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1.
Precipitable water vapor estimation in India from GPS-derived zenith delays using radiosonde data 总被引：1，自引：0，他引：1
Dinesh Singh Jayanta Kumar Ghosh Deepak Kashyap 《Meteorology and Atmospheric Physics》2014,123(3-4):209-220
One of the most recent applications of global positioning system (GPS) is the estimation of precipitable water vapor (PWV). It requires proper modeling to extract PWV from zenith wet delay (ZWD). The existing global models take no account of latitudinal and seasonal variation of meteorological parameters in the atmosphere. In fact, they ignore the atmospheric conditions at a specific location. Therefore, site-specific PWV models have been developed for five stations spread over the Indian subcontinent, using 3-year (2006–2008) radiosonde data from each of these stations. Furthermore, a similar regional PWV model is also developed for the Indian region. The purpose of the developed site-specific as well as regional model was to convert ZWDs into PWV without using surface meteorological parameters. It has been found that the developed regional and site-specific PWV models show about mm-level accuracy in estimating PWV using derived ZWD from radiosonde as input. The developed site-specific, regional models were also used to extract PWV from GPS-derived ZWD at Bangalore and New Delhi. The accuracy of the developed site-specific and regional model is of the same level. The PWV accuracy obtained with the developed regional model is about 6.28, 6.6 mm in comparison to radiosonde PWV at Bangalore and New Delhi, respectively. 相似文献
2.
《大气与海洋》2013,51(4):455-471
Abstract Integrated atmospheric moisture has been derived from a network of Global Positioning System (GPS) receivers established in southern Alberta. GPS receivers and post‐processing techniques provide the ability to estimate integrated precipitable water vapour (PWV) at temporal and spatial scales not usually available using conventional observational techniques and without costly expendables. GPS‐derived PWV was evaluated during the Alberta GPS Atmospheric Moisture Evaluation (A‐GAME) using nearby radiosonde observations from the Airdrie, Olds‐Didsbury and Sundre airports during field campaigns in the summers of 2003 and 2004. For the 2004 A‐GAME period, the regional (15 km) Global Environmental Multiscale model (GEM)‐modelled PWV was compared to the GPS derived PWV using a distance weighting approach. GEM model performance was assessed with regards to prognosis time (from 0 to 9 hours), grid cell elevation, location and the presence of storms in the study region. The results show that there is good agreement between radiosonde‐derived PWV and PWV derived from nearby GPS sites with correlations (r2) ranging from 0.76 to 0.84; the GPS‐derived PWV showed a small dry bias averaging 0.6 mm. When compared to GPS‐derived PWV, GEM model performance was found to be favourable out to the hour‐3 prognosis with an overall correlation (r2) of 0.63. Performance decreased with increasing prognosis time and as a result of the presence of storm activity in the study region but did not decrease with increasing grid cell elevation. 相似文献
3.
In this paper, we compare integrated water vapour (IWV) retrievals from the Moderate Resolution Spectrometer (MODIS) instrument on board the polar-orbiting Terra platform with those from the coupled regional climate model system BALTIMOS for a period of 2 years (October 2001 to October 2003). The comparison was made for the whole drainage basin of the Baltic Sea as well as major parts of Central Europe. The qualitative comparison between the two data sets of the integrated water vapour shows a good agreement. The patterns in the spatial distribution of the averaged integrated water vapour in both data sets are quite similar. However, significant differences occur in the Hungarian Lowlands, along the Po River and the Wallachia (Romania) in the order of 2.5 to 7.0 kg/m2. For these areas, the BALTIMOS model is dryer than the MODIS observations. This could be an indication for the known summer drying effect of BALTIMOS but needs further investigations. The annual cycle as well as a diurnal developing of integrated water vapour from 09:00 to 12:00 UTC is well pronounced in both data sets. For both data sets, the overall annual variations are 17.5 kg/m2. The observed overall diurnal variability are 1.4 kg/m2 for MODIS and 1.04 kg/m2 for BALTIMOS, respectively. 相似文献
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5.
区域GPS网对流层延迟直接推算可降水量研究 总被引：3，自引：3，他引：0
针对武汉地区GPS气象网资料进行GPS对流层延迟直接推算可降水量的研究。推导了对流层延迟直接推算可降水量的模型,并对模型结果进行检验。从武汉东湖站GPS对流层延迟与无线电探空可降水量的比较中可知,两者具有很好的相关性,相关系数达到0.931;由该站对流层延迟转换的可降水量与无线电探空可降水量的比较可得,均方根为4.45 mm,相关系数为0.905,对流层延迟转换的可降水量与GPS可降水量的均方根为2.23 mm,相关系数为0.988。说明在没有气象数据的地区,对流层延迟直接推算的可降水量可以作为气象短期预报的参考依据。 相似文献
6.
Isabella Bordi Klaus Fraedrich Alfonso Sutera Xiuhua Zhu 《Theoretical and Applied Climatology》2014,115(3-4):615-625
Ground-based GPS and weather stations time series for the period 2010–2012 of precipitable water vapor (PWV), relative humidity (RH), and surface temperature (T) of half-hourly resolution are analyzed to demonstrate their value for dynamical analyses and weather forecasting. Three sample stations in the USA from the SoumiNet network are considered, which have rather continuous data for the last 3 years and a few missing values. Results for the three stations reveal the following features: (1) PWV time behavior is dominated by the annual cycle superimposed on high-frequency fluctuations with missing daily cycle, indicating a prevailing large-scale transport source of precipitable water at these sites; (2) RH is characterized by the daily cycle and high-frequency variability, while the annual cycle is missing; (3) T mainly varies following the annual and diurnal cycles; and (4) all variables show similar scaling properties of their variance spectra, S(f)?～?f –β , with a high-frequency regime of red noise type scaling (β?～?2) up to a day and long-term persistence beyond a week (β?～?0.5), with a week-long frequency interval of transition. Detrended fluctuation analysis of relative humidity indicates a clear long-term persistence scaling covering more than three decades. Implications of these findings on weather forecasting and climate modeling are discussed. 相似文献
7.
正1Key Laboratory of Radiometric Calibration and Validation for Environmental Satellites,China Meteorological Administration, Beijing 100081, China2National Satellite Meteorological Center, China Meteorological Administration, Beijing 100081, China 相似文献
8.
Wayan Suparta 《Meteorology and Atmospheric Physics》2012,115(3-4):153-162
A katabatic wind event which dramatically affects the polar climate has been detected using GPS meteorology measurements. GPS-derived precipitable water vapor (GPS PWV) variability and its relation to a katabatic event at Scott Base station, Antarctica was investigated. The investigations using the data gathered from 21 to 30 November of 2002. They showed that the water vapor profile exhibited an irregular pattern with a maximum PWV of 7.38?mm (~6?mm on average). This event was strongly influenced by relative humidity than by wind speed activity. The dominant wind flow during this period was from the North to Northeast (blowing from the Ross Sea) with a mean speed of 3.79?ms?1. The PWV increased when the temperature was between ?15 and ?11°C. During the katabatic event identified between 21:30 UT of 28 November and 18:40 UT on 29 November, the wind blew from the Southeast to South direction (from the Ross Ice Shelf) with a maximum speed of 10.92?ms?1. The PWV increased ~1.0?mm (23%) from the mean value accompanied by severe wind had pronounced effect on GPS observations. 相似文献
9.
利用成都地区地基GPS观测网2007年9-11月的观测数据, 结合自动气象站资料计算出30 min间隔GPS遥感的大气水汽总量(GPS-PWV)。将成都地区秋季降雨分为阵性降雨和连续性降雨(秋绵雨), 结合其他气象要素资料, 分析了GPS-PWV变化与成都秋雨之间的关系。结果表明:高值的水汽总量是产生降水的必要条件; 不同的降水过程, GPS-PWV的变化幅度、极值水平和持续时间存在明显差异。水汽的增长、上升运动的增强和温度的减少是造成阵性降水的主要原因; 而秋绵雨过程中, 水汽的增长和地面露点温度差与降水过程有较好的对应关系。 相似文献
10.
