Pole-to-pole: lidar observations of middle and upper atmosphere temperature and polar mesospheric clouds over the North and South Poles

Global climate change resulting from greenhouse gas increase has extended into the middle and upper atmosphere. Modelling studies show that the effects are more significant at high latitudes. Thus, the observations at the poles may provide some of the first conclusive evidence of global changes in the middle and upper atmosphere, and also provide a convenient mean of calibrating general circulation models. However, the middle and upper atmosphere region is difficult to study. To help address the measurement needs, we developed a new robust lidar system using an Fe Boltzmann technique. The new lidar utilizes mesospheric iron as a fluorescence tracer and relies on the temperature dependence of the population difference of two closely spaced Fe transitions. We deployed this new lidar to the North and South Poles from 1999 through 2001 to measure the temperatures and polar mesospheric clouds in the middle and upper atmosphere for both day and nighttime. Important scientific results and issues have emerged from our observations at the poles, especially on the polar mesospheric clouds (PMC) and temperatures. Significant hemispheric differences in PMC altitudes were found during our pole-to-pole measurements. Interpretation of these results has led to a new insight into the solar radiative forcing on the Earth atmosphere and a baseline for calibrating the atmospheric general circulation models. We review the pole-to-pole observations and results in this paper.

[1]  Xinzhao Chu,et al.  Fe Boltzmann temperature lidar: design, error analysis, and initial results at the north and south poles. , 2002, Applied optics.

[2]  D. Hartmann,et al.  The dynamics of the stratospheric polar vortex and its relation to springtime ozone depletions. , 1991, Science.

[3]  G. Reid.  Ice Clouds at the Summer Polar Mesopause , 1975 .

[4]  R. Garcia,et al.  The importance of dynamical feedbacks on doubled CO2‐induced changes in the thermal structure of the mesosphere , 1995 .

[5]  G. Papen,et al.  First lidar observations of middle atmosphere temperatures, Fe densities, and polar mesospheric clouds over the north and south poles , 2001 .

[6]  C. Gardner,et al.  Lidar studies of interannual, seasonal, and diurnal variations of polar mesospheric clouds at the South Pole , 2003 .

[7]  Gary E. Thomas,et al.  Is the polar mesosphere the miner's canary of global change? , 1996 .

[8]  G. Baumgarten,et al.  Noctilucent clouds above ALOMAR between 1997 and 2001: Occurrence and properties , 2003 .

[9]  G. Papen,et al.  Characteristics of Fe ablation trails observed during the 1998 Leonid Meteor Shower , 2000 .

[10]  G. Papen,et al.  Lidar observations of polar mesospheric clouds at South Pole: Diurnal variations , 2001 .

[11]  Raymond G. Roble,et al.  How will changes in carbon dioxide and methane modify the mean structure of the mesosphere and thermosphere , 1989 .

[12]  C. Gardner.  Sodium resonance fluorescence lidar applications in atmospheric science and astronomy , 1989, Proc. IEEE.

[13]  G. Thomas.  Mesospheric clouds and the physics of the mesopause region , 1991 .

[14]  C. Gardner,et al.  The temperature structure of the winter atmosphere at South Pole , 2002 .

[15]  Rolando R. Garcia,et al.  'Downward control' of the mean meridional circulation and temperature distribution of the polar winter stratosphere , 1994 .

[16]  C. Gardner,et al.  Structure and seasonal variability of the nighttime mesospheric Fe layer at midlatitudes , 1993 .

[17]  Jerry A. Gelbwachs.  Iron Boltzmann factor lidar: proposed new remote sensing technique for mesospheric temperature , 1994, Proceedings of IGARSS '94 - 1994 IEEE International Geoscience and Remote Sensing Symposium.

[18]  A. Aikin,et al.  Temperature trends in the lower mesosphere , 1991 .

[19]  C. Gardner,et al.  Seasonal variations of the atmospheric temperature structure at South Pole , 2003 .