Author Archives: CAICE

Local Meteorology and Air Quality

During certain periods, the air here at Bodega Marine Lab (BML) has been stunningly clean — approaching what might be found in the remote ocean.  We’re finding, somewhat unsurprisingly, that local meteorology heavily affects the composition of particles that we sample at BML.

Here’s a case study from last weekend.  The scene: nothing but Pacific Ocean to our west, with cow pastures, campgrounds, and a popular vacation town to our east and south.  On sunny days under fair weather (high pressure) we experience a diurnal cycle of sea breeze and land breeze.  In aerosol particle terms, we see a very segmented signal: distinct ‘sea breeze’ and ‘land breeze’ aerosol characteristics.  Let’s have a look at the aerosol particle size distributions next to the surface meteorological conditions (from the nearby DRI met station on Bodega Marine Reserve):

SeaBreezeCycle_BBY

Two days of aerosol particle size distributions (top two panels), carbon monoxide and solar radiation (3rd panel from top), ambient temperature and RH, with wind speed and direction on the bottom panel. The correlation of wind direction with the number concentration of small particles (2nd panel from top) is striking.

The sources of particles in air masses that we sample during the sea breeze (wind from 300 degrees) are ideally very limited: particles ejected from the ocean as sea spray, and particles that form through chemical reactions in the atmosphere just above the ocean.  In contrast, the land breeze (wind from about 140 degrees)  carries with it particles from a wide variety of sources: fossil fuel combustion, biomass combustion (fires), food cooking, and agriculture.

If you aren’t familiar with this kind of data, and you have a keen eye, you’ll start to figure out what’s happening just by thinking about what particle sources we’re sampling under the land breeze vs the sea breeze.  Since the sea breeze contains sea spray, you can see that sea spray aerosol particles are typically characterized by larger particle sizes (the colors in the top plot show higher concentrations near the 1 micron diameter mark), compared to the kinds of aerosols observed during the land breeze episodes (smaller proportions of larger particles compared with to the huge number of small particles).  It’s well known to atmospheric chemists that particles that are emitted directly from combustion sources (so-called ‘primary’ combustion aerosol) are very small, and tend to grow as they react with other trace gases in the atmosphere or are incorporated into clouds and fogs.

I can tell you anecdotally, that the composition of the particles is very different between these two episodes.  Sea salt particles (containing mainly sodium chloride) that travel through polluted air quickly react with the nitrogen oxide pollutants to form sodium nitrate particles.  The land breezes also bring with them fresh combustion particles.  You’ll notice some small spikes in carbon monoxide on either end of the sea breeze periods, just before and after the switch — those are actually from fires from local campgrounds directly upwind of us — it was a weekend in a vacation destination town after all!

One really exciting thing for a atmospheric chemist is to see their science in the world around them.  To live in and around the environment; to observe with your own senses what you’re observing with your instruments.  This is why I’m an environmental scientist.

-Doug Collins, Grad Student (UCSD)

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We have arrived at Bodega Marine Lab!

The Prather Group has now successfully deployed the Mobile Lab to coastal Northern California at Bodega Bay.  Our sampling site is about 100 meters from the Pacific Ocean on the campus of the Bodega Marine Laboratory.  We’ve settled into our new workplace quite well, and we’re gearing up for a solid 4 weeks of sampling.  Just on our first day here at Bodega Bay, we’ve seen some really cool interesting cloud features just offshore, lots of fog, and a little sprinkle of rain last night.  We’re looking forward to more substantial rain this weekend!

Our objective for this season is to take our prior studies of aerosols, clouds, and precipitation in the Sierra Nevada Mountains, and extend them to the Coastal Mountains, which have some meteorological similarities, but also major geographical differences.  What we really need to learn about is the behavior of aerosol particles here at this semi-remote coastal location just to the west of the coastal range, so we can come to understand the scope of their impact on precipitation in this region, which is one of the wettest areas of California.  We’ll dig more into the science behind our trip in future posts, so please check back with us often.  We’ll be posting several times every week for the next month or so.

Buzzcut, G1 style

It’s not often that we land-lubbers at Sugar Pine get to talk about the airplane, but today we got a great view of it as they flew over us at low altitude.  The aircraft team did an extended spiral over our ground site… must have been 6 or 8 circles in all, with a couple of passes straight through the middle over our sampling setup (one of which gave us a pretty ‘intimate’ view of the underbelly of the plane!).  I took lots of video, and I’m hoping I can get it edited and put together so I can post here in the near future.

PNNL-G1 over Sugar Pine
The DOE/PNNL G-1 research aircraft flying a spiral over Sugar Pine Dam on March 5. The spiral path covered a large vertical profile with the ground site in the center.
View of Sugar Pine Dam
Sugar Pine Dam as seen from the DOE/PNNL G-1 aircraft on March 5

It seems nearly surreal that the study is nearly over… we have about 1.5 days of sampling left before we pack the trailer and head back to San Diego.  The last research flights will be tomorrow (Sunday)!!  I can speak for those of us at the ground site and say that this is the most adventurous and fun study we’ve done, albeit difficult on the body, dealing with such deep snow and moving equipment in and out of the site (the picture of us moving a pump a few posts back was only the tip of the iceberg!).  I think this is the first time the Prather Lab has dealt with snowmobiles, snowshoes, lots of shoveling, walking in snow up to the thighs, and a backhoe to tow us out of the field site.  This is most definitely what I signed up for when I joined the lab 20 months ago!!

Snow Anyone?