梅雨期是江淮流域从春季到夏季一个重要的过渡时期。传统诊断入梅的方法主要根据雨日和温度及副热带高压位置等来确定。由于雨日的不连续, 天气形势的多变, 常会引起诊断入梅日期的分歧。利用长江三角洲地区地基GPS网所反演的连续的大气水汽总量 (GPS/PWV) 资料详细分析了长江三角洲地区2002—2005年入梅情况, 发现GPS/PWV资料可以反映出入梅前后大气中水汽发生显著季节性跳跃的特征, 总结出利用大气中水汽变化特征来诊断入梅时间的方法 (PWV方法)。采用1980—2000年的历史探空资料计算的大气水汽总量 (PWV) 资料, 对该方法进行了检验:21年中有13年的入梅日期与历史上传统方法诊断的入梅日期相吻合; 对两种方法诊断的入梅日期相差较大的3年的入梅情况进行的分析表明, PWV方法诊断出的入梅日比原定入梅日更合理。该方法在2006年入梅诊断的应用也得到验证。 相似文献
11.
We first analyzed GPS precipitable water vapor (GPS/PWV) available from a ground-based GPS observation network in Guangdong from 1 August 2009 to 27 August 2012 and then developed a method of quality control before GPS/PWV data is assimilated into the GRAPES 3DVAR system. This method can reject the outliers effectively. After establishing the criterion for quality control, we did three numerical experiments to investigate the impact on the precipitation forecast with and without the quality-controlled GPS/PWV data before they are assimilated into the system. In the numerical experiments, two precipitation cases (on 6 to 7 May, 2010 and 27 to 28 April, 2012 respectively) that occurred in the annually first raining season of Guangdong were selected. The results indicated that after quality control, only the GPS/PWV data that deviates little from the NCEP/PWV data can be assimilated into the system, has reasonable adjustment of the initial water vapor above Guangdong, and eventually improves the intensity and location of 24-h precipitation forecast significantly. 相似文献
12.
C. Di Biagio A. di Sarra P. Eriksen S. E. Ascanius G. Muscari B. Holben 《Climate Dynamics》2012,39(3-4):953-969
This study is based on ground-based measurements of downward surface shortwave irradiance (SW), columnar water vapour (wv), and aerosol optical depth (τ) obtained at Thule Air Base (Greenland) in 2007–2010, together with MODIS observations of the surface shortwave albedo (A). Radiative transfer model calculations are used in combination with measurements to separate the radiative effect of A (ΔSWA), wv (ΔSWwv), and aerosols (ΔSWτ) in modulating SW in cloud-free conditions. The shortwave radiation at the surface is mainly affected by water vapour absorption, which produces a reduction of SW as low as ?100 Wm?2 (?18%). The seasonal change of A produces an increase of SW by up to +25 Wm?2 (+4.5%). The annual mean radiative effect is estimated to be ?(21–22) Wm?2 for wv, and +(2–3) Wm?2 for A. An increase by +0.065 cm in the annual mean wv, to which corresponds an absolute increase in ΔSWwv by 0.93 Wm?2 (4.3%), has been observed to occur between 2007 and 2010. In the same period, the annual mean A has decreased by ?0.027, with a corresponding decrease in ΔSWA by 0.41 Wm?2 (?14.9%). Atmospheric aerosols produce a reduction of SW as low as ?32 Wm?2 (?6.7%). The instantaneous aerosol radiative forcing (RFτ) reaches values of ?28 Wm?2 and shows a strong dependency on surface albedo. The derived radiative forcing efficiency (FEτ) for solar zenith angles between 55° and 70° is estimated to be (?120.6 ± 4.3) for 0.1 < A < 0.2, and (?41.2 ± 1.6) Wm?2 for 0.5 < A < 0.6. 相似文献
13.
GPS遥感大气可降水量在暴雨天气过程分析中的应用 总被引：13，自引：3，他引：10
利用北京市气象局地基GPS监测试验网遥感大气可降水量（PWV）数据,分析2004年汛期暴雨天气过程PWV的变化特征及其与降雨量、降雨强度的关系;通过分析地面、高空的位势高度场、风场,以及比湿外水汽通量Q及水汽通量散度AQ等物理量诊断场分布,研究天气系统与大尺度水汽输送、辐合的关系,大尺度水汽输送、辐合与PWV变化的关系;探讨GPS遥感大气水汽资料在预报强降雨天气过程中的应用。得出：PWV的增长方式受当地天气系统的支配和制约,对于明显降雨过程,当地面、高空天气系统有利于暖湿空气的输送时,在北京附近形成等湿度线密集区,PWV逐渐增长（降雨开始前的13-24h）的趋势;当地面、高空有辐合系统东移或生成,或有中小尺度天气系统影响时,PWV显著增长（降雨开始前的3～4h）;当PWV大于某阈值后出现较强降雨,PWV值及增量的大小与降雨量的大小没有明显的关系。 相似文献
14.
