Looking at the influence of continentality in atmospheric circulation. (by Diego Fdez-Sevilla)

Looking at the influence of continentality in atmospheric circulation. (by Diego Fdez-Sevilla)

DOI: 10.13140/RG.2.1.2180.1843

Comments updated at the bottom. (10/06/2014)

In my research I try to find the state of knowledge about some questions that I find relevant. Through debate I try to find input exploring the perception that others might have about those questions.

In this particular case I explore the state of knowledge justifying the line of research looking at the influence of continentality in atmospheric circulation. Following this idea, the environmental performance derived from land use and cover management would become a relevant factor to look at when considering factors involved in climatic interferences.

The global continent/ocean asymmetry leads to a dominance of water in the Southern Hemisphere and land in the Northern Hemisphere. In contrast, the polar areas of the Southern Hemisphere are land, versus those of the North, which are water. The high elevation (ca. 3,000 m) of the former is distinctive. Both poles are largely covered by ice and snow, so that the albedo is always high but is variable perennially. North / south contrasts are most important at midlatitudes. In the Southern Hemisphere, continents alternate with oceans, whereas in the Northern Hemisphere, the amalgamation of Eurasia and North Africa is not balanced by North America. Climatologically, this imbalance generates powerful fluctuations between zonal (westerly) and meridional (south-north) modes of circulation. “Oceanicity,” or maritime air flow, alternates with “continentality,” or turbulent and meridional air flow. In the Southern Hemisphere, the greater dominance of oceans means that strong continent / ocean contrasts are absent. Global climate systems are therefore dominated by the Northern Hemisphere, given the present continental configuration. Therefore, the Northern Hemisphere will dictate global periodicities during Ice Age fluctuations between glacial and interglacial states.

The differences between the stratosphere in the Southern Hemisphere (SH) and NH are indicative of the important interactions among dynamics, radiation and chemistry. Because the stratosphere is very nearly in geostrophic and hydrostatic balance, the strength of the wintertime westerly vortex that encircles the polar cap region is proportional to the temperature contrast between the polar cap region and lower latitudes. Consistent with the lower temperatures in the polar cap region, the wintertime SH polar vortex is much stronger and longer lasting than its NH counterpart. The SH wintertime stratospheric polar vortex forms about a month earlier in autumn than its NH counterpart, and it persists about 2 months later into the spring .

The wintertime westerly vortex interacts strongly with the flux of planetary wave activity into the stratosphere from below. If the vortex is properly conditioned or the planetary waves are sufficiently strong, planetary waves propagating up from the troposphere can give rise to abrupt midwinter warmings. Planetary wave forcing in the SH is much weaker and vortex variability is much less in winter than in the NH. The weaker wave-driven meridional circulation during the SH winter is reflected in the relative warmth of the tropical tropopause during that season.

The work of Thompson and Wallace (1998) points out that the variability in the Arctic Oscillation (AO) consists of a transfer of mass in and out of the circumpolar polar vortex. A similar mode of variability (the Antarctic Oscillation or AA O) is known to exist in the Southern Hemisphere where the signature in the troposphere is even more symmetric about the pole (Thompson and Wallace, 2000). It seems likely that the bias towards the North Atlantic in the surface and middle troposphere structure of the AO is a consequence of the land-sea contrasts in the Northern Hemisphere (Thompson and Wallace, 1998) and presumably also the mountain ranges (e.g. The Rockies and Greenland) that cut across the path of the tropospheric jet stream.

Jet streams in the upper troposphere usually reach their maximum on the western side of the oceanic basins where the land-sea thermal contrasts are the strongest. East of the same basins, synoptic eddies get larger amplitude and feedback onto the jet streams. This feedback is characterized by the breaking of Rossby waves in the upper troposphere and plays a crucial role in the low-frequency atmospheric variability like the North Atlantic Oscillation (NAO). Two kinds of wave breaking exist; cyclonic wave-breaking pushing the jet southward and closely linked with the negative phase of the NAO and anticyclonic wave-breaking shifting the jet poleward and favoring the positive phase.

