In the last post, I introduced the changing patterns of the Korean Monsoon (Changma) and how this crucial part of Korean summers was making all of us - including me - quite confused. I wanted to investigate what factors were contributing to the changes in Changma; in today's post, I'll talk about the relationship between Eurasian snow cover and Korean summer rainfall. While I was researching specifically for information that pertains to Korea, I found quite a lot more research done on other regions such as Punjab of India - if you are interested in Eurasian snow cover and the rainfall in your own country, I'm sure you'll find a huge number of research papers done on that topic :)
The first document I used for my little research was the Korean Meteorological Administration's Changma Report of 2011. I was incredibly impressed with its rich content of diagrams and graphs, although the explanations and reasoning for the information they provided was a bit lacking. Still, I was able to find the work of many researchers such as Bamzai & Shukla 1999, Bhanukuma 1988 and Liu & Yanai 2002. I'll put the links to all the information I used at the end of this blog post.
Before I go further, though, I realize that changes in rainfall patterns are part of climate change, and climate change may be considered a natural phenomenon. On the other hand, the biggest contributor to the recent change in climate is thought to be global warming. With my own experiences and research scientists' statements and findings*, I also agree that the increased global temperature and rainfall variability are anthropologically related. Please tell me what you think in the comments below - debate on climate change is always interesting :)
Western Eurasia is considered a unique geographical region where there is notable inverse correlation between winter snow cover and the subsequent summer monsoon rainfall in South East Asia. This inverse relationship is observed especially when the snow cover was greater or less than usual for both winter and the consecutive spring season.
When the snow cover of Eurasia's western region is greater and eastern region less than usual in the spring, Korea's summer rainfall tends to increase. With excessive snow cover anomalies, the cooling and cyclonic circulation anomaly in the lower troposphere appear over northern Eurasia. This leads to a huge circulation response and then a weakened East Asia summer monsoon with deficient rainfall. Eurasian snow cover forms more than 60% of the Northern Hemisphere's snow cover, thus the changes in its snow cover give rise to massive changes in the nearby regions.
But all of the above information still doesn't specifically answer why Eurasian snow cover influences the rainfall other regions...so what it is about the snow anomalies that cause changes in precipitation patterns? Persistent Eurasian snow irregularities in winter and spring cause changes in the temperatures of the surface and atmosphere. This causes albedo and soil hydrological effects; these are particularly important because they widen the difference between the land and sea thermal temperatures and the monsoon that follows. Albedo is known as the power of reflection of a surface (ratio of reflected radiation from the surface to incident radiation upon it). Snow albedo is particularly more variable: 0.2 for dirty snow, 0.4 for melting snow, and 0.9 for freshly fallen snow.
I think this explains at least an important part of the relationship between Eurasian snow cover and Korea's Changma...but it's important to realize that although a lot of studies have been done on this topic, there is little data spanning many decades. Also, most of the research I found was focused on the Indian or Chinese monsoon, rather than other regions of Asia. If you happen to know a good source for information that is specifically about Korea, do tell me :)
* Before the 1970s, the variation and monsoon rainfall in East Asia showed generally varying increases. Since the 1970s, global precipitation's divergent data demonstrated increases that almost coincided with increases in global temperature anomalies during the same period. For further information, please check out this research paper.
- http://onlinelibrary.wiley.com/doi/10.1002/joc.784/full
- http://www.pmd.gov.pk/rnd/rnd_files/vol5_issue10/8.%20The%20Effect%20of%20Eurasian%20Snow%20Cover%20on%20the%20Monsoon%20Rainfall%20of%20Pakistan.pdf
- http://onlinelibrary.wiley.com/doi/10.1002/joc.784/pdf
- http://www.sciencedirect.com/science/article/pii/S167498711400036X
- http://green.blogs.nytimes.com/2012/09/04/q-and-a-climate-change-and-the-monsoon/?_php=true&_type=blogs&_r=0&module=ArrowsNav&contentCollection=Science&action=keypress®ion=FixedLeft&pgtype=Blogs
- http://www.climatenewsnetwork.net/2014/04/south-asian-monsoon-is-on-the-change/
- http://web.kma.go.kr/eng/
The first document I used for my little research was the Korean Meteorological Administration's Changma Report of 2011. I was incredibly impressed with its rich content of diagrams and graphs, although the explanations and reasoning for the information they provided was a bit lacking. Still, I was able to find the work of many researchers such as Bamzai & Shukla 1999, Bhanukuma 1988 and Liu & Yanai 2002. I'll put the links to all the information I used at the end of this blog post.
