scholarly journals Using the Moist Static Energy Budget to Understand Storm-Track Shifts across a Range of Time Scales

2017 ◽  
Vol 74 (8) ◽  
pp. 2427-2446 ◽  
Author(s):  
Pragallva Barpanda ◽  
Tiffany Shaw
Keyword(s):  
Time Scales ◽  
El Niño ◽  
El Nino ◽  
Storm Track ◽  
La Niña ◽  
Net Energy ◽  
Flux Divergence ◽  
La Nina ◽  
Mean Meridional Circulation ◽  
Static Energy

Abstract Storm tracks shift meridionally in response to forcing across a range of time scales. Here the authors formulate a moist static energy (MSE) framework for storm-track position and use it to understand storm-track shifts in response to seasonal insolation, El Niño minus La Niña conditions, and direct (increased CO2 over land) and indirect (increased sea surface temperature) effects of increased CO2. Two methods (linearized Taylor series and imposed MSE flux divergence) are developed to quantify storm-track shifts and decompose them into contributions from net energy (MSE input to the atmosphere minus atmospheric storage) and MSE flux divergence by the mean meridional circulation and stationary eddies. Net energy is not a dominant contribution across the time scales considered. The stationary eddy contribution dominates the storm-track shift in response to seasonal insolation, El Niño minus La Niña conditions, and CO2 direct effect in the Northern Hemisphere, whereas the mean meridional circulation contribution dominates the shift in response to CO2 indirect effect during northern winter and in the Southern Hemisphere during May and October. Overall, the MSE framework shows the seasonal storm-track shift in the Northern Hemisphere is connected to the stationary eddy MSE flux evolution. Furthermore, the equatorward storm-track shift during northern winter in response to El Niño minus La Niña conditions involves a different regime than the poleward shift in response to increased CO2 even though the tropical upper troposphere warms in both cases.

scholarly journals Indo-Pacific Variability on Seasonal to Multidecadal Time Scales. Part II: Multiscale Atmosphere–Ocean Linkages

2018 ◽  
Vol 31 (2) ◽  
pp. 693-725 ◽  
Author(s):  
Dimitrios Giannakis ◽  
Joanna Slawinska
Keyword(s):  
Time Scales ◽  
El Niño ◽  
El Nino ◽  
Walker Circulation ◽  
La Niña ◽  
Central Pacific ◽  
Australian Monsoon ◽  
La Nina ◽  
Combination Modes ◽  
Sst Anomalies

The coupled atmosphere–ocean variability of the Indo-Pacific domain on seasonal to multidecadal time scales is investigated in CCSM4 and in observations through nonlinear Laplacian spectral analysis (NLSA). It is found that ENSO modes and combination modes of ENSO with the annual cycle exhibit a seasonally synchronized southward shift of equatorial surface zonal winds and thermocline adjustment consistent with terminating El Niño and La Niña events. The surface winds associated with these modes also generate teleconnections between the Pacific and Indian Oceans, leading to SST anomalies characteristic of the Indian Ocean dipole. The family of NLSA ENSO modes is used to study El Niño–La Niña asymmetries, and it is found that a group of secondary ENSO modes with more rapidly decorrelating temporal patterns contributes significantly to positively skewed SST and zonal wind statistics. Besides ENSO, fundamental and combination modes representing the tropospheric biennial oscillation (TBO) are found to be consistent with mechanisms for seasonally synchronized biennial variability of the Asian–Australian monsoon and Walker circulation. On longer time scales, a multidecadal pattern referred to as the west Pacific multidecadal mode (WPMM) is established to significantly modulate ENSO and TBO activity, with periods of negative SST anomalies in the western tropical Pacific favoring stronger ENSO and TBO variability. This behavior is attributed to the fact that cold WPMM phases feature anomalous decadal westerlies in the tropical central Pacific, as well as an anomalously flat zonal thermocline profile in the equatorial Pacific. Moreover, the WPMM is found to correlate significantly with decadal precipitation over Australia.

scholarly journals The Predictability of Interdecadal Changes in ENSO Activity and ENSO Teleconnections

