Eyes on the Southwest Pacific

Over the last couple of days a large region of enhanced cloudiness propagated from north of Australia towards the South Pacific Convergence Zone (SPCZ). In association with the passage of the region we saw the development of several tropical cyclones. There is good evidence that these are, at least partly due, by the eastward propagation of an active phase of the Madden-Julian Oscillation  (MJO). Below is an animation of the last days over this region.

Why this suspicion, well first CPC has low-level wind anomaly maps, which is showing a region of strong westerly wind anomalies north of Australia. 

Second, the now famous index for monitoring MJO activity of Wheeler and Hendon (2004, http://cawcr.gov.au/staff/mwheeler/maproom/RMM/) is showing a large index at phase 8. The corresponding map for a phase 8 disturbance is shown in the bottom right panel below. Both the CPC wind anomalies and the cloudiness over the southwest Pacific are consistent with an active MJO event in this region. 

I highly recommend people to check out the link below to see the Google Earth streamlines for this region, linked below

http://earth.nullschool.net/#current/wind/isobaric/1000hPa/orthographic=-186.51,-11.97,512

Coloring the grey skies: prologue

About a year ago I was walking in the hallways at a science festival in eastern Washington when I overheard a lady talking to his kids, two boys. The kid said to his mom:

"Mami yo quiero ir a estudiar a UW cuando sea grande" (Mom I wanna study at UW when I grow up)

To which his mother replied: "Si hijo eso sería maravilloso pero tendríamos que ahorrar mucho dinero" (Yes son that'd be wonderful  but we have to save a lot of money for that)

At that point I felt compelled to interrupt their conversation (and probably take them by surprise cause in all likelihood they weren't expecting me to understand their conversation) and talk to them in Spanish for a bit.

The conversation went like "I want my kids to go to a good college to get a great education but our family cannot afford it", to which I walked over a table, grabbed a tiny notepad and a pen and wrote down about 10 scholarships for her kids to apply to and a bunch of websites that gave tips on how to get into college. There were scholarships that helped with tuitions, loans, applications, SAT tips, well ... everything.

The lady thanked me and asked me why I helped her and I said:

"Todos merecemos tener la oportunidad de al menos luchar por lo que queremos tener"
(We all deserve a change to at least fight for what we want)

I think this is probably that I have responded to this kind of question this way. I usually say something that comes out as awkward or silly and then have to deal with embarrassment the rest of the day.  I could have honestly said something better anyways.

The truth is that I saw those kids, preteens. At such a young age they knew they wanted to go to college and get a degree. They had that sparkle in their eyes that only kids with ambition have. How could you deny them the opportunity to have a fighting chance?

So with a simple smile I gave them the notepad and pen and directed them to a bunch of booths where other people might be even more helpful. Outreach, sometimes I consider it the highlight of my career, to talk to people about science and all the excitement and travel you could possibly do.  It can be a double-edge sword, however. It's like you're at this beach with a bunch of people and you point them at this great island, and perhaps you help them get geared up to swim that way, but you don't tell them there's an undercurrent along the way.

Turned out that was the first pair of kids I talked to about college that day out of many. This is not a particularly special day, it has happened a couple of other times.  I just couldn't help but to wonder how life would be if every kid that wished to have a chance to pursue what they wanted could have a chance to do it? Truth be told, it hurts deep down in the soul to just think about that day, cause I feel like I sold them dreams to sweeten a bitter reality.

The warm hemisphere

I have been inspired to start the writing process again. This time inspired by the latest events. A couple of weeks ago I flew to east Asia for the first time for this amazing opportunity to present my work.  Another reason that I wanted to talk about this region is the recent devastation caused by Typhoon Haiyan, one of the strongest tropical cyclones ever recorded. At the time of this writing, Haiyan has claimed over 3600 lives. For information about how to help the victims of the typhoon, follow this link.

This sparked some curiosity to learn about the weather and climate of southeast Asia, Oceania (informally called here the Maritime Continent), and northern Australia. Some people have asked me: "Can a storm like Haiyan hit the U.S. coast?", and "How can storms like this form?". While the details of these questions can be left to tropical cyclone experts, there are some aspects about the region where Haiyan formed that are well known by many.  I will talk a little about these salient features through several blog posts. 

