Impact of Common Sea Surface Temperature Anomalies on Global Drought and Pluvial Frequency

2010 ◽  
Vol 23 (3) ◽  
pp. 485-503 ◽  
Author(s):  
Kirsten L. Findell ◽  
Thomas L. Delworth

Abstract Climate model simulations run as part of the Climate Variability and Predictability (CLIVAR) Drought Working Group initiative were analyzed to determine the impact of three patterns of sea surface temperature (SST) anomalies on drought and pluvial frequency and intensity around the world. The three SST forcing patterns include a global pattern similar to the background warming trend, a pattern in the Pacific, and a pattern in the Atlantic. Five different global atmospheric models were forced by fixed SSTs to test the impact of these SST anomalies on droughts and pluvials relative to a climatologically forced control run. The five models generally yield similar results in the locations of drought and pluvial frequency changes throughout the annual cycle in response to each given SST pattern. In all of the simulations, areas with an increase in the mean drought (pluvial) conditions tend to also show an increase in the frequency of drought (pluvial) events. Additionally, areas with more frequent extreme events also tend to show higher intensity extremes. The cold Pacific anomaly increases drought occurrence in the United States and southern South America and increases pluvials in Central America and northern and central South America. The cold Atlantic anomaly increases drought occurrence in southern Central America, northern South America, and central Africa and increases pluvials in central South America. The warm Pacific and Atlantic anomalies generally lead to reversals of the drought and pluvial increases described with the corresponding cold anomalies. More modest impacts are seen in other parts of the world. The impact of the trend pattern is generally more modest than that of the two other anomaly patterns.

2015 ◽  
Vol 28 (10) ◽  
pp. 4034-4060 ◽  
Author(s):  
Belen Rodríguez-Fonseca ◽  
Elsa Mohino ◽  
Carlos R. Mechoso ◽  
Cyril Caminade ◽  
Michela Biasutti ◽  
...  

Abstract The Sahel experienced a severe drought during the 1970s and 1980s after wet periods in the 1950s and 1960s. Although rainfall partially recovered since the 1990s, the drought had devastating impacts on society. Most studies agree that this dry period resulted primarily from remote effects of sea surface temperature (SST) anomalies amplified by local land surface–atmosphere interactions. This paper reviews advances made during the last decade to better understand the impact of global SST variability on West African rainfall at interannual to decadal time scales. At interannual time scales, a warming of the equatorial Atlantic and Pacific/Indian Oceans results in rainfall reduction over the Sahel, and positive SST anomalies over the Mediterranean Sea tend to be associated with increased rainfall. At decadal time scales, warming over the tropics leads to drought over the Sahel, whereas warming over the North Atlantic promotes increased rainfall. Prediction systems have evolved from seasonal to decadal forecasting. The agreement among future projections has improved from CMIP3 to CMIP5, with a general tendency for slightly wetter conditions over the central part of the Sahel, drier conditions over the western part, and a delay in the monsoon onset. The role of the Indian Ocean, the stationarity of teleconnections, the determination of the leader ocean basin in driving decadal variability, the anthropogenic role, the reduction of the model rainfall spread, and the improvement of some model components are among the most important remaining questions that continue to be the focus of current international projects.


2020 ◽  
Vol 33 (22) ◽  
pp. 9653-9672
Author(s):  
Shaobo Qiao ◽  
Meng Zou ◽  
Shankai Tang ◽  
Ho Nam Cheung ◽  
Haijing Su ◽  
...  

AbstractThe impact of the wintertime North Atlantic Oscillation (NAO) on the subsequent sea surface temperature (SST) anomalies over the tropical Atlantic has experienced obvious interdecadal changes during 1950–2015. During 1995–2015, the negative (positive) phase of the wintertime NAO favors positive (negative) SST anomalies over the tropical Atlantic in the subsequent spring–summer, whereas the NAO–SST connection is insignificant during 1970–94 and is confined to the northern tropical Atlantic (NTA) during 1950–69. Compared to 1970–94, the much stronger influence on the NTA SST during 1995–2015 and 1950–69 is associated with a southward shift of the southern boundary of the NAO. During 1995–2015, the inverted NAO-related warming of the tropical Atlantic consists of three stages: 1) the pronounced increase in SST over the subtropical North Atlantic (SNA) and the tropical South Atlantic (TSA) during December–January, 2) the pronounced increase in SST over the northwestern tropical Atlantic (NWTA) during February–April, and 3) the persistent warming over the tropical Atlantic during May–August. The increases in SST over the SNA and the TSA are attributed to significant positive latent heat flux anomalies via the wind–evaporation effect, which are connected by the suppressed regional Hadley circulation. Afterward, the associated anomalous downward motion over the NWTA persists into February–April, which induces more incoming shortwave radiation and results in a significant increase in the local SST via the cloud–radiation effect. In contrast, during 1950–69, due to the decreased interannual variability of the vertical motion over the NWTA, the anomalous downward branch aloft and the low-level cross-equatorial northwesterly winds associated with the inverted NAO are not evident, and thus the regions with an increase in SST are confined to the Northern Hemisphere.