2006 ◽  
Vol 19 (19) ◽  
pp. 4755-4771 ◽  
Author(s):  
Scott Power ◽  
Malcolm Haylock ◽  
Rob Colman ◽  
Xiangdong Wang
Keyword(s):  
Time Scales ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
La Niña ◽  
Enso Teleconnections ◽  
La Nina ◽  
Sst Anomaly ◽  
The Relationship ◽  
Interdecadal Changes

Abstract El Niño–Southern Oscillation (ENSO) in a century-long integration of a Bureau of Meteorology Research Centre (BMRC) coupled general circulation model (CGCM) drives rainfall and temperature changes over Australia that are generally consistent with documented observational changes: dry/hot conditions occur more frequently during El Niño years and wet/mild conditions occur more frequently during La Niña years. The relationship between ENSO [as measured by Niño-4 or the Southern Oscillation index (SOI), say] and all-Australia rainfall and temperature is found to be nonlinear in the observations and in the CGCM during June–December: a large La Niña sea surface temperature (SST) anomaly is closely linked to a large Australian response (i.e., Australia usually becomes much wetter), whereas the magnitude of an El Niño SST anomaly is a poorer guide to how dry Australia will actually become. Australia tends to dry out during El Niño events, but the degree of drying is not as tightly linked to the magnitude of the El Niño SST anomaly. Nonlinear or asymmetric teleconnections are also evident in the western United States/northern Mexico. The implications of asymmetric teleconnections for prediction services are discussed. The relationship between ENSO and Australian climate in both the model and the observations is strong in some decades, but weak in others. A series of decadal-long perturbation experiments are used to show that if these interdecadal changes are predictable, then the level of predictability is low. The model’s Interdecadal Pacific Oscillation (IPO), which represents interdecadal ENSO-like SST variability, is statistically linked to interdecadal changes in ENSO’s impact on Australia during June–December when ENSO’s impact on Australia is generally greatest. A simple stochastic model that incorporates the nonlinearity above is used to show that the IPO [or the closely related Pacific Decadal Oscillation (PDO)] can appear to modulate ENSO teleconnections even if the IPO–PDO largely reflect unpredictable random changes in, for example, the relative frequency of El Niño and La Niña events in a given interdecadal period. Note, however, that predictability in ENSO-related variability on decadal time scales might be either underestimated by the CGCM, or be too small to be detected by the modest number of perturbation experiments conducted. If there is a small amount of predictability in ENSO indices on decadal time scales, and there may be, then the nonlinearity described above provides a mechanism via which ENSO teleconnections could be modulated on decadal time scales in a partially predictable fashion.

scholarly journals The Consistency of MJO Teleconnection Patterns on Interannual Time Scales

2020 ◽  
Vol 33 (9) ◽  
pp. 3471-3486 ◽  
Author(s):  
Kai-Chih Tseng ◽  
Eric Maloney ◽  
Elizabeth A. Barnes
Keyword(s):  
Time Scales ◽  
Rossby Wave ◽  
El Niño ◽  
El Nino ◽  
Reanalysis Data ◽  
La Niña ◽  
Wave Source ◽  
Teleconnection Patterns ◽  
La Nina ◽  
Wave Ray

AbstractThe Madden–Julian oscillation (MJO) excites strong variations in extratropical geopotential heights that modulate extratropical weather, making the MJO an important predictability source on subseasonal to seasonal time scales (S2S). Previous research demonstrates a strong similarity of teleconnection patterns across MJO events for certain MJO phases (i.e., pattern consistency) and increased model ensemble agreement during these phases that is beneficial for extended numerical weather forecasts. However, the MJO’s ability to modulate extratropical weather varies greatly on interannual time scales, which brings extra uncertainty in leveraging the MJO for S2S prediction. Few studies have investigated the mechanisms responsible for variations in the consistency of MJO tropical–extratropical teleconnections on interannual time scales. This study uses reanalysis data, ensemble simulations of a linear baroclinic model, and a Rossby wave ray tracing algorithm to demonstrate that two mechanisms largely determine the interannual variability of MJO teleconnection consistency. First, the meridional shift of stationary Rossby wave ray paths indicates increases (decreases) in the MJO’s extratropical modulation during La Niña (El Niño) years. Second, a previous study proposed that the constructive interference of Rossby wave signals caused by a dipole Rossby wave source pattern across the subtropical jet during certain MJO phases produces a consistent MJO teleconnection. However, this dipole feature is less clear in both El Niño and La Niña years due to the extension and contraction of MJO convection, respectively, which would decrease the MJO’s influence in the extratropics. Hence, considering the joint influence of the basic state and MJO forcing, this study suggests a diminished potential to leverage the MJO for S2S prediction in El Niño years.

