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5. Conclusions

1) Almost half of tropical stations showed evidence of a spurious temperature shift (tidal shift) sometime during 1985-99. These are probably due to changes in solar heating of thermistors, and

(2) If so, such shifts are mostly downward and cause trends to be underestimated; average error (over all stations) at 100 hPa in tropics is ~ --0.1 K/decade.

(3) Most if not all spurious trends due to instrument changes appear detectable from tidal information (accurate quantifiability of the T-jump still questionable however).

(4) IUK method yields better information from stations with infrequent reporting. ~2 K/decade cooling in lower stratosphere occurs with curious "mouse-ear" lat/ht pattern.

(5) Sharp change from little or no T trendat 100 hPa and below, to big cooling at 70 hPa. Eventual promise of horizontal detailin trends.

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