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ENSO teleconnections - Analysis of time lag between tropical Pacific sea surface temperature and climate and vegetation anomalies

Navrátil, Jiri LU (2020) In Student thesis series INES NGEM01 20192
Dept of Physical Geography and Ecosystem Science
Abstract
El Niño-Southern Oscillation (ENSO) affects weather and climate in regions spread all around the Earth via teleconnections. While quite a lot of research has been done on recognizing what regions are affected by these and what is the sign of the associated temperature, rainfall and vegetation anomalies, not that much attention has been paid to the timing of the impacts with respect to the ENSO state. This project found that the ENSO-caused anomalies were never at their peak simultaneously with an ENSO event culmination for any of the three examined variables – precipitation, temperature and normalized difference vegetation index (NDVI) – in any of the eight study areas. It was also found that there is no seasonally uniform time lag between... (More)
El Niño-Southern Oscillation (ENSO) affects weather and climate in regions spread all around the Earth via teleconnections. While quite a lot of research has been done on recognizing what regions are affected by these and what is the sign of the associated temperature, rainfall and vegetation anomalies, not that much attention has been paid to the timing of the impacts with respect to the ENSO state. This project found that the ENSO-caused anomalies were never at their peak simultaneously with an ENSO event culmination for any of the three examined variables – precipitation, temperature and normalized difference vegetation index (NDVI) – in any of the eight study areas. It was also found that there is no seasonally uniform time lag between sea surface temperature (SST) anomalies in tropical Pacific and the associated anomalies in a specific region. On the contrary, the anomalies are generally strongest in late northern hemisphere spring to early northern hemisphere summer for all the variables in all the regions and that they are mainly affected by the ENSO state in the preceding northern hemisphere summer and northern hemisphere winter. Since these findings were not expected in comparison with studies already published, it seems necessary to test the time lag between tropical Pacific SST and impacts of ENSO teleconnections in more studies with possibly diverse methodologies before drawing conclusions that would revise the so far published knowledge about the timing of ENSO teleconnections impacts as suggested by the results of this study. (Less)
Abstract (Uncoded languages)
El Niño-Jižní oscilace (ENSO) ovlivňuje počasí a podnebí v oblastech rozprostřených po celém světě skrz dálkové vazby. Zatímco existuje mnoho studií věnujících se identifikaci těchto oblastí a znaménku souvisejících odchylek teploty, srážek a vegetace, ne mnoho pozornosti bylo dosud věnováno načasování zmíněných odchylek s ohledem na stav ENSO. Tato studie ukázala, že odchylky ani jedné ze zmiňovaných veličin – teploty, srážek a vegetačního indexu NDVI – nikdy nekulminovaly současně s kulminací jedné z fází ENSO (El Niño či La Niña) v žádné ze zkoumaných studijních oblastí. Zároveň nebylo nalezeno žádné zpoždění mezi povrchovou teplotou moře (SST) v tropickém Tichém oceánu a souvisejícími odchylkami v určitém regionu, jež by bylo zřejmé ve... (More)
El Niño-Jižní oscilace (ENSO) ovlivňuje počasí a podnebí v oblastech rozprostřených po celém světě skrz dálkové vazby. Zatímco existuje mnoho studií věnujících se identifikaci těchto oblastí a znaménku souvisejících odchylek teploty, srážek a vegetace, ne mnoho pozornosti bylo dosud věnováno načasování zmíněných odchylek s ohledem na stav ENSO. Tato studie ukázala, že odchylky ani jedné ze zmiňovaných veličin – teploty, srážek a vegetačního indexu NDVI – nikdy nekulminovaly současně s kulminací jedné z fází ENSO (El Niño či La Niña) v žádné ze zkoumaných studijních oblastí. Zároveň nebylo nalezeno žádné zpoždění mezi povrchovou teplotou moře (SST) v tropickém Tichém oceánu a souvisejícími odchylkami v určitém regionu, jež by bylo zřejmé ve všech ročních obdobích. Naopak bylo zjištěno, že tyto odchylky všech zkoumaných proměnných jsou ve všech zkoumaných oblastech většinou největší v pozdním jaru a brzkém létě severní polokoule a že jsou způsobené hlavně stavem ENSO v předcházejícím létě a zimě severní polokoule. Vzhledem k tomu, že tyto výsledky nebyly v porovnání s již publikovanými studiemi očekávané, zdá se být nezbytné nejprve otestovat zpoždění dopadů dálkových vazeb ENSO za SST v tropickém Pacifiku ve vice studiích (s případně odlišnými použitými metodami) než vyvozovat závěry, které by pozměňovaly dosud publikované poznatky o načasování dopadů dálkových vazeb ENSO tak, jak by navrhovaly výsledky této práce. (Less)
Please use this url to cite or link to this publication:
author
Navrátil, Jiri LU
supervisor
organization
course
NGEM01 20192
year
type
H2 - Master's Degree (Two Years)
subject
keywords
Physical Geography and Ecosystem Analysis, ENSO, teleconnections, climate, NDVI
publication/series
Student thesis series INES
report number
500
language
English
id
9006356
date added to LUP
2020-03-10 17:24:05
date last changed
2020-03-10 17:24:05
@misc{9006356,
  abstract     = {El Niño-Southern Oscillation (ENSO) affects weather and climate in regions spread all around the Earth via teleconnections. While quite a lot of research has been done on recognizing what regions are affected by these and what is the sign of the associated temperature, rainfall and vegetation anomalies, not that much attention has been paid to the timing of the impacts with respect to the ENSO state. This project found that the ENSO-caused anomalies were never at their peak simultaneously with an ENSO event culmination for any of the three examined variables – precipitation, temperature and normalized difference vegetation index (NDVI) – in any of the eight study areas. It was also found that there is no seasonally uniform time lag between sea surface temperature (SST) anomalies in tropical Pacific and the associated anomalies in a specific region. On the contrary, the anomalies are generally strongest in late northern hemisphere spring to early northern hemisphere summer for all the variables in all the regions and that they are mainly affected by the ENSO state in the preceding northern hemisphere summer and northern hemisphere winter. Since these findings were not expected in comparison with studies already published, it seems necessary to test the time lag between tropical Pacific SST and impacts of ENSO teleconnections in more studies with possibly diverse methodologies before drawing conclusions that would revise the so far published knowledge about the timing of ENSO teleconnections impacts as suggested by the results of this study.},
  author       = {Navrátil, Jiri},
  keyword      = {Physical Geography and Ecosystem Analysis,ENSO,teleconnections,climate,NDVI},
  language     = {eng},
  note         = {Student Paper},
  series       = {Student thesis series INES},
  title        = {ENSO teleconnections - Analysis of time lag between tropical Pacific sea surface temperature and climate and vegetation anomalies},
  year         = {2020},
}