The area that encompasses the Maritime Continent, Southeast Asia, India  and Northern Australia is colloquially called the Indo-Pacific Warm Pool. This is a special region of the globe, where a combination of factors, including having the Maritime Continent near the equator, the nearly isolated Indian Ocean,  as well as even the planet's rotation combine to create some of the warmest sea surface temperatures (SSTs) in the world. Below is an animation of SST throughout the year. Notice how the warmest temperatures are in the Western Pacific Ocean throughout the year, with some wobbling north and south with changes in season.

Animation of climatological sea surface temperatures.

For these, and many other reasons, the Eastern Hemisphere is often described as the Warm Hemisphere (note that the western hemisphere tropics aren't cold,  they're  just not as warm as the Eastern Hemisphere tropics). Perhaps the signature of the warmer temperatures are even more obvious in a product called column integrated water vapor, which describes the total amount of water vapor in the troposphere.  Below is the column water vapor obtained from the ECMWF 40-year Reanalysis (ERA-40) Atlas, a nice open source tool that shows nice climatological plots. 

For boreal summer (June-August, JJA), it is clear that the Warm Pool is the region where the largest amounts of water vapor are.  This feature has profound impacts regionally,  in the form of the monsoon system, and globally. 

Column integrated water vapor JJA climatology from the ERA-40 Atlas

One of the many interesting results of all this is that this region has a lot more diabatic heating from condensation than anywhere else in the world, especially during the boreal summer months (JJA). Just see where the deepest shades of red are in the plot below. There are some regions of strong heating outside the Warm pool, corresponding to the Intertropical Convergence Zone, and a signature of the Gulf stream over the east coast of the US, which is also the signature of disturbances that curve to the northeast over that location.

Diabatic heating JJA climatology from the ERA-40 Atlas

This massive area of heating is crucial to the climate system, and an important contributor to the transport of heat towards higher (colder) latitudes. It also influnences significantly the circulation of the atmosphere by generating what we call stationary waves. Below is a map I made showing the difference of SST over the hemispheres by removing the mean SST from each latitude. This plot makes it clear where the warmest SSTs are found. Additionally, I show geopotential height anomalies, which can be thought as pressure. Over the tropical western Pacific, the atmosphere is "thicker", which means pressure is lower near the surface, but higher upper portions of the troposphere. It is the opposite over the eastern Pacific and the Atlantic.  Why so? I will cover the reasons why in a future blog entry.

Thoughts on long-distance cycling

It's been a while since I've written a blog post, and I think it's been long due that I write something that could be interesting yet fun to read. Anyways, this weekend I was doing the Seattle to Portland Bicycle Classic (STP), a two-day (for me) 200-mile ride from, well, Seattle to Portland. This is the first one of two double centuries I will be doing this summer (and one I signed up for on the last minute)

I am surprised that my body is not as devastated as I thought it would be, considering how tired I was every time I finished training.  Like any other ride, there are some neat tricks that'll make life easier for you, and some of them are related to the atmosphere. I will focus and those observations, and also describe the meteorological conditions during the two-day ride, which distracted me a lot! 

On the map below are the two routes for these year's double century rides. STP is to the left. A more interactive map can be found on this link.  Notice that is a pretty straightforward ride, with the only significant elevation gain occurring at abotu 40 miles into the ride.  The second climb happens at about 115 miles in. While these are only modest changes in elevation, they did have an effect on the temperature and wind I felt during the ride.

Overall, the weekend was beautiful, we had sunny weather and barely any clouds in the sky, which allowed for some amazing sunrises and sunsets, as well as a noticeable diurnal cycle.  Below is a meteogram from the rooftop of our Atmospheric Sciences Building. The red line was [roughly] the time I started biking on day 1 and 2, and the blue line is the time I finished. The only relevant part (since I was on the move all day) is the bottom plot, which is solar radiation. Notice how we got uninterrupted sun both days. I got a bit sunburnt even though I used sunscreen. The third plot shows temperature, which had a similar behavior throughout the ride. The highest temperatures happened after I arrived at Portland, which I kept in mind the whole time since it becomes much harder to ride when temperatures are above 80°F.  Anyways, now those are the preliminaries, now lets discuss the two days!

DAY 1:
We took off at about 7 am on Saturday from the parking lot of UW's gym, and temperatures were quite mild and winds calm. Nearly perfect conditions for exercise I'd say. With a ride that had over 11,000 riders, it's hard to ride ahead  of anybody at the beginning. I will forever remember the sound of hundreds of people clipping and unclipping their shoes.  After getting a couple of miles in, the bikers began to disperse, but it was still pretty calm, so there was no real strategy other than eating snacks and drinking water/Gatorade ever 30 minutes or so.  However, it started getting pretty warm early in the afternoon, so the second 50 miles of the first day included more breaks, and more stops for drinks.  I reached the mid-point at about 4:30 pm, which was a bit slower than expected. A picture of the mid-point (Centralia College) is shown below. Overall I think I kept a pace of 10-15 mph on the first day, with 4 breaks in between.

DAY 2:
Now this day was interesting. Since I stayed the night on a valley on a clear night, a surface inversion developed, and it was pretty foggy over some areas. Most noticeably, there was fog right above streams and flat fields. The temperature was about 40°F, which together with my sore body made for a miserable begginning for day 2.  About an hour in the ride there was a climb of about 200 feet, and my body warmed up from that, but a thermometer located in a school right after the hill showed the temperature was also a couple of degrees warmer.  Winds were pretty calm over the valley, but some areas had a light wind on top of the hill, which made pedaling a bit harder. This is where biking with groups becomes a great idea. If you stay behind groups, the leading bikers will break the mean wind into smaller eddies, and you feel less impact from the wind. This makes you bike about 1-2 mph faster over modest to moderate winds, which is small but it makes a good difference over long distances.   I managed to drift with several groups and with smaller breaks in between, I managed to finish day two in about 6-6.5 hours. Another hassle of day 2 was the fast increase in temperature. By 11 am temperatures were already in the upper 70s while I was crossing a shadeless road.  At that moment I was glad I wasn't wearing a sweater, and definitely thought that I made a fair tradeoff when I didn't put a sweater on during that crisp, chilly morning. Overall I averaged 15-20 mph on day two, with the higher speeds achieved while biking with a group, pretty good for a first timer!

Anyways, it comes to show you how important it is to be aware of your surrounding atmosphere, strategize and be up-to-date on the latest weather forecasts; at least for these long rides.

When tropical scales meets other scales: A global view of current Atlantic weather

The major news outlets lately have been completely focused on the threat of hurricane Sandy . Indeed, it has been rumored that it is one of the biggest threats to hit the Northeast [US] in years, and rightly so. The circulation pattern that is leading to this event is rare. It is comprised of a set of events on different scales, both tropical and extratropical, that is leading to this set of events.

The image below shows a hemispheric look of what's currently happening. The most prominent  feature are the two cyclones over the Atlantic ocean. The first one is obviously hurricane Sandy, the second is a not so different looking extratropical cyclone, which has been persisting for several days.

While these two low pressure patterns are quite obvious in satellite imagery, some other strong patterns are ocurring that are not as obvious in a picture.  The figure below shows the forecast of geopotential heighs (and anomalies) within the next couple of days. Geopotential heights are analogous to pressure.

The first and most most interesting pattern in the figure  is the major pattern localized over the Atlantic. Check out how the jet immediately shifts northward near the east coast of the USA. That red bullseye over northeast Canada is an anomalous ridge. That ridging pattern, flanked by two lows (seen above) is often called an "omega" pattern because of its resemblance to the greek capital omega.

Indeed, we are currently in a period where the jet is weaker, and more wavelike features dominate weather patterns. This is very evident in the latest Arctic Oscillation (AO) Index, which has been negative for a while. A negative AO index indicates strong wave features, with potential for Arctic spills over the US, and anomalously warm Arctic temperatures. The pattern, however, is forecast to weaken in the following weeks, thus anomalous blocking patterns like the one seen above may become  less likely.

Typhoon Sanba

Typhoon Sanba has become the object of attention lately, with its characteristic appearance of a robust tropical cyclones.  Below is an animation from NRL of the cyclone during the last couple of hours.

