Arctic Sea Ice Seasonal & Decadal Variations – આર્ટિક સી આઇશ નું સીઝનલ ફેર ફાર તેમજ 2009 અને 2019 વર્ષ નો ફરક

The Arctic sea ice extent changes throughout the year. The minimum sea ice extent is normally around September of each year. The ice extent grows again till February/March when it reaches its maximum extent and subsequently again the sea ice extent starts to decrease till September. This cycle repeats each year.

This post has three images of Arctic sea ice extent for different dates to illustrate the changes in ice extent. Image source NSIDC.

The Ice extent on 17-01-2019 was 14.2 million sq. km. The change over 10 years for the same date of the year 17-01-2019 is not very significant and the Ice extent was 13.8 million sq. km. and can be attributed to natural variations. The third image of 17-09-2018 is just four months back when the ice extent was at yearly minimum at 4.6 million sq. km. compared to 13.8 million sq. km. on 17-01-2019. This would mean that within a span of four months the ice extent has grown three times. Nothing surprising about this and this is also natural phenomenon which happens every year.


આર્ટિક આઇસ ના સમગ્ર વર્ષ દરમિયાન ના વિસ્તાર ની ખરી હકીકત:
   
દર વર્ષે દરરોજ આર્ટિક આઇસ ના વિસ્તાર માં વધ ઘટ થતી હોય છે. આ વિસ્તાર સામાન્ય રીતે સપ્ટેમ્બર મહીના માં નીચા સ્તરે પહોંચે અને ફરી વધવાનું ચાલુ થાય. મહત્તમ વિસ્તાર ફેબ્રુઆરી/માર્ચ મહિના માં થઇ જાય.
   
17-09-2018 બરફ નો વિસ્તાર ફક્ત 4.6 મિલિયન ચો. કિ.મી. હતો જે 4 મહિનામાં કુદરતી ત્રણ ગણો થઇ ગયો. કઈ નવું નથી.
   
17-01-2019 બરફ નો વિસ્તાર 13.8 મિલિયન ચો. કિ.મી. છે.
Arctic Sea Ice Extent on 17th September 2018 is 4.6 Million Sq. Km.


Arctic Sea Ice Extent on 17th January 2019 is 13.8 Million Sq. Km.
10 વર્ષ માં શું ફરક પડ્યો ? 17-01-2009 બરફ નો વિસ્તાર 14.2 મિલિયન ચો. કિ.મી. હતો.
તેની સામે 17-01-2019 બરફ નો વિસ્તાર 13.8 મિલિયન ચો. કિ.મી. છે, જે કોઈ અસાધારણ ફેર ફાર ના કહેવાય.

Arctic Sea Ice Extent on 17th January 2009 is 14.2 Million Sq. Km.

Weak La Nina Exists Till The End Of April 2018 – એપ્રિલ આખર સુધી સામાન્ય લા નિના હજુ અસ્તિત્વ માં છે

ENSO Status on 4th May 2018

Weak La Nina Exists Till The End Of April 2018.

2018 એપ્રિલ આખર સુધી સામાન્ય લા નિના હજુ અસ્તિત્વ માં છે.

 

The ONI is based on SST departures from average in the Niño 3.4 region, and is a principal measure for monitoring, assessing, and predicting ENSO. Defined as the three-month running-mean SST departures in the Niño 3.4 region. Departures were based on a set of improved homogeneous historical SST analyses (Extended Reconstructed SST – ERSST.v4) and have now been updated to further improved homogeneous historical SST analyses (Extended Reconstructed SST – ERSST.v5). Explanation about ERSST.v5 is given here.

The SST reconstruction methodology is described in Huang et al., 2015, J. Climate, vol. 28, 911-930.
CPC uses current Climatology based on 1986-2015 which has been changed late last year from base years 1981-2010. Explanation about Climatology base years change is given here.

NOAA Operational Definitions for El Niño and La Niña, El Niño: characterized by a positive ONI greater than or equal to +0.5ºC. La Niña: characterized by a negative ONI less than or equal to -0.5ºC. By historical standards, to be classified as a full-fledged El Niño or La Niña episode, these thresholds must be exceeded for a period of at least 5 consecutive overlapping 3-month seasons.

CPC considers El Niño or La Niña conditions to occur when the monthly Niño3.4 OISST departures meet or exceed +/- 0.5ºC along with consistent atmospheric features. These anomalies must also be forecast to persist for 3 consecutive months.