Before I go further, though, I realize that changes in rainfall patterns are part of climate change, and climate change may be considered a natural phenomenon. On the other hand, the biggest contributor to the recent change in climate is thought to be global warming. With my own experiences and research scientists' statements and findings*, I also agree that the increased global temperature and rainfall variability are anthropologically related. Please tell me what you think in the comments below - debate on climate change is always interesting :)
Western Eurasia is considered a unique geographical region where there is notable inverse correlation between winter snow cover and the subsequent summer monsoon rainfall in South East Asia. This inverse relationship is observed especially when the snow cover was greater or less than usual for both winter and the consecutive spring season.
When the snow cover of Eurasia's western region is greater and eastern region less than usual in the spring, Korea's summer rainfall tends to increase. With excessive snow cover anomalies, the cooling and cyclonic circulation anomaly in the lower troposphere appear over northern Eurasia. This leads to a huge circulation response and then a weakened East Asia summer monsoon with deficient rainfall. Eurasian snow cover forms more than 60% of the Northern Hemisphere's snow cover, thus the changes in its snow cover give rise to massive changes in the nearby regions.
But all of the above information still doesn't specifically answer why Eurasian snow cover influences the rainfall other regions...so what it is about the snow anomalies that cause changes in precipitation patterns? Persistent Eurasian snow irregularities in winter and spring cause changes in the temperatures of the surface and atmosphere. This causes albedo and soil hydrological effects; these are particularly important because they widen the difference between the land and sea thermal temperatures and the monsoon that follows. Albedo is known as the power of reflection of a surface (ratio of reflected radiation from the surface to incident radiation upon it). Snow albedo is particularly more variable: 0.2 for dirty snow, 0.4 for melting snow, and 0.9 for freshly fallen snow.
I think this explains at least an important part of the relationship between Eurasian snow cover and Korea's Changma...but it's important to realize that although a lot of studies have been done on this topic, there is little data spanning many decades. Also, most of the research I found was focused on the Indian or Chinese monsoon, rather than other regions of Asia. If you happen to know a good source for information that is specifically about Korea, do tell me :)
Next post will be about an absolutely AMAZING discovery I made on my trip last weekend to Gwangju - see the picture below:
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Can you figure out what this is? It looks like wood...
but there is also a metallic/rocky texture!
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* Before the 1970s, the variation and monsoon rainfall in East Asia showed generally varying increases. Since the 1970s, global precipitation's divergent data demonstrated increases that almost coincided with increases in global temperature anomalies during the same period. For further information, please check out this research paper.
- http://onlinelibrary.wiley.com/doi/10.1002/joc.784/full
- http://www.pmd.gov.pk/rnd/rnd_files/vol5_issue10/8.%20The%20Effect%20of%20Eurasian%20Snow%20Cover%20on%20the%20Monsoon%20Rainfall%20of%20Pakistan.pdf
- http://onlinelibrary.wiley.com/doi/10.1002/joc.784/pdf
- http://www.sciencedirect.com/science/article/pii/S167498711400036X
- http://green.blogs.nytimes.com/2012/09/04/q-and-a-climate-change-and-the-monsoon/?_php=true&_type=blogs&_r=0&module=ArrowsNav&contentCollection=Science&action=keypress®ion=FixedLeft&pgtype=Blogs
- http://www.climatenewsnetwork.net/2014/04/south-asian-monsoon-is-on-the-change/
- http://web.kma.go.kr/eng/