The cyclone strengthened rapidly while it passed an area of high ocean heat content, as seen below (image courtesy of CIMMS and RSMAS).  Although it has gained a lof of strength, reaching the Saffir-Simpson category 5 scale, it will likely not hold it for very long as it is leaving this area of high ocean heat toward one with cooler sea surface temperature.

As an additional sidenotem the cyclone is also dominating the upper-level divergence pattern in the form of velocity potential (divergence is the laplacian of velocity potential). In the plot below, yellow contours denote the velocity potential associated with large-scale upper level divergence, also associated with ascending motion. Green contours denote the opposite. Note the tight contours in the area where the storm lies.  The filled contours denote the upper level streamfunction. Tropical cyclones do not tend to project strongly in the rotation in the upper levels. The contours in that area are likely due to Rossby waves.

In a couple of days, Sanba might become a threat to some land areas in this region.We should keep close attention as this situation unfolds. 

About research money, outreach and people ...

Every once in a while I meet up with people I haven't seen in a while.  When you don't see people for a long time,  they seem to go through a similar routine of questions. Some of the questions include "What are you doing now?", "What's meteorology?" and the infamous "So meteorologists work with [insert something that's wrong but funny]?".  Last week I got asked if I worked with dinosaur bones! 

Sometimes you get thought-provoking questions, the ones that you keep thinking about long after the conversation is over.  For example, a couple of days ago I had another student ask me about funding. His questions were basically "How do you pay for school?", "Why are you getting this funding?" and "What is expected from you with this money. They look like pretty simple questions, and they are. The thing about them is that they make you think about the way that you are using your money,  what do you expect out of yourself, and so on. Naturally I told him about research assistantship, teaching assistantship and the many fellowship opportunities that are out there.  But then I started thinking "What do they want from me with that money?".

The fact is that they want you to do research with that money. Hopefully you will find interesting things, get some papers published, etc. All in all they just want you to add another drop to the cup of advancement of science. It is a topic that I keep mentioning in several blog posts.  In our field, one of the main goals is to improve weather prediction, so we can have better forecasts. 

Take for example what I do:  My research is focused on the MJO. While great progress has been made from it's discovery in the early 70's, there is still so much to get done.  It's complex behavior in the last couple of weeks has been discussed even among experts. All in all, we are still long ways to get a good grip over this big guy. 

It's erratic behavior has not been the only thing that's troublesome. Last year we had a good number of tropical cyclones that came to be, at least in part, due to the enhanced moisture and vorticity provided by the active MJO over the Indian Ocean/ Warm Pool region. Tropical cyclones Keila, Washi ,  Grant and Thane all were generated like this, to name a few.  Some of these storms caused significant damage to the areas they affected. In particular, Washi is responsible for more than a thousand deaths.

Images showing precipitation from TS Washi during the specified dates. The larger swath corresponds to TRMM's Microwave Imager (TMI)  while the smalle swath corresponds to the Precipitation Radar (PR).

These storms did plenty of damage, but what about other events. What about floods that come from prolonged rainfall, not associated with tropical cyclones. What about flash floods from convective precipitation? What about everything else that can be caused by anomalous weather. The truth is that we barely hear about these things. In fact, most people probably don't even know about the damage the tropical cyclones themselves did. The reality is that these events barely ever hit the headlines, and yet they happen on a year to year basis, claiming hundreds to thousands of lives. 

That's one of the reasons behind the heavy funding for research. If we could understand all this better, we could predict it better, hence reducing the likelihood of having a significant weather event claiming lives. But, is this really enough? The answer is inarguably no. 

There is a lot more to the safety of people than proper weather prediction. While it is great that nowadays we count with weather forecasts that are as easy to access as pressing your cellphone's button; it's pretty worthless is the reader has no idea how to interpret the forecast, even less if he/she doesn't know how to act to it. This is where outreaching comes into play.

Just as important as the science itself is spreading the knowledge to the public. But it is not something as simple as writing about it once and leaving it as is. It is a constant process. You have to let it be known with certain frequency, and be persistent about it. You also need enough facts and be convincing when you talk or else you might be shut down. It is a very difficult task. 

