scholarly journals An alternative index to NINO3.4 for predicting monthly rainfall anomaly in East Java

2021 ◽  
Vol 893 (1) ◽  
pp. 012005
Author(s):  
B E A Haq ◽  
M Ryan ◽  
A Kurniawan ◽  
A M Rafi
Keyword(s):  
Rainfall Anomaly ◽  
Monthly Rainfall ◽  
Sea Surface ◽  
Average Difference ◽  
Simple Linear Regression ◽  
General Representation ◽  
Maritime Continent ◽  
Simulation Based ◽  
Alternative Index ◽  
Lag Times

Abstract ENSO and NINO3.4 index are known to have some relation with Indonesian monthly rainfall anomaly. There is a gap between scientific studies on one hand and forecasting operational problems on the other hand since previous studies are not giving enough attention to the N+1,2,3 concept. The concept is about giving three next month rainfall anomaly prediction rather than connecting ENSO index with three-monthly rainfall anomaly. Here we propose an alternative index for ENSO. The median of categorical gridded rainfall anomaly of East Java is used as a general representation. Plots of correlation between the median and anomaly sea surface temperature from ReynSmithOIv2 are used to determine locus candidate to be compared with NINO3.4. The Near Maritime Continent (NMC) index is selected and proven to have a significant average difference in correlation between based on bootstrap technique. Verification of prediction used in this study is simulation-based and only uses binary hit-miss final result. Prediction is generated by simple linear regression with three lag times (2,3, and 4). Verification based on three categories shows that NMC’s hits are higher than NINO.34 in lag-2 and lag-3. In lag-2, NMC’s verification is 57.5% compared to only 38.7% for NINO3.4. However, NINO3.4 is a still better predictor in lag-4. Radar charts of monthly verifications are also developed.

scholarly journals El-NINO DAN PENGARUHNYA TERHADAP CURAH HUJAN DI MANADO SULAWESI UTARA

2011 ◽  
Vol 11 (1) ◽  
pp. 102 ◽  
Author(s):  
Seni Herlina J. Tongkukut
Keyword(s):  
El Niño ◽  
Southern Oscillation Index ◽  
El Nino ◽  
Southern Oscillation ◽  
Linear Regression Analysis ◽  
Monthly Rainfall ◽  
Rainfall Data ◽  
Sea Surface ◽  
Simple Linear Regression ◽  
North Sulawesi

Telah dilakukan analisis El-Nino dan pengaruhnya terhadap curah hujan di Manado Sulut dengan menggunakan data curah hujan bulanan dan Southern Oscillation Index SOI selama thn 1999-2009. Data curah hujan diperoleh dari BMKG Kayuwatu Manado Sulut dan data SOI diunduh dari website Biro Meteorologi Australia BoM. Analisis dilakukan dengan analisis regresi linear sederhana. Diperoleh hasil bahwa curah hujan kota Manado secara umum dari thn 1999-2008 dipengaruhi oleh SOI namun pada thn 2009 ketika terjadi El-nino, curah hujan bulanan Manado tidak dipengaruhi oleh efek El-nino. Hal ini karena pada saat yang sama suhu muka laut perairan Indonesia juga menghangat. EL-NINO AND ITS EFFECT ON RAINFALL IN MANADONORTH SULAWESIABSTRACTAnalysis of El-Nino and its effect on rainfall in Manado, North Sulawesi, using monthly rainfall data and the Southern Oscillation Index SOI during the years 1999-2009 has been carried out. Rainfall data obtained from BMKG Kayuwatu Manado and SOI data downloaded from the website of Australian Bureau of Meteorology (BoM). The analysis was performed with simple linear regression analysis. The results obtained indicate that rainfall in Manado , in general, was influenced by SOI from the years 1999-2008, but when there is an El-Nino in 2009, monthly rainfall in Manado is not affected by the El-Nino effect. This is due to, at the same time, sea surface temperature in Indonesian territory are also warm.

