Friday, October 28, 2011

Leaving the Maldives

I am leaving the Maldives tomorrow, and hence this will likely be my last post from the field. I leave with some bit of regret as I enjoyed the people of the Maldives as well as the enriching experience of being out in the field, but also feel that I leave with so much more to learn about the tropical atmosphere. I have gained a newfound appreciation of the complexity of the tropical atmosphere over the last couple of weeks, something that is difficult to gain from sitting at a desk in Fort Collins. Gust fronts propagate this way that blow up intense precipitation cells, upper level stratiform clouds move the opposite direction, dry air advects in from Africa and the Middle East in the west, and equatorial waves breeze through quickly, fundamentally altering the winds over the entire basin in the matter of a day or so. These are just some of the things I observed. I think that we also observed the initiation of a very interesting MJO event during my time here, and I experienced some of the heavy rains associated with this event. While we aren’t close to a complete understanding of how this event started in the Indian Ocean, we do know a few things so far. The central Indian Ocean near our observation array started out very dry in early October, and winds were generally from the west near the surface. At some point around October 10, the winds shifted rather abruptly to the east over much of the ocean. Accompanying this wind shift, moistening seemed to initiate on the equator first, and then soon was followed by moistening of the western Arabian Sea by east winds blowing moist air across India from the Bay of Bengal. We saw this moistening and shift in wind direction very nicely from the array of soundings we deployed during the project, and these will provide an invaluable resource to diagnose what precisely caused the moistening, in addition to model investigations we plan to do next. One other thing we realized during this project is that some of our commonly used indices used to diagnose the existence of the MJO may not perform well during all events. However, our understanding of what happened here is in its infancy. Tomorrow I leave on my 40+ hour adventure back to Fort Collins and reality. The Maldives will seem like a distant dream in a few days, I am sure. However, the DYNAMO field program is nowhere near over. My colleague Shuguang Wang arrived in the Maldives a couple of days ago to continue the experience of the modelers. Next, Adam Sobel and Zhiming Kuang arrive in November. They will likely experience many fascinating things on Addu Atoll and in the tropical atmosphere that are different from what I experienced here and will add to our fascination and understanding. This experience makes me want to come back to the field soon, as I feel that there are even more things that I need to learn. You may hear more from me in future blog posts, but these will likely be from behind my desk in Fort Collins or sitting on my living room couch (it was 3 degrees in Fort Collins last night! It will be quite the shock to the system to transition from our balmy 85 degree weather.)


  1. Eric, the initiation of this event sounds fascinating... did any of the forecast models manage to predict its onset?

  2. Hi Mike,

    Before enhanced convection really got going in the Indian Ocean, most models actually predicted a complete collapse of intraseasonal variability in the tropics (based on the Wheeler and Hendon diagnostics applied to forecast fields). Thus, the vast majority didn't do a great job of predicting this event initiation (most of their ensemble members were very consistent). There were some exceptions. The NICAM model did seem to want to produce an event initiation.