该文利用2002年“973”项目安徽GPS外场试验和2000年北京GPS/VAPOR试验积累的资料对GPS遥感的大气可降水量与局地降水之间关系进行了定量分析。结果表明:在降水前后, GPS遥感的大气可降水量有很大的变化; 在2002年入梅前后, 其变化甚至大于30mm; 在海拔高的山区台站, 2hGPS遥感的大气可降水量增量和本站是否发生降水关系密切; 多数情况下, 降水出现在GPS遥感的大气可降水量迅速增加的3~4h内; 每小时降水量峰值和GPS遥感的大气可降水量增量的大小有关。 相似文献
15.
成都地区秋、冬季GPS可降水量的时空分析 总被引：6，自引：4，他引：2
利用成都地区5个测站地基GPS2007年9月-2008年2月的观测数据,解算出1 min间隔的天顶总延迟,结合自动气象站资料计算出30 min间隔的大气可降水量(GPS-PWV).对月平均的GPS-PWV分析表明:秋、冬季变化趋势从9月开始下降,1月达到最小值,2月又逐渐上升.在大气环流相同的情况下,地理位置相近的站,海拔高的地区大气中的水汽量比海拔低的地区要少,且变化较大;海拔高度相近的站,大气中的水汽含量由南向北减少.日合成分析显示:在静稳天气下,日变化特征显著,具有双峰型特征:白天峰值与气温的最大值相对应;夜间峰值与降水量的峰值相对应;GPS-PWV与地面空气相对湿度白天呈负相关,夜间呈正相关. 相似文献
16.
利用WRF模式、地基GPS资料以及常规气象观测资料,结合模式输出资料的高空间分辨率(10km)和GPS大气可降水量(GPS-PWV)资料的高时间分辨率(30min)的优点,对2008年7月20—22日四川盆地一次暴雨过程的水汽变化特征及各物理量与大气可降水量的关系进行综合分析。结果表明:此次降雨过程是由高原涡和西南涡共同作用引起,WRF模式能够较好地模拟出降雨落区和强度。GPS-PWV反映的大气可降水量增减趋势与WRF模拟的较为一致。水汽密度垂直分布反映了大气可降水量分布,水汽密度随高度增加而递减,降雨初期,水汽密度随高度减小迅速,降雨强盛时期,水汽密度随高度减小的速度减慢。水汽辐合使得水汽密度和大气可降水量增大,风的散度项与水汽通量散度的变化一致,而水汽平流项对水汽辐合贡献较小,水汽的辐合主要由风场辐合造成。 相似文献
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18.
Effects of atmospheric river landfalls on the cold season precipitation in California 总被引：2，自引：0，他引：2
Jinwon Kim Duane E. Waliser Paul J. Neiman Bin Guan Ju-Mee Ryoo Gary A. Wick 《Climate Dynamics》2013,40(1-2):465-474
Effects of atmospheric river (AR) landfalls in the California coast on the cold-season precipitation in California are examined for the cold seasons of 10 water years (WYs) 2001–2010 using observed data and regional modeling in conjunction with AR-landfall inventory based on visual inspections of precipitable water vapor (PWV) from remote sensing and reanalysis. The PWV in the SSM/I and SSMIS retrievals and the ERA-Interim reanalysis shows 95 AR-landfall days in the California coast that are almost evenly split between the northern and southern coasts across 37.5N. The CPC/NCEP gridded daily precipitation analysis shows that 10–30% of the cold-season precipitation totals in California have occurred during these AR landfalls. The analysis also reveals that the percentage of precipitation and the precipitation intensity during AR landfalls in California are characterized by strong north-to-south gradient. This north–south contrast in the AR precipitation is reversed for the non-AR precipitation in the coastal range. The frequency of AR landfalls and the cold-season precipitation totals in the Sierra Nevada region are only marginally correlated. Instead, AR landfalls are closely related with the occurrence of heavy precipitation events. The freezing-level altitudes are systematically higher for AR wet days than non-AR wet days indicating warmer low-troposphere during AR storms. Cold season simulations for the 10 WYs 2001–2010 show that the Weather Research and Forecast (WRF) model can reasonably simulate important features in both the seasonal and AR precipitation totals. The daily pattern correlation coefficients between the simulated and ERA-Interim upper-air fields exceed 0.9 for most of the period. This suggests that the simulated temporal variations in the atmospheric circulation agree reasonably with the reanalysis over seasonal time scales, characteristics critical for reliable simulations of regional scale hydrologic cycle. The simulated seasonal and AR precipitation totals also agree reasonably with the CPC/NCEP precipitation analysis. The most notable model errors include the overestimation (underestimation) of the season-total and AR precipitation in the northern (southern) California region. The differences in the freezing-level altitudes during the AR- and non-AR wet days in the simulation agree with those from the ERA-Interim reanalysis. The freezing level altitudes are systematically overestimated in the simulations, suggesting warm biases in the low troposphere. Overall, WRF appears to perform reasonably in simulating the key features in the cold season precipitation related with AR landfalls, an important capability for assessing the impact of global climate variations and change on future hydrology in California. 相似文献
19.
