M. Jarisch

Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) data processing and atmospheric temperature and trace gas retrieval

The Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) experiment aboard the Shuttle Pallet Satellite (SPAS) was successfully flown in early November 1994 (STS 66) and in August 1997 (STS 85). This paper focuses on the first flight of the instrument, which was part of the Atmospheric Laboratory for Application and Science 3 (ATLAS 3) mission of NASA. During a free flying period of 7 days, limb scan measurements of atmospheric infrared emissions were performed in the 4 to 71 μm wavelength region. For improved horizontal resolution, three telescopes (viewing directions) were used that sensed the atmosphere simultaneously. Atmospheric pressures, temperatures, and volume mixing ratios of various trace gases were retrieved from the radiance data by using a fast onion-peeling retrieval technique. This paper gives an overview of the data system including the raw data processing and the temperature and trace gas profile retrieval. Examples of version 1 limb radiance data (level 1 product) and version 1 mixing ratios (level 2 product) of ozone, ClONO 2 , and CFC-11 are given. A number of important atmospheric transport processes can already be identified in the level 1 limb radiance data. Radiance data of the lower stratosphere (18 km) indicate strong upwelling in some equatorial regions, centered around the Amazon, Congo, and Indonesia. Respective data at the date line are consistent with convection patterns associated with El Nino. Very low CFC-11 mixing ratios occur inside the South Polar vortex and cause low radiance values in a spectral region sensitive to CFC-11 emissions. These low values are a result of considerable downward transport of CFC-11 poor air that occurred during the winter months. Limb radiance profiles and retrieved mixing ratio profiles of CFC-11 indicate downward transport over ∼5 km. The accuracy of the retrieved version 1 mixing ratios is rather different for the various trace gases. In the middle atmosphere the estimated systematic error of ozone is ∼14%. Ozone data of correlative satellite measurements are well within this error bar. CRISTA agrees, for example, with Atmospheric Trace Molecule Spectroscopy Experiment (ATMOS) sunset measurements typically within 5%. The random error of version 1 ozone mixing ratios is 4%. Similar values apply to other trace gases. These low random errors allow the identification of small and medium scale horizontal and vertical structures in the measured trace gas distributions. Examples of structures in mixing ratio fields of ozone, ClONO 2 , and CFC-11 are given.

Measurements of trace gases by the cryogenic infrared spectrometers and telescopes for the atmosphere (CRISTA) experiment

Abstract The CRISTA experiment aboard the Shuttle Pallet Satellite (SPAS) was flown on STS 66 in early November 1994. During a free flying period of seven days measurements of atmospheric temperatures and of 15 trace gases were performed with unprecedented horizontal resolution. This paper gives a brief description of the instrument and of the observational technique. Preliminary results of CIONO 2 retrievals are presented and discussed in terms of atmospheric dynamics and photochemistry.

Dynamics of the middle atmosphere during CRISTA‐2 as simulated by the National Center for Atmospheric Research thermosphere‐ionosphere‐mesosphere‐electrodynamics general circulation model

[1] The National Center for Atmospheric Research (NCAR) thermosphere-ionosphere-mesosphere-electrodynamics general circulation model (TIME GCM) was run to study middle and upper atmospheric dynamics during the second flight of the Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) instrument on 7-16 August 1997. Strong quasi-stationary zonal wave number 1 and 2 signatures characterize the TIME GCM middle and high-latitude dynamics in the Southern Hemisphere. There is a migrating diurnal tide and a westward propagating wave number 2 nonmigrating diurnal tide at equatorial and low latitudes in both hemispheres. A westward propagating zonal wave number 1 quasi 5-day wave and a migrating semidiurnal tide are also evident in the TIME GCM mesopause region. We subsequently sample the TIME GCM results along the CRISTA orbital trajectory and process this subset of model data using the techniques invoked for the CRISTA data analyses. We compare these results with the full model analysis and find that the quasi-stationary wave 1 and wave 2 estimates are slightly affected by unresolved signatures of the semidiurnal tide and propagating planetary wave(s) in the middle and high-latitude Southern Hemisphere. The satellite sampling also results in a convolved migrating and nonmigrating diurnal tidal signature at low latitudes. We compare the TIME GCM sampled results with the CRISTA observations and find that the modeled stationary planetary waves are more confined to stratospheric high latitudes than the observed waves are, but there is more favorable model measurement agreement aloft. TIME GCM underestimates the diurnal tide that CRISTA observed throughout the middle atmosphere at equatorial and low middle latitudes.

Zonal asymmetries in middle atmosphere temperatures

Zonal asymmetries are frequently seen in stratospheric temperature or trace gas fields as surf zones, streamers, filaments etc. They are also seen as very small-scale fluctuations, the intensity of which varies with longitude. Similar structures might be expected in the mesosphere as well, and several examples have recently been found. CRISTA 1 large-scale data are presented that indicate a surf zone in the middle mesosphere at the beginning of winter. Very small-scale data are shown from the CRISTA 2 mission. Mesospheric variability is found to be high at all altitudes, latitudes, and longitudes. There are considerable non-zonal structures in these fluctuations. (The duration of the Crista missions was about one week each.) Zonal asymmetries have been known for a long time from comparisons of ground stations measuring the same parameter in the mesosphere/lower thermosphere. As an example, upper mesosphere temperatures derived from OH∗ emissions are compared here for Wuppertal and Moscow (Zvenigorod), which are about 2000 km apart. A systematic and substantial difference in temperature is obtained, with higher temperatures at Wuppertal than at Moscow. The difference appears to follow the solar cycle: it is small at solar maximum and large (up to 28 K) at solar minimum. The reason for this surprising behavior is as yet unknown. The Moscow and Wuppertal temperatures have also been analyzed for long-term trends: a trend discrepancy between the two stations is not seen in the data interval common to the two stations.

Horizontal temperature variability in the stratosphere: global variations inferred from CRISTA data

Abstract In two separate orbital campaigns (November, 1994 and August, 1997), the Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) instrument acquired global stratospheric data of high accuracy and high spatial resolution. The standard limb-scanned CRISTA measurements resolved atmospheric spatial structures with vertical dimensions ≥ 1.5 – 2 km and horizontal dimensions ≥ 100 – 200 km. A fluctuation analysis of horizontal temperature distributions derived from these data is presented. This method is somewhat complementary to conventional power-spectral analysis techniques.