CORRELATION BETWEEN PEAK INTENSITY OF EXTREME AFTERNOON SHORT-DURATION RAINFALL AND HUMIDITY AND SURFACE AIR TEMPERATURE IN SOUTHEAST COAST OF CHINA

Using hourly rainfall intensity, daily surface air temperature, humidity and low-level dew point depressions at55 stations in the southeast coast of China, and sea surface temperature from reanalysis in the coastal region, this paper analyzes the connection between peak intensity of extreme afternoon short-duration rainfall(EASR) and humidity as well as surface air temperature. The dependency of extreme peak intensity of EASR on temperature has a significant transition. When daily highest surface temperature is below(above) 29°C, the peak rainfall intensity shows an ascending(descending) tendency with rising temperature. Having investigated the role of moisture condition in the variation of EASR and temperature, this paper discovered that the decrease of peak rainfall intensity with temperature rising is connected with the variation of relative humidity. At higher temperatures, the land surface relative humidity decreases dramatically as temperature further increases. During this process, the sea surface temperature maintains basically unchanged, resulting in indistinct variations of water vapor content at seas. As water vapor over land is mainly contributed by the quantitative moisture transport from adjacent seas, the decline of relative humidity over land will be consequently caused by the further rise of surface air temperature.

Retrieval and analysis of sea surface air temperature and relative humidity

Air temperature and relative humidity have been the main parameters of meteorology study. In the past data could be obtained from in-situ observations, but the observations are local and sparse, especially over ocean. Now we can get them from satellites, yet it is hard to estimate them from sat- ellites directly so far. This paper presents a new method to retrieve monthly averaged sea air temper- ature （SAT） and relative humidity （RH） near sea surface from satellite data with artificial neural networks （ANN）. Compared with the observations in Pacific and Atlantic, the root mean square （RMS） and the correlation between the estimated SAT and the observations are about 0.91 ~C and 0.99, respectively. The RMS and the correlation of RH are about 3.73% and 0.65, respectively. Compared with the multiple regression method, the ANN methodology is more powerful in building nonlinear relations in this research. Thus the global monthly average SAT and RH are retrieved from the fixed ANN network from July 1987 to May 2004. In general the annual average SAT shows the increasing trend in recent 18 years. The abnormality of SAT is decomposed with the empirical or- thogonal function （EOF）. The leading three EOFs could explain 84% of the total variation. EOF1 （76.1%） presents the seasonal change of the SAT abnormality. EOF2 （4.6%） is mainly related with ENSO. EOF3 （3.3%） shows some new interesting phenomena appearing in the three main currents in Pacific, Atlantic and Indian Ocean.

Atmospheric correction of Landsat data for the retrieval of sea surface temperature in coastal waters

A mono-window algorithm was introduced to retrieve sea surface temperature （SST） using Landsat data in coastal waters. In this algorithm, the effective mean air temperature and the water vapor content of air column were estimated with the local meteorological parameters of air temperature and relative humidity, based on the facts that in the troposphere, （ 1 ） air temperature decreases linearly with the altitude, and （2） water vapor content lapses exponentially with the altitude. The sea-truth temperature data and MODIS Terra SST product were used to validate the SST retrieved from Landsat TM and ETM ＋ thermal infrared （TIR） data with the algorithm. The results show that the algorithm can improve the spatial temperature contrast which is often masked due to water vapor effects, and the temperature derived from the algorithm is closer to the sea-truth SST. When applying the algorithm, the initial parameters of air temperature and relative humidity can be easily collected from local meteorological stations, and there is no need to identify the model of air profile.

Modeling of Air Temperature for Heat Exchange due to Vertical Turbulence and Horizontal Air Flow

In order to calculate the air temperature of the near surface layer in urban environment,the surface layer air was divided into several layers in the vertical direction,and some energy balance equations were developed for each air layer,in which the heat exchange due to vertical turbulence and horizontal air flow was taken into account.Then,the vertical temperature distribution of the surface layer air was obtained through the coupled calculation using the energy balance equations of underlying surfaces and building walls.Moreover,the measured air temperatures in a small area(with a horizontal scale of less than 500 m)and a large area(with a horizontal scale of more than 1 000 m)in Guangzhou in summer were used to validate the proposed model.The calculated results agree well with the measured ones,with a maximum relative error of 4.18%.It is thus concluded that the proposed model is a high-accuracy method to theoretically analyze the urban heat island and the thermal environment.