2021 ◽  
Author(s):  
Nicola Scafetta

AbstractThe 0.6 °C warming observed in global temperature datasets from 1940 to 1960 to 2000–2020 can be partially due to urban heat island (UHI) and other non-climatic biases in the underlying data, although several previous studies have argued to the contrary. Here we identify land regions where such biases could be present by locally evaluating their diurnal temperature range (DTR = TMax − TMin trends between the decades 1945–1954 and 2005–2014 and between the decades 1951–1960 and 1991–2000 versus their synthetic hindcasts produced by the CMIP5 models. Vast regions of Asia (in particular Russia and China) and North America, a significant part of Europe, part of Oceania, and relatively small parts of South America (in particular Colombia and Venezuela) and Africa show DTR reductions up to 0.5–1.5 °C larger than the hindcasted ones, mostly where fast urbanization has occurred, such as in central-east China. Besides, it is found: (1) from May to October, TMax globally warmed 40% less than the hindcast; (2) in Greenland, which appears nearly free of any non-climatic contamination, TMean warmed about 50% less than the hindcast; (3) the world macro-regions with, on average, the lowest DTR reductions and with low urbanization (60S-30N:120 W–90 E and 60 S–10 N:90 E–180 E: Central and South America, Africa, and Oceania) warmed about 20–30% less than the models’ hindcast. Yet, the world macro-region with, on average, the largest DTR reductions and with high urbanization (30 N–80 N:180 W–180 E: most of North America, Europe, and Central Asia) warmed just a little bit more (5%) than the hindcast, which indicates that the models well agree only with potentially problematic temperature records. Indeed, also tree-based proxy temperature reconstructions covering the 30°N–70°N land area produce significantly less warming than the correspondent instrumentally-based temperature record since 1980. Finally, we compare land and sea surface temperature data versus their CMIP5 simulations and find that 25–45% of the 1 °C land warming from 1940–1960 to 2000–2020 could be due to non-climatic biases. By merging the sea surface temperature record (assumed to be correct) and an adjusted land temperature record based on the model prediction, the global warming during the same period is found to be 15–25% lower than reported. The corrected warming is compatible with that shown by the satellite UAH MSU v6.0 low troposphere global temperature record since 1979. Implications for climate model evaluation and future global warming estimates are briefly addressed.


2003 ◽  
Vol 16 (9) ◽  
pp. 1364-1377 ◽  
Author(s):  
Gaëlle de Coëtlogon ◽  
Claude Frankignoul

Abstract The impact of the seasonal variations of the mixed-layer depth on the persistence of sea surface temperature (SST) anomalies is studied in the North Atlantic, using observations. A significant recurrence of winter SST anomalies during the following winter occurs in most of the basin, but not in the subtropical area of strong subduction. When taking reemergence into account, the e-folding timescale of winter SST anomalies generally exceeds 1 yr, and is about 16 months for the dominant SST anomaly tripole. The influence of advection by the mean oceanic currents is investigated by allowing for a displacement of the maximum recurrent correlation and, alternatively, by considering the SST anomaly evolution along realistic mean displacement paths. Taking into account the nonlocality of the reemergence generally increases the wintertime persistence, most notably in the northern part of the domain. The passive response of the mixed layer to the atmospheric forcing thus has a red spectrum down to near-decadal frequencies.


Atmosphere ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 454
Author(s):  
Andrew R. Jakovlev ◽  
Sergei P. Smyshlyaev ◽  
Vener Y. Galin

The influence of sea-surface temperature (SST) on the lower troposphere and lower stratosphere temperature in the tropical, middle, and polar latitudes is studied for 1980–2019 based on the MERRA2, ERA5, and Met Office reanalysis data, and numerical modeling with a chemistry-climate model (CCM) of the lower and middle atmosphere. The variability of SST is analyzed according to Met Office and ERA5 data, while the variability of atmospheric temperature is investigated according to MERRA2 and ERA5 data. Analysis of sea surface temperature trends based on reanalysis data revealed that a significant positive SST trend of about 0.1 degrees per decade is observed over the globe. In the middle latitudes of the Northern Hemisphere, the trend (about 0.2 degrees per decade) is 2 times higher than the global average, and 5 times higher than in the Southern Hemisphere (about 0.04 degrees per decade). At polar latitudes, opposite SST trends are observed in the Arctic (positive) and Antarctic (negative). The impact of the El Niño Southern Oscillation phenomenon on the temperature of the lower and middle atmosphere in the middle and polar latitudes of the Northern and Southern Hemispheres is discussed. To assess the relative influence of SST, CO2, and other greenhouse gases’ variability on the temperature of the lower troposphere and lower stratosphere, numerical calculations with a CCM were performed for several scenarios of accounting for the SST and carbon dioxide variability. The results of numerical experiments with a CCM demonstrated that the influence of SST prevails in the troposphere, while for the stratosphere, an increase in the CO2 content plays the most important role.


