Some Background

• I’m in the wind business ---– My thesis dealt with the mathematical

solution for PBL winds

– I’ve written two texts on flow equations; in the PBL and entire atmosphere.

– At one time I was PI or co-PI on 5 EOS grants: LAWS, Seawinds, SSMI (Wetnet) and 2 interdisciplinaries

– We have programs to use winds in weather & climate analyses

– I want winds from ANY source

Winds are not --- have never been --- on

NASA/s menu. Why?• I surveyed EOS investigators:

“It is assumed that the winds will be provided by GCMs”

• Scatterometer data showed this is not true:– Missing storms, details

– PBL Winds unphysical, often too low

• Mainly a resolution problem, but also because GCMs cannot handle Turbulence in many cases (PBL, Conv. Towers, tropopause, jets….) or sub-grid organized flow (OLE).

Better GCM Progs

Better Storms Definition

Higher Winds (heat fluxes)

Little Science things like: Proof of ubiquity of Rolls (OLE)

Applications

RABrown 2001

Better Climate Models

A Winds Motivation• High Marine Surface Winds

do not appear in: – Buoy data– Climate records– General Circulation Models– Satellite sensor algorithms

• High Marine Surface Winds do appear in:– Ocean Meteorology Ship reports– Dedicated Airplane PBL Flights– A PBL model that includes OLE

• Higher winds imply higher heat fluxes in climatology; revised ocean mixed layer models.

R.A. Brown, 1997, 2000; ‘01

There exists an opportunity for satellite data

• Measurements from sondes, ships & buoys incur large errors due to turbulence & OLE• There are few measurements of winds in the PBL in situ• There are no satellite determined winds IN the PBL

o The fluxes (air-surface) require boundary layer windso Climate Analyses have been made on extremely poor climatology data

R. A. Brown 1/2001

Sources of Surface Wind Fields for Climate Studies

• From Surface Measurements– Ships & Buoys– Radiosondes

• From Models– GCM (with K-theory PBLs)– UW Similarity Model (with OLE)

R.A. Brown, 1997, 2001

Satellite Wind Sensors

•ScatterometersERS (ESA); Quikscat (USA) (2001 - );SeaWinds on Adeos (USA,Japan) (2002); AScat (ESA) (2004)

•SARs ERS (ESA); Radarsat (Canada);

Envisat (ESA)**********

• Passive Radiometers Windsat (USA) (2002)

•Lidars ESA (2008)

Scatterometer wind fields here

Pressure field

SAR Wind field

A conversation in 1977: Businger to Brown: “You’re a fluiddynamacist, we’d like the solution to the relation between the surface wind and the wave generation”

Brown to Businger: “OK”

(I know it’s impossible, but it’s a living)

Bottom line: (20 years later) There is no proven theory for wind generation of waves. However, in the best tradition of Atmospheric Science --- there is a curve fit

Epilogue: Satellite Data Prove PBL Winds Theory

Appraisal of Basics: Theory for

Scatterometer, SAR, radiometer

Data: cm-scale, average density of capillaries and short gravity waves in a footprint. 50km 25km 7km 100m (SAR)

Theory: State: 1-10, poor to excellent

Wind generation of water waves 1 % energy into short/long waves 2 Wave-wave interaction 3 Surface layer wind 8 PBL wind (without OLE) 4

(with OLE) 8

R.A. Brown 2001

Appraisal of Basics:

Microwave Data from Scatterometry, SAR, Radiometers

Data: cm-scale, average density of capillaries and short gravity waves in a footprint. 50km 25km 7km 100m (SAR)And surface ‘truth’ wind.

Parameterizations State: 1-10, poor to excellent

U10 (u*) land 8 U10 (u*) ocean 5 PBL U(z) (similarity) 7

Scatterometer Model Function

u* (o) 4 U10 (o) 8 P (o) 7

R.A. Brown 2001

Ship winds: Sparse and inaccurate (except Met. Ships).Buoy winds: Sparse; a point. Tilt; variable height - miss high winds and low wind directions.GCM winds: Bad physics in PBL Models; Too low high winds, too high low winds. Resolution coarse (getting better).Satellite winds: Lack good calibration data. Resolution (”).

11-99, 5/00, 7/01 RAB

Practical Aspects of Wind Measurements (Surface ‘Truth’ Limits)

Height meters

200

100

The Surface Layer = the log layer

= the law of the wall

V

U10/VG

0.7

Practical Aspects of a Geostrophic Wind Model

Function (Pressures)Surface ‘Truth’ Limits

• Radiosondes (winds) Sparse; NG in PBL

• Buoy and ship pressures: Accurate in low and high wind regimes; sparse• GCM (winds & pressures): Poor winds. Good pressure verification, compatible

11-99, 7/01 RAB

Surface Stress, u*

Ocean surface

Geostrophic

Flow

U10Surface Layer

Ekman Layer with OLE

Thermal Wind

Nonlinear OLE

Advection,centrifugal termsNon steady-state

U10(u*) effects

Stratification

Variable Surface Roughness

VG(u*) effects

R.A. Brown PORSEC 2000

Gradient Wind

1-3 km

0 – 100 m

The surface layer relation, hence U10 {u*(o ) }works well 0 < z < 100 meters

• There is almost no surface truth --- buoy or GCM surface winds with U10 > 25 m/s

• The U10 model function can be extrapolated to about 35 m/s

• There are indications that o responds to the sea state for U10>40 m/s. (H-pol > 60 m/s?)

• There is a Model function yielding winds possibly to 60 m/s (2000)

The PBL model yields U(z), 0 < Z < 1 km (gradient)

• Requires U10.

• Requires Stratification Information

CONCLUSIONS

RABrown, ’99; ‘01

Dark Ages 11 in USAI Star Wars 11

A Brief History of Scatterometers1970

1980

1990

2000

2010

SeaSat Built --- with Scat, SAR, SMMR, AltSeaSat Launch --- Lasts 99 days

NSCAT conceived and built

Dark Ages: launch $ to gulf & carribean wars, refurbish battleships, 200 ship fleet, Star WarsERS-1 Launch (turned off)

NSCAT launched on ADEOS --- 9 mos.ERS-2 LaunchQuikscat Launch

R. A. Brown 1/2001

SeaWinds on ADEOS - II

ESA A-SCAT

Programs and Fields available onhttp://pbl.atmos.washington.edu

Questions to rabrown, neal or jerome@atmos.washington.edu

• Direct PBL model: PBL_LIB. (’75 -’01) An analytic solution for the PBL flow with rolls, U(z) = f( P, To , Ta , )

• The Inverse PBL model: Takes U10 field and calculates surface pressure field (VG) P (U10 , To , Ta , ) (1986 - 2001)

• Pressure fields directly from the PMF: P (o) along all swaths (exclude 0 - 5° lat) (2001; in progress)

• Surface stress fields from PBL_LIB corrected for stratification effects along all swaths (2001; in progress) R.A. Brown 2000, ‘01