In my previous posts, I sounded excited about getting a lot of snow…. well I thought we had a lot of snow at that time.  It’s nothing compared to what we recieved this weekend.  Friday’s snowstorm landed the biggest single-day’s worth of snow that any of us have ever seen.  In the evening, when the weather began to taper, Greg Roberts and Scott Noblitt, with the help of the owner of the very cool lodge they are staying at up here in the backcountry, were able to access the site via snowmobile to ensure that none of our equipment was damaged by the unreliable electric service during the storm.  When Jack, Jessie, and I arrived in the morning, we were greeted with more than 3.5 feet of new snow (on top of the 1 foot we had remaining from the previous storm).  If you have trouble grasping how much this really is… trust me, I’m still trying and I’m in the middle of it… here’s a picture of Jessie (about 5′ 5″ tall) clearing snow off to top of NOAA’s box trailer.  Remember, all of that fell in ONE DAY.

Snow on the NOAA trailer after the 2/25 storm

Jessie Creamean posing for a photo while clearing snow from the top of the NOAA trailer at Sugar Pine Dam after the storm on 2/25/11.

According to meteorological data, this past storm may have been associated with Atmospheric River conditions, a notion that jives well with the heavy precipitation we received here in the Sierra in a short amount of time.  These kinds of conditions, where water vapor is transported directly from the tropics to the western margin of North America, have been responsible for some of the heaviest rain and snowfall on record for this region.  The band of water vapor that hit the coast here on Friday moved southward to the San Diego area on Saturday, giving our friends back home a good soaking.

In terms of aerosol science, it was great to have this second storm a week after the first one: we collected some great snow samples and were able to look for reproducible conditions surrounding the two storms.  We’re collecting lots of nice data up here, and we’re all confident that we’ll learn a lot from our observations thus far.  We’re just about 10 days or so from the end of the intensive sampling campaign.  We’re looking to finish strong… I got word today that there are plans to do lots of flights over Sugar Pine Dam in the G1.  I still haven’t had the opportunity to spot them by eye over the site (every time I’ve been available to look, it’s been cloudy).

-Doug

“Unsettled Weather – Carry Chains”

We saw this message on a motorist alert sign on I-80 today heading in the direction of Donner Pass… it seemed appropriate for the situation.  This weekend we had 3+ feet of snow dumped on the field site at Sugar Pine Dam.  Things got more interesting with electric service becoming as unpredictable as the weather.  Once we finally felt settled and stabilized our research payload, the Sugar Pine crew got a little snow-related activity in this weekend.

BlueSky

A view from the Humbug Loop in the China Wall area of Tahoe National Forest

It’s a very good thing we decided to rent those snowshoes… we simply would not have made it down the access road without them.  Knee-to-hip high snow was the norm for the ensuing 2 days… and wouldn’t you know it, we needed to transport some urgently needed (and very heavy) equipment to the site.  We decided a ski-patrol/mountain rescue procedure was in order — though we used a slightly lower-tech approach…

Snowshoe Sled

Jack and Doug utilize a mountain rescue technique to bring important supplies to the Prather Group's Portable Aerosol Observatory while it's under 3+ feet of snow.

Science-wise, we’ve all been very interested in the preliminary results at Sugar Pine.  It looks like we’ll be able to present some very interesting findings once we all get our data processed and compared.  It’s great to have multiple views of the conditions at our site, with Greg Roberts and Scott Noblitt joining us this year on a day-to-day basis.

-Doug

More SNOW at Sugar Pine!

It’s been an incredibly snowy 2 days here at Sugar Pine Dam.  Last we saw around noon today, there was about 16 inches of snow on the ground… we’re expecting maybe another foot of accumulation by the time we make it into the site tomorrow.  Our exit from the site was about as snowy as I’m comfortable with… we were going to go back in to check our equipment one more time at the end of the afternoon, and decided not to based on quickly deteriorating conditions and daylight.  We rented snowshoes for tomorrow….

Sugar Pine Snow Day

Approximately 12 inches of snow blankets the Sugar Pine Dam field site in the Foresthill, CA backcountry.

Things are ‘heating up’

Well… actually, it’s a lot colder than it was, but who’s counting.  We now have some snow at Sugar Pine Dam — about 2-3 inches.  We had to come up early today to get our communications back on line, as snow and satellite uplinks don’t mix well.  It’s a good thing we have a substantial 4×4 vehicle.  There was a stuck pickup truck on the access road to Sugar Pine Dam… at least it was less serious than when we came upon an overturned Jeep during one of last year’s storms.  I never thought we’d actually have to use the chains and the come-along winch we brought along…. this year we’ve managed to not need it (yet!!).

Sugar Pine in the Snow

Sugar Pine Dam recieved about 2-3 inches of snow overnight 2/15-2/16.

Once we trudged our way into the site, by 4×4 and then by foot at the end, we were able get communications back up and running, check our instruments, bring in the collected slush from overnight for offline analysis, and relay some certainty of the conditions before the G1 aircraft flew over the site (and the rest of the central Sierra), about which I’m sure Kim will have much more to say.  We heard them fly over us twice today… they were squarely in the thick cloud deck, but the G1’s twin turbo-prop was clearly audible.  As I write to you now, the G1 is flying over the Donner Summit and Norden (home of the Central Sierra Snow Lab… and some really great skiing).

We’ve been very excited about our preliminary looks at data, and communicating lots with those back at the aircraft HQ at McClellan Airport.  All of our measurements are up and running well at SPD… let’s hope it stays that way!  Stay tuned….

-Doug Collins