MPO 581 Class number 4/27   Jan 31, 2011

Topic: Basic statistics

Loose ends from last class:

Today's material:

Math/Stat Operation

MPO Science behind doing it

Average (x)
  • over time (q t)
  • over distance (qx)
  • over area (qxy) or volume (qxyz) or mass (qxyp)
Linear effects (terms in governing equations)
  • dT/dt = Q type conservation laws for masses of matter
  • divergence theorem ∫ ∫ (∇• F) dA = ∮Fn
  • Climate heat budget over ocean + atm
    • ∫ (ρCp
      ∂T
      ∂t
      ) dV = ∫ ∫ (Frad_TOA) dA     +small
Weighted average
get mass or area average from irregular-grid data (p or lat)
Deviation from average (anomaly or perturbation)
"anomalies" may obey linearized equations about "base state" (Taylor expansion)
Average of nonlinear transformed variable
Nonlinear physics:  OLR = σT4,  |U| = √+v²,  WD = atan(u/v), Flux = (wq)
Average of squared value
just characterizing variability as positive definite? sometimes Energy
Variance (square - mean2) ≡ σ2
standard deviation has units of the quantity (variance: units are squared)
Average of cube, 4th power, ... ⇒ "moments" just statistics? but distributions can imply processes (future lecture)

Open questions, assignments, and loose ends for next class:

Testable questions about today's material: