کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1777586 | 1523673 | 2009 | 11 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
First continuous temperature measurements within polar mesosphere summer echoes
دانلود مقاله + سفارش ترجمه
دانلود مقاله ISI انگلیسی
رایگان برای ایرانیان
کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
فیزیک زمین (ژئو فیزیک)
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: First continuous temperature measurements within polar mesosphere summer echoes First continuous temperature measurements within polar mesosphere summer echoes](/preview/png/1777586.png)
چکیده انگلیسی
Simultaneous measurements of polar mesosphere summer echoes (PMSE) by a VHF radar and temperatures in the mesopause region by a potassium lidar were performed on Spitsbergen (78âN) in the years 2001 and 2003. In total 254Â h of simultaneous observations are available. The lidar also detected 226Â h of noctilucent clouds. In the presence of PMSE temperatures are practically always lower than the frost point which confirms the importance of ice particles for PMSE. However, we also observe extremely low temperatures but no PMSE which we explain by too weak or missing turbulence. The potential role of missing water vapor is discussed in the manuscript. Around the mesopause approximately 80% of the observations show very low temperatures but not PMSE. The importance of sufficiently strong turbulence increases with height since increasing viscosity destroys small scale fluctuations. This explains why PMSE intensity rapidly decreases above the maximum signal at â¼83-89Â km, and why the radar very seldom detected PMSE above â¼92km, although it is persistently cold there and ice particles presumably exist. These observations demonstrate that the non-existence of PMSE cannot be taken as a proof for the absence of ice particles. Furthermore, our measurements indicate that the freeze-drying effect may not be as important as previously anticipated. From our temperature measurements we derive huge degrees of saturation (up to 106-108) which allows for homogeneous nucleation. In the altitude range of best data coverage (â¼88-93Â km) the contribution of S>100(S>10,000) to all cases of supersaturation is approximately 40-50% (10-20%). The very large values may explain why models which ignore homogeneous nucleation notoriously create too few ice particles.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Atmospheric and Solar-Terrestrial Physics - Volume 71, Issues 3â4, March 2009, Pages 453-463
Journal: Journal of Atmospheric and Solar-Terrestrial Physics - Volume 71, Issues 3â4, March 2009, Pages 453-463
نویسندگان
F.-J. Lübken, J. Lautenbach, J. Höffner, M. Rapp, M. Zecha,