Near ground air temperature calculation model based on heat transfer of vertical turbulent and horizontal air flow

In order to calculate the air temperature of the near surface layer in urban environment,the surface layer air was divided into several sections in the vertical direction,and some energy balance equations were developed for each air layer,in which the heat exchange due to vertical turbulence and horizontal air flow was taken into account.Then,the vertical temperature distribution of the surface layer air was obtained through the coupled calculation using the energy balance equations of underlying surfaces and building walls.Moreover,the measured air temperatures in a small area(with a horizontal scale of less than 500 m) and a large area(with a horizontal scale of more than 1 000 m) in Guangzhou in summer were used to validate the proposed model.The calculated results accord well with the measured ones,with a maximum relative error of 4.18%.It is thus concluded that the proposed model is a high-accuracy method to theoretically analyze the urban heat island and the thermal environment.

Humid Air Plasma Treatment of Birnessite Surface: Application to the Removal of Cochineal Red

The thin layers of birnessite (Mn7O13?5H2O) are exposed to reactive species gliding arc plasma in humid air, which induces the treatment of the thin layers surface. Plasma treatment thin layer of birnessite was used for the degradation of Cochineal Red. The experimental results showed that 95% of the CR solution was completely decolorized by thin layer of birnessite treated by plasma compared to 80% of the same solution after interaction of thin layer of birnessite untreated. The decay kinetics always follows a pseudo-first order reaction. The application of the humid air plasma for the surface treatment of thin layers of birnessite improves the efficiency of treatment for Cochineal Red degradation.

Characteristics of atmospheric boundary layer structure and its influencing factors under different sea and land positions in Europe

This study identifies quantitatively the dominant contributions of meteorological factors on the development of the boundary layer heights(BLH)in the European region,based on 32 years(1990-2021)of radiosonde observations.The spatial variability of the BLH is further discussed by location,by classifying recording stations as inland,coastal,or bay.We find that the BLH in Europe varies considerably from day to night and with the seasons.Nighttime BLH is higher in winter and lower in summer,with the highest BLH recorded at coastal stations.Daytime BLH at coastal stations shows a bimodal structure with peaks in spring and autumn;at inland and bay stations,daytime BLH is lower in winter and higher in summer.The daily amplitudes of BLH at the inland and bay stations are stronger than those at coastal stations.Based on our multiple linear regression analysis and our decoupling analysis of temperature and specific humidity,we report that the development of the nighttime BLH at all types of stations is strongly dominated by the variations of surface wind speed(and,at coastal stations,wind directions).The main contributors to daytime BLH are the near-surface temperature variability at most coastal and inland stations,and,at most bay stations,the variation of the near-surface specific humidity.

Surface warming patterns dominate the uncertainty in global water vapor plus lapse rate feedback

Climate feedbacks have been usually estimated using changes in radiative effects associated with increased global-mean surface temperature. Feedback uncertainties, however, are not only functions of global-mean surface temperature increase. In projections by global climate models, it has been demonstrated that the geographical variation of sea surface temperature change brings significant uncertainties into atmospheric circulation and precipitation responses at regional scales. Here we show that the spatial pattern of surface warming is a major contributor to uncertainty in the combined water vapour-lapse rate feedback. This is demonstrated by computing the global-mean radiative effects of changes in air temperature and relative humidity simulated by 31 climate models using a methodology based on radiative kernels. Our results highlight the important contribution of regional climate change to the uncertainty in climate feedbacks, and identify the regions of the world where constraining surface warming patterns would be most effective for higher skill of climate projections.

