Ellipticity and clockwise, counterclockwise amplitudes (14 Dec 07): global_all3.ps.gz

Eccentricity and clockwise, counterclockwise amplitudes (12 Dec 07): global_all2.ps.gz

Eccentricity (26 Nov 07): eccentricity.ps
Ellipticity (26 Nov 07): ellipticity.ps

Regional map (4 panels, amplitude and phase, clockwise and anticlockwise, 19 Nov 07): namibia_all.ps

Global map (3 panels with clockwise, anticlockwise, and ratios, 24 Nov 07): global_all.ps.gz.

Updated regional maps based on Monte Carlo simulation. (19 Nov 07) anticlockwise: namibia_ac3.ps, clockwise: namibia_c3.ps, both amplitudes and ratio: namibia_c_ac.ps

Global maps (updated 19 Nov 07). anticlockwise: stress_mc_ac.ps, clockwise: stress_mc_c.ps,
Regional maps. original anticlockwise: namibia_ac1.ps, anticlockwise with Monte Carlo: namibia_ac.ps original clockwise: namibia_c1.ps, clockwise with Monte Carlo: namibia_c.ps

Sample GMT files for sine and cosine amplitudes: gmt_sample_0.25degree.tar
Global sine and cosine amplitudes: hyder_extract_globe.dat with columns (1) lat, (2) lon, (3) mean u, (4) mean v, (5) u cosine amplitude, (6) u sine amplitude, (7) cosine amplitude, (8) v sine amplitude, and then o error estimates
Sample GMT files: gmt_sample.tar
Topography data: topogrid.dat
April-September data: read_block_amjjas.dat
October-March data: read_block_ondjfm.dat

ASCII data for 7 year time series: ascii.tar.gz
6 month summer/winter, 7 year record encapsulated postscript: log_6mo_hr.ps
6 month summer/winter, 7 year record jpg: log_6mo_hr.jpg
6 month summer/winter, 7 year record png: log_6mo_hr.png


Preliminary Land/Sea Breeze Images [pre-publication]

Sarah Gille and Nick Statom

Scripps Institution of Oceanography and Department of Mechanical and Aerospace Engineering
UCSD
GRL draft manuscript.pdf
talk.pdf
The ADEOS-II and QuikSCAT tandem mission measures wind 4 times a day, at 6:00, 10:30, 18:00 and 22:30.  We have used
the first 155 days of the tandem mission to study diurnal variations in global wind fields.  In coastal regions, diurnal variability corresponds to the land/sea breeze, forced by differential heating of the land and ocean.  A previous analysis based only on QuikSCAT data allowed us to observe
statistically significant wind fluctuations but did not permit us to estimate the maximum amplitude or timing of these variations [Gille et al.,
2003].  The tandem mission allows us to examine how winds vary through the course of the day.

Diurnal wind variations describe an ellipse defined by five parameters:  a major axis a, a minor axis b, the geographic orientation of the major axis theta, the time of day when winds are oriented along the major axis, and the direction of rotation.  A weighted least-squares fitting procedure is used to determine these parameters from the four wind observations available each day.  For this analysis, data are sorted into quarter-degree geographic boxes.

Southern Baja California experiences strong diurnal winds and is therefore a useful case study region for evaluating the tandem scatterometer mission's skill at detecting land/sea breeze effects.


Major and minor axis lengths are plotted when they are
statistically different from zero in a 10\degrees\ by 10\degrees\
region off the coast of Baja California.   Major axes indicate
strongest sea breeze effects in locations adjacent to the coast.


Time of day when wind is aligned with major axis
varies over a 12 hour span, because of the symmetry in the ellipse.
Here, zero corresponds to midnight or noon.
The time of day when wind is aligned with the minor axis is offset by
six hours from values plotted here.


Rotation of winds is typically clockwise (red)
off the Baja coastline through the course of the day.


Orientation of major axis is roughly perpendicular to the coastline
in most locations.  Here angular orientations are plotted only in regions
where the major axis is statistically significant, and vectors point in
the direction of morning winds.


Major and minor axes of diurnal wind ellipses
are statistically significant along coastlines in many regions of
the world. Available wind data are primarily from the Northern Hemisphere
summer. Since summer sea breeze effects are expected to be more
readily detectable than winter sea breezes, the diurnal cycle is expected
to be more noticeable in the Northern Hemisphere than in the Southern
Hemisphere.


The time of day when winds are aligned along the major axis
appears to propagate offshore along most of the world's coastlines where
land/sea breeze effects are detectable.


Winds rotate clockwise (red) in the Northern Hemisphere and
counterclockwise (blue) in the Southern Hemisphere.


The geographic orientation of the wind ellipses is generally
perpendicular to the coastline in coastal regions. Here vectors indicate
the direction of flow in the time span between midnight and noon.