M. G. Mlynczak

Achieving Climate Change Absolute Accuracy in Orbit

The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission will provide a calibration laboratory in orbit for the purpose of accurately measuring and attributing climate change. CLARREO measurements establish new climate change benchmarks with high absolute radiometric accuracy and high statistical confidence across a wide range of essential climate variables. CLARREOs inherently high absolute accuracy will be verified and traceable on orbit to Systeme Internationale (SI) units. The benchmarks established by CLARREO will be critical for assessing changes in the Earth system and climate model predictive capabilities for decades into the future as society works to meet the challenge of optimizing strategies for mitigating and adapting to climate change. The CLARREO benchmarks are derived from measurements of the Earths thermal infrared spectrum (5–50 μm), the spectrum of solar radiation reflected by the Earth and its atmosphere (320–2300 nm), and radio occultation refractivity from which...

Seasonal and quasi-biennial variations in the migrating diurnal tide observed by Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics (TIMED)

We present periodic variations of the migrating diurnal tide from Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics ( TIMED) temperature and wind data from 2002 to 2007 and meteor radar data at Maui (20.75 degrees N, 156.43 degrees W). There are strong quasi-biennial oscillation (QBO) signatures in the amplitude of the diurnal tidal temperature in the tropical region and in the wind near +/- 20 degrees. The magnitude of the QBO in the diurnal tidal amplitude reaches about 3 K in temperature and about 7 m/s ( Northern Hemisphere) and 9 m/s ( Southern Hemisphere) in meridional wind. The period of the diurnal tide QBO is around 24-25 months in the mesosphere but is quite variable with altitude in the stratosphere. Throughout the mesosphere, the amplitude of the diurnal tide reaches maximum during March/April of years when the QBO in lower stratospheric wind is in the eastward phase. Because the tide shows amplification only during a limited time of the year, there are not enough data yet to determine whether the tidal variation is truly biennial (24-month period) or is quasi-biennial. The semiannual (SAO) and annual oscillations (AO) in the diurnal tide support previous findings: tidal amplitude is largest around equinoxes ( SAO signal) and is larger during the vernal equinox ( AO signal). TIMED Sounding of the Atmosphere using Broadband Emission Radiometry (TIMED/SABER) temperature and atmospheric pressure data are used to calculate the balance wind and the tides in horizontal wind. The comparison between the calculations and the wind observed by TIMED Doppler Interferometer (TIDI) and meteor radar indicates qualitative agreement, but there are some differences as well.

Mesopause structure from Thermosphere, Ionosphere, Mesosphere, Energetics, and Dynamics (TIMED)/Sounding of the Atmosphere Using Broadband Emission Radiometry (SABER) observations

[1] Thermosphere, Ionosphere, Mesosphere, Energetics, and Dynamics (TIMED)/ Sounding of the Atmosphere Using Broadband Emission Radiometry (SABER) temperature observations are used to study the global structure and variability of the mesopause altitude and temperature. There are two distinctly different mesopause altitude levels: the higher level at 95–100 km and the lower level below 86 km. The mesopause of the middle- and high-latitude regions is at the lower altitude in the summer hemisphere for about 120 days aroundsummer solstice and is at the higher altitude during other seasons. At the equator the mesopause is at the higher altitude for all seasons. In addition to the seasonal variation in middle and high latitudes, the mesopause altitude and temperature undergomodulationbydiurnalandsemidiurnaltidesatalllatitudes.Themesopauseisabout 1 km higher at most latitudes and 6–9 K warmer at middle to high latitudes around December solstice than it is around June solstice. These can also be interpreted as hemispheric asymmetry between mesopause altitude and temperature at solstice. Possible causes of the asymmetry as related to solar forcing and gravity wave forcing are discussed.

Global structure and long‐term variations of zonal mean temperature observed by TIMED/SABER

Received 14 February 2007; revised 9 August 2007; accepted 17 September 2007; published 25 December 2007. [1] In this paper, we present a method of extracting zonal mean temperature and tides from TIMED/SABER satellite and discuss the features of the zonal mean temperature. The global temperature structure is presented, and the mean variations at each latitude and altitude are decomposed into semiannual (SAO), annual (AO), and quasi-biennial (QBO) components. The SAO is strong in the tropical upper stratosphere, mesosphere, and lower thermosphere. The SAO phase (measured by the time of the maximum) is at the equinox at 85 km and at solstice at 75 km. The amplitude is large compared to the annual mean temperature structure, which leads to a mesospheric inversion layer (MIL) in the zonal mean temperature around the equator at equinox. The AO is most evident at middle latitudes and displays a clear hemispheric asymmetry at solstices. The QBO in temperature is strongest in the tropical lower stratosphere; its period there is 26.6 months. There are also weak QBO signals near the mesopause and throughout the middle atmosphere at midlatitudes. The analysis of longer-term variations of the zonal mean temperature, probably affected by the solar cycle but also containing any other trends, indicates that in most regions, the zonal mean temperature decreases during the period of 5 years and is positively correlated with the solar radiation. These results use version 1.06 of the SABER temperature data, which have some known biases in the vicinity of the mesopause.

