Coveting CAPE

COSMIC / FORMOSAT 3

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There are times that I really really hate paywalls.

At the American Geophysical Union web site, there is an interesting abstract for an article:

http://www.agu.org/journals/ABS/2010/2009JD012535.shtml

It has a heading on it for the Journal of Geophysical Research Atmospheres and covers a topic I’m interested in at the moment. But, sadly, it is paywalled. So that line of enquiry is truncated.

It looks at “Seasonal and diurnal variation of convective available potential energy (CAPE) using COSMIC/FORMOSAT-3 observations over the tropics”.

Convective Available Potential Energy. Exactly the kind of thing that would help visualize and observe the non-stable atmosphere as it goes through its energy redistributive motions using convection. The very embodiment of “MixING” showing that the atmosphere is not mixED when it comes to heat and energy patterns. Ah well.

What we do have is the abstract. First up, the ‘who, where, when’, then we’ll skip down to the ‘what’:

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 115, D04102, 8 PP., 2010
doi:10.1029/2009JD012535

Seasonal and diurnal variation of convective available potential energy (CAPE) using COSMIC/FORMOSAT-3 observations over the tropics

A. Narendra Babu
Physics Department, National Central University, Jhongli, Taiwan
LakiReddy Bali Reddy College of Engineering, Mylavaram, India
J. B. Nee
Physics Department, National Central University, Jhongli, Taiwan
Karanam Kishore Kumar
Space Physics Laboratory, VSSC, Trivandrum, India
[…]
Received 25 May 2009; accepted 29 September 2009; published 17 February 2010.

Citation: Narendra Babu, A., J. B. Nee, and K. K. Kumar (2010), Seasonal and diurnal variation of convective available potential energy (CAPE) using COSMIC/FORMOSAT-3 observations over the tropics, J. Geophys. Res., 115, D04102, doi:10.1029/2009JD012535.

So it’s been around for a bit over a year, published a bit less than one. What it does is take a look at data from a Taiwan / Formosa satellite. Looks like a lot of folks are putting ‘eyes in the skys’ these days… I’ve bolded some bits of the abstract:

The global pattern of convective available potential energy (CAPE) at seasonal and diurnal time scales is discussed using 1 year of COSMIC/FORMOSAT-3 satellite observations. The calculation of CAPE using temperature and humidity measurements of COSMIC is described. The estimated CAPE is grouped into 5 × 5 grid and is further classified into four seasons, namely, winter, spring, summer, and autumn.

The CAPE magnitudes in general have high values over land as compared to oceanic region, which confirmed the consistency of CAPE calculations. The systematic migration of CAPE from Northern Hemisphere to Southern Hemisphere is observed during Northern Hemisphere summer to winter, coinciding with the movement of intertropical convergence zone. Once the seasonal pattern is established, the composite diurnal patterns of CAPE with 2 h resolution are obtained by combing all the observations in one season.

Diurnal variation of CAPE has shown domination of semidiurnal variations at some latitudes (12 h) and diurnal variation (24 h) at some other latitudes. The mean removed CAPE is then subjected to Fourier analysis to extract the diurnal variation amplitudes. During the observational period, larger CAPE magnitudes are observed over the Indian Ocean during most of the seasons, comparable in magnitude to that of the land regions. As the CAPE and precipitation patterns have correlation, the present study demonstrated the capability of COSMIC/FORMOSAT-3 to study the diurnal patterns of CAPE, which will have implications in interpreting the tropical diurnal precipitation patterns.

And there the abstract / tease ends.

But what can we glean from it?

That humidity matters. Temperature alone is not sufficient.

That CAPE as a metric has predictive power. That also confirms its theoretical merits.

That there are daily and even half daily patterns of change. That there are seasonal drifts. Even that the values over land are different from those over ocean (most ocean, at any rate).

So…

What next.

It’s a nice little mystery. A bit of a peek into the future, when we start to (again) properly account for convection and energy. Humidity and both thermal as well as potential energy in the air mass.

At least it’s nice to know there are some folks out there looking at the physics that actually drive things and not wandering 40 years in the CO2 desert…

Some more about the COSMIC mission and the US involvement here:

http://www.cosmic.ucar.edu/about.html

Now I get to decide how much time to put into looking for similar insight from other sources. Ah, well. The pattern is shaping up fairly consistently, at least. Daily cycling of energy into / out of the earth surface systems. Longer duration drift as the solar / seasonal input changes. Full accounting of energy flows, not just temperatures, as the important base to build upon. Weather as the strongest and most important determiner of where energy starts, and more importantly, ends, in any given flow.

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