Histograms and composites
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Histograms and composites. multimodal is always interesting. qualitative distinction! Regimes or modes (literal meaning). Buoy downwelling radiation along Pacific cold tongue as TIWs go by in the ocean.
Histograms and composites
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multimodal is always interesting • qualitative distinction! • Regimes or modes (literal meaning)
Buoy downwelling radiation along Pacific cold tongue as TIWs go by in the ocean
Figure 3.16 – Width vs. top height of each EO for 16 June 2006 – 31 May 2008. Distribution is weighted by total number of pixels (volume) per EO to emphasize larger EOs. Bin size is 10 pixels (~ km) by 240 m. Width is the horizontal span of the EO.
climatological time meansmust not be iid sums (->normal dist)
The science • bimodal = 2 “modes” = distinct “regimes” • wet and dry • young and old air masses (age since saturation) • in temporal variations at a point • convective vs. nonconvective regions in bimodal climatological mean spatial histograms
Even unimodal can be a basis for composites, but these aren’t “regimes”
indeed all similar • except offset
indeed very similar • except offset
Khairoutdinov, Marat, David Randall, 2006: High-Resolution Simulation of Shallow-to-Deep Convection Transition over Land. J. Atmos. Sci., 63, 3421–3436. High-Resolution Simulation of Shallow-to-Deep Convection Transition over Land Marat Khairoutdinov and David Randall Nice use of 2-dimensional histograms, and weighted histograms (= composites of multiple fields in each bin) Clouds as connected regions (have a size)
all points w > 5m/s
conditional sampling • cetegories so arbitrary unless there are multiple modes in some distribution
suppose we want precip flux • F = (frequency)(qp)(w)(density) • Product of these 3 distributions (*density) • rare events clearly important • from obs, would need to adjust (sampling)