scholarly journals Analisis Karakteristik Kekeringan DAS Kapuas Kalimantan Barat Berdasarkan Luaran Global Climate Model

POSITRON ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 74
Author(s):  
Andi Ihwan ◽  
Hidayat Pawitan ◽  
Rahmat Hidayat ◽  
Arnida Lailatul Latifah ◽  
Muh. Taufik
Keyword(s):  
El Niño ◽  
Input Data ◽  
Standardize Precipitation Index ◽  
Climate Model ◽  
El Nino ◽  
Global Climate ◽  
Global Climate Model ◽  
Precipitation Index

Daerah aliran sungai (DAS) Kapuas, walaupun berada di wilayah benua maritim Indonesia dengan curah hujan yang tinggi sepanjang tahun, namun sering mengalami kebakaran lahan dan hutan. Bencana kebakaran lahan dan hutan tersebut merupakan dampak dari kekeringan yang berkepanjangan. Informasi tentang karakteristik kekeringan di wilayah DAS Kapuas masih kurang diungkap terutama terkait dengan penggunaan data iklim global. Penelitian ini bertujuan untuk menganalisis karakteristik kekeringan meteorologis dan kekeringan hidrologis DAS Kapuas. Analisis kekeringan meteorologis digunakan pendekatan Standardize Precipitation Index (SPI) dan kekeringan hidrologis digunakan Standarized Runoff Index (SRI). Data curah hujan dan runoff dari Global Climate Model (GCM) yang telah di-downscaling menjadi 20 km x 20 km digunakan sebagai input data. Berdasarkan indeks kekeringan skala satu bulanan selama 30 tahun (1981-2010), diperoleh bahwa DAS Kapuas telah mengalami kekeringan meteorologis sebanyak 45 kali dan 48 kali kekeringan hidrologis dengan kategori moderat kering sampai dengan ekstrim kering. Luas wilayah yang mengalami kekeringan meteorologis maksimum terjadi pada tahun 1986 yakni 11,01% dari total wilayah DAS, kekeringan hidrologis maksimum terjadi pada tahun 1991 yakni 13,9% dari total wilayah DAS. Durasi kejadian kedua jenis kekeringan tersebut dominan berdurasi satu bulan. Luas wilayah kekeringan, tingkat keparahan, frekuensi, dan durasi kekeringan cenderung meningkat saat kejadian El-Niño. Hasil analisis karakteristik kekeringan menunjukkan bahwa data GCM dapat digunakan untuk analisis kekeringan di DAS Kapuas.

scholarly journals The Tropical Atmospheric El Niño Signal in Satellite Precipitation Data and a Global Climate Model

2007 ◽  
Vol 20 (14) ◽  
pp. 3580-3601 ◽  
Author(s):  
Yonghua Chen ◽  
Anthony D. Del Genio ◽  
Junye Chen
Keyword(s):  
El Niño ◽  
General Circulation ◽  
Climate Model ◽  
El Nino ◽  
Global Climate ◽  
Global Climate Model ◽  
Circulation Model ◽  
Western Indian Ocean ◽  
Correlation Technique ◽  
Atmospheric Response

Abstract Aspects of the tropical atmospheric response to El Niño related to the global energy and water cycle are examined using satellite retrievals from the Tropical Rainfall Measuring Mission and the Advanced Microwave Scanning Radiometer-E and simulations from the Goddard Institute for Space Studies (GISS) general circulation model (GCM). The El Niño signal is extracted from climate fields using a linear cross-correlation technique that captures local and remote in-phase and lagged responses. Passive microwave and radar precipitation anomalies for the 1997/98 and 2002/03 El Niños and the intervening La Niña are highly correlated, but anomalies in stratiform–convective rainfall partitioning in the two datasets are not. The GISS GCM produces too much rainfall in general over ocean and too little over land. Its atmospheric response to El Niño is weaker and decays a season too early. Underestimated stratiform rainfall fraction (SRF) and convective downdraft mass flux in the GISS GCM and excessive shallow convective and low stratiform cloud result in latent heating that peaks at lower altitudes than inferred from the data. The GISS GCM also underestimates the column water vapor content throughout the Tropics, which causes it to overestimate outgoing longwave radiation. The response of both quantities to interannual Hadley circulation anomalies is too weak. The GISS GCM’s Walker circulation also exhibits a weak remote response to El Niño, especially over the Maritime Continent and western Indian Ocean. This appears to be a consequence of weak static stability due to the model’s lack of upper-level stratiform anvil heating, excessive low-level heating, and excessive dissipation due to cumulus momentum mixing. Our results suggest that parameterizations of mesoscale updrafts, convective downdrafts, and cumulus-scale pressure gradient effects on momentum transport are keys to a reasonable GISS GCM simulation of tropical interannual variability.

scholarly journals The Hiatus in Global Warming and Interactions between the El Niño and the Pacific Decadal Oscillation: Comparing Observations and Modeling Results

Climate ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 72 ◽  
Author(s):  
Knut Seip ◽  
Hui Wang
Keyword(s):  
Global Warming ◽  
Pacific Decadal Oscillation ◽  
El Niño ◽  
Climate Model ◽  
El Nino ◽  
Global Climate ◽  
Global Climate Model ◽  
The Pacific ◽  
Common Cycles ◽  
Hadley Centre

Ocean oscillations interact across large regions and these interactions may explain cycles in global temperature anomaly, including hiatus periods. Here, we examine ocean interaction measures and compare results from model simulations to observations for El Niño and the Pacific decadal oscillation (PDO). We use the global climate model of the Met Office Hadley Centre. A relatively novel method for identifying running leading-agging LL-relations show that the observed El Niño generally leads the observed PDO and this pattern is strengthened in the simulations. However, LL-pattern in both observations and models shows that there are three periods, around 1910–1920, around 1960 and around 2000 where El Niño lags PDO, or the leading signature is weak. These periods correspond to hiatus periods in global warming. The power spectral density analysis, (PSD), identifies various ocean cycle lengths in El Niño and PDO, but the LL-algorithm picks out common cycles of 7–8 and 24 years that shows leading-lagging relations between them.

scholarly journals Response of O<sub>2</sub> and pH to ENSO in the California Current System in a high resolution global climate model

2017 ◽  
Author(s):  
Giuliana Turi ◽  
Michael Alexander ◽  
Nicole S. Lovenduski ◽  
Antonietta Capotondi ◽  
James Scott ◽  
...  
Keyword(s):  
High Resolution ◽  
El Niño ◽  
Climate Model ◽  
El Nino ◽  
Global Climate ◽  
Current System ◽  
Global Climate Model ◽  
California Current ◽  
California Current System ◽  
La Nina

Abstract. We use a novel, high-resolution global climate model (GFDL-ESM2.6) to investigate the influence of warm and cold El Niño/Southern Oscillation (ENSO) events on the physics and biogeochemistry of the California Current System (CalCS). We focus on the effect of ENSO on variations in the O2 concentration and the pH of the coastal waters of the CalCS. An assessment of the CalCS response to six El Niño and seven La Niña events in ESM2.6 reveals significant variations in the response between events. However, these variations overlay a consistent physical and biogeochemical (O2 and pH) response in the composite mean. Focusing on the mean response, our results demonstrate that O2 and pH are affected rather differently in the euphotic zone above ~100 m. The strongest O2 response reaches up to several 100 km offshore, whereas the pH signal occurs only within a ~100 km-wide band along the coast. By splitting the changes in O2 and pH into individual physical and biogeochemical components that are affected by ENSO variability, we found that O2 variability in the surface ocean is primarily driven by changes in surface temperature that affect the O2 solubility. In contrast, surface pH changes are predominantly driven by changes in dissolved inorganic carbon (DIC), which in turn is affected by upwelling, explaining the confined nature of the pH signal close to the coast. Below ~100 m, we find conditions with anomalously low O2 and pH, and by extension also anomalously low aragonite saturation, during La Niña. This result is consistent with findings from previous studies and highlights the stress that the CalCS ecosystem could periodically undergo in addition to impacts due to climate change.

scholarly journals Predicting the '97 El Niño event with a global climate model

1998 ◽  
Vol 25 (13) ◽  
pp. 2273-2276 ◽  
Author(s):  
Josef M. Oberhuber ◽  
E. Roeckner ◽  
M. Christoph ◽  
M. Esch ◽  
M. Latif
Keyword(s):  
El Niño ◽  
Climate Model ◽  
El Nino ◽  
Global Climate ◽  
Global Climate Model ◽  
El Niño Event

scholarly journals Investigating the Response of the Botswana High to El Niño Southern Oscillation using a Variable-Resolution Global Climate Model

2021 ◽  
Author(s):  
Molulaqhooa Linda Maoyi ◽  
Babatunde Joseph Abiodun
Keyword(s):  
Southern Africa ◽  
El Niño ◽  
Climate Model ◽  
El Nino ◽  
Southern Oscillation ◽  
Global Climate ◽  
Global Climate Model ◽  
El Nino Southern Oscillation ◽  
Grid Spacing ◽  
Variable Resolution

