Rennie Selkirk, NASA-Ames/BAER InstituteHolger Vömel, University of Colorado Leonhard Pfister, NASA-Ames

Jessica Valverde, Universidad Nacional Werner Stolz, Insituto Meteorológico NacionalWalter Fernández and Jorge Andrés Diaz, Universidad de Costa Rica Jimena Lopez, NASA-Ames/BAER

Insitute

Forecasting tropopause temperatures over Costa Rica for

TC4

BACKGROUND

Supplementary material for NASA TC4 Science Team meeting, Lanham-Seabrook, MD, April 2007

Vertically propagating equatorial waves, probably mixed Rossby-gravity waves, have been

observed in the lower stratosphere and TTL during each of the 3 summer Ticosonde

campaigns since 2004. Most prominent contribution to the variability of tropopause temperature at timescales of

several days or more Temperature variations are NOT directly forced by convection Twice in 2005, wave-induced cooling was sufficient to dehydrate the tropopause to mixing

ratios of 3 ppmv and lower (CFH dehydration events on July 11 and 19.) Tropopause temperature anomaly amplitudes appear to be sensitive to the phase of the

QBO: the strong easterly phase in 2005 ‘bottled up’ wave energy at the tropopause, inducing

larger variance than in the weak easterlies in 2004.

Significance for TC4

Supplementary material for NASA TC4 Science Team meeting, Lanham-Seabrook, MD, April 2007

Tropopause temperatures during TC4 will exhibit regular variations on the 3-4 day timescale w/ amplitude of ~5 °C

Widespread cirrus more likely during wave-induced cold events

If strong easterly phase of QBO (like 2005), expect increased amplitude of tropopause temperature anomalies and possible dehydration events

Forecasting Ttrop during TC4

Ticosonde will provide continual updates of time-height diagrams of temperature and wind using both the sondes

and analysis/forecast datasets

• Vaisala RS92-SGP radiosondes– 4X daily: 16 July – 24 August– typically ascents to ~28 km– 2-sec resolution @ 10 m

• CU CFH and ECC ozonesondes– 24 launches: 8 – 25 July– most @ 18 UT; 5 @ 00 UT (night)– typical balloon burst at ~30 km

Time-height cross-sections from Ticosonde-Aura/TCSP 2005

Supplementary material for NASA TC4 Science Team meeting, Lanham-Seabrook, MD, April 2007

Ticosonde-TCSP 2005 time-height X-section:

Temperature anomalies

Cold point range

T

July 11 Dehydration observed by

CFH

July 19 Dehydration observed by

CFH

CFH observations

Supplementary material for NASA TC4 Science Team meeting, Lanham-Seabrook, MD, April 2007

Ticosonde-TCSP 2005 time-height X-section:

Temperature anomalies

Cold point range

T

Arrows = cold T anoms

July 11 Dehydration observed by

CFH

July 19 Dehydration observed by

CFH

CFH observations

Supplementary material for NASA TC4 Science Team meeting, Lanham-Seabrook, MD, April 2007

Ticosonde-TCSP 2005 time-height X-section:

zonal wind anomalies

Cold point range

July 11 Dehydration observed by

CFH

July 19 Dehydration observed by

CFH UCFH observations

Supplementary material for NASA TC4 Science Team meeting, Lanham-Seabrook, MD, April 2007

Ticosonde-TCSP 2005 time-height X-section:

zonal wind anomalies

Cold point range

U

arrows = cold T anoms

July 11 Dehydration observed by

CFH

July 19 Dehydration observed by

CFH

CFH observations

Supplementary material for NASA TC4 Science Team meeting, Lanham-Seabrook, MD, April 2007

Ticosonde-TCSP 2005 time-height X-section:

meridional wind anomalies

Cold point range

July 11 Dehydration observed by

CFH

July 19 Dehydration observed by

CFH VCFH observations

Supplementary material for NASA TC4 Science Team meeting, Lanham-Seabrook, MD, April 2007

Ticosonde-TCSP 2005 time-height X-section:

meridional wind anoms

Cold point range

V

July 11 Dehydration observed by

CFH

July 19 Dehydration observed by

CFH

arrows = cold T anoms CFH observations

Supplementary material for NASA TC4 Science Team meeting, Lanham-Seabrook, MD, April 2007