Observing small-scale waves with satellite nadir and limb techniques

Dong Wu

NCAR gravity wave retreat, 26-30 July 2006, Boulder, CO

• What atmospheric variables (e.g., T, ρ, ρelectron clouds) cause radiance fluctuations?

• What wave scales are these instruments sensitive to (i.e., visibility function, smoothing, cutoff, noise)?

• How can these observations be used to improve model physics and parameterization (e.g., wave source, propagation, breakdown)?

Key Questions Associated with Satellite Observations:

RadianceI'

AtmosphereT', ρ', u', v'

e.g. MLS

Waves

(A) Nadir or Slant Path• good horizontal resolution• limited vertical resolution• sensitive to waves of large z/h ratios in T• instruments: e.g., AMSU-A, AIRS, SSMIS

(B) Limb and Opaque Path

• good horizontal resolution• limited vertical resolution• sensitive to waves of moderate z/h ratios in T• instruments: e.g., MLS

(C) Limb and Transparent Path

• good vertical resolution• limited horizontal resolution• sensitive to waves of small z/h ratios in ρ• instruments: e.g., LIMS, CRISTA, GPS, SABER, MLS, CLAES, HIRDLS

e.g. CLAES, GPSWaves

e.g. AIRS, AMSUWaves

Convolution Between Small-Scale Waves with Sensor Weighting Functions

Possible cloudcontamination

MLSUARS (1991-1997)

Aura (2004-)

AIRS(Aqua 2002-)

Temp Weighting Func

Instruments for T Sounding(Types A and B)

Temp Weighting Func

AMSU-AN-15 (1998-)N-16 (2000-)

N-17 (2002-2004)N-18 (2005-)Aqua (2002-)

UARSMLS

21 Jan. 2003

Wu and Zhang (JGR 2004)

Jet Streaksover N. Atlantic

Mountain Wavesover Scandinavia

Eckermann et al. (ACPD 2006)

80 hPa, 14 Jan. 2003

80 hPa 40 hPa

20 hPa 10 hPa

5 hPa 2 hPa

Heard Is.

PrinceEdward

Is.

New Zealand& Islands

Macquario Is.South

Sandwich Is.AntarcticPeninsula

Andes SouthGeorgia Is.

Tasmania

FalklandIs.

Crozet Is.

Kerguelen Is.

Victoria Land

Wu et al (ASR 2006)

AMSU-A radiance variance at 5 hPa for June-Aug 2003

?

TES (nadir)

AM

SU

-A

AIR

S

Au

ra M

LS

GPS (1 profile)

CR

IST

A-1

CLAES(1 profile)

Convectivelygenerated

waves

Mountain Waves

Gravity wave dispersion relation

?U

AR

S M

LS

GPS/CHAMP 50-Hz Data

E-regionirregularities

Raw data

Perturbations

SNR

SNR

L1 phase

L1 phase

Iono-freephase

Iono-freephase

Neutral atmos.irregularities

Wu et al. (JASTP, 2005)

Receiver power L1 Phase Delay

GPS/CHAMP Variances for July 2002

Receiver power L1 Phase Delay L2 Phase Delay

CHAMP variancesin the upper troposphere and lower stratosphere

Short-scalecomponents

Long-scalecomponents

28km

25km

22km

18km

Receiver power L1 Phase Delay

2001 2003 2005 2007 2001 2003 2005 2007

CHAMP variances in the E-region ionosphere

120km

100km

80km

60km

Annual variations dominate

QBO variations make the variances stronger in NH 2003 and 2005; in SH 2002 and 2004.

Variations are stronger in NH than in SH.

Effects of the 11-year solar activity are evident mostly at latitudes > 60.2001 2003 2005 2007 2001 2003 2005 2007

Receiver power L1 Phase Delay

The Quasi-Biennial Oscillation

Baldwin et al. (1999)

UARS HRDI winds

Discussions

• Consistency among observations:CRISTA, MLS, LIMSMLS, AMSU-A, AIRSGPS, radiosondeMLS, GPS

• Observational constraints on model parametersGCMMesoscale models

• Sampling issues and statistics of transient processes

Backup materials

• Multiple wave sources• Filtering at different altitudes

Figure 3a: GPS/CHAMP January 2002

Figure 5: GPS/CHAMP July 2002

Chen et al. (2006)

Gravity waves excited by typhoons

Waves excited by convective storms

AIRSRadiance perturbations 13 Jan 2003

14 Jan 2003

15 Jan 2003

24 January 2005

Study of gravity waves with extended ARPS (Limpasuvan et al. 2006)

Simulated T’T’ after convolved with

AIRS wfuncAIRS T’

Estimated <u’w’> Mean wind before Mean wind after