Friday, March 18, 2016

Pollen and geology leads to SearchResearch

Just about now, 

in early spring, pollen starts to show up in the gutters.  

In between the bursts of rain, early flowering trees—where I live it’s the plums, almonds, and acacia—all start producing pollen in abundance. It all washes down from the stamens, over petals and into the drains, leaving long strands of cadmium yellow along the rainwater’s edge.   Fecundity’s promise, denied and discarded, but leaving brilliant streaky color along the way to sea. 

In the San Francisco Bay area, those rains visit only between November and March, just five months of the year.  Maybe because they’re so rare, they seem to bring wonderful moments of pure delight.

As I walked down the street just after a long rain, the sun emerged for a moment drenching the wet surfaces in warmth and light; a momentary pause in the rain that filled with brilliant sunlight.  I turned around, looking away from the sun, hoping to catch a rainbow in the droplets reflections, but missed seeing anything.  I kept walking.  As I passed a tall pine tree, one drop fell off the tree limb into the sunlight, an aerial jewel.  Then another, and another… until an entire shimmering cascade came off the long needles and into the shaft of light with a hush of quiet velvet sound.  No rainbows in the moment, but there’s a curtain of falling crystals to see. 

It was just an avalanche of raindrops; it happens constantly, nothing special in particular.  But in that moment, in that quintessence of a fragment of time, I missed the rainbow, but saw diamonds in mid-flight, surging to the ground.  

Earlier that morning I’d gone for a run at the Stanford Dish, it’s an open area featuring a gigantic radio-telescope, a landmark in Silicon Valley.  But for locals, this is one of those standard runs you do often, just because you know exactly how far it is, what the trail is and what to expect.  It’s not an exploration so much as it is a familiar ritual. 

In rainy weather, though, it can be surprising.  The Dish is in a hilly region of Palo Alto, with spectacular, open views in all directions.  When it’s clear, you can see from San Francisco to San Jose (thirty miles to the north, thirty miles to the south) up and down the bay.  To the west, the Santa Cruz mountains form a woodsy barrier wall.  And when it rains, the clouds seem to always be especially dramatic from this hilltop.

Naturally, being a curious guy, I was thinking about that as I ran on the crestline trail.  It’s where the views are best, and where the view of rain, clouds and sky are always most impressive.  Why is it so consistently impressive?  Is it just the openness of the viewshed?
On this run, this time, I noticed two patches of rain off in the distance.  One was to the north, roughly over San Mateo, where there’s a gap in the western coastal mountains that lets the fog through in the summertime.  The other rainy patch was to the south, roughly over Los Gatos, where there’s another gap in the mountains.  An insight begins to dawn… Those two patches of rain are coming from the sea to the west, and are coming through the gaps in the mountains.  

Of course!  The reason the clouds are always so spectacular is that the Dish happens to sit between two major mixing points between the marine layer of air (coming through the gaps) and the air that sits in the bay (or in the summertime, that’s coming from the east, off the Central Valley).  

In essence, this is the eddy between the mixers. Swirls, bumps, and lumps in the clouds happen preferentially here.  Shafts of light that come through the breaks happen here as well, for just that reason—it’s an accident of geology.  

The San Mateo gap is well-known.  It’s what lets the summer fog over the mountains, often causing SFO to shut down.  The gap at Los Gatos is also well-known—it’s where Highway 17 takes the low pass over the mountains to reach Santa Cruz.  

When I get home I do the obvious thing and search for a rainfall density map of the Bay area, looking for confirmation that my gap theory is actually true.  And after searching for a while (the key insight was to realize I needed a “precipitation” map, not a “rainfall” map), I found just the diagram I sought.  And it’s true.  Extending eastward from both mountain gaps are regions of increased rainfall.  Los Gatos averages about 33% higher rainfall than the Dish, with similar numbers for San Mateo.  Even better, the map shows a plume-like structure to the rain distribution: it’s the gaps causing the focusing of precipitation.  
And now, naturally, being a curious guy, I wonder if there is a difference in the types of pollen you’d find in the gutters and waterways of Los Altos (to the south) and San Mateo (in the north) as compared to the location of the Dish.  I suspect so.

That search continues.  I will tell you that in the process of searching for differential pollen patterns in the Bay area, I learned a new word:  palynology—the study of pollen… and its distribution.  The word dates from 1944, and was coined in the Pollen Analysis Circular (a small journal that published from 1943 to 1954 and then merged with the larger publication, Micropaleontologist).

The question is, can I link geological features to pollenfall patterns?  What kind of research would I have to do to get the answer? That’s the joy of finding stuff out—the chance to look at the world, do a bit of deep looking and digging in the literature, pulling together ideas, linking them together to learn something brand new. 

I love doing research both professionally and at a small, personal scale.  And I now know why running the Dish on a rainy day is almost always rewarding—it’s fertile ground for observing the world and launching into small personal research quests. 

The next step is just connecting literatures between geography, meteorology, and palynology—a cross pollenization of academic disciplines, if you will. 