scholarly journals Honing in on bioluminescent milky seas from space

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Steven D. Miller ◽  
Steven H. D. Haddock ◽  
William C. Straka ◽  
Curtis J. Seaman ◽  
Cynthia L. Combs ◽  
...  
Keyword(s):  
Scientific Inquiry ◽  
Water Mass ◽  
Marine Ecosystem ◽  
Sea Surface ◽  
Surface Currents ◽  
Maritime Continent ◽  
Low Light ◽  
Composition Formation ◽  
Mass Isolation ◽  
New Generation

AbstractMilky seas are a rare form of marine bioluminescence where the nocturnal ocean surface produces a widespread, uniform and steady whitish glow. Mariners have compared their appearance to a daylit snowfield that extends to all horizons. Encountered most often in remote waters of the northwest Indian Ocean and the Maritime Continent, milky seas have eluded rigorous scientific inquiry, and thus little is known about their composition, formation mechanism, and role within the marine ecosystem. The Day/Night Band (DNB), a new-generation spaceborne low-light imager, holds potential to detect milky seas, but the capability has yet to be demonstrated. Here, we show initial examples of DNB-detected milky seas based on a multi-year (2012–2021) search. The massive bodies of glowing ocean, sometimes exceeding 100,000 km2 in size, persist for days to weeks, drift within doldrums amidst the prevailing sea surface currents, and align with narrow ranges of sea surface temperature and biomass in a way that suggests water mass isolation. These findings show how spaceborne assets can now help guide research vessels toward active milky seas to learn more about them.

scholarly journals An approach to quality analysis, gap filling and homogeneity of monthly rainfall series

2021 ◽  
Vol 29 ◽  
pp. 157-168
Author(s):  
Janaina Cassiano dos Santos ◽  
Gustavo Bastos Lyra ◽  
Marcel Carvalho Abreu ◽  
Daniel Carlos de Menezes
Keyword(s):  
Linear Regression ◽  
Rio De Janeiro ◽  
The State ◽  
Monthly Rainfall ◽  
Rainfall Series ◽  
Quality Analysis ◽  
Linear Regression Method ◽  
Simple Linear Regression ◽  
Gap Filling ◽  
Unsupervised Approaches

The aim of this work was to propose a method for the consistency of climatic series of monthly rainfall using a supervised and unsupervised approach. The methodology was applied for the series (1961-2010) of rainfall from weather stations located in the State of Rio de Janeiro (RJ) and in the borders with the states of São Paulo, Minas Gerais and Espírito Santo with the State of Rio de Janeiro. The data were submitted to quality analysis (physical and climatic limit and, space-time tendency) and gap filling, based on simple linear regression analysis, associated with the prediction band (p < 0.05 or 0.01), in addition to the Z-score (3, 4 or 5). Next, homogeneity analysis was applied to the continuous series, using the method of cumulative residuals. The coefficients of determination (r²) between the assessed series and the reference series were greater than 0.70 for gap filling both for the supervised and unsupervised approaches. In the analysis of data homogeneity, supervised and unsupervised approaches were effective in selecting homogeneous series, in which five out of the nine final stations were homogeneous (p > 0.9). In the other series, the homogeneity break points were identified and the simple linear regression method was applied for their homogenization. The proposed method was effective to consist of the rainfall series and allows the use of these data in climate studies.

scholarly journals Large-Scale Environmental Characteristics of MJOs that Strengthen and Weaken over the Maritime Continent

2018 ◽  
Vol 31 (14) ◽  
pp. 5731-5748 ◽  
Author(s):  
Casey D. Burleyson ◽  
Samson M. Hagos ◽  
Zhe Feng ◽  
Brandon W. J. Kerns ◽  
Daehyun Kim
Keyword(s):  
Seasonal Cycle ◽  
Large Scale ◽  
Longwave Radiation ◽  
Sea Surface ◽  
Madden Julian Oscillation ◽  
Moist Static Energy ◽  
Maritime Continent ◽  
New Finding ◽  
Field Campaigns ◽  
Static Energy