Back when I was in high school I was involved in a lot of community service. One of the things I got involved was doing a march against the abuse of elderlies. I directed the march and hundreds attended. It was one of the most fulfilling events of my life! In response to the march I got so much help from different people to help out with the, with people donating checks to wheelchairs. The next year I looked to follow up with a second march, or an event of similar magnitude. Because I was out of town for college I was unable to direct, so a new group emerged to make it happen. Communication between us was low, and the event never happen. That was it for the marches against elderly violence ...

Image from the march against elderly violence. 

That second march could have happened. It just needed more motivation, more persistence and the right attitude. This is what happens fairly often in many of lives situation, you bail on it thinking there's no solution when you can actually seek out an alternative. While this might be too simple with certain scenarios, like climate change, it is generally fairly true for many others. 

So are improvement and outreach all that we need? I don't think so. There's even more to all this than what I have mentioned. People's safety from weather, or other dangerous events depends just as much on each individual and the local government as it does on the other communities that work with it.  In the end it is a multifaceted task, which requires a drop of effort from many people. With the writing of this blog, I hope I do a little bit on the outreaching part. What about you?

Thank you for your time.

Ángel F. 

[Res] Recapping the last active MJO

I want to start off this new year recapping the last 6-8 weeks of activity in the Indian Ocean area, where research is ongoing and activity has not even come close to ceasing. Just to show off how things have been, below is an visible image from Meteosat 7, provided by NRL. Here we see two active tropical cyclones: the now gone Cyclone Thane in the upper corner, and Cyclone Benilde in the lower portion of the image. 

Cyclone Thane in particular caused some significant damage to India's southeastern coast, uprooting several treen, causing power outages and claiming the lives of at least 42 people according to several news reports (Click here for some images of the aftermath of Thane). Below is a loop of IR images from Meteosat 7, showing the cyclones developing and moving westward, with Thane making landfall in the Indian coastline. 

What is trully fascinating about these two cyclones is that their birth may largely be due to the rejuvenated (or newly formed) active MJO phase. In the image below, provided from NOAA's CPC, you can see the restart of OLR anomalies in the Maritime Continent sector. It's remarkable to see that, up to this moment, the anomalies associated with the MJO have had a similar pattern in OLR, particularly in their initiation part. I'm personally a little hesitant to say that this late December event is completely new, but from this picture, it almost looks like a new one started just further east than the other events. 

In the MIMIC-TWP loop below you can see both cyclones taking up moisture from the active MJO and from the apparent ITCZ in the southern Indian Ocean. It is also interesting to see some moisture from the remnants of Thane coming offshore on the western coast of India. Additionally, notice the dryer air mass creeping into the Maritime Continent.

The following loops shows a vertical cross section of moisture convergence over the Indian Ocean region for the last two months. When an MJO starts over the region convergence has much more vertical reach. Also, it seems to happen all over the region, making the method of initiation seem even more mysterious. 

The followig loop shows the 200 hPa moisture convergence and it's irrotational wind vectors for December 2011. Notice how when the December event strengthens, things start bubbling up in this region.  Overall things that makes one ponder about the dynamics of tropical instability

Nearing a close: 2011

I always love to make some sort of writing at the end of the year, mentioning some of the most memorable things. This year is no exception, it's been a special year. As 2010 marked a year of personal transformation, 2011 has been a year of continued growth.

In some ways it is also like every other year. You know, life has to go on, and it does every year. For me funny things have to happen to me every year, and this year was no exception. A few noteworthy things were:

1. I lost my keys and had broke into my own apartment.  I got in but still looked like a crook. I had some explaining to do to my neighbors after that!
2. Went snorkeling on the Florida Keys, got a cramp, everybody thought I was getting attacked by a shark.
3. Bought my 14th set of headphones (that I recall) since high school. This time I was smart enough to put a 2 year warranty on it. I finally learned!

Ok that's done with. Overall I feel like I have learned so much this year. I began research as a graduate student. That means that now I read scientific papers on a weekly basis. I am in no way near being an expert right now, but I have realized that there is just so much to learn in my field!!

Just look at the image below. Now normally one would just see the picture and say "Woah look at the clouds", or something like that. Nowadays I look at it and think "Wow that looks like complicated physics". You change like that. In a way you kinda become a little more insane, but not in a bad way.

