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In situ measurements of the relative humidity with respect to ice (RHi) and of nitric acid (HNO3) were made in both natural and contrail cirrus clouds in the upper troposphere. At temperatures lower than 202 kelvin, RHi values show a sharp increase to average values of over 130% in both cloud types. These enhanced RHi values are attributed to the presence(More)
Stratospheric water vapor concentrations decreased by about 10% after the year 2000. Here we show that this acted to slow the rate of increase in global surface temperature over 2000-2009 by about 25% compared to that which would have occurred due only to carbon dioxide and other greenhouse gases. More limited data suggest that stratospheric water vapor(More)
Interannual variations of stratospheric water vapor over 1992–2003 are studied using Halogen Occultation Experiment (HALOE) satellite measurements. Interannual anomalies in water vapor with an approximate 2-yr periodicity are evident near the tropical tropopause, and these propagate vertically and latitudinally with the mean stratospheric transport(More)
Tropical stratospheric water vapor measured by the microwave limb sounder (M 1.S), " Geophys. Comparison of C1O measurements made by airborne and spaceborne microwave radiometers in the arctic winter stratosphere 1993, " Geophys. Correlated ollservations of HC1 and C1ONO2 from UARS and implications for stratospheric chlorine partitioning, " Geophys. Res.(More)
Airborne in situ measurements over the eastern Pacific Ocean in January 2004 have revealed a new category of nitric acid (HNO 3)-containing particles in the tropical lower stratosphere. These particles are most likely composed of nitric acid trihydrate (NAT). They were intermittently observed in a narrow layer above the tropopause (18±0.1 km) and over a(More)
Seasonally and vertically resolved changes in the strength of the Brewer–Dobson circulation (BDC) were inferred using temperatures measured by the Microwave Sounding Unit (MSU), Stratospheric Sounding Unit (SSU), and radiosondes. Linear trends in an empirically derived ''BDC index'' (extratropical minus tropical temperatures), over 1979–2005, were found to(More)
We have developed a chemical ionization mass spectrometry technique for precise in situ measurements of hydrochloric acid (HCl) from a high-altitude aircraft. In measurements at subtropical latitudes, minimum HCl values found in the upper troposphere (UT) were often near or below the detection limit of the measurements (0.005 parts per billion by volume),(More)
WB‐57F aircraft flew 26 science flights during TC4. The ER‐2 employed 11 instruments as a remote sampling platform and satellite surrogate. The WB‐57F used 25 instruments for in situ chemical and microphysical sampling in the tropical tropopause layer (TTL). The DC‐8 used 25 instruments to sample boundary layer properties, as well as the radiation,(More)
Previous studies have shown that lower-stratosphere temperatures display a near-perfect cancellation between tropical and extratropical latitudes on both annual and interannual time scales. The out-of-phase relationship between tropical and high-latitude lower-stratospheric temperatures is a consequence of variability in the strength of the Brewer–Dobson(More)