atmospheric flows

Fall 1985.Includes bibliographical references (pages 66-69).The applicability of the second-order turbulence closure technique to atmospheric mesoscale flows is investigated. Analytical and numerical studies of various closure schemes are performed. Theoretical investigations of the well-known Mellor and Yamada approach result in new realizability conditions for the Level 2.5 and Level 3.0 schemes. The bulk parameters (eddy exchange coefficients) are calculated from the full second order closure model. The comparison of these parameters with the experimental data reveals that the simple Richardson number-based scaling is not adequate. The Level 2.5 and Level 4.0 models are developed and applied to a California stratocumulus case. The new realizability conditions are applied in the Level 2.5 model. The results are presented and show good agreement with experimental data collected off the California shoreline. On the basis of these studies, conclusions about applicability of simplified second-order turbulence closure technique are formulated.Supported by the Air Force Geophysics Laboratory under contract #F19628-84-C0005.Supported by the Electric Power Research Institute under contract #RFP 1630-25

Patrones de circulación asociados a descensos bruscos de temperatura mínima del aire en la Sierra Sur y Centro del Perú

Universidad Nacional Agraria La Molina. Facultad de Ciencias. Departamento Académico de Ingeniería Ambiental, Física y MeteorologíaEn la presente investigación se clasificó eventos de descensos bruscos de temperaturas mínimas (DBTM) en la sierra sur y centro del Perú por patrones de circulación utilizando datos de reanalysis del ERA5 (0.25°x0.25°), con el fin de proponer al menos un modelo conceptual atmosférico que ayude a la identificación de dichos eventos. Para realizar la clasificación por patrones de circulación, se asociaron circulaciones sinópticas y parámetros meteorológicos a los eventos de DBTM identificados entre el 2009 y 2018, y una vez dada la clasificación, cada patrón fue explicado por las ecuaciones cuasi-geostróficas (EQ) de tendencia geopotencial y omega. Los resultados muestran que se tiene una región convergente en niveles altos de la tropósfera sobre el Pacífico, frente del norte y centro de Chile, provocando subsidencia sobre esa zona y, en consecuencia, una tropósfera con menor contenido de humedad. Vientos del sur en niveles medios advectan esta región de aire seco (capa entre 600 y 300hPa con humedad relativa menor al 20%) desde el Pacífico hacia el sur y centro del Perú. Las zonas convergentes en niveles altos están asociadas a jet streams acoplados por su lado convergente, así como a su posición y configuración en particular, mientras que los vientos del sur están asociados principalmente a un sistema dorsal – vaguada. En la investigación, también se encontró un mecanismo similar, con la diferencia que la región de aire seca provenía de continente (Bolivia), y afectaba con DBTM principalmente la sierra sur oriental del Perú. Finalmente, se muestran mapas de isotermas para un evento de DBTM (25 de marzo de 2018 al 8 de abril de 2018), elaborados a partir de datos de temperatura mínima de estaciones meteorológicas y termohigrómetros de Tambos, en los cuales se identifica que las zonas con temperaturas mínimas más bajas se sitúan sobre las zonas altas de las regiones de Tacna, Puno, Moquegua, Arequipa y Cusco.In this research, minimum temperature abrupt drops (MTAD) events in central and southern Perú Andes were classified by circulation patterns using ERA 5 Reanalysis (0.25°x0.25°) with the aim of proposing at least one atmospheric conceptual model to identify these events. To make this classification, synoptic circulations and weather parameters were associated to MTAD events identified between 2009 and 2018, and then were explained by cuasigeostrophic omega equation and cuasi-geostrophic height-tendency equation. Results show the presence of a convergence (negative divergence) zone in high-level troposphere above the Pacific, in front of northern and central Chile, producing subsidence on that area and, therefore, a lower humidity content in troposphere. Southern winds in mid-level troposphere advect this dry air region (mean relative humidity between 600-300hPa layer lesser than 20%) from the Pacific towards southern and central Perú. Convergence zones are related to coupled jet streams on its convergent side, their location and configuration, whereas southern winds are mainly related to a ridge – trough system. In this research, it was also found a similar mechanism, but in this case the dry air region came from continent (Bolivia) and it mainly affected with MTAD over south eastern Perú Andes. Finally, isotherms maps are shown for a specific event (25th March 2018 to 8th April 2018). These maps were elaborated from minimum temperature data of weather stations and thermohygrometers (Tambos), and it can be identified that lowest values are located in high altitudes of the regions Tacna, Puno, Moquegua, Arequipa and Cusco

Climate Models

Climate models is a very broad topic, so a single volume can only offer a small sampling of relevant research activities. This volume of 14 chapters includes descriptions of a variety of modeling studies for a variety of geographic regions by an international roster of authors. The climate research community generally uses the rubric climate models to refer to organized sets of computer instructions that produce simulations of climate evolution. The code is based on physical relationships that describe the shared variability of meteorological parameters such as temperature, humidity, precipitation rate, circulation, radiation fluxes, etc. Three-dimensional climate models are integrated over time in order to compute the temporal and spatial variations of these parameters. Model domains can be global or regional and the horizontal and vertical resolutions of the computational grid vary from model to model. Considering the entire climate system requires accounting for interactions between solar insolation, atmospheric, oceanic and continental processes, the latter including land hydrology and vegetation. Model simulations may concentrate on one or more of these components, but the most sophisticated models will estimate the mutual interactions of all of these environments. Advances in computer technology have prompted investments in more complex model configurations that consider more phenomena interactions than were possible with yesterday s computers. However, not every attempt to add to the computational layers is rewarded by better model performance. Extensive research is required to test and document any advantages gained by greater sophistication in model formulation. One purpose for publishing climate model research results is to present purported advances for evaluation by the scientific community