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Hu L.,CAS Institute of Atmospheric Physics | Hu L.,University of Chinese Academy of Sciences | Yang S.,National Oceanic and Atmospheric Administration | Li Y.,CAS Institute of Atmospheric Physics | And 2 more authors.
Advances in Atmospheric Sciences | Year: 2010

The diurnal variability of precipitation depth over the Tibetan Plateau and its surrounding regions is investigated using nine years of Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) measurements. The Tibetan Plateau, the plains area, and the East China Sea are selected as the focus regions in this study. The average precipitation depths (PD) are about 4.6 km, 5.8 km, and 5.6 km, while convective (stratiform) PDs are about 6.6 (4.5) km, 7.5 (5.7) km, and 6.0 (5.6) km over the plateau, the plains, and the ocean region, respectively. Results demonstrate a prominent PD diurnal cycle, and its diurnal phase is generally a few hours behind the surface precipitation. The spatial variation of the PD diurnal magnitude is weaker near the coastal areas than that of surface precipitation. The height of the PD diurnal peak is around 6-7 km for convective systems and 5-6 km for stratifrom systems. The dominant afternoon diurnal peak for convective PD and the flat diurnal peak for stratiform PD over the Tibetan Plateau indicate that solar diurnal forcing is the key mechanism of the PD diurnal cycle over land. In addition, the diurnal variation is obvious for shallow and deep convective systems, but not for shallow and deep stratiform systems. © Chinese National Committee for International Association of Meteorology and Atmospheric Sciences, Institute of Atmospheric Physics, Science Press and Springer Berlin Heidelberg 2010. Source


Hu L.,National Satellite Meteorological Center | Hu L.,CAS Institute of Atmospheric Physics | Li Y.,CAS Institute of Atmospheric Physics | Li Y.,Beijing Aviation Meteorological Institute | Deng D.,CAS Institute of Atmospheric Physics
Advances in Atmospheric Sciences | Year: 2013

The relationship between surface rain rate and depth of rain system (rain depth) over Southeast Asia is examined using 10-yr Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) measurements. Results show that, in general, a large surface rain rate is associated with a deep precipitating system, but a deep rain system may not always correspond with a large surface rain rate. This feature has a regional characteristic. Convective rain develops more frequently over land than over the ocean, while stratiform rain can extend to higher altitudes over the ocean than over land. A light surface rain rate has the largest probability to occur, regardless of rain depth. A convective rain system is more likely associated with a stronger surface rain rate than a stratiform rain system. Results show that precipitation systems involve complex microphysical processes. Rain depth is just one characteristic of precipitation. A linear relationship between surface rain rate and rain depth does not exist. Both deep convective and stratiform rain systems have reflectivity profiles that can be divided into three sections. The main difference in their profiles is at higher levels, from 4.5 km up to 19 km. For shallow stratiform rain systems, a two-section reflectivity profile mainly exists, while for convective systems a three-section profile is more common. © 2013 Chinese National Committee for International Association of Meteorology and Atmospheric Sciences, Institute of Atmospheric Physics, Science Press and Springer-Verlag Berlin Heidelberg. Source


He Y.-M.,PLA University of Science and Technology | Wang H.-J.,Chinese Academy of Sciences | Zhang H.-F.,Beijing Aviation Meteorological Institute
Jiefangjun Ligong Daxue Xuebao/Journal of PLA University of Science and Technology (Natural Science Edition) | Year: 2011

To detect land cover change, and evaluate carbon cycle and global environment status, the latest progresses of international researches on land cover classification were introduced from four aspects including the remote sensing data, the classification method, the land cover classification system and the outcome comparison. It is believed that establishing a classification system reflecting Chinese condition and compatible with other international systems, and a public and updating land use/cover database, is the most important thing to be solved. Source


Hu L.,National Satellite Meteorological Center | Hu L.,CAS Institute of Atmospheric Physics | Li Y.D.,CAS Institute of Atmospheric Physics | Li Y.D.,Beijing Aviation Meteorological Institute | And 2 more authors.
Science China Earth Sciences | Year: 2011

Seasonal variations in tropical and subtropical convective and stratiform precipitation of the East Asian monsoon are analyzed using 10-year (1998-2007) Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) rain products (2A25). Datasets from the Intergovernmental Panel on Climate Change Fourth Assessment Report (AR4) 24 general circulation models (GCMs) are evaluated using TRMM PR rain products in terms of their ability to simulate convective and stratiform precipitation and their deficiencies. The results show that Asian monsoon convective and stratiform precipitation increases significantly after onset of the summer monsoon, but the percentage of convective precipitation clearly decreases over tropical areas while it increases in subtropical regions. The GCMs simulate well the seasonal variation in the contribution of Asian monsoon subtropical convective precipitation to the total rainfall; however, the simulated convective precipitation amount is high while the simulated stratiform precipitation amount is low relative to TRMM measurements, especially over the Asian monsoon tropical region. There is simultaneous TRMM-observed convective and stratiform precipitation in space and time, but GCMs cannot simulate this relationship between convective and stratiform precipitation, resulting in the deficiency of stratiform precipitation simulations. © 2011 Science China Press and Springer-Verlag Berlin Heidelberg. Source


Zhuhua Z.,Beijing Aviation Meteorological Institute | Yuling L.,Beijing Aviation Meteorological Institute | Wenjun Z.,Beijing Aviation Meteorological Institute | Rong F.,Beijing Institute of Applied Meteorology
AIP Conference Proceedings | Year: 2013

Satellites provide an opportunity of obtaining spatially continuous visibility data. This paper develops an algorithm that retrieves visibility from the Medium Resolution Spectral Imager (MERSI) onboard the FY-3A satellite. The visibility retrieval algorithm consists of two basic steps. First, aerosol optical depth (AOD) is retrieved with MERSI observations at the 2.1 μm, 0.47 μm, and 0.65 μm channels based on look-up-table approach. Second, visibility is calculated with the relationship between visibility and aerosol optical thickness and aerosol scale height, which can be derived from the Koschmieder equation. Two sets of aerosol scale heights are tested, one based on climatic statistics and the other on mixing layer height forecasts. Results show that the distribution pattern and the high and low centers of retrieved visibility match well with that of the surface observations. Compared to the results derived based on climatologically aerosol scale heights, the ones based on mixing layer heights deviate less from surface observations. © 2013 AIP Publishing LLC. Source

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