2008 ◽  
Vol 21 (11) ◽  
pp. 2451-2465 ◽  
Author(s):  
Yan Du ◽  
Tangdong Qu ◽  
Gary Meyers

Abstract Using results from the Simple Ocean Data Assimilation (SODA), this study assesses the mixed layer heat budget to identify the mechanisms that control the interannual variation of sea surface temperature (SST) off Java and Sumatra. The analysis indicates that during the positive Indian Ocean Dipole (IOD) years, cold SST anomalies are phase locked with the season cycle. They may exceed −3°C near the coast of Sumatra and extend as far westward as 80°E along the equator. The depth of the thermocline has a prominent influence on the generation and maintenance of SST anomalies. In the normal years, cooling by upwelling–entrainment is largely counterbalanced by warming due to horizontal advection. In the cooling episode of IOD events, coastal upwelling–entrainment is enhanced, and as a result of mixed layer shoaling, the barrier layer no longer exists, so that the effect of upwelling–entrainment can easily reach the surface mixed layer. Horizontal advection spreads the cold anomaly to the interior tropical Indian Ocean. Near the coast of Java, the northern branch of an anomalous anticyclonic circulation spreads the cold anomaly to the west near the equator. Both the anomalous advection and the enhanced, wind-driven upwelling generate the cold SST anomaly of the positive IOD. At the end of the cooling episode, the enhanced surface thermal forcing overbalances the cooling effect by upwelling/entrainment, and leads to a warming in SST off Java and Sumatra.


2022 ◽  
Author(s):  
Hector Luis D’Antoni ◽  
Lidia Susana Burry ◽  
Patricia Irene Palacio ◽  
Matilde Elena Trivi ◽  
Mariano Somoza

2018 ◽  
Vol 53 (1-2) ◽  
pp. 173-192 ◽  
Author(s):  
Wei-Ching Hsu ◽  
Christina M. Patricola ◽  
Ping Chang

Author(s):  
R. Shunmugapandi ◽  
S. Gedam ◽  
A. B. Inamdar

Abstract. Ocean surface phytoplankton responses to the tropical cyclone (TC)/storms have been extensively studied using satellite observations by aggregating the data into a weekly or bi-weekly composite. The reason behind is the significant limitations found in the satellite-based observation is the missing of valid data due to cloud cover, especially at the time of cyclone track passage. The data loss during the cyclone is found to be a significant barrier to efficiently investigate the response of chl-a and SST during cyclone track passage. Therefore it is necessary to rectify the above limitation to effectively study the impact of TC on the chlorophyll-a concentration (chl-a) and the sea surface temperature (SST) to achieve a complete understanding of their response to the TC prevailed in the Arabian Sea. Intending to resolve the limitation mentioned above, this study aims to reconstruct the MODIS-Aqua chl-a, and SST data using Data Interpolating Empirical Orthogonal Function (DINEOF) for all the 31 cyclonic events occurred in the Arabian Sea during 2003-2018 (16 years). Reconstructed satellite retrieved data covering all the cyclonic events were further used to investigate the chl-a and SST dynamics during TC. From the results, the exciting fact has been identified that only two TC over the eastern-AS were able to induce phytoplankton bloom. On investigating this scenario using sea surface temperature, it was disclosed that the availability of nutrients decides the suitable condition for the phytoplankton to proliferate in the surface ocean. Relevant to the precedent criterion, the results witnessed that the 2 TC (Phyan and Ockhi cyclone) prevailed in the eastern AS invoked a suitable condition for phytoplankton bloom. Other TC found to be less provocative either due to less intensity, origination region or the unsuitable condition. Thereby, gap-free reconstructed daily satellite-derived data efficiently investigates the response of bio-geophysical parameters during cyclonic events. Moreover, this study sensitised that though several TC strikes the AS, only two could impact phytoplankton productivity and SST found to highly consistent with the chl-a variability during the cyclone passage.


Check List ◽  
2014 ◽  
Vol 10 (6) ◽  
pp. 1563
Author(s):  
Javier Quiñones ◽  
Karla García Burneo ◽  
Claudio Barragan

The presence of the Yellow-bellied Sea Snake (Hydrophis platurus) in the Southeast Pacific is rarely reported, with only one confirmed observation from northern Perú made in the early 1950s. We present new information based on a live-stranded specimen recently found in Peruvian waters, having washed ashore at Máncora (04.1255° S, 81.0958° W) in northern Perú on 12 July 2012. This stranding was associated with a Modoki El Niño warm event, since positive sea surface temperature (SST) anomalies up to 2.5°C were registered at this time.


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