scholarly journals Glacial to interglacial climate variability in the southeastern African subtropics (25–20° S)

2021 ◽  
Vol 17 (1) ◽  
pp. 345-360
Author(s):  
Annette Hahn ◽  
Enno Schefuß ◽  
Jeroen Groeneveld ◽  
Charlotte Miller ◽  
Matthias Zabel
Keyword(s):  
Climate Variability ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Climatic Variability ◽  
Sea Surface ◽  
Temperate Climate ◽  
Small Scale ◽  
Convergence Zone ◽  
The Past ◽  
Catchment Areas

Abstract. We present a continuous and well-resolved record of climatic variability for the past 100 000 years from a marine sediment core taken in Delagoa Bight, off southeastern Africa. In addition to providing a sea surface temperature reconstruction for the past ca. 100 000 years, this record also allows a high-resolution continental climatic reconstruction. Climate sensitive organic proxies, like the distribution and isotopic composition of plant-wax lipids as well as elemental indicators of fluvial input and weathering type provide information on climatic changes in the adjacent catchment areas (Incomati, Matola and Lusutfu rivers). At the transition between glacials and interglacials, shifts in vegetation correlate with changes in sea surface temperature in the Agulhas Current. The local hydrology, however, does not follow these orbitally paced shifts. Instead, precipitation patterns follow millennial-scale variations with different forcing mechanisms in glacial vs. interglacial climatic states. During glacials, southward displacement of the Intertropical Convergence Zone facilitates a transmission of northern hemispheric signals (e.g., Heinrich events) to the southern hemispheric subtropics. Furthermore, the southern hemispheric westerlies become a more direct source of precipitation as they shift northward over the study site, especially during Antarctic cold phases. During interglacials, the observed short-term hydrological variability is also a function of Antarctic climate variability; however, it is driven by the indirect influence of the southern hemispheric westerlies and the associated South African high-pressure cell blocking the South Indian Ocean Convergence Zone related precipitation. As a consequence of the interplay of these effects, small-scale climatic zones exist. We propose a conceptual model describing latitudinal shifts of these zones along the southeastern African coast as tropical and temperate climate systems shift over glacial and interglacial cycles. The proposed model explains some of the apparent contradictions between several paleoclimate records in the region.

scholarly journals Glacial to interglacial climate variability in the southeastern African subtropics (25–20° S)

2020 ◽  
Author(s):  
Annette Hahn ◽  
Enno Schefuß ◽  
Jeroen Groeneveld ◽  
Charlotte Miller ◽  
Matthias Zabel
Keyword(s):  
Climate Variability ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Climatic Variability ◽  
Sea Surface ◽  
Temperate Climate ◽  
Small Scale ◽  
Convergence Zone ◽  
The Past ◽  
Catchment Areas

Abstract. We present a continuous and well-resolved record of climatic variability for the past 100,000 yrs from a marine sediment core taken in Delagoa Bight, off southeastern Africa. In addition to providing a sea surface temperature reconstruction for the past ca. 100,000 yrs, this record also allows a high-resolution continental climatic reconstruction. Climate sensitive organic proxies, like the distribution and isotopic composition of plant-wax lipids as well as elemental indicators for fluvial input and weathering type provide information on climatic changes in the adjacent catchment areas (Incomati, Matola, and Lusutfu rivers). At the transition between glacials and interglacials, shifts in vegetation correlate with changes in sea surface temperature in the Agulhas current. The local hydrology, however, does not follow these orbital-paced shifts. Instead, precipitation patterns follow millennial scale variations with different forcing mechanisms in glacial versus interglacial climatic states. During glacials, southward displacement of the Intertropical Convergence Zone facilitates a transmission of northern hemispheric signals (e.g. Heinrich events) to the southern hemispheric subtropics. Furthermore, the southern hemispheric westerlies become a more direct source of precipitation as they shift northward over the study site, especially during Antarctic cold phases. During interglacials, the observed short-term hydrological variability is also a function of Antarctic climate variability, however, it is driven by the indirect influence of the southern hemispheric westerlies and the associated South African high-pressure cell blocking the South Indian Ocean Convergence Zone related precipitation. As a consequence of the interplay of these effects, small scale climatic zones exist. We propose a conceptual model describing latitudinal shifts of these zones along the southeastern African coast as tropical and temperate climate systems shift over glacial and interglacial cycles. The proposed model explains some of the apparent contradictions between several paleoclimate records in the region.