Last five ONI Index are OND 2017 -0.9ºC, NDJ 2018 -1.0ºC, DJF 2018 -0.9ºC, JFM 2018 -0.8ºC and FMA 2018 -0.6ºC. La Nina event was already in existence and since the latest 3-monthly seasonal ONI Index is less than or equal to -0.5ºC it fulfills the NOAA criteria for continuance of La Nina at the end of April 2018.

La Nina event 2017-18 has officially evolved at the end of March 2018 (JFM 2018). This La Nina event is the second consecutive La Nina event, the other being 2016-17 La Nina event that ended at the end of January 2017 (NDJ 2017).

 

Latest Oceanic Nino Index (ONI) Graph Showing Continuance Of La Nina For FMA 2018 Season

 

The Table below shows the monthly SST of Nino3.4 Region and the Climate adjusted normal SST and SST anomaly for last two years. Climate Base 1986-2015. ERSST.v5

Period    Nino3.4 ClimAdjust
YR   MON  Temp.ºC Temp.ºC ANOM ºC

2016   3   28.90   27.21    1.70
2016   4   28.73   27.73    0.99
2016   5   28.24   27.85    0.39
2016   6   27.70   27.65    0.05
2016   7   26.82   27.26   -0.44
2016   8   26.28   26.91   -0.63
2016   9   26.15   26.80   -0.65
2016  10   25.98   26.75   -0.78
2016  11   25.95   26.75   -0.80
2016  12   26.10   26.65   -0.55
2017   1   26.12   26.45   -0.33
2017   2   26.68   26.66    0.02
2017   3   27.33   27.21    0.12
2017   4   28.04   27.73    0.30
2017   5   28.30   27.85    0.45
2017   6   28.06   27.65    0.41
2017   7   27.54   27.26    0.28
2017   8   26.70   26.91   -0.21
2017   9   26.29   26.80   -0.51
2017  10   26.15   26.75   -0.60
2017  11   25.74   26.75   -1.01
2017  12   25.62   26.65   -1.04
2018   1   25.58   26.45   -0.88
2018   2   25.98   26.66   -0.68
2018   3   26.50   27.21   -0.71
2018   4   27.27   27.73   -0.46

 

CPC considers El Niño or La Niña conditions to occur when the monthly Niño3.4 OISST departures meet or exceed +/- 0.5°C along with consistent atmospheric features. These anomalies must also be forecast to persist for 3 consecutive months.

 

Southern Oscillation Index

 

As per BOM, Australia:

The 30-day Southern Oscillation Index (SOI) to 2nd May 2018 was +2.4, while the 90-day SOI remains within the neutral range.

 

Sustained positive values of the SOI above +7 typically indicate La Niña while sustained negative values below −7 typically indicate El Niño. Values between about +7 and −7 generally indicate neutral conditions.

Recent (preliminary) Southern Oscillation Index values as per The Long Paddock – Queensland Government.

30 Days average SOI was +4.02 at the end of April 2018 and was +0.85 on 4th May 2018 as per The Long Paddock – Queensland Government and 90 Days average SOI was +2.55.

 

SOI Monthly graph up to April 2018 as per The Long Paddock – Queensland Government.

 

 

 

 

 

Summary by: Climate Prediction Center / NCEP  Dated 30th April 2018

ENSO Alert System Status: La Niña Advisory

La Niña conditions are present.*
Equatorial sea surface temperatures (SSTs) are near-to-below average across the east-central and eastern Pacific Ocean.
La Niña is expected to transition to ENSO-neutral during the April-May, with ENSO-neutral then likely (greater than 50% chance) to continue through the Northern Hemisphere summer 2018.

 

As per BOM -Australia 24th April 2018

ENSO outlooks

All earlier updates are listed below:

Click here for Update “Full Fledged La Nina Event Has Developed At The End Of March 2018”

Click here for Update “La Nina Event 2017-18 Expected To Commence At The End Of March”

Click here for Update “Three Consecutive 3-Monthly Seasons Have Oni -0.5ºC Or Below”

Click here for Update “ENSO Neutral Conditions Prevails”

Click here for Update “ENSO Neutral Conditions Prevails With JAS 2017 ONI Index At -0.2ºC”

Click here for Update “Theoretically El Nino Not Possible During 2017”

Click here for Update “Theoretically El Nino Not Possible During The Indian Southwest Monsoon 2017”