Abstract The Botswana High is an important component of the regional atmospheric circulation during austral spring, summer and autumn. While the high tends to be stronger during El Niño and weaker during La Niña, its direct response to El Niño Southern Oscillation (ENSO) remains unknown. To that end, a variable resolution global climate model (Model Prediction Across Scales version 7, hereafter MPAS) is applied with relatively high resolution (48 km grid spacing) over southern Africa and a coarser resolution (240 km grid spacing) over the rest of the globe for the study period 1980–2010. The first model experiment uses observed SSTs everywhere during the study period, while the second experiment uses observed SSTs everywhere except over the Pacific Ocean, where monthly climatological SSTs are imposed. The model results were validated against satellite data (Global Precipitation Climatology Project, GPCP), reanalysis datasets (Climate Forecast System Reanalysis, CFSR; European Centre for Medium-Range Weather Forecasts version 5, ERA5). The results of the study show that the MPAS model gives a credible simulation of the temporal variability of the Botswana High, the seasonal rainfall and 500 hPa geopotential heights over southern Africa. In the absence of ENSO forcing, the amplitude of the Botswana High variability reduces but the signal of the variability remains. Hence, this study shows that ENSO enhances the strength of the Botswana High but does not aid in the formation of the Botswana High.

scholarly journals The Impact of Obliquity Change on El Niño Southern Oscillation (ENSO) and La Niña Climate Episodes

2022 ◽  
Author(s):  
Paul C. Rivera
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Global Climate ◽  
Global Climate Model ◽  
La Niña ◽  
El Niño Southern Oscillation ◽  
El Nino Southern Oscillation ◽  
La Nina ◽  
The Impact

An alternative physical mechanism is proposed to describe the occurrence of the episodic El Nino Southern Oscillation (ENSO) and La Nina climatic phenomena. This is based on the earthquake-perturbed obliquity change (EPOCH) model previously discovered as a major cause of the global climate change problem. Massive quakes impart a very strong oceanic force that can move the moon which in turn pulls the earth’s axis and change the planetary obliquity. Analysis of the annual geomagnetic north-pole shift and global seismic data revealed this previously undiscovered force. Using a higher obliquity in the global climate model EdGCM and constant greenhouse gas forcing showed that the seismic-induced polar motion and associated enhanced obliquity could be the major mechanism governing the mysterious climate anomalies attributed to El Nino and La Nina cycles.

scholarly journals Implications of the permanent El Niño teleconnection "blueprint" for past global and North American hydroclimatology

2011 ◽  
Vol 7 (3) ◽  
pp. 723-743 ◽  
Author(s):  
A. Goldner ◽  
M. Huber ◽  
N. Diffenbaugh ◽  
R. Caballero
Keyword(s):  
United States ◽  
North America ◽  
North American ◽  
El Niño ◽  
Climate Model ◽  
El Nino ◽  
Global Climate Model ◽  
Future Climate Change ◽  
Analogue Model ◽  
Change In Mean

Abstract. Substantial evidence exists for wetter-than-modern continental conditions in North America during the pre-Quaternary warm climate intervals. This is in apparent conflict with the robust global prediction for future climate change of a northward expansion of the subtropical dry zones that should drive aridification of many semiarid regions. Indeed, areas of expected future aridification include much of western North America, where extensive paleoenvironmental records are documented to have been much wetter before the onset of Quaternary ice ages. It has also been proposed that climates previous to the Quaternary may have been characterized as being in a state with warmer-than-modern eastern equatorial sea surface temperatures (SSTs). Because equatorial Pacific SSTs exert strong controls on midlatitude atmospheric circulation and the global hydrologic cycle, the teleconnected response from this permanent El Niño-like mean state has been proposed as a useful analogue model, or "blueprint", for understanding global climatological anomalies in the past. The present study quantitatively explores the implications of this blueprint for past climates with a specific focus on the Miocene and Pliocene, using a global climate model (CAM3.0) and a nested high-resolution climate model (RegCM3) to study the hydrologic impacts on global and North American climate of a change in mean SSTs resembling that which occurs during modern El Niño events. We find that the global circulation response to a permanent El Niño resembles a large, long El Niño event. This state also exhibits equatorial super-rotation, which would represent a fundamental change to the tropical circulations. We also find a southward shift in winter storm tracks in the Pacific and Atlantic, which affects precipitation and temperature over the mid-latitudes. In addition, summertime precipitation increases over the majority of the continental United States. These increases in precipitation are controlled by shifts in the subtropical jet and secondary atmospheric feedbacks. Based on these results and the data proxy comparison, we conclude that a permanent El Niño like state is one potential explanation of wetter-than-modern conditions observed in paleoclimate-proxy records, particularly over the western United States.