scholarly journals Tropical and Extratropical predictions of the summer and autumn Niño3.4 Index: a comparison

2016 ◽  
Vol 42 ◽  
pp. 73-81
Author(s):  
Miguel Tasambay-Salazar ◽  
María José OrtizBeviá ◽  
Antonio RuizdeElvira ◽  
Francisco José Alvarez-García
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Linear Models ◽  
Southern Oscillation ◽  
Heat Content ◽  
Sea Surface ◽  
South Pacific Convergence Zone ◽  
Lead Times ◽  
Convergence Zone ◽  
The World

Abstract. The El Niño-Southern Oscillation (ENSO) phenomenon is the main source of the predictability skill in many regions of the world for seasonal and interannual timescales. Longer lead predictability experiments of Niño3.4 Index using simple statistical linear models have shown an important skill loss at longer lead times when the targeted season is summer or autumn. We develop different versions of the model substituting some its variables with others that contain tropical or extratropical information, produce a number of hindcasts with these models using two different predictions schemes and cross validate them. We have identified different sets of tropical or extratropical predictors, which can provide useful values of potential skill. We try to find out the sources of the predictability by comparing the sea surface temperature (SST) and heat content (HC) anomalous fields produced by the successful predictors for the 1980–2012 period. We observe that where tropical predictors are used the prediction reproduces only the equatorial characteristics of the warming (cooling). However, where extratropical predictors are included, the predictions are able to simulate the absorbed warming in the South Pacific Convergence Zone (SPCZ).

scholarly journals Centennial‐Scale SE Pacific Sea Surface Temperature Variability Over the Past 2,300 Years

2019 ◽  
Vol 34 (3) ◽  
pp. 336-352
Author(s):  
James A. Collins ◽  
Frank Lamy ◽  
Jérôme Kaiser ◽  
Nicoletta Ruggieri ◽  
Susann Henkel ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Temperature Variability ◽  
Sea Surface ◽  
The Past

scholarly journals Sea surface temperature variability in the Pacific sector of the Southern Ocean over the past 700 kyr

2012 ◽  
Vol 27 (4) ◽  
Author(s):  
Sze Ling Ho ◽  
Gesine Mollenhauer ◽  
Frank Lamy ◽  
Alfredo Martínez-Garcia ◽  
Mahyar Mohtadi ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Temperature Variability ◽  
Sea Surface ◽  
The Past ◽  
The Pacific

scholarly journals Extreme Convection and Tropical Climate Variability: Scaling of Cold Brightness Temperatures to Sea Surface Temperature

2016 ◽  
Vol 29 (10) ◽  
pp. 3893-3905 ◽  
Author(s):  
Sun Wong ◽  
João Teixeira
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Southern Oscillation ◽  
Convective Cloud ◽  
Sea Surface ◽  
South Pacific Convergence Zone ◽  
Convergence Zone ◽  
Test Bed ◽  
Brightness Temperatures ◽  
Warming World