  1. Interesting stuff. May I suggest incorporating local winds. We know around these parts that even small hills of a few hundred feet produce noticeable changes in weather. Same for depressions. Is not pollen mostly blown around?

    palynology; I was thinking this was the study of someone from Alaska

    jon >

  2. I regularly visit SearchResearch and am chuffed that you are examining a very relevant topic. I am a botanist (weeds) ... I ♥ pollen ... A genetic strain of the weed Nassella trichotoma has emerged that is resistant to the selective herbicide flupropanate; the gene is spread in pollen that disperse in wind; seeds of the weed are on panicle heads that readily disperse by wind.

    Relevance to your SearchResearch blog:
    ► Might we see patterns of resistance associated with wind direction and strength across the landscape based on:
    1] time of pollination? (→ wind rose for Goulburn October)
    2] time of seed dispersal? (→ wind rose for Goulburn December)
    ► Might other atmospheric phenomena affect pollen dispersal? (→ what is an inversion layer)
    ► How might other vectors (insects) spread pollen across the landscape? (→ habitat of blue banded bee. N.B., geology affects the vegetation that will grow across the landscape; insects associate with different vegetation)
    ► How might dispersal as contaminant in hay occur across the landscape? (→ arable land in nsw)
    ► Reality check: While these are interesting points of inquiry, I must bear in mind a. Big Hill NSW is renowned for its fierce winds, b. wind tends to blow all over the place, even if there are predominant winds, c. the resistance probably developed decades ago before it became noticeable to the farmer, d. resistant plants are now very abundant on the initial farms, e. resistant plants are now regularly seen across the landscape, f. patterns of pollen spread across the landscape would make very interesting but academic research, g. it's too late for 10,000 farmers who will have their livelihoods affected.

    SearchResearch - Dispersal of pollen. Some friends did PhD studies on ancient pollen across the landscape. I could ask them about points of inquiry. But it is a Saturday - they have knocked off and so have I. So I reframed the topic:

    ► *What other windborne particle distribution information might be informative?*
    Points of inquiry:
    • Herbicide spray drift across the landscape - I have written extensively on the topic on my work account -
    • Spray paint booths - really interesting; the paint is meant to land on the object, but the air needs to be breathable and non-flammable.
    • Spread of radioactive stuff ...

    SearchResearch = How might I find out how radioactive stuff is dispersed across the landscape - a geography of radioactivity
    Preamble = I remember that radioactive dust from the South Australian nuclear bomb tests is regularly mapped.
    Search = Maralinga radiation
    Search results = first four results seemed to be about the history lesson; the fifth one caught my eye:
    Further inquiry = Maralinga radiation Caesium
    Search results = The sixth result particularly caught my eye; it is a pdf from an authority:

    P.S., Successful pollen moves from the male bit of a flower to the female bit of a flower of the same species; stuff happens (Google it; botanists talk dirty all the time). Unsuccessful pollen lodges on the ground, on to another part of the target plant, onto another species, onto a target flower that has already been pollinated, or blows right outside the range of the target plant.

    1. Oh, and ...
      → what is anemochory, and anemophily (this topic is about one, but I am more interested in the other).

      Other interesting stories of spread of things as airborne particles ...
      In 2007 I was involved in the successful eradication of equine influenza from NSW. Mostly it spread by as suspension - particles so fine that there is little or no difference in effect of gravity of the particle compared to the wind substrate. (→ spread of equine influenza nsw)
      But I also heard of a winter mist spreading equine influenza in fog water aerosol droplets (→ spread of equine influenza nsw in mist)

    2. Didn't know about anemochor and anemophily. Fascinating. Drop me a line if you have any ideas that might be turned into future SRS Challenges!

    3. terminology, general & regionally based… good reminder to notice & search unfamiliar related terms…
      wiki summation
      multiple factors?
      Queensland bulletin

    4. BM means something else downunder
      luckily, there's a Subway nearby…
      on the move, 2007
      proud wooly/Cementus-Baa-Ram-Ewe Password
      the night look
      the back view… a wee bit blue…Sweet as
      that's fair dinkum, that is
      tall poppy
      Maa & Old Ewe
      Aussie related
      Magda Szubanski
      "The big merino, in southern New South Wales, will move to a new home early next year.
      The giant construction, nicknamed Rambo, has lost 40 busloads of visitors a day since the Sydney to Melbourne freeway bypassed Goulburn.
      Merino visitor centre manager Lindy Kerr says the move also means some homes will no longer have to face the concrete ram's huge backside.
      She says getting closer to the Hume Highway will be a major effort.
      "It's really going to be like moving a big house. It'll be on a large transporter. It'll be headed out to the highway and I believe part of the median strip will have to be ripped up," she said.
      "The powerlines all the way down the highway will be cut. Country Energy ... I guess they're going to be virtually following the sheep as it progresses down the road. They'll be reconnecting the power lines.""
      ABC, 2 Oct 2005