Xiquan Dong Behnjamin J. Zib Baike Xi Ryan Stanfield Yi Deng Xiangdong Zhang Bing Lin Charles N. Long 《Climate Dynamics》2014,43(1-2):53-70
Along with significant changes in the Arctic climate system, the largest year-to-year variation in sea-ice extent (SIE) has occurred in the Laptev, East Siberian, and Chukchi seas (defined here as the area of focus, AOF), among which the two highly contrasting extreme events were observed in the summers of 2007 and 1996 during the period 1979–2012. Although most efforts have been devoted to understanding the 2007 low, a contrasting high September SIE in 1996 might share some related but opposing forcing mechanisms. In this study, we investigate the mechanisms for the formation of these two extremes and quantitatively estimate the cloud-radiation-water vapor feedback to the sea-ice-concentration (SIC) variation utilizing satellite-observed sea-ice products and the NASA MERRA reanalysis. The low SIE in 2007 was associated with a persistent anticyclone over the Beaufort Sea coupled with low pressure over Eurasia, which induced anomalous southerly winds. Ample warm and moist air from the North Pacific was transported to the AOF and resulted in positive anomalies of cloud fraction (CF), precipitable water vapor (PWV), surface LWnet (down-up), total surface energy and temperature. In contrast, the high SIE event in 1996 was associated with a persistent low pressure over the central Arctic coupled with high pressure along the Eastern Arctic coasts, which generated anomalous northerly winds and resulted in negative anomalies of above mentioned atmospheric parameters. In addition to their immediate impacts on sea ice reduction, CF, PWV and radiation can interplay to lead to a positive feedback loop among them, which plays a critical role in reinforcing sea ice to a great low value in 2007. During the summer of 2007, the minimum SIC is 31 % below the climatic mean, while the maximum CF, LWnet and PWV can be up to 15 %, 20 Wm?2, and 4 kg m?3 above. The high anti-correlations (?0.79, ?0.61, ?0.61) between the SIC and CF, PWV, and LWnet indicate that CF, PWV and LW radiation are indeed having significant impacts on the SIC variation. A new record low occurred in the summer of 2012 was mainly triggered by a super storm over the central Arctic Ocean in early August that caused substantial mechanical ice deformation on top of the long-term thinning of an Arctic ice pack that had become more dominated by seasonal ice. 相似文献
20.
大气加权平均温度Tm是地基GPS水汽遥感的关键参数,决定了水汽反演的精度。利用2008—2011年全国123个探空站点资料,分析了Tm与其影响要素纬度、海拔、地面气温、水汽压及大气压之间的关系,结果表明:Tm与纬度和海拔随季节变化呈周期性负相关,与地面温度和水汽压的自然对数呈正相关,与大气压呈负相关;Tm的空间变化具有纬度地带性和明显的气候分布特征,其变异程度在空间分布上有显著差别,不同地理位置的Tm受季节性影响程度不一,Tm也具有明显的年际周期性变化,年内Tm的每日变化符合二次函数分布规律。按照全国、气候分区和季节分区方法,分别建立了Tm单因子和多因子回归模型,并利用2012年1—5月数据对所建模型进行验证,Tm的估算误差能满足GPS水汽遥感2%的精度,模型普遍适用于我国地基GPS水汽遥感中Tm的估算。 相似文献