Abstract Changes in tropical convective events provide a test bed for understanding changes of extreme convection in a warming climate. Because convective cloud top in deep convection is associated with cold brightness temperatures (BTs) in infrared window channels, variability in global convective events can be studied by spaceborne measurements of BTs. The sensitivity of BTs, directly measured by an Atmospheric Infrared Sounder (AIRS) window channel, to natural changes (the seasonal cycle and El Niño–Southern Oscillation) in tropical sea surface temperature (SST) is examined. It is found that tropical average BTs (over the ocean) at the low percentiles of their probability distributions scale with tropical average SSTs (higher SST leading to colder BTs), with the lower percentiles being significantly more sensitive to changes in SST. The sensitivity is reduced for high percentiles of BT and is insignificant for the median BT, and has similar magnitudes for the two natural changes used in the study. The regions where the lower-percentile BTs are most sensitive to SST are near the edges of the convection active areas (intertropical convergence zone and South Pacific convergence zone), including areas with active tropical cyclone activity. Since cold BTs of lower percentiles represent stronger convective events, this study provides, for the first time, global observational evidence of higher sensitivity of changes in stronger convective activity to a changing SST. This result has important potential implications in answering the key climate question of how severe tropical convection will change in a warming world.

Tropical Pacific and Atlantic Climate Variability in CCSM3

2006 ◽  
Vol 19 (11) ◽  
pp. 2451-2481 ◽  
Author(s):  
Clara Deser ◽  
Antonietta Capotondi ◽  
R. Saravanan ◽  
Adam S. Phillips
Keyword(s):  
Climate Variability ◽  
Surface Temperature ◽  
Spatial Pattern ◽  
Sea Surface Temperature ◽  
Wind Stress ◽  
El Nino ◽  
Coupled Model ◽  
Sea Surface ◽  
Thermocline Depth ◽  
Tropical Atlantic

Abstract Simulations of the El Niño–Southern Oscillation (ENSO) phenomenon and tropical Atlantic climate variability in the newest version of the Community Climate System Model [version 3 (CCSM3)] are examined in comparison with observations and previous versions of the model. The analyses are based upon multicentury control integrations of CCSM3 at two different horizontal resolutions (T42 and T85) under present-day CO2 concentrations. Complementary uncoupled integrations with the atmosphere and ocean component models forced by observed time-varying boundary conditions allow an assessment of the impact of air–sea coupling upon the simulated characteristics of ENSO and tropical Atlantic variability. The amplitude and zonal extent of equatorial Pacific sea surface temperature variability associated with ENSO is well simulated in CCSM3 at both resolutions and represents an improvement relative to previous versions of the model. However, the period of ENSO remains too short (2–2.5 yr in CCSM3 compared to 2.5–8 yr in observations), and the sea surface temperature, wind stress, precipitation, and thermocline depth responses are too narrowly confined about the equator. The latter shortcoming is partially overcome in the atmosphere-only and ocean-only simulations, indicating that coupling between the two model components is a contributing cause. The relationships among sea surface temperature, thermocline depth, and zonal wind stress anomalies are consistent with the delayed/recharge oscillator paradigms for ENSO. We speculate that the overly narrow meridional scale of CCSM3's ENSO simulation may contribute to its excessively high frequency. The amplitude and spatial pattern of the extratropical atmospheric circulation response to ENSO is generally well simulated in the T85 version of CCSM3, with realistic impacts upon surface air temperature and precipitation; the simulation is not as good at T42. CCSM3's simulation of interannual climate variability in the tropical Atlantic sector, including variability intrinsic to the basin and that associated with the remote influence of ENSO, exhibits similarities and differences with observations. Specifically, the observed counterpart of El Niño in the equatorial Atlantic is absent from the coupled model at both horizontal resolutions (as it was in earlier versions of the coupled model), but there are realistic (although weaker than observed) SST anomalies in the northern and southern tropical Atlantic that affect the position of the local intertropical convergence zone, and the remote influence of ENSO is similar in strength to observations, although the spatial pattern is somewhat different.

scholarly journals A sea surface temperature reconstruction for the southern Indian Ocean trade wind belt from corals in Rodrigues Island (19° S, 63° E)