In many ways I think this year by far has been two things. First of all I think it's been my most successful year professionally.  There is only one reason behind this: I just worked a little harder. I got my serious groove on and did an hour more of work per day. It has made a big difference. It doesn't mean I don't take breaks, I do, I am just better at organizing my time now (though I still get those moments in which I just sit on my exercise ball and do nothing).

Out of the things that 2011 has brought me, one is this obsession of constantly looking at what's going on in the Indian Ocean. A lot of the times it's kinda boring, but sometimes interesting things can brew, like on the loop below.

I guess that's just how it is sometimes. Just take the PhD comic below and substitute the question marks by the loop above, and you get my life on weekdays!

Well okay so maybe it's a little more than that. It's more like thinking about weather instruments, classes, research and donuts! Ok that's not true either! It's a pretty normal life actually, which is pretty much what I always wanted anyways.

Ok so I'm done with this post. Here's saying goodbye to what's probably been my happiest year so far (seriously). So it is with a little bit of sorrow that I say goodbye to it! Here's hoping for a great 2012!

Still merging science with wacky
Ángel F

Latest activity over the tropics

It's been a couple of days since I've posted an entry. Well, to be honest I am currently on Christmas break, so things have been going slow, especially since I am at home in PR. By no means this means that I am taking a break from everything!

The last couple of days have been fairly interesting in terms of tropical activity. The biggest story has been tropical storm Washi, which could become one of 2011's most deadly disasters, with the current death count nearing a thousand in southern Philippines. It has not been a major headline but it has been mentioned in several websites, like CNN, the Australian, Washington Post, and other sources.

The Moderate Resolution Imaging Spectroradiometer (MODIS), on NASA's Terra satellite was able to capture this visible image of the cyclone on December 16.  While not a particularly powerful storm, the combination of heavy rains and the island's terrain (topography, flora, agriculture) are likely the main cause of the deadly flash floods and landslides that claimed the lives of hundreds and left thousand of others homeless.

Elsewhere in the tropical region, some interesting activity has been occurring over the Caribbean region, as the remnants of a cold front affects the area (seen as the line of moisture moving southward in the CIMMS TPW loop) . While these cause great changes in temperatures in the continental U.S., here they're mostly known for modest changes and temperature and light rain. The NWS in San Juan, PR calls for a low to medium chance of showers during the next couple of days as more of these systems keep affecting the area. 

To put things in a clearer perspective, the North American Mesoscale Model (NAM), as well as other numerical models, continue to forecast several bands of these frontal systems to move into, and linger, over this region the next couple of days.

Forecast for sea level pressure (contours), precipitation (colors), and vorticity maxima (red crosses) from the NAM model. Image from UW's weather loops.

A global stiched IR image from NRL shows a resurgence of cold clouds in the Eastern Indian Ocean/Maritime Continent region as seen in the image below. Data from NOAA's Climate Prediction Center (CPC) suggest's that the MJO has restrengthened after stalling in that area.

A cross section of moisture convergence (from the 12 EST GFS analysis) over the Indian Ocean sector shows that, once again, convergence is considerably strong, even at mid levels, as can be seen in the image below. Vertical motion also has considerably increased.

Mosture convergence cross section

Perhaps more informative is a time series of moisture convergence going back in time to 700 hours.  The first maxima shown in the plot was in mid November, when the active phase entered the Indian Ocean region. Convergence rapidly declined as the area became dominated by the suppressed phase. It is worth mentioning that while the current moisture convergence values are not quite as high as before, they have been on the rise. I doubt they will reach values as high as they did before, since the MJO will likely propagate away from the area (or weaken), sometime in the next week or two.

The tropics, my home, part 3: Beyond the clouds

Prepare for a long entry! And by the way, even though some I put links on the same names over and over, I may be putting new websites that might be of interest to the reader. 

On the last post from this series I wrote about a little bit about tropical clouds, rain, and how they influence our culture and lifestyles (with one last picture below). Today I will talk on what moves around these clouds, and give a story on things I’ve learned about the tropics through the years that have made it an even more interesting place to me!

