Source: /home/strow/Work/Nh3

Data: /asl/s1/strow/Data/Nh3

Juying Warner is measuring NH\(_3\) using AIRS. The signal sensitivity is dependent on the surface to air temperature contrast. She is seeing increasing NH\(_3\) over time in the U.S. The concern is that this may be a false signal if the surface to air temperature contrast is also changing.

A 13-year record of air to surface temperature contrast was generating using ERA as the truth. The actual data came from the AIRS AIRIBRAD random stats (not yet in final resting place, say where they reside here later).

A subset of the random daytime data for the U.S. was made, and these were binned daily for only the case where the temperature contrast (surface - air) is greater than 4K. This is what Juying uses for the threshold to even attempt an NH\(_3\) retrieval.

Figure 1 shows the time series for the contrast, the a residual after fitting to a standard time series equation. This has been heavily smoothed (for plotting purposes) with a 100 day moving window, thus the artifacts at the end of the time series.

The slope is small (added to the residual in the figure), but the seasonal variability of the contrast can be significant.

Juying is working to somehow normalize this effect in her analysis.