The zonal thermal contrast on the western border of the North Atlantic has shown to be responsible for the localization of a dipolar structure in sea-level pressure and height fields, which bears a strong resemblance to the North Atlantic Oscillation (NAO). In this region, the response to thermal land–sea contrast is evident on both annular and planetary- wave patterns, with a NAO-like dipole being the dominant regional feature. In the North Pacific, on the other hand, diabatic forcing is balanced primarily by meridional temperature advection, because here (contrarily to the north- west Atlantic region) the surface temperature gradient is stronger in the meridional than in the zonal direction. Therefore, the modification of the annular mode by zonal temperature advection at the Asia-North Pacific border produces a different pattern from that associated with the thermal balance of a COWL-like planetary wave. This study concludes that ‘thermally-balanced wave mode’ is a dynamically appropriate description for the pattern previously identified as the second EOF of low-frequency 500-hPa height variability, or empirically defined as the Cold-Ocean/Warm-Land pattern. Since this mode accounts for a large proportion of the upper-air inter-decadal variations in the second half of the 20th century, it is being suggested that such variations are dynamically consistent over the hemispheric domain; therefore they should be understood in terms of planetary-scale dynamics, rather than by the casual superposition of regional effects.

Looking at the influence of continentality in atmospheric circulation, how much impact can we expect in the climate from land use and land cover management?

(Free access) Interactions between the atmosphere and terrestrial ecosystems: influence on weather and climate. Global Change Biology (1998) 4, 461–475

Even though the following studies have limited access I believe they are worthy of being acknowledged:

2010 Investigating soil moisture–climate interactions in a changing climate: A review.

2013. Land-atmosphere interactions and climate change: Recent results and new perspectives (Invited). American Geophysical Union, Fall Meeting 2013, abstract #H11L-01. http://adsabs.harvard.edu/abs/2013AGUFM.H11L..01S


About Diego Fdez-Sevilla, PhD.

Citing This Site "Title", published online "Month"+"Year", retrieved on "Month""Day", "Year" from http://www.diegofdezsevilla.wordpress.com. By Diego Fdez-Sevilla, PhD. More guidance on citing this web as a source can be found at NASA webpage: http://solarsystem.nasa.gov/bibliography/citations#! Bachelor in General Biology, Masters degree "Licenciado" in Environmental Sciences (2001, Spain). PhD in Aerobiology (2007, UK). Lived, acquired training and worked in Spain, UK, Germany and Poland. I have shared the outcome from my previous work as scientific speaker in events held in those countries as well as in Switzerland and Finland. After couple of years performing research and working in institutions linked with environmental research and management, I find myself in a period of transition searching for a new position or funding to support my research. In the present competitive scenario, instead of just moving my cv and wait for my next opportunity to arrive, I have decided to invest also my energy and time in opening my own line of research showing what I am capable of. The value of the data and the original nature of the research presented in this blog has proved to be worthy of consideration by the scientific community as well as for publication in scientific journals. However, without a position as member of an institution, it becomes very challenging to be published. I hope that this handicap do not overshadow the value of my work and the intellectual rights represented by the license of attribution attached are respected and considered by the scientist involved in this line of research. Any comment and feedback aimed to be constructive is welcome. In this blog I publish pieces of research focused on addressing relevant environmental questions. Furthermore, I try to break the barrier that academic publications very often offer isolating scientific findings from the general public. In that way I address those topics which I am familiar with, thanks to my training in environmental research, making them available throughout my posts. (see "Framework and Timeline" for a complete index). At this moment, 2017, I am living in Spain with no affiliation attachments. Free to relocate geographically worldwide. If you feel that I could be a contribution to your institution, team and projects don´t hesitate in contact me at d.fdezsevilla (at) gmail.com or consult my profile at LinkedIn, ResearchGate and Academia.edu. Also, I'd appreciate information about any opportunity that you might know and believe it could match with my aptitudes. The conclusions and ideas expressed in each post as part of my own creativity are part of my Intellectual Portfolio and are protected by Intellectual Property Laws. Licensed under Creative Commons Attribution-NonCommercial conditions. In citing my work from this website, be sure to include the date of access. (c)Diego Fdez-Sevilla, PhD, 2016. Filling in or Finding Out the gaps around. Publication accessed 20YY-MM-DD at http://www.diegofdezsevilla.wordpress.com/
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26 Responses to Looking at the influence of continentality in atmospheric circulation. (by Diego Fdez-Sevilla)

  1. (LinkedIn member)
    Meteorologist at DOC/NOAA/OAR/AOML

    I’d bet it would come in at 20 – 30%, maybe more, if you consider changes like desertification and/or drought. Cities are also normally ~2ºC warmer than vegetated county.