The ñapa picture of a sunset behind some activity. Picture courtesy of Gian A. Villamil (Physics/Meteorology UPRM)

During the year 1995 we had a very active hurricane season. This was actually the first season I can recall almost completely (I was like 7 back then). Interestingly, this marked the beginning of as series of active seasons that’s still ongoing; largely attributed to the Atlantic MultidecadalOscillation (get used to oscillations, we like to name our phenomena the “Blah Blah” Oscillation, it’s that or the “Yata Yata” Mode or the “Some Guy’s” Wave).

So it was 1995.  It was late August/early September. It was near my birthday, and we had this approaching system. It developed from what we call African Easterly Waves , whose signature can often be traced in those westward moving cloud clusters. That benign looking cluster developed into monster truck of a hurricane, named Luis. That hurricane (by then a large category 4 in the Saffir-Simpson wind scale) started lurking in our area, and the media starting buzzing about it. Being a puertorrican myself, and knowing how we are, I give my good word that I am not exaggerating when I quote:

            “Every supermarket, grocery store and Walgreens was left barren.”

Hurricane Luis

This was a big deal; it was the first hurricane since Hugo in 1989 slaughtered almost every leaf in El Yunque (it's even documented in a journal, pic below). Because of this it was understandable that people overreacted (although we overreact for every hurricane). I recall my dad putting metal and wooden bars in every window of our house, and considered taking down some of the trees in our backyard because of their potential danger to our house. In the end not much happened. Luis curved northward and we got spared. 

Image from the USGS report on Hugo's damage on the El Yunque region 

Later that year we got threatened by more systems, including a scrape from Marilyn.  The last one people talked about was Sebastien, which fizzled off without even getting close, so much for that one.

Hurricane Marilyn

Tropical cyclones are a special thing. In terms of atmospheric things they are not very common, with roughly about 90 tropical storms, and a fraction of that becoming strong enough to be called hurricanes, typhoons, etc. You need several conditions for them to develop,  and some more stuff for them to get big and strong. I like to think about most tropical phenomena as types of vehicles. In this sense, hurricanes are a sort of fancy car.  Compared to other vehicles, they are more powerful, beautiful and expensive. 

A fancy car.

So, if hurricanes are fancy cars, then what are the other cars then? Well it so happens that the tropical atmosphere is full of waves and disturbances moving about. It can be to the east, or to the west, fast or slow. One particularly active place is the Intertropical Convergence Zone. This is one of the most energetic places on Earth, with giant clouds towering many kilometers up in the atmosphere.  This area is responsible for a good fraction of the planet’s rainfall. You can easily recognize the ITCZ by looking at a map of the planet and seeing this thin belt clouds close to the Equator. In a way, the ITCZ is like the tropics’ highway.

There are also some bigger things that like to move around. There is the behemoth I’ve been mentioning a lot in my entries called the Madden-Julian Oscillation. This guy is like a carrier truck, a big truck that can carry many other vehicles in it. They are pretty slow but tend to enjoy ruling the road. They are also not as common as cars and motorcycles.

Of course, I did not know of most of these things when I was a kid. All I knew back then were tropical waves, hurricanes and clouds, and I thought that was pretty awesome. I learned of these, more complicated things in college, particularly grad school. Learning about these things has made me realize how dynamic the sky I used to watch as a kid actually is, and how complex it is.  It is so complex that there are some phenomena that have been studied for decades by some of the world’s brightest people and there is still a lot to be understood about them.

But that’s not the end of it. There are even more things going on. Ever heard of the El Niño Southern Oscillation (remember when I mentioned that we like to call everything an oscillation, there you go!). This is a coupled ocea-atmosphere phenomena that has implications all over the world. A particular case happened in 1997, which people call it the El Niño of the century. It was extremely strong, and its effects made constant headlines on the news (look at the animation of all the super typhoons that year).  It comes to show you just how something that happens in one place in the planet can affect everything. Like I said in a previous post, it really is just one Earth.

But why confine myself to where clouds form. Way up in the tropical stratosphere we have an interesting thing going on. It’s a shift in the winds that has the name of the Quasi-Biennial Oscillation (yet another oscillation!).

So there you have it, there are so many things going on it almost makes your brain explode.  The place I was born in and the place I’m currently dedicating my career to: the tropical atmosphere. I’m not alone in this, because there are conferences just dedicated to this topic in which hundreds attend. What can I say, it’s a pretty awesome place with huge clouds and beautiful beaches. What else can a guy ask for?