Abstract The characteristics of Madden–Julian oscillation (MJO) events that strengthen and weaken over the Maritime Continent (MC) are examined. The real-time multivariate MJO (RMM) index is used to assess changes in global MJO amplitude over the MC. The MJO weakens at least twice as often as it strengthens over the MC, with weakening MJOs being twice as likely during El Niño compared to La Niña years and the reverse for strengthening events. MJO weakening shows a pronounced seasonal cycle that has not been previously documented. During the Northern Hemisphere (NH) summer and fall the RMM index can strengthen over the MC. MJOs that approach the MC during the NH winter typically weaken according to the RMM index. This seasonal cycle corresponds to whether the MJO crosses the MC primarily north or south of the equator. Because of the seasonal cycle, weakening MJOs are characterized by positive sea surface temperature and moist-static energy anomalies in the Southern Hemisphere (SH) of the MC compared to strengthening events. Analysis of the outgoing longwave radiation (OLR) MJO index (OMI) shows that MJO precipitation weakens when it crosses the MC along the equator. A possible explanation of this based on previous results is that the MJO encounters more landmasses and taller mountains when crossing along the equator or in the SH. The new finding of a seasonal cycle in MJO weakening over the MC highlights the importance of sampling MJOs throughout the year in future field campaigns designed to study MJO–MC interactions.

scholarly journals An oceanic pathway for Madden–Julian Oscillation influence on Maritime Continent Tropical Cyclones

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Karthik Balaguru ◽  
L. Ruby Leung ◽  
Samson M. Hagos ◽  
Sujith Krishnakumar
Keyword(s):  
Numerical Model ◽  
Tropical Cyclones ◽  
Large Scale ◽  
Sea Surface ◽  
Madden Julian Oscillation ◽  
Surface Cooling ◽  
Maritime Continent ◽  
Large Scale Circulation ◽  
Model Simulations ◽  
Sea Surface Cooling

AbstractWhile the Madden–Julian Oscillation (MJO) has been shown to affect tropical cyclones (TCs) worldwide through its modulation of large-scale circulation in the atmosphere, little or no role for the ocean has been identified to date in this influence of MJO on TCs. Using observations and numerical model simulations, we demonstrate that MJO events substantially impact TCs over the Maritime Continent (MC) region through an oceanic pathway. While propagating across the MC region, MJO events cause significant sea surface cooling with an area-averaged value of about 0.35 ± 0.12 °C. Hence, TCs over the MC region immediately following the passage of MJO events encounter considerably cooler sea surface temperatures. Consequently, the enthalpy fluxes under the storms are reduced and the intensification rates decrease by more than 50% on average. These results highlight an important role played by the ocean in facilitating MJO-induced sub-seasonal variability in TC activity over the MC region.

Sea surface radar backscatter simulation based on eigenvector decomposition

2012 ◽  
Author(s):  
Bo Wang ◽  
Bertrand Chapron ◽  
Gregoire Mercier ◽  
Rene Garello ◽  
Ming-Xia He
Keyword(s):  
Sea Surface ◽  
Radar Backscatter ◽  
Simulation Based

scholarly journals GNSS-R Delay-Doppler Map Simulation Based on the 2004 Sumatra-Andaman Tsunami Event

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Qingyun Yan ◽  
Weimin Huang
Keyword(s):  
Region Of Interest ◽  
Final Analysis ◽  
Satellite System ◽  
Sea Surface ◽  
Scattering Coefficient ◽  
Scattering Coefficients ◽  
Coefficient Distribution ◽  
Simulation Based ◽  
Global Navigation Satellite ◽  
Fixed Region

A new method for simulating Global Navigation Satellite System-Reflectometry (GNSS-R) delay-Doppler maps (DDMs) of a tsunami-dominant sea surface is presented. In this method, the bistatic scattering Z-V model, the sea surface mean square slope model of Cox and Munk, and the tsunami-induced wind perturbation model are employed. The feasibility of the Cox and Munk model under a tsunami scenario is examined by comparing the Cox and Munk model based scattering coefficient with the Jason-1 measurement. A good consistency between these two results is obtained with a correlation coefficient of 0.93. After confirming the applicability of the Cox and Munk model for a tsunami-dominated sea, this study provides the simulations of the scattering coefficient distribution and the corresponding DDMs of a fixed region of interest before and during the tsunami. In the final analysis, by subtracting the simulation results that are free of tsunami from those with presence of tsunami, the tsunami-induced variations in scattering coefficients and DDMs can be clearly observed. As a result, the tsunami passage can be readily interpreted.

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