# Presentation: 310970

## Measurements of HCl During the AVE Campaigns

**Measurements of HCl During the AVE Campaigns**

**Tim Marcy***

- P.J. Popp*, R.S. Gao, D.W. Fahey*, E.C. Richard*, T.L. Thompson
*NOAA Aeronomy Laboratory*
**and CIRES, University of Colorado*
- E. Atlas
*University of Miami*
- M. Lowenstein
*NASA Ames Research Center*
- S.C. Wofsy, E.M. Weinstock
*Harvard University*
- L. Froidevaux
*NASA JPL*

## Trace Gas Measurements in the UT/LS

- from Stohl *et al*., BAMS 2003

-  The tropical tropopause layer (**TTL**) is not well understood.
-  Does the stratosphere influence the **TTL**?
-  The AVE data provide a unique look at the **TTL**.
-  In situ HCl measurements and HCl-O3 correlations provide a good basis for validation of MLS HCl.

**Trace Gas Measurements in the UT/LS**

## Trace Gas Measurements

**Trace Gas Measurements**

- NASA WB-57F High Altitude Aircraft

- NOAA CIMS **HCl**
- Precision: 5-15 ppt
- Accuracy: 25-30%

-  Measurements were made in the **tropics** (10oN-3oS) and **mid-latitudes** (22-42oN) during the NASA AVE missions in Houston and Costa Rica.
-  Measurements up to **19 km** into the LS in the deep tropics.
-  **HCl** and HNO3:  *NOAA AL*
-  O3:  Richard, *NOAA AL*
-  CO:  Lowenstein, *NASA Ames*
-  H2O:  Weinstock, *Harvard*
-  CO2:  Wofsy, *Harvard*
-  Chlorinated organics:  Atlas, *Miami*

## Tracer Profiles in the Tropics

-  Unique dataset
-  Tracer profiles correspond to the **TTL**
-  Vertical ascent slower than horizontal mixing
-  Low levels of HCl in the **TTL** -- Source?
-  CH3Cl loss > HCl gain
-  **Mixing/STT or in situ chemistry?**

**Tracer Profiles in the Tropics**
- (January 27, 29 and 30, 2004)

- Jan. 30

**Notes:**
LRM = Lapse Rate Minimum

## HCl-O3 Correlations

- HCl-O3 correlation is consistent over time and latitude.

## HCl-O3 Correlations

**HCl-O****3**** Correlations**

## HCl-O3 Correlations

**HCl-O****3**** Correlations**

- Good agreement among different measurement methods.

## HCl-O3 Correlations

## MLS HCl Comparison

- November 3, 2004

- Linear HCl-O3 correlation is largely independent of sample volume.

## MLS HCl Comparison

- November 3, 2004

- How does one compare data from a 1-D aircraft trajectory through the 3-D space sampled by satellite with the satellite measurements?

## CIMS and MLS HCl

**CIMS and MLS HCl**

- Oct. 29, 2004

- Nov. 12, 2004

- Nov. 3, 2004

- AVE04 flights along the MLS track with high HCl

## Conclusions

-  The AVE campaigns have provided the opportunity to collect a rare data set that can advance our understanding of the UT/LS.
-  A high resolution photochemical transport model is needed to fully understand and utilize the measurements.
-  The HCl-O3 correlation is a powerful tool for validation of satellite measurements.
-  The comparison of MLS HCl data HCl-O3 correlations with CIMS HCl data is encouraging.
-  When several MLS data points along a WB-57 flight track are averaged, day to day variations in HCl can be distinguished.

**Thanks** to the pilots and crew of the NASA WB-57F

## Slide 13

## Tracers vs. O3 

-  Linear HCl - O3 correlations in the LS extend into the UT.
-  These plots suggest that air is irreversibly mixed between the UT and LS.
-  Can in situ chemistry explain these correlations?
-  A sophisticated model may be necessary to distinguish STE from in situ chemistry in the TTL.

- Jan. 30, 2004

## Mid-Latitude HCl Profiles

-  Many large and small intrusions
-  Horizontal or vertical movement?
-  Active “surf zone”
-  HCl and O3 measurements can be used to calculate a lower bound for stratospheric O3 in the UT
-  Statistics of natural variability of HCl in the UT/LS?

- Idealized HCl
- Profile

## Slide 16