Subjects: Geosciences >> Atmospheric Sciences submitted time 2017-11-01
Abstract： The reflectance of cirrus clouds is an important parameter in weather,climate and earth energy balance studies. The fast algorithm for calculating the reflectance of cirrus clouds plays an importance role in the retrieval the characteristicsofcirrusclouds. Based on the variations of the reflectance of cirrus clouds with the relevant factors, such as cirrus optical thickness, effective particle size, solar zenith angle, observation zenith angle, the relative azimuth angle et al, a prepared Look-Up-Table(LUT) was developed by using DISORT to compute the reflectance of cirrus clouds. A fast algorithm for calculating the cirrus reflectance was established with utilization of the LUT. The cirrus reflectivity was calculated from the parameters of cirrus clouds, including cirrus optical thickness, effective particle size, solar zenith angle, observation zenith angle, the relative azimuth angle, which were read from the cloud products of MODIS. A comparison between the derived reflectivity with the proposed fast algorithm and the measured one was performed.The correlation coefficient is 0.94 and an average deviation isless than 18.5%. The result indicates that the fast algorithm for calculated cirrus reflectance is reasonable and feasible.
Peer Review Status:
Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2017-10-31
Abstract： The thermal structure and energy balance of upper atmosphere are dominated by solar activity. The response of Cold-Point-Mesopause(CPM) to solar activity is an important form. This article presents the response of Temperature-of-CPM(T-CPM) to solar activity using fourteen-year SABER data series over 80°S–80°N regions. These regions are divided into 16 latitude zones with 10° interval, and the spatial areas of 80°S—80°N,180°W—180°E are divided into 96 lattices with 10°(latitude)×60°(longitude) grid. The annual-mean values of T-CPM and F10.7 are calculated. The least squares regression method and correlation analysis are applied to these annual-mean series. First, the results show that the global T-CPM is significantly correlated to solar activity at the 0.05 level of significance with correlation coefficient of 0.90. The global solar response of T-CPM is 4.89±0.67K/100 Solar-Flux-Units(SFU). Then, for each latitude zone, the solar response of T-CPM and its fluctuation are obtained. The solar response of T-CPM becomes stronger with increasing latitude. The fluctuation ranges of solar response at middle latitude regions are smaller than those of equator and high latitude regions, and the global distribution takes on W-shape. The co-relationship analysis shows that the T-CPM is significantly correlated to solar activity at the 0.05 level of significance for each latitude zone. The correlation coefficients at middle latitude regions are higher than those of equator and high latitude regions, and the global distribution takes on M-shape. At last, for each grid cell, the response of T-CPM to solar activity and their correlation coefficient are presented.
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Atmospheric Sciences submitted time 2017-10-31
Abstract： The Trends of the Cold-Point Tropopause CPT are presented using high-resolution radiosonde observations from 77 stations over China during 1979—2014. The latitude region from 18°N to 53°N is divided into 7 latitude zones with every 5° intervals and the spatial area of 18°N—53°N 75°E—135°E is divided into 27 lattices with 5°×10° grids. The annual-mean values of Height-of-CPT H-CPT and Temperature-of-CPT T-CPT are obtained. First by using the least squares regression method it is found that the H-CPT increases with rate of 273m/decade and overall significant cooling rate of -0.70K/decade for the T-CPT over China. Then the trends and latitude distribution of H-CPT and T-CPT for each latitude zone are reached. The change rates even the change direction of H-CPT H-CPT show obviously latitude distribution characteristics. The characteristic difference of H-CPT among latitude distribution is reducing year by year and corresponding T-CTP is enlarging. The H-CPT displays uplift trend between 28°N—53°N latitude region with the positive change rates and corresponding it has decline trend between 18°N—28°N latitude region with the negative change rates. The change rates of T-CPT are negative values for all latitude zones. Third the spatial latitude-longitude distribution of long-term trends of H-CPT T-CPT for each grid are obtained. The change rates of H-CPT T-CPT are not only dependent on latitude but also on longitude. At last the spatial structure of annual fluctuation of H-CPT T-CPT for each grid are obtained. The fluctuation of standard deviations of T-CPT is not only related to spatial distribution but also to economic belt of China.
Peer Review Status:Awaiting Review
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