Interaction of gravity waves with the QBO: A satellite perspective

One of the most important dynamical processes in the tropical stratosphere is the quasi-biennial oscillation (QBO) of the zonal wind. Still, the QBO is not well represented in weather and climate models. To improve the representation of the QBO in the models, a better understanding of the driving of the QBO by atmospheric waves is required. In particular, the contribution of gravity waves is highly uncertain because of the small horizontal scales involved, and there is still no direct estimation based on global observations. We derive gravity wave momentum fluxes from temperature observations of the satellite instruments HIRDLS and SABER. Momentum flux spectra observed show that particularly gravity waves with intrinsic phase speeds <30m/s (vertical wavelengths <10km) interact with the QBO. Gravity wave drag is estimated from vertical gradients of observed momentum fluxes and compared to the missing drag in the tropical momentum budget of ERA-Interim. We find reasonably good agreement between their variations with time and in their approximate magnitudes. Absolute values of observed and ERA-Interim missing drag are about equal during QBO eastward wind shear. During westward wind shear, however, observations are about 2 times lower than ERA-Interim missing drag. This could hint at uncertainties in the advection terms in ERA-Interim. The strong intermittency of gravity waves we find in the tropics might play an important role for the formation of the QBO and may have important implications for the parameterization of gravity waves in global models.

Comparative study of short-term diurnal tidal variability

Examination of the simultaneous temperature measurement from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument, on board the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite, not only confirms the existence of the inversion layer but also reveals the global nature of the inversion, suggesting the presence of a transient planetary wave in the mesosphere. The large tidal variability, therefore, is probably a consequence of the interaction between the transient planetary wave and tides. This possibility is investigated by using the NCAR thermosphere-ionosphere-mesosphere-electrodynamics general circulation model (TIME-GCM) and by comparing model results with the lidar, SABER, and TIMED Doppler Interferometer (TIDI) measurements. With a large transient planetary wave specified at the model lower boundary, the model is able to produce strong diurnal tidal variability comparable to that from the lidar observation, and the modeled temperature inversion is similar to that from the SABER measurement. The model results suggest that the planetary/tidal wave interaction excites nonmigrating tides and modulates the gravity modes and/or the rotational modes of the diurnal migrating tide. Among the nonmigrating tides, the diurnal zonally symmetric (S = 0) component is the strongest, and its interaction with the planetary wave leads to a strong diurnal eastward wave number 1 component.

Comparison between the temperature measurements by TIMED/SABER and lidar in the midlatitude

Comparisons of monthly mean nighttime temperature profiles observed by the sodium lidar at Colorado State University and TIMED/SABER overpasses are made. In the altitude range from 85 km to about 100 km, the two observations are in very good agreement. Though within each others error bars, important differences occur below 85 km in the entire year and above 100 km in the summer season. Possible reasons for these difference are high photon noise below 85 km in lidar observations and less than accurate assumptions in the concentration of important chemical species like oxygen (and its quenching rate) in the SABER retrieval above 100 km. However, the two techniques both show the two-level mesopause thermal structure, with the times of change from one level to the other in excellent agreement. Comparison indicates that the high-level (winter) mesopause altitudes are also in excellent agreement between the two observations, though some difference (2-3 km) may exist in the low-level (summer) mesopause altitudes between ground- based and satellite-borne data. In addition, the difference in local time dependency between lidar and SABER is investigated; this difference makes the comparison of mesopause altitudes difficult.

Ground-based high spectral resolution observations of the entire terrestrial spectrum under extremely dry conditions

[1] A field experiment was conducted in northern Chile at an altitude of 5.3 km to evaluate the accuracy of line-by-line radiative transfer models in regions of the spectrum that are typically opaque at sea level due to strong water vapor absorption. A suite of spectrally resolved radiance instruments collected simultaneous observations that, for the first time ever, spanned the entire terrestrial thermal spectrum (i.e., from 10 to 3000 cm 1 , or 1000 to 3.3 mm). These radiance observations, together with collocated water vapor and temperature profiles, are used to provide an initial evaluation of the accuracy of water vapor absorption in the farinfrared of two line-by-line radiative transfer models. These initial results suggest that the more recent of the two models is more accurate in the strongly absorbing water vapor pure rotation band. This result supports the validity of the Turner et al. (2012) study that demonstrated that the use of the more recent water vapor absorption model in climate simulations resulted in significant radiative and dynamical changes in the simulation relative to the older water vapor model. Citation: Turner, D. D., et al. (2012), Ground-based high spectral resolution observations of the entire terrestrial spectrum under extremely dry conditions, Geophys. Res. Lett., 39, L10801,

Seasonal oscillations of middle atmosphere temperature observed by Rayleigh lidars and their comparisons with TIMED/SABER observations

The long-term temperature data sets obtained by Rayleigh lidars at six different locations from low to high latitudes within the Network for the Detection of Atmospheric Composition Change (NDACC) were used to derive the annual oscillations (AO) and semiannual oscillations (SAO) of middle atmosphere temperature: Reunion Island (21.8°S); Mauna Loa Observatory, Hawaii (19.5°N); Table Mountain Facility, California (34.4°N); Observatoire de Haute Provence, France (43.9°N); Hohenpeissenberg, Germany (47.8°N); Sondre Stromfjord, Greenland (67.0°N). The results were compared with those derived from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument onboard the Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite

CIRRIS‐1A limb spectral measurements of mesospheric 9.6‐µm airglow and ozone

Limb infrared spectral measurements of the 9.6-μm mesospheric ozone airglow were made by the Cryogenic Infrared Radiance Instrumentation for Shuttle (CIRRIS-IA) during one flight of the space shuttle Discovery (April 28 th to May 6 th 1991). A significant difference between ozone nightglow and dayglow is observed. The measured spectrally integrated ozone ν 3 fundamental band radiance profile is used to retrieve the ozone (ν 3 = 1) excited state density. Modeled ozone (ν 3 = 1) vibrational temperatures are used to infer the total ozone density. Night and day ozone abundance profiles inferred from ozone 9.6-μm infrared spectral emissions and comparisons with photochemical model calculations are reported. The observed ozone abundance is significantly larger than predicted by the photochemical model.