2016 ◽  
Author(s):  
J. Zinke ◽  
L. Reuning ◽  
M. Pfeiffer ◽  
J. Wassenburg ◽  
E. Hardman ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
El Niño ◽  
El Nino ◽  
Sea Surface ◽  
Southern Indian Ocean ◽  
Trade Wind ◽  
The Past ◽  
Indian Ocean Trade

Abstract. The western Indian Ocean has been warming rapidly over the past decades and this has adversely impacted the Asian Monsoon circulation. It is therefore of paramount importance to improve our understanding of links between Indian Ocean Sea Surface Temperature (SST) variability, climate change, and sustainability of reef ecosystems. Here we present two monthly-resolved coral Sr/Ca records (Totor, Cabri) from Rodrigues Island (63° E, 19° S) in the south-central Indian Ocean trade wind belt, and reconstruct SST based on the linear relationship with the Sr/Ca proxy. The records extend to 1781 and 1945, respectively. We assess the reproducibility of the Sr/Ca records, and potential biases in our reconstruction associated with the orientation of corallites. We quantify long-term SST trends and identify interannual relationships with the El Niño-Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO). We conclude that careful screening for diagenesis and orientation of corallites is of paramount importance to assess the quality of Sr/Ca-based SST reconstructions. Our proxy records provide a reliable SST reconstruction between 1945 and 2006. We identify strong teleconnections with the ENSO/PDO over the past 60 years, eg. warming of SST during El Niño or positive PDO. We suggest that additional records from Rodrigues Island can provide excellent records of SST variations in the southern Indian Ocean trade wind belt and teleconnections with the ENSO/PDO on longer time scales.

scholarly journals VULNERABILITY ANALYSIS OF YELLOWFIN TUNA (THUNNUS ALBACARES) BASED ON THE SEA SURFACE TEMPERATURE DYNAMICS

2021 ◽  
Vol 56 (5) ◽  
pp. 404-415
Author(s):  
Abu Bakar Sambah ◽  
Dayu Dityo Kisworo ◽  
Gatut Bintoro ◽  
Feni Iranawati ◽  
M. A. Zainul Fuad ◽  
...  
Keyword(s):  
Climate Change ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Fisheries Management ◽  
Climatic Variability ◽  
Vulnerability Analysis ◽  
Yellowfin Tuna ◽  
Sea Surface ◽  
Integrated Analysis ◽  
Temperature Dynamics

The vulnerability of fisheries to climatic variability can be measured through the capacity of species to adapt to environmental change. It was also analyzed based on the analysis of fish production and susceptibility. Yellowfin tuna is one of the main commodities in the Palabuhanratu fishing port of Indonesia. The condition of yellowfin tuna fisheries needs to be studied due to the vulnerability of existing fishing activities and climate change parameters. This research was conducted at the Palabuhanratu fishing port, Sukabumi, West Java, Indonesia. Productivity and susceptibility analysis was used to determine the value of species vulnerability to fishing activities and based on the climatic variability. This study aims to analyze the vulnerability level of capture fisheries, especially for yellowfin tuna, to the Sea Surface Temperature dynamics through the analysis of productivity and susceptibility. The research will support capture fisheries management based on vulnerability analysis by providing a novel integrated analysis between productivity, susceptibility, and oceanographic data. The result of the productivity score was 2.11, and the susceptibility score was 2.17. It means that yellowfin tuna landed at the Palabuhanratu fishing port was threatened by vulnerability, but yellowfin tuna can recover and survive properly against fishing activities. The vulnerability score of yellowfin tuna was 1.6, which was classified as low vulnerability. The relationship between climate change parameters, namely sea surface temperature, and yellowfin tuna parameter, has a low-medium correlation and has an inverse relationship. Sea surface temperature can affect the development of larvae and eggs and the availability of yellowfin tuna food. By knowing the vulnerability of the yellowfin tuna fishery, sustainable fisheries management can be carried out both based on the regulation of the fishing season and the level of utilization.

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