    (My reply)
    Diego Fernández Sevilla, Ph.D.
    Aerobiologist and Environmental Research Analyst in active job search mode worldwide

    Thanks Robert,
    I am not so fond on using numbers to give answers to environmental issues. You have seen already in my comments about “solar activity and anthropogenic interactions” what I think about the limitations of searching for correlations as the ultimate answer. Let me break the ice here, you might recall “The Answer to the Ultimate Question of Life, the Universe, and Everything” is: 42. (if you don´t know where I am coming from you should watch “The Hitchhiker’s Guide to the Galaxy by Douglas Adams”. You might enjoy it.)

    Once identified the links between soil processes, atmospheric circulation and surface energy budget (SEB) I see the next step in studying the difference between natural oscillation (natural perturbations that the environment is capable to absorb through resilience) and perturbations that interfere with the capacity of those mechanisms of resilience to absorb the perturbations.

    If you haven´t I deeply suggest you to check out the papers that I mention in the post because they identify pretty well the interconnections and feedbacks. If you don´t have access to some information I will send it to you by email.

    With more time I will try to extend my point of view about the state of knowledge identifying perturbations that interfere with the capacity of mechanisms of resilience to absorb the perturbations due to land use and cover.


  2. Pingback: “The Answer to the Ultimate Question of Life, the Universe, and Everything” is … 42 | diego fdez-sevilla

  3. (open debate with members from LinkedIn. Names are kept anonymously (unless specifically stated by author) for privacy reasons.)
    Alternative Energy Developer at Enery Efficiency & Environmental Health Services

    This is an extremely interesting question; I am looking forward to reading everyone’s comments !
    Member,Planning and Advisory Board (PAB) at Science for Inclusive and Integrated Development Trust

    Vegetative land cover can help environment in several ways; we recently estimated carbon sequestration by a tropical grass, vetiver in India which fixes more than 15tC/ha/year.
    Forestry Research Associate

    Proper management of the existing forests’ lands in the tropics will reduce the emission of carbon dioxides which ultimately reduce land encroachment by wate ror wind . Also the main problem in the third world especially in the Africa is shifting cultivation that caused in the conversation of the forests land and cover to deserts and let to climate change which adversely affected land poroductivity in terms of crops . However, management of the land use will lead to positive signs to let the land be productive and contribute in reducing climate change effects that taking place now world wide..
    Horticulturist, Life Member, Nepal Horticulture Society

    Proper land use classification and management and commitment on the part of the Government to implement could bring impact on climate change.
    Graduated in MSc Hydrology (VU University Amsterdam)

    How does this carbon sequatration calculation work? I would expect an absolute amount of carbon would be stored over an period of time instead of an negetiv carbon flux.
    Member,Planning and Advisory Board (PAB) at Science for Inclusive and Integrated Development Trust

    Perennial plants retain C for long time.However, there will be recycling of C due to the decomposition of organic matter. We need strategies to minimize loss of C to the atmosphere.
    Environmental Geoscientist


    You raise questions about climate change that get lost in the obsession with GHG. The public gets sold on the albedo-ice-feed-back threat with some expert in the Arizona desert demonstrating how much hotter dark surfaces get than white surfaces. What they don’t mention is that as the angle of incidence increases the effective absorbance of surface decreases. At 60 degrees the efficiency is only 50%. At a 60 degree latitude the efficiency if less due to the planetary surface albebo, increased scattering over greater atmospheric distance and the earth surface albedo.

