Launched in 2013, and 2017 respectively, Chinese Fengyun-3C and 3D meteorological satellites are equipped with two microwave sounders, Microwave Temperature Sounder (MWTS) and Microwave Humidity Sounder -2 (MWHS-2), whose observations play an important role in numerical weather prediction by data assimilation. Data quality control should be carried out before assimilation to filter out bad data, such as cloud- or rain-polluted data and questionable data. This work can’t be accomplished purely depending on MWTS or MWHS-2 themselves. MWHS-2 is taken as an example to do quality control in the paper, and the method is suitable for MWTS too. Multi-source information from other instruments onboard FY-3 is extracted to assist in the work. Cloud mask product from VIRR (Visible and InfraRed Radiometer), oceanic cloud liquid water content product from MWRI (Microwave Radiation Imager), and global rain rate product from MWRI are mapped to MWHS-2 for quality control in combination with oceanic rain detection product from MWHS-2 itself. 6 kinds of cloud and rain detection schemes are then designed to get the best choice by analyzing the characteristics of background departure. RTTOV v10 is adopted to simulate brightness temperature of MWHS-2 at all channels. The results suggested that scheme RI RC (MWRI cloud and rain information ingested) and scheme RC (all information ingested) are the two best choices for numerical assimilation application, and scheme RI RC can retain more samples. Questionable data can also be found in the way to help monitor the operational status of instruments.
Retrieval of atmospheric profiles from the vertical atmospheric sounding suite aboard the Chinese
FY-3A satellite has been investigated. A statistical retrieval approach is used to generate atmospheric
temperature and moisture profiles. The statistical retrieval method is only applied to the clear-sky
simulated radiances, achieving good retrieval accuracy. For example, in the simulated experiment, the
retrieved atmospheric temperature and moisture profiles show good agreement with independent
atmospheric samples. The RMS is about 1.2K on the average for temperature profile. The RMS is large
for the near surface levels. The RMS of moisture profile is approximately 11%. The temperature and
moisture fields agree well with the NWP analyses of NCEP.
The Common Land Model (CLM) has been validated by observation experiments over
different land surfaces in various climate zones throughout the world. These experiments
have shown that CLM simulates the characteristics of land-atmosphere interactions over
different land surfaces, except in the East Asian monsoon zone where complex land surface
conditions exist. China lies on this East Asian monsoon zone which consists of complex
terrain, various vegetation types, and specific land surface conditions, and experiences
frequent drought and flood disasters. It is important to study how varying land surfaces
affect the interaction of energy, mass, and momentum between land and atmosphere.
Owing to poor simulation of soil moisture by most land surface models, CLM has chosen
to simulate the distribution of soil moisture over China. Meanwhile, station-observed soil
moisture, drought monitoring data from a pole orbit meteorology satellite, and Advanced
Microwave Scanning Radiometer-EOS (AMSR-E) remote-sensed soil moisture are used to
verify the capability of CLM simulation, especially for surface and soil moisture at a 20 cm
depth. The results show that the surface soil moisture distribution and variation trend of
CLM simulation coincides with pole orbit meteorology satellite monitoring and AMSR-E,
and that soil moisture at a 20 cm depth coincides with station observation products from the
National Climate Center. It also illustrates that CLM can reasonably simulate the
distribution and variation of soil moisture over China. It is meaningful to study the climate
response of the lack of soil moisture on soil moisture data.
Key words: CLM, soil moisture, drought, AMSR-E
KEYWORDS: Data modeling, Soil science, Atmospheric modeling, Climatology, Systems modeling, Meteorological satellites, Satellites, Solar radiation models, Error analysis, Radiative transfer
For the land products retrieved from the remotely sensed datasets better using in the land surface model and
weather/climate model, Land Data Assimilation Systems (LDAS) based on EnKF Technology and Community Land
Model, has been developed at NSMC/CMA. In the context of numerical weather prediction applications, LDAS can
provide optimal estimates of land surface state initial conditions by integrating with an ensemble of land surface models,
the available atmospheric forcing data, remotely sensed observations of precipitation, radiation and some land surface
parameters such as land cover and leaf area index. The validation from Yucheng comprehensive experiment site
indicates that the preliminary results obtained are still inspiring. There are still many detailed work to do for the
routine operation of LDAS, such as how to get dynamic P in 3dvar, how to select the spacing interpolation
algorithm, etc.
An analysis of correlation coefficients for climatological data covering the period 1978-2005 for six locations in China has been made in order to highlight the relationships between temperature, precipitation (rain and snow) and snow in summer and in winter. The results show that the evolution of snow depth and area is in good agreement with the climatic change studies from other dataset, with an abrupt jump during the year 1990, and with change cycle about 5 year; The colder air mass from the Western-North China and East-North invade the southern China along western-north-eastern-south aisle and eastern-north-western-south aisle, which makes the influence of snow information on the temperature and precipitation extending to the South China; In the sensitive region, the snow information in three regions all has effect on the temperature and precipitation, the real effect of snow information on temperature and precipitation should be the result of competition among these three snow covered regions; The snow information in Tibet region has larger scale effect on the temperature and precipitation than the other two, which is in accordance with its characteristics able to inspire the larger scale atmospheric circulation.
This paper examines the performance of an off-line version of the Community Land Model (CLM3.0) by simulating the
soil properties: soil temperature, and soil wetness, in Tibetan Plateau, and the modeled results are validated with direct
measurements at three filed sites. The soil properties in the model are initialized with field measurements and are driven by
half-hourly observed atmospheric variables (temperature, humidity, wind speed, surface pressure and downward radiation
(solar and infrared). The observation (or direct measurements) of the soil properties and atmospheric fields are collected
through the Global Energy and Water Cycle Experiment (GEWEX) Asian Monsoon Experiment (GAME)-Tibet project.
Results indicate the CLM is able to capture general characteristics of soil in Tibetan Plateau. The model shows sensitivity
to initial soil properties, particularly soil moisture. The initial error in the soil moisture contributes largely the simulated
bias in soil moisture.
Land surface albedo is a key parameter in modeling radiative transfer in the atmosphere. Simulated climates are sensitive to specified albedo in models. The MODIS BRDF/Albedo Science Data Product represents the latest attempt at providing a dataset suitable for climate model comparisons. It is necessary to analyze the feature of white-sky and black-sky albedo before its use in land surface models. White-sky (diffuse) and black-sky albedo (direct at local solar noon) in China from MODIS based on Lucht algorithm are calculated and analyzed. The differences of white-sky and black-sky albedo for different land use/land cover are compared. The derived albedo exhibits clear interannual variation with large variation in Northern China. Black-sky albedo and white-sky albedo are characterized with different features for different land covers.
In an attempt to understand the relative strengths of two state-of-art mesoscale models: WRF (Weather Research and Forecasting Model) and Penn State/NCAR MM5, a nested domain was constructed to simulate a precipitation process induced by land-sea wind shear in Southeastern China with the two models. The results indicate that both WRF and MM5 capture the local circulation and the heavy rainfall area well, but precipitation amounts are overestimated relative to observations. The WRF model is better than the MM5 in precipitation strength, but worse in the location of maximum rainfall. In comparison with the observations, the simulation by both MM5 and WRF is larger than observation, but the simulation of WRF is closer to observation than MM5. Except that the distribution tendency of simulated wind field by MM5 is better than by WRF, the distribution trend of 2-m temperature and precipitation simulated by WRF is closer to observation than by MM5, but there exists phase difference between simulation by WRF and observation, for precipitation with lagged phase, and for temperature with phase ahead
Using AVHRR (1982-1999) and MODIS (2000-2004) LAI products from 1982 to 1999, seasonal and interannual variability of LAI in China were analyzed. The results indicate that the LAI in most of China increase at different ratio while decreases in some area of Tibetan Plateau, the south of Xinjiang, Yunnan, and Sichuang Provinces and part of northeastern China. With the correlative degree method, it is demonstrated that temperature is the most closely related to the LAI change in China in this period; It also shows such LAI change has close relationship with soil moisture and precipitation as well. We compared the multi-year-averaged monthly LAI from AVHRR during 1982-1999 with the monthly LAI from MODIS during 2000-2004, finding that in winter, the LAI from AVHRR agrees to the LAI from MODIS, but in summer, during which the vegetation is growing up, the LAI from AVHRR is larger than from MODIS. The LAI from AVHRR is in good agreement with MODIS in each month in arid and semi-arid region. This long-term LAI data can be used in land surface model. Analysis was conducted to examine how sensitive land surface parameters are to LAI interannual variability. The result shows that the response is mainly in the range of ±15%, but for the fraction of the direct beam absorbed by canopy, the relative error is even larger than 40%, which suggest that the inter-annual difference of LAI must be considered in climate models.
To make better use of the land, the regional climate response to vegetation change with oasis-desert-nesting structure in sensitive climatic area was studied in this paper. Three vegetation change experiments with different oasis-desert-nesting structure were designed and the differential charts between control and sensitivity simulation run were made. The results indicated that for oasis-desert-nesting structure, whose width reached certain width so as to engender local circulation, such as EXP1 and EXP2, its width change mainly affected intensity of climatic response while its complexity affected spatial distribution of climatic response. For commensurate mosaic oasis-desert nested structures in the same sensitive area, they had the same distribution type of climatic response but different intensity. EXP1, EXP2, and EXP3 presented that certain complexities can make nesting fields appear with a whole-field characteristic; there were different climate response to vegetation change between sensitive climatic area and ordinary one, the former with greater response than the latter.
Since we started the National Key Project of Fundamental Research (China), “The research on eco-environmental evolution, control and adjustment for arid land in Western China,” four years ago we have made a number of important progresses. These progresses include many research fields: the palaeoclimate rebuilding and environmental change; the development process and driving forces of oases; the water-salt balance and main hydrology processes of oases; the oasis ecosystem’s structure, ecological process and stability; the coupling mechanism of three major ecosystems of mountain, oasis, and desert; the ecological landscape patterns’ evolution and its responses climate change; the ecological environmental effects of large industrial (construction) projects; the cause and spatial-temporal distribution of desertification; the establishment of experimental demonstration bases of ecological recovery and rebuilding; and adjustment and control of ecosystem and management models.
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