The net effect of ultraviolet radiation on atmospheric dimethylsulphide over the Southern Indian Ocean

Author(s):  
Dominic R. Kniveton ◽  
Martin C. Todd ◽  
Jean Sciare ◽  
Nikos Mihalopoulos

Dimethylsulphide (DMS) in the atmosphere may play an important role in the climate system. This study shows an inverse relationship between ultraviolet extremes and atmospheric DMS, independent of changes in wind speed, sea–surface temperature and photosynthetically active radiation, as measured at Amsterdam Island in the Southern Indian Ocean.

2004 ◽  
Vol 45 (1-2) ◽  
pp. 55-73 ◽  
Author(s):  
Andrey G. Kostianoy ◽  
Anna I. Ginzburg ◽  
Michel Frankignoulle ◽  
Bruno Delille

2016 ◽  
Author(s):  
J. Zinke ◽  
L. Reuning ◽  
M. Pfeiffer ◽  
J. Wassenburg ◽  
E. Hardman ◽  
...  

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.


2005 ◽  
Vol 18 (9) ◽  
pp. 1351-1368 ◽  
Author(s):  
Pascal Terray ◽  
Sébastien Dominiak

Abstract Here the 1976–77 climate regime shift that was accompanied by a remarkable change in the lead–lag relationships between Indian Ocean sea surface temperature (SST) and El Niño evolution is shown. After the 1976–77 regime shift, a correlation analysis suggests that southern Indian Ocean SSTs observed during late boreal winter are a key precursor in predicting El Niño evolution as the traditional oceanic heat content anomalies in the equatorial Pacific or zonal wind anomalies over the equatorial western Pacific. The possible physical mechanisms underlying this highly significant statistical relationship are discussed. After the 1976–77 regime shift, southern Indian Ocean SST anomalies produced by Mascarene high pulses during boreal winter trigger coupled air–sea processes in the tropical eastern Indian Ocean during the following seasons. This produces a persistent remote forcing on the Pacific climate system, promoting wind anomalies over the western equatorial Pacific and modulating the regional Hadley cell in the southwest Pacific. These modulations, in turn, excite Rossby waves, which produce quasi-stationary circulation anomalies in the extratropical South Pacific, responsible for the development of the southern branch of the “horseshoe” El Niño pattern. The change of the background SST state that occurred in the late 1970s over the Indian Ocean may also explain why ENSO evolution is different before and after the 1976–77 regime shift. These results shed some light on the possible influence of global warming or decadal fluctuations on El Niño evolution through changes in teleconnection patterns between the Indian and Pacific Oceans.


2007 ◽  
Vol 24 (6) ◽  
pp. 1131-1142 ◽  
Author(s):  
Anant Parekh ◽  
Rashmi Sharma ◽  
Abhijit Sarkar

A 2-yr (June 1999–June 2001) observation of ocean surface wind speed (SWS) and sea surface temperature (SST) derived from microwave radiometer measurements made by a multifrequency scanning microwave radiometer (MSMR) and the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) is compared with direct measurements by Indian Ocean buoys. Also, for the first time SWS and SST values of the same period obtained from 40-yr ECMWF Re-Analysis (ERA-40) have been evaluated with these buoy observations. The SWS and SST are shown to have standard deviations of 1.77 m s−1 and 0.60 K for TMI, 2.30 m s−1 and 2.0 K for MSMR, and 2.59 m s−1 and 0.68 K for ERA-40, respectively. Despite the fact that MSMR has a lower-frequency channel, larger values of bias and standard deviation (STD) are found compared to those of TMI. The performance of SST retrieval during the daytime is found to be better than that at nighttime. The analysis carried out for different seasons has raised an important question as to why one spaceborne instrument (TMI) yields retrievals with similar biases during both pre- and postmonsoon periods and the other (MSMR) yields drastically different results. The large bias at low wind speeds is believed to be due to the poorer sensitivity of microwave emissivity variations at low wind speeds. The extreme SWS case study (cyclonic condition) showed that satellite-retrieved SWS captured the trend and absolute magnitudes as reflected by in situ observations, while the model (ERA-40) failed to do so. This result has direct implications on the real-time application of satellite winds in monitoring extreme weather events.