scholarly journals The non-linear impact of El Nino, La Nina and the Southern Oscillation on seasonal and regional Australian precipitation

2017 ◽  
Vol 67 (1) ◽  
pp. 25
Author(s):  
Christine T. Y. Chung ◽  
Scott B. Power
Keyword(s):  
Time Scales ◽  
El Niño ◽  
Southern Oscillation Index ◽  
El Nino ◽  
Southern Oscillation ◽  
La Niña ◽  
La Nina ◽  
Non Linear ◽  
The Relationship ◽  
Enso Indices

The relationship between El Niño-Southern Oscillation (ENSO) indices and precipitation (P) in some parts of Australia has previously been shown to be non-linear on annual and seasonal time scales. Here we examine the relationship between P and the Southern Oscillation Index (SOI) at all Australian locations and in all seasons. We show that in many Australian regions, there is more-than-expected P during strong La Niña years (SOI>13), but less-than-expected drying during strong El Niño years (SOI

scholarly journals Climatology and ENSO-Related Variability of North American Extratropical Cyclone Activity

2006 ◽  
Vol 19 (10) ◽  
pp. 2076-2093 ◽  
Author(s):  
Timothy Eichler ◽  
Wayne Higgins
Keyword(s):  
North American ◽  
El Niño ◽  
East Coast ◽  
Extreme Event ◽  
El Nino ◽  
Storm Track ◽  
La Niña ◽  
Boreal Winter ◽  
Enso Cycle ◽  
La Nina

Abstract The climatology and interannual variability of North American extratropical cyclones are examined using 6-hourly sea level pressure data from the NCEP–NCAR reanalysis for the period 1950–2002 and ECMWF 40-yr Re-Analysis (ERA-40) data from 1971 to 2000. The climatology includes an evaluation of the seasonal frequency and intensity of storms as well as an analysis of extreme event intensity. ENSO variability is evaluated by ENSO phase with emphasis on boreal winter. Results show an enhanced East Coast storm track during El Niño as well as an equatorward shift in storm tracks in the North Pacific for storms generated from both the NCEP–NCAR reanalysis and ERA-40 datasets. Observed precipitation close to a storm’s center is used to determine which phase of the ENSO cycle is associated with the most productive storms and where they occur. During El Niño winters, a precipitation maximum is located east of the Appalachians and is associated with an enhanced East Coast storm track. During La Niña winters, the precipitation maximum shifts to the Ohio Valley and is associated with an enhanced Great Lakes storm track. Along the U.S. west coast, there is a precipitation maximum in the Pacific Northwest during La Niña winters, which is due to a storm track west of Washington State.

scholarly journals Simulation of ENSO teleconnections to precipitation extremes over the US in the high resolution version of E3SM

2021 ◽  
pp. 1-62
Author(s):  
Qi Tang ◽  
Noel D. Keen ◽  
Jean-Christophe Golaz ◽  
Luke P. van Roekel
Keyword(s):  
El Niño ◽  
Large Scale ◽  
El Nino ◽  
Storm Track ◽  
La Niña ◽  
Model Bias ◽  
Enso Teleconnections ◽  
La Nina ◽  
The Pacific ◽  
Storm Track Activity

Abstract We evaluate the simulated teleconnection of El Niño Southern Oscillation (ENSO) to winter season precipitation extremes over the United States in a long (98 years) 1950-control high resolution version (HR, 25 km nominal atmosphere model horizontal resolution) of US Department of Energy’s (DOE) Energy Exascale Earth System Model version 1 (E3SMv1). Model bias and spatial pattern of ENSO teleconnections to mean and extreme precipitation in HR overall are similar to the low-resolution model’s (LR, 110 km) historical simulation (4-member ensemble, 1925-1959). However, over the Southeast US (SE-US), HR produces stronger El Niño associated extremes, reducing upon LR’s model bias. Both LR and HR produce weaker than observed increase in storm track activity during El Niño events there. But, HR improves the ENSO associated variability of moisture transport over SE-US. During El Niño, stronger vertical velocities in HR produce stronger large-scale precipitation causing larger latent heating of the troposphere that pulls in more moisture from the Gulf of Mexico into the SE-US. This positive feedback also contributes to the stronger mean and extreme precipitation response in HR. Over the Pacific Northwest, LR’s bias of stronger than observed La Niña associated extremes is amplified in HR. Both models simulate stronger than observed moisture transport from the Pacific Ocean into the region during La Niña years. The amplified HR bias there is due to stronger orographically driven vertical updrafts that create stronger large scale precipitation, despite weaker La Niña induced storm track activity.