scholarly journals Response of O<sub>2</sub> and pH to ENSO in the California Current System in a high-resolution global climate model

Ocean Science ◽  
2018 ◽  
Vol 14 (1) ◽  
pp. 69-86 ◽  
Author(s):  
Giuliana Turi ◽  
Michael Alexander ◽  
Nicole S. Lovenduski ◽  
Antonietta Capotondi ◽  
James Scott ◽  
...  
Keyword(s):  
High Resolution ◽  
Climate Model ◽  
Coastal Upwelling ◽  
El Nino ◽  
Global Climate ◽  
Current System ◽  
Global Climate Model ◽  
California Current ◽  
California Current System ◽  
La Nina

Abstract. Coastal upwelling systems, such as the California Current System (CalCS), naturally experience a wide range of O2 concentrations and pH values due to the seasonality of upwelling. Nonetheless, changes in the El Niño–Southern Oscillation (ENSO) have been shown to measurably affect the biogeochemical and physical properties of coastal upwelling regions. In this study, we use a novel, high-resolution global climate model (GFDL-ESM2.6) to investigate the influence of warm and cold ENSO events on variations in the O2 concentration and the pH of the CalCS coastal waters. An assessment of the CalCS response to six El Niño and seven La Niña events in ESM2.6 reveals significant variations in the response between events. However, these variations overlay a consistent physical and biogeochemical (O2 and pH) response in the composite mean. Focusing on the mean response, our results demonstrate that O2 and pH are affected rather differently in the euphotic zone above ∼ 100 m. The strongest O2 response reaches up to several hundreds of kilometers offshore, whereas the pH signal occurs only within a ∼ 100 km wide band along the coast. By splitting the changes in O2 and pH into individual physical and biogeochemical components that are affected by ENSO variability, we found that O2 variability in the surface ocean is primarily driven by changes in surface temperature that affect the O2 solubility. In contrast, surface pH changes are predominantly driven by changes in dissolved inorganic carbon (DIC), which in turn is affected by upwelling, explaining the confined nature of the pH signal close to the coast. Below ∼ 100 m, we find conditions with anomalously low O2 and pH, and by extension also anomalously low aragonite saturation, during La Niña. This result is consistent with findings from previous studies and highlights the stress that the CalCS ecosystem could periodically undergo in addition to impacts due to climate change.

scholarly journals Implications of the permanent El Niño teleconnection "blueprint" for past global and North American hydroclimatology

2011 ◽  
Vol 7 (1) ◽  
pp. 199-240
Author(s):  
A. Goldner ◽  
M. Huber ◽  
N. Diffenbaugh ◽  
R. Caballero
Keyword(s):  
United States ◽  
North America ◽  
Atmospheric Circulation ◽  
North American ◽  
El Niño ◽  
Climate Model ◽  
El Nino ◽  
Global Climate Model ◽  
Future Climate Change ◽  
Analogue Model

Abstract. Substantial evidence exists for wetter-than-modern continental conditions in past warm climates. This is in apparent conflict with the robust global prediction for future climate change of a northward expansion of the subtropical dry zones that should drive aridification of many semiarid regions. Areas of expected aridification include much of Western North America, where extensive paleoenvironmental records from North America point to wetter conditions before the onset of Quaternary ice ages. It has been proposed that climates previous to the early Pliocene may have been characterized as being in a state with warmer-than-modern eastern equatorial sea surface temperatures (SSTs). Because Equatorial Pacific SSTs exert strong controls on midlatitude atmospheric circulation and the global hydrologic cycle, the teleconnected response from this permanent El Niño-like mean state has been proposed as a useful analogue model, or "blueprint", for understanding global climatological and hydrological anomalies in the past. The present study quantitatively explores the implications of this blueprint for past climates, using a global climate model (CAM3.0) and a nested high-resolution climate model (RegCM3) to study the hydrologic impacts of a permanent El Niño on global and North American climate. We find that the global circulation response to a permanent El Niño resembles a large, long El Niño event. However, this state also exhibits equatorial super-rotation, which would represent a fundamental change to the tropical circulations. We also find intensification and southward drift in winter storm tracks in the Pacific, which affects precipitation and temperature over the mid-latitudes via large shifts in atmospheric circulation. In addition, summertime precipitation increases over the majority of the continental United States, with these increases likely controlled by shifts in the subtropical jet and secondary atmospheric feedbacks. Based on these results, we conclude that a permanent El Niño is a good explanation of the Pre-Quaternary wetter-than-modern conditions observed in paleo proxy records, particularly over the Western United States.

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