Head in a Cloud

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On the Road (pt 1)

June 15th, 2007 by Sean Davis · 1 Comment

I’m almost a week in to a summer of being on the road. Not quite the Jack Kerouac type of on the road, but still pretty exciting for a scientist…


I’m currently on the road in Karlsruhe, Germany, where I just finished attending a workshop on upper tropospheric relative humidity hosted by the Swiss ETH and the Forschungzentrum Karlsruhe, among others. In addition to this, I’ve had a busy couple of months for getting ready for the upcoming NASA TC4 field campaign in Costa Rica, which starts (in Houston, unfortunately) on July 1st and lasts until mid-August.

I thought this would be a good time to reflect on some work of mine that was recently published, what this workshop was about, what will be going on during TC4, and how all of these issues tie together. Doing this will require a considerable amount of verbage, so I’ve decided to break this post into (at least) 3 parts that I’ll post over the coming months.

First, I’d like to talk a bit about the work that I’ve been involved with that was recently published. I’ve had two papers published in the past couple of months (submitted over a year a part, so it’s really just a coincidence!). The first is an instrument paper published in JTECH entitled “Measurement of Total Water with a Tunable Diode Laser Hygrometer: Inlet Analysis, Calibration Procedure, and Ice Water Content Determination” (non-moneywalled version available here). The second was published in JGR, and is entitled “Comparisons of in situ measurements of cirrus cloud ice water content“. Both papers are related, and the second is a follow on to the first. The first paper describes our instrument, how it is calibrated, and how the data are used to calculate cirrus cloud ice water content. The second paper describes intercomparisons of our instrument with two other instruments that have flown together on the WB-57 aircraft. In this paper, we show that the three instruments generally agree within their uncertainty estimates, except perhaps at the very smallest of IWC. The upshot of this is that while discrepancies still exist, particularly in subvisual cirrus, the data agree well enough to give confidence that they can be used for purposes such as modeling and satellite validation. It’s not the most exciting paper ever written, but it was an important piece of work to get out in the literature, especially considering all of the questions and controversy regarding water vapor measurements. I’ll touch on those issues in the next post because they are too much detail to go into here. But in the meantime, if you’re interested there is a website (and interesting use of wiki, if I might add) here that discusses the discrepancies between the various water vapor measurements in quite some detail.

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1 response so far ↓

  • 1 Lab Lemming // Jun 16, 2007 at 6:14 am

    Congrats on the papers. But how is instrument calibration not exciting?

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