On the Relationship between Climatic Variables and Pressure Systems over Saudi Arabia in the Winter Season

The synoptic circulation over Saudi Arabia is complicated and frequently governed by the effect of large-scale pressure systems. In this work, we used NCEP–NCAR global data to illustrate the relationship between climatic variables and the main pressure systems that affect the weather and climate of Saudi Arabia, and also to investigate the influence of these pressure systems on surface air temperature（SAT） and rainfall over the region in the winter season. It was found that there are two primary patterns of pressure that influence the weather and climate of Saudi Arabia. The first occurs in cases of a strengthening Subtropical High（Sub H）, a weakening Siberian High（Sib H）, a deepening of the Icelandic Low（Ice L）, or a weakening of the Sudanese Low（Sud L）. During this pattern, the Sub H combines with the Sib H and an obvious increase of sea level pressure（SLP） occurs over southern European, the Mediterranean, North Africa, and the Middle East. This belt of high pressure prevents interaction between midlatitude and extratropical systems, which leads to a decrease in the SAT,relative humidity（RH） and rainfall over Saudi Arabia. The second pattern occurs in association with a weakening of the Sub H, a strengthening of the Sib H, a weakening of the Ice L, or a deepening of the Sud L. The pattern arising in this case leads to an interaction between two different air masses： the first（cold moist） air mass is associated with the Mediterranean depression travelling from west to east, while the second（warm moist） air mass is associated with the northward oscillation of the Sud L and its inverted V-shape trough. The interaction between these two air masses increases the SAT, RH and the probability of rainfall over Saudi Arabia, especially over the northwest and northeast regions.

利用Landsat数据反演近岸海水表层温度的大气校正算法

介绍了一种将大气效应考虑在内、利用Landsat TM、ETM+热红外数据进行近海岸海表水温反演的单窗算法.在该算法中,将地表气温、相对湿度等常规气象资料作为初始参数,根据对流层中大气温度随高度呈线性降低、水汽随高度呈指数衰减的规律,建立了估算平均大气温度及水汽含量的通用模式.通过与实测数据及MODIS Terra海表水温产品比较发现,该算法能够提高运用TM/ETM+TIR单波段数据进行近岸海表水温(SST)反演的精度:一方面,反演所得结果更接近于海表实际水温;另一方面,它在一定程度上剔除大气中的水汽对SST反演的影响,进而提高海表水温的温度对比度.该提出的大气校正算法只需地表大气温度及相对湿度资料,该算法也无需进行大气模式的界定.

The extreme dry/wet events in northern China during recent 100 years

Using monthly precipitation and monthly mean temperature, a surface humid index was proposed. According to the index, the distributed characteristics of extreme dryness has been fully analyzed. The results indicated that there is an obvious increasing trend of extreme dryness in the central part of northern China and northeastern China in the last 10 years, which shows a high frequency period of extreme dryness; while a low frequency period in the regions during the last 100 years. Compared with variation trend of the temperature in these regions, the region of high frequent extreme dryness is consistent with the warming trend in the same region.

热带太平洋淡水通量年际变率对ENSO的作用机制及数值模拟研究

海气界面间淡水通量(freshwater flux, FWF;定义为降水减蒸发)是热带太平洋气候系统中对海洋有重要作用的大气强迫之一,与风应力和热通量共同影响厄尔尼诺-南方涛动(El Nino-Southern Oscillation, ENSO)。尽管这些大气强迫场共同作用于海洋,但FWF在其中的单独强迫作用及相关过程和机制仍需深入探究。本文通过海洋环流模式(ocean general circulation model, OGCM)进行模拟,进一步使用温度和盐度收支分析以及区分温盐相对贡献的诊断分析方法,量化热带太平洋FWF年际变率对上层海洋的净作用。结果表明,在El Nino事件发生时,FWF正异常强迫直接导致赤道太平洋中部海表盐度(sea surface salinity, SSS)降低,同时增强上层海洋层结稳定度。此外,FWF正异常强迫还会导致赤道太平洋中部浮力通量(buoyancy flux, BF)增加,从而减弱了次表层的混合和夹卷作用,使局地的混合层变浅。从气候效应来看,由FWF年际变率引起的海洋过程有助于赤道东太平洋海表温度(sea surface temperature, SST)暖异常的维持和增强。通过定量分析表明,SSS变化与FWF强迫强度密切相关,赤道太平洋中部FWF异常每增加1.0 mm/d会使得SSS异常降低约0.02,并且使得赤道太平洋东部SST异常升高约0.12℃,在增温过程中垂直混合和夹卷作用是主导的贡献项。以1997~1998年的El Nino事件为例,FWF正异常引起的SST暖异常增量占总异常的11.8%。本文所揭示的FWF强迫场对ENSO的单独作用有助于完善我们对整个热带太平洋海气耦合系统的认知,为进一步改进ENSO的过程表征和预测提供科学指导。

Determining asphalt surface temperature using weather parameters

Temperature affects the structural response of asphalt concrete(AC) pavement To evaluate the performance,it is important to accurately predict the pavement surface temperature.This study develops three regression models to determine the surface temperature of an asphalt pavement using field measured data such as air temperature,wind speed,wind direction,relative humidity,and solar radiation.Three models namely,24-h model,day-time model and night-time model were developed based on one-year continuous data.The weather data were measured from October 2012 to October 2013 at an instrumented pavement section on Interstate I-40 near Albuquerque,New Mexico.The developed regression models were validated using October 2014 to June 2015 weather data,which were not used in developing the regression models.Surface temperatures predicted using the developed regression models were then compared to those predicted using the pavement mechanistic-empirical(ME) software’s default model.It is observed that the regression models are better predictors of pavement surface temperatures than the ME default models.A parametric study was also performed in this study to identify the effects of weather parameters on the pavement surface temperature prediction.The authors of this study expect that this study will be useful in pavement design especially in cold regions.

北部湾一次持续性混合型海雾过程分析

利用北部湾沿岸海岛站观测资料和ERA5数据,对混合型(高压后部型转西南倒槽型)海雾出现概率和一次典型过程进行了分析。结果表明:(1)2015—2020年混合型海雾过程出现概率最高,累计出现15次(58天),占比34.9%(39.5%)。(2)2016年3月15—23日海雾过程具有持续时间长、范围广的特点。前期北部湾受入海高压后部偏东气流影响,后期高原槽发展东移,北部湾逐渐转为受西南倒槽边缘偏南气流控制。(3)热力条件上,低空急流的强暖湿输送,一方面使北部湾上空比湿增大,饱和层从近地面延伸至800 hPa,另一方面使逆温层建立,逆温层与其下方高湿区配合形成稳定状态。动力条件方面,垂直方向维持一定强度的风切变,有利于边界层的湍流混合,并与斜压大气形成有利于低层稳定层结维持的配置。此外800 hPa以下为弱上升运动,利于水汽在低层抬升凝结,促进海雾发展及维持。(4)海雾发生期间,前期(后期)气海温差大多在0~1.5℃(1.5~2.5℃)之间。

岱海水面蒸发与气象要素关系分析

该文以岱海为研究对象,以乌兰察布市凉城县岱海镇三苏木水文站为依托,以水面蒸发物理成因为基础,根据蒸发实测资料,建立了20 cm口径蒸发器与E601型蒸发器与气温、相对湿度、水汽压、降水量、风速、地温、日照等气象要素的相关性分析,通过SPSS双侧相关性检验以及散点图趋势线分析,20 cm口径蒸发器监测蒸发量时更灵敏,与气象要素相关性更好,对于气象要素的变化反应更敏感;气象要素对蒸发量的影响中,对蒸发量影响最大的是最高地面温度,其次是日照时数、平均相对湿度和最高气温,最高地面温度、最高气温越高、日照时数越长、风速越高,蒸发量越大;平均相对湿度越大,环境中水汽含量越高,蒸发量越小。

杭州城市园林绿化对小气候的影响

进行了园林绿化对气温和相对湿度的影响研究 ,结果表明 ,在杭州的夏季 ,经过园林绿化后 ,气温能降低 0 .7℃、最高可降 2 .3℃、相对湿度提高 4 %、最高可达 15 % ;冬季阴雨天气时没有降温作用 .没有绿化的主街是个热源 ,经过绿化的小区比主街低 0 .6℃ .良好的行道树具有降温作用 ,能降低 0 .5～ 1℃ ,相对湿度提高 4 % .不同的植物类型降温作用有差别 ,总的说来 ,树冠高大、枝叶浓密的降温作用大 ,乔木的降温作用大于草坪 .植物表面的温度低于人工下垫面 ,夏季可降低 4～ 8℃ .