scholarly journals Precipitation response to El Niño/La Niña events in Southern South America – emphasis in regional drought occurrences

2016 ◽  
Vol 42 ◽  
pp. 1-14 ◽  
Author(s):  
Olga Clorinda Penalba ◽  
Juan Antonio Rivera
Keyword(s):  
Time Series ◽  
South America ◽  
Time Scales ◽  
El Niño ◽  
El Nino ◽  
La Niña ◽  
Southern South America ◽  
La Nina ◽  
Precipitation Response ◽  
Drought Conditions

Abstract. The ENSO phenomenon is one of the key factors that influence the interannual variability of precipitation over Southern South America. The aim of this study is to identify the regional response of precipitation to El Niño/La Niña events, with emphasis in drought conditions. The standardized precipitation index (SPI) was used to characterize precipitation variabilities through the 1961–2008 period for time scales of 3 (SPI3) and 12 (SPI12) months. A regionalization based on rotated principal component analysis allowed to identify seven coherent regions for each of the time scales considered. In order to identify the regional influence of El Niño and La Niña events on the SPI time series, we calculated the mean SPI values for the El Niño and La Niña years and assessed its significance through bootstrap analysis. We found coherent and significant SPI responses to ENSO phases in most of the seven regions considered, mainly for the SPI12 time series. The precipitation response to La Niña events is characterized with regional deficits, identified with negative values of the SPI during the end of La Niña year and the year after. During El Niño events the precipitation response is reversed and more intense/consistent than in the case of La Niña events. This signal has some regional differences regarding its magnitude and timing, and the quantification of these features, together with the assessment of the SST composites during drought conditions provided critical baseline information for the agricultural and water resources sectors.

scholarly journals Análise Quantitativa da Variabilidade da Chuva em João Pessoa-PB, em Várias Escalas de Tempo (Quantitative Analysis of the Rain Variability in João Pessoa-PB, on Several Time Scales)

2016 ◽  
Vol 8 (6) ◽  
pp. 1748
Author(s):  
Biancca Correia de Medeiros ◽  
Aldinete Bezerra Barreto ◽  
José Diorgenes Alves de Oliveira ◽  
Regina Aragão Silva
Keyword(s):  
Time Scales ◽  
El Niño ◽  
El Nino ◽  
Rainfall Variability ◽  
La Niña ◽  
Land Breeze ◽  
Monthly Precipitation ◽  
Rainfall Events ◽  
Area Of Interest ◽  
La Nina

A área de interesse para este estudo foi João Pessoa, capital do Estado da Paraíba, localizada no litoral do Nordeste do Brasil. Neste estudo foram utilizados totais diários (1961 a 2012) da precipitação observada na estação climatológica do Instituto Nacional de Meteorologia (INMET), em João Pessoa-PB. Os dados foram usados para estudar a variabilidade da chuva em várias escalas de tempo, investigando as anomalias de precipitação em anos de El Niño e La Niña, como também identificar eventos de chuva intensa com ênfase em casos extremos. Os resultados destacam os meses de abril a julho como o período de picos máximos da precipitação média mensal e da frequência máxima do número de dias com chuva, bem como o período de número máximo de eventos extremos de chuva. Os desvios padronizados de precipitação (DPP) mensais apresentam valores negativos e positivos, entre -1,7 e 3,7. Observou-se que os DPP negativos predominam tanto na época de El Niño (62,04%) quanto de La Niña (56,37%), o que significa uma diminuição no volume de chuva, mas não representa uma evidência significativa da influência dos fenômenos El Niño e La Niña sobre a variabilidade da chuva. No ciclo diário, ficou evidente a importância da circulação de brisa terrestre no regime de precipitação da cidade de João Pessoa, já que favorece a chuva no final da noite até o inicio da manhã, com frequência máxima as 6 HL (Horário Local).   A B S T R A C T The area of interest for this study was João Pessoa, capital of Paraiba State, located on the coast of Northeast Brazil. In this study daily (1961-2012) rainfall totals observed at the meteorological station of the National Institute of Meteorology (INMET) in João Pessoa-PB were employed. The data were used to study the variability of rainfall on various time scales, investigating the precipitation anomalies in El Niño and La Niña years, as well as identifying heavy rainfall events with an emphasis on extreme cases. The results highlight the months from April to July as the period of maxima in the mean monthly precipitation, and in the frequency of rain days and extreme rainfall events. The monthly standardized precipitation deviation (DPP) shows negative and positive values ranging from -1.7 to 3.7. It was observed that negative DPP are more frequent both at the time of El Niño (62.04%) and La Niña (56.37%), which means a decrease in the volume of rainfall. But these results do not confirm a significant evidence of the influence of El Niño and La Niña phenomena on rainfall variability. In the daily cycle, it was evident the importance of the land breeze circulation in the precipitation regime of the city of João Pessoa, since it favors rainfall in late evening up to early morning, with maximum frequency at 6 LT (Local Time). Keywords: Urban Area. Precipitation. Extreme Event. Standard Deviation.   

ANALISIS DAERAH RAWAN KEKERINGAN LAHAN JAGUNG BERDASARKAN IKLIM OLDEMAN DAN KETERSEDIAN AIR TANAH DI NUSA TENGGARA TIMUR SAAT PERIODE EL NINO DAN LA NINA

2019 ◽  
Vol 3 ◽  
pp. 1219
Author(s):  
Oki Adrianto ◽  
Sudirman Sudirman ◽  
Suwandi Suwandi
Keyword(s):  
El Niño ◽  
El Nino ◽  
La Niña ◽  
La Nina

Perekonomian Provinsi Nusa Tenggara Timur secara sektoral masih didominasi sektor pertanian.Tanaman jagung menjadi salah satu produksi tanaman pangan terbesar berdasarkan data dari Dinas Pertanian dan Perkebunan Provinsi Nusa Tenggara Timur tahun 2015. Peningkatan produksi pertanian dapat dilakukan melalui berbagai strategi adaptasi dan upaya penanganan bencana, salah satu upaya tersebut adalah dengan penyediaan informasi iklim terkait penentuan daerah-daerah rawan kekeringan. Tujuan dari penelitian ini adalah untuk mengetahui sebaran wilayah rawan kekeringan lahan jagung bulanan di Provinsi Nusa Tenggara Timur saat kondisi El Nino dan La Nina dengan periodeisasi bulanan januari hingga desember. Data yang digunakan dalam penelitian ini adalah data curah hujan rata rata bulanan di 19 pos hujan di Provinsi Nusa Tenggara Timur dan suhu udara rata-rata bulanan dihitung menggunakan pendekatan teori Brack dengan titik referensi Stasiun Klimatologi Lasiana Kupang. Periode dari masing-masing data yang digunakan adalah dari tahun 1991 dan 1997 digunakan sebagai tahun El Nino dan tahun 1999 dan 2010 digunakan sebagai tahun La Nina. Metode yang digunakan untuk menentukan tingkat rawan kekeringan dengan menggunakan pembobotan berdasarkan penjumlahan bobot tipe iklim Oldeman dan bobot ketersediaan air tanah. Hasil penelitian menunjukkan sebaran daerah kekeringan di Provinsi Nusa Tenggara Timurpada tahun el nino lebih luas dibandingkan tahun la nina.

A Influência dos fenômenos El Niño e La Niña sobre a dinâmica climática da região Amazônica

2018 ◽  
Vol 1 ◽  
pp. e2018014
Author(s):  
Samya de Freitas MOREIRA ◽  
Cleiciane Silva da CONCEIÇÃO ◽  
Milla Cristina Santos da CRUZ ◽  
Antônio PEREIRA JÚNIOR
Keyword(s):  
El Niño ◽  
El Nino ◽  
La Niña ◽  
La Nina
Sign in / Sign up

Export Citation Format

Share Document