    Land use changes to the albebo and the its impact on the radiation balance are more significant in the mid latitudes and equatorial region – where people do and have lived. This is consequently where most land use changes have occurred. Deforestation, and worst, desertification due to over grazing and poor agricultural practices increase reflection of energy, both of which have been happening thousands of years.
    B.A. Environmental Planning & Design

    The impact in climate relating to land use and land cover (i’m assuming vegetation?) management is immense. The implications of our euclidean style zoning (separating individual land uses) has led to a segregation of our built environment. This makes people have to travel further and further distances to get to where they need to go. Especially since most housing developments you have to drive 15 mins just to go to the store. Fact of the matter is, our climate is directly linked to the way we are making decisions about land use as well as land cover both artificial and naturally preserved areas. It’s not a matter of how much impact can we expect but more of how much impact are we actually seeing. With our current land use practices sprawl, traffic congestion, social injustices, lack of community, loss of culture, decreased livelihood and more are all a part of what we are creating through the land use decisions we are making as cities, counties and regions. Our land use decisions need to reflect and work off of our local and regional transportation investments. And our land cover management needs to be considered historically, contextually, and critically.


  4. The impact of land use and cover management is not coming only from the modifications of the physical properties of the soil being managed (Vegetative land cover, albedo, heat absorption and reflection, moisture content…) due to uses aimed for agriculture, forestry, urbanization, industrialization, water resources compartmentalization, … but also, by the materials released into the ground and into the atmosphere by the activities carried out (aerosols, GHGs, NOs, SOs…). I am surprised by how much debate there is just to identify and unify conceptual postures, set the state of awareness and explore the implications about how much potential has what is being done overland, to interfere with the climatic energy budget and its distribution.
    The oscillations we might find in our ecosystem could well be the result of mechanisms of resilience acting due to natural processes of variability that we can easily identify like solar activity, planetary seasonal tilt and position and sea-land thermal contrast. However, there have been identified already forces adding strength to natural processes coming from anthropogenic activity. Increasing the strength of natural processes could result in an increasing effect over natural oscillations breaking the “pendulum like pattern” of those oscillations. First by being more extreme in their amplitude, reaching lower or higher extremes of variance. Lately, if the perturbation is constant, unidirectional and strong enough, the oscillation might reach an inflexion point of no return. And that would be a new complete matter on its own.
    Either way, in today’s debate, if the impact of human development in the climate is happening now or not, is not tackling the main question of foreseeing the real threat of happening sooner or later. And the later we understand how that can happen, the shorter is going to be the time frame reaction to do something about it. Unless… there is no debate about the existence of a real threat from considering human development as a force capable of having an impact in the climate…neither now, nor in the future.


  5. “The final part of the positive feedback loop requires that the extra humidity above the wet surface can increase rainfall. It is hypothesized that the humidity gradients play an important role in modulating the dynamics of squall lines locally when they pass over. Squall lines derive their energy from moisture in the lowest layers of the atmosphere, and from a simple energetics perspective, more moisture being fed into the storm at low levels is likely to result in more vigorous convection, and hence rainfall. This hypothesis is currently being tested with a numerical model of a squall line, and initial results suggest that rainfall is indeed heavier over wet soils.”
    Feedbacks between the land surface and the atmosphere in the Sahel.
    by Christopher M. Taylor.


  6. (open debate with members from LinkedIn. Names are kept anonymously (unless specifically stated by author) for privacy reasons.)
    Air Quality Scientist

    Brookhaven national Lab has several papers out relating to land use impacts on climate, especially local climate, and it is significant. The IPCC report also states this and then basically gives it little attention. There is not much we can do about cities and farming. However it is interesting to note that the eastern US was basically deforested in the 1800’s and early 1900’s to build the railroads and other things.
    Computer Engineer

    Good question. Remote sensing can help find the answers.
    There is a new web site, Global Forest Watch (GFW), which is dynamic online forest monitoring and alert system. GFW can display current forest change (loss/gain) for any country, forest cover percentage for any country and etc. I think this tool is important because forest change is highly correlated to climate change. Also, land use and cover management are highly correlated to forest change, i.e. tree cover loss or gain.



  7. Diego Fdez-Sevilla. PhD.
    Aerobiologist and Environmental Research Analyst in active job search mode worldwide.

    Thanks all for your comments.
    I want to leave here a link to a study which I find very interesting regarding the topic in hand.

    Study: Emissions from forests influence first stage of cloud formation.


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