不同遮荫水平对茶树光合环境及茶叶品质的影响

试验研究了夏秋季80%、61%、37%遮光率遮阳网覆盖处理对茶园生态环境、茶树光合作用特性和茶叶内含成分的影响。结果表明:与露地对照茶园相比,3种遮光率遮荫处理茶园夏秋季气温、叶面温度、地面温度和土壤温度均明显降低;茶园土壤水分含量、茶园空气湿度明显提高。遮荫改善了茶园生态环境,且遮光率越高,效果越明显。与对照茶园比较,80%、61%、37%遮光率遮阳网覆盖处理日平均净光合速率增加了365%、283%和68%;茶叶新梢的叶绿素a含量增加了57.5%、29.3%和15.9%,叶绿素总量增加了52.2%、29.2%和14.3%;茶叶氨基酸含量增加了68.6%、33.5%和2.16%;茶叶茶多酚含量降低了15.3%、12.5%和5.4%。80%遮光率处理1芽2叶新梢制作的茶叶酚氨比达到名优绿茶标准,61%遮光率和37%遮光率处理的茶叶酚氨比也均达到高档绿茶标准,茶叶品质明显优于对照茶园。

定量遥感地表净辐射通量所需大气下行长波辐射估算模型改进

利用半湿润季风气候类型夏季近地层气象观测资料,对得到广泛应用的十种晴天大气下行辐射估算模型和两种昙天大气下行辐射估算模型进行检验。指出其中Iziomon(2003)晴天大气下行辐射估算模型是半湿润季风气候类型夏季较适用的估算模型。然而,在有云天空,Iziomon(2003)昙天估算模型误差比较大。本文依据实测资料,对Iziomon(2003)昙天大气下行辐射估算模型进行修正,修正后的模型估算值与实测值非常接近。由于应用常规气象站的大气温湿度来估算大气下行辐射仅代表近地层大气对其的贡献,不能反映整层大气的贡献,尤其在近地层与高空大气的水汽状况不一致时,上述模型将有较大的误差。为此本文结合Iziomon(2003)晴天模型中大气比辐射率的表达式,提出了运用红外辐射计以37°高度角对天空的观测值,来推算大气下行辐射的新方法。小汤山的试验数据表明,新模型的反演精度优于上述传统模型。

中国近代北方极端干湿事件的演变规律

利用中国1951～2000年的月降水和月平均气温构造了一个适合于研究我国北方地区地表干湿状况的地表湿润指数,以此为基础对我国北方地区极端干旱的分布特征进行深入的研究。结果指出:在东北和华北地区,近10年极端干旱频率显著增加,是近百年少有的大范围高强度的极端干旱频发期,而这些地区极端湿润发生的频率相对减少。和温度变化趋势比较发现,极端干旱的频发区往往对应增温明显的地区。

天津城区大雾过程近地面层特征研究

地面倒槽、华北地形槽和地面弱高压是天津冬季雾日多见的地面气压系统。为了解雾事件在上述三种天气系统下近地面层气象要素的演变规律,利用天津市250m气象铁塔梯度观测和常规气象观测资料,分别选取2002、2003和2004年相应气压场下的雾个例,比较分析了冬季雾天近地面层结构及低层水汽分布特征。结果表明:(1)三种天气系统条件下,均存在近地层逆位温层结和增湿现象,近地面40m以下高度为弱风。(2)地面倒槽形势下的平流雾过程中,逆温层结稳定且厚达千米,近地层呈多层逆温或弱逆位温层结;80m以上,雾前风力较强,雾中风力较弱;低空各层水汽显著上升时间提前于起雾时间约15h,且日夜增速持续均匀,雾中呈现出逆湿特征,雾顶超过250m。(3)华北地形槽和地面弱高压下的辐射雾过程中,日落后近地面浅薄逆温层结生成并于05时(北京时间,下同)左右达最强,日出后减弱,于11时左右消散;仅夜间近地层水汽显著增加,且塔层250m逆温强度达到3.0℃时才开始出现,距起雾时间约2～9h;雾形成后,逆温层底抬升,雾体中逐渐演变呈不稳定层结;雾中呈现下湿上干特征,雾厚分别为80m和60m左右。(4)华北地形槽和地面弱高压下的风廓线演变规律有显著差异,即前者80m以上6m.s-1左右南风和北风呈规律性日变化转换特征,而后者250m低层大气恒为弱风控制。