Author(s):  
Muhammad Zainuddin Lubis ◽  
Wenang Anurogo ◽  
Husnul Kausarian ◽  
Ganda Surya ◽  
Tiggi Choanji

This study aimed to observe the characteristics of sea surface temperature (SST) and wind velocity and its relation with the Indian Ocean Dipole (IOD) in the waters of Batam. The data used in this study were the SST datasets and the wind speed of 2016 in the waters of Batam. The method used in this research were the visual analysis using the data ocean view (ODV) to observe at the spatial and temporal distribution of the SST and the wind speed in Batam waters at different seasons. The next method is a fast Fourier transform (FFT). The earlier monsoon season that occurred in April has the highest wind speed with the value of 3.9 MS ** - 1 for components U. As for the V, the component has the highest value of -3.6 MS ** - 1. The SST Batam observed high in April occurred on 19-04-2016 with a value of 304.2 ° K (31.05 ° C). West monsoon winds that occurred in January has the highest wind speed with a value of 4.5 MS ** - 1 for components U. As for the V, the component has the highest value of 5.2 MS ** - 1 in the waters of Batam. The highest SST in Batam was  occurred in January on 19-01-2016 with a value of 302.8 ° K (29.65 ° C). Based on the results of the FFT, wind speed and SST in the waters of the Island has a dominant 6-month period (semiannual).


Author(s):  
Araceli Puente ◽  
Xabier Guinda ◽  
Jose A. Juanes ◽  
Elvira Ramos ◽  
Beatriz Echavarri-Erasun ◽  
...  

In the frame of the COST ACTION ‘EMBOS’ (Development and implementation of a pan-European Marine Biodiversity Observatory System), coverage of intertidal macroalgae was estimated at a range of marine stations along the European coastline (Subarctic, Baltic, Atlantic, Mediterranean). Based on these data, we tested whether patterns in macroalgal diversity and distribution along European intertidal rocky shores could be explained by a set of meteo-oceanographic variables. The variables considered were salinity, sea surface temperature, photosynthetically active radiation, significant wave height and tidal range and were compiled from three different sources: remote sensing, reanalysis technique and in situ measurement. These variables were parameterized to represent average conditions (mean values), variability (standard deviation) and extreme events (minimum and maximum values). The results obtained in this study contribute to reinforce the EMBOS network approach and highlight the necessity of considering meteo-oceanographic variables in long-term assessments. The broad spatial distribution of pilot sites has allowed identification of latitudinal and longitudinal gradients manifested through species composition, diversity and dominance structure of intertidal macroalgae. These patterns follow a latitudinal gradient mainly explained by sea surface temperature, but also by photosynthetically active radiation, salinity and tidal range. Additionally, a longitudinal gradient was also detected and could be linked to wave height.


2018 ◽  
Vol 127 (1) ◽  
Author(s):  
B Nanda Kishore Reddy ◽  
R Venkatesan ◽  
Krishna K Osuri ◽  
Simi Mathew ◽  
Jagadeesh Kadiyam ◽  
...  

2016 ◽  
Vol 13 (20) ◽  
pp. 5827-5847 ◽  
Author(s):  
Jens Zinke ◽  
Lars Reuning ◽  
Miriam Pfeiffer ◽  
Jasper A. Wassenburg ◽  
Emily Hardman ◽  
...  

Abstract. The western Indian Ocean has been warming rapidly over recent decades, causing a greater number of extreme climatic events. 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 tropical coral reef ecosystems. Here we present monthly resolved coral Sr ∕ Ca records from two different locations from Rodrigues Island (63° E, 19° S) in the south-central Indian Ocean trade wind belt. We reconstruct SST based on a linear relationship with the Sr ∕ Ca proxy with records starting from 1781 and 1945, respectively. We assess relationships between the observed long-term SST and climate fluctuations related to the El Niño–Southern Oscillation (ENSO), the Subtropical Indian Ocean Dipole Mode (SIOD) and the Pacific Decadal Oscillation (PDO) between 1945 and 2006, respectively. The reproducibility of the Sr ∕ Ca records is assessed as are the potential impacts of diagenesis and corallite orientation on Sr ∕ Ca–SST reconstructions. We calibrate individual robust Sr ∕ Ca records with in situ SST and various gridded SST products. The results show that the SST record from Cabri provides the first Indian Ocean coral proxy time series that records the SST signature of the PDO in the south-central Indian Ocean since 1945. We suggest that additional records from Rodrigues Island can provide excellent records of SST variations in the southern Indian Ocean trade wind belt to unravel teleconnections with the SIOD/ENSO/PDO on longer timescales.


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