Tuesday, March 31, 2015

Cowl Finished

I finished a couple of projects last weekend. Neither took very long, but they attest to the psychological power of making lists instead of moving on to the next shiny thing.

The cowl shown here on the needles is complete, with ends woven in and wet-blocked.
It's about a foot longer than I had hoped.  That's what I get for not wet-blocking my swatch before calculating the number of stitches to cast on.  (12 st repeat * 22 repeats)
I messed up my first attempt with a 360 degree complete twist.  Frogging these yarns was not easy and I lost some fancy yarn yardage.  That mistake, and the additional length, meant the cowl lost some width.
But it looks quite substantial (yet light!) worn doubled.
I made this with the intention of blinging up my black shirts and knit tops. But, that wouldn't photograph well.

What do you think about mauve? Matronly? Timeless? The shirt still has the store tags on it, despite languishing in my closet for years.  Do I dare wear mauve in public?

Pattern (see copyright stuff at the footer of the page):
  1. With plain yarn: cast on your desired number of 12 stitch repeats on a long circular needle, placing markers every 12 stitches and stitch counter or other marker at start of round.
  2. Knit 8-10 rows (4-5 ridges) garter stitch back and forth.
  3. Place stitches on 2 long circular needles to ensure that there are no twists.  Join into the round.
  4. With fancy yarn, set up pattern (Row 1 of 4 row repeat): 
    • *k4, centered double decrease, k4, k1 into bar between stitches, k1, slide marker, k1 into bar between stitches*, *repeat between*
    • Centered double decrease:  slide two stitches together from L to R needles as if to k2tog, k1, slip two slipped stitches over the knitted stitch.  This doesn't sound like it will create a row of centered stitches, but it does.
    • For larger holes, use a yo instead of the lifted bar increase.  For no holes, use a pair of m1R and m1L.
    • Row 2: at start of round, k1 into bar between stitches, knit to end of round.
    • Row 3: repeat Row 1
    • Row 4: repeat Row 2
  5. With plain yarn, knit rows 1-2 three times for 6 rows total.
  6. Repeat rows 1-10 till desired width or out of yarn, ending with the fancy yarn.
  7. Knit 8-10 rows (4-5 ridges) garter stitch back and forth.
  8. Seam garter selvedge edges together, weave in ends.
  9. Wet block, soaking in warm water and then stretching firmly to open the stitches.

Wednesday, March 25, 2015

Reliving storms past

I can't bring rain to drought-plagued California, but I can bring virtual showers by making movies showing historic Atmospheric Rivers (ARs) that hit California.

ARs can be defined in terms of satellite measurements of "20 mm of water vapor and is > 2000 km long and < 1000 km wide."  They average about 400 km wide.

First, I made a global animation of Dec 26, 2004 to January 11, 2005 so you can see atmospheric rivers peeling off from the moisture belt of the tropics and subtropics.  I used the NOAA/CIRES Twentieth Century Global Reanalysis Version 2c (20thC R2c) because I want to highlight a newly available dataset by showing cool things you can do with it.

Global animation of NOAA/CIRES Twentieth Century Global Reanalysis Version 2c for December 26, 2004 to January 11, 2005.
Precipitable water is a measure of the total, column-integrated, water vapor in the atmosphere at that point.  If all the water vapor condenses, the equivalent depth of the water can be measured as a length (often mm), or as mass per unit area (kg per square meter).  1 kg m-2 of water is equivalent to 1 mm of water.  In the global animation, ARs are light cyan to red in color.

Precipitable water can be estimated (pretty well!) using microwave remote sensing from satellites.  Modern Global scale models usually assimilate all available data, including satellite and ground-based measurements, to generate estimates of physical parameters, including precipitable water. But, because 20thC R2c goes back to 1851, this analysis was performed using just the three types of data available in 1851: surface pressure (from land-based ground stations), sea surface temperatures (from ship observations) and sea ice extent.

Then I zoomed in to the regional-scale and changed the color range of the precipitable water scale from [0.1, 70] to [0.1, 40] to better show the structure in mid-latitudes like California.  In this animation, ARs are yellow to red.
Regional-scale animation of NOAA/CIRES Twentieth Century Global Reanalysis Version 2c for December 26, 2004 to January 11, 2005.

Notice a first pulse of moisture that came in through the Gulf of California, responsible for the record-setting heavy rains in Death Valley and the inland deserts of California that filled up Lake Manly.  Yes, that is a kayaker in Death Valley.

Then an atmospheric river hit the coast of California with multiple pulses of heavy moisture. According to NOAA's California Nevada River Forecast Center's Heavy Precipitation Report for this event, these two storms dropped an impressive amount of rain in southern California, including a whopping 51.77 inches at Opids Camp.

 Can you feel the rain?

I made the visualizations with the help of NASA's free Panoply data viewer and GIFMaker.  You can easily make your own, too.

Links:

Wordless Wednesday