Aqua 위성 AMSU-A 고도별 온도자료를 이용한 열적 대류권계면 고도 산출 및 활용

Obtaining temperature and humidity profiles with high vertical resolution is essential for describing and predicting atmospheric motion, and, in particular, for understanding the evolution of medium- and small-scale weather processes, making short-range and near-term weather forecasting, and implementing weather modifications (artificial rainfall, artificial rain elimination, etc.). Ground-based microwave radiometers can acquire vertical tropospheric atmospheric data with high temporal and spatial resolution. However, the accuracy of temperature and relative humidity retrieval is still not as accurate as that of radiosonde data, especially in cloudy conditions. Therefore, improving the observation and retrieval accuracy is a major challenge in current research. The focus of this study was to further improve the accuracy of atmospheric temperature and humidity profile retrieval and investigate the specific effects of cloud information (cloud-base height and cloud thickness) on temperature and humidity profile retrieval. The observation data from the ground-based multichannel microwave radiometer (GMR) and the millimeter-wave cloud radar (MWCR) were incorporated into the retrieval process of the atmospheric temperature and relative humidity profiles. The retrieval was performed using the backpropagation neural network (BPNN). The retrieval results were quantified using the mean absolute error (MAE) and root mean square error (RMSE). The statistical results showed that the temperature profiles were less affected by the cloud information compared with the relative humidity profiles. Cloud thickness was the main factor affecting the retrieval of relative humidity profiles, and the retrieval with cloud information was the best retrieval method. Compared with the retrieval profiles without cloud information, the MAE and RMSE values of most of the altitude layers were reduced to different degrees after adding cloud information, and the relative humidity (RH) errors of some altitude layers were reduced by approximately 50%. The maximum reduction in the RMSE and MAE values for the retrieval of temperature profiles with cloud information was about 1.0 °C around 7.75 km, and the maximum reduction in RMSE and MAE values for the relative humidity profiles was about 10%, which was obtained around 2 km.

Validation of INSAT-3DR sounder retrieved temperature profile with GPS radiosonde and AIRS observations

MODIS land surface temperature data (MODIS Ts) products are quantified from the earth surface’s reflected thermal infrared signal via sensors onboard the Terra and Aqua satellites. MODIS Ts products are a great value to many environmental applications but often subject to discrepancies when compared to the air temperature (Ta) data that represent the temperature measured at 2 m above the ground surface. Although they are different in their nature, the relationship between Ts and Ta has been established by many researchers. Further validation and correction on the relationship between these two has enabled the estimation of Ta from MODIS Ts products in order to overcome the limitation of Ta that can only provide data in a point form with a very limited area coverage. Therefore, this study was conducted with the objective to assess the accuracy of MODIS Ts products, i.e., MOD11A1, MOD11A2, MYD11A1, and MYD11A2 against Ta and to identify the performance of a modified Linear Scaling using a constant and monthly correction factor (LS-MBC), and Quantile Mapping Mean Bias Correction (QM-MBC) methods for lowland area of Peninsular Malaysia. Furthermore, the correction factor (CF) values for each MBC were adjusted according to the condition set depending on the different bias levels. Then, the performance of the pre- and post-MBC correction for by stations and regions analysis were evaluated through root mean square error (RMSE), percentage bias (PBIAS), mean absolute error (MAE), and correlation coefficient (r). The region dataset is obtained by stacking the air temperature (Ta_r) and surface temperature (Ts_r) data corresponding to the number of stations within the identified regions. The assessment of pre-MBC data for both 36 stations and 5 regions demonstrated poor correspondence with high average errors and percentage biases, i.e., RMSE = 3.33–5.42 °C, PBIAS = 1.36–12.07%, MAE = 2.88–4.89 °C, and r = 0.16–0.29. The application of the MBCs has successfully reduced the errors and bias percentages, and slightly increased the r values for all MODIS Ts products. All post-MBC depicted good average accuracies (RMSE and MAE < 3 °C and PBIAS between ±5%) and r between 0.18 and 0.31. In detail, for the station analysis, the LS-MBC using monthly CF recorded better performance than the LS-MBC using constant CF or the QM-MBC. For the regional study, the QM-MBC outperformed the others. This study illustrated that the proposed LS-MBC, in spite of its simplicity, managed to perform well in reducing the error and bias terms of MODIS Ts as much as the performance of the more complex QM-MBC method.

본 연구에서는 2010년 12월 27일부터 28일까지 서울을 포함한 수도권 지역에 많은 강설을 일으킨 사례의 종관적, 열역학적 및 역학적 특징을 조사하였다. 이 사례는 극저기압으로 분류할 수 있는 특성을 지녔다. 분석에 사용된 자료는 지상 및 상층 일기도, 강설량, 해수면온도, 위성사진, 연직프로파일 및 미국 국립환경예측센터의 전구 <TEX>$1^{\circ}{\times}1^{\circ}$</TEX> 재분석자료 등이다. 극저기압은 대기 하층에서 양의 경압성이 강하게 나타나며 925 hPa에 온난이류가, 700 hPa에 한랭이류가 있어 조건부 불안정층이 뚜렷하게 보이는 곳에서 형성되는 것으로 사료된다. 극저기압의 발달기구는 대류권계면 접힘에 의한 성층권 공기의 유입과 그에 따른 위치 소용돌이도의 증가로 하층에 수렴과 저기압성 순환의 유발에 기인한다. 이는 눈구름의 발달로 이어져 서울 지역에는 10 cm, 남부지방에는 최고 20 cm까지 적설을 보였다. 강설의 발달기간동안 상층 500 hPa에는 <TEX>$-45^{\circ}C$</TEX>의 한랭핵이 존재하였고 단파골과 지상 기압골간의 위상차도 <TEX>$3-5^{\circ}$</TEX>를 이루어 극저기압이 온난역의 저기압성 소용돌이도 이류 지역에서 발달할 수 있었다. 발달의 최성기에는 역학적 대류권계면이 700 hpa까지 하강하였고 위치소용돌이도의 증가로 상승기류도 강화되었다. 전반적으로 강설의 발생과 대류권계면의 파상운동과는 깊은 관련을 보였다. 극저기압이 한반도를 통과하는 동안 대류권계면이 하강하는 지점의 동쪽에 소용돌이도와 상승기류가 강화되었고 동시에 많은 습기가 이류되는 곳에서 강설량도 최대로 나타났다. The synoptic, thermodynamic, and dynamic characteristics of a heavy snowfall event that occurred in Seoul metropolitan area on 27 to 28 December 2010 was investigated. During this period there was a distinctive case that was identified as a polar low. We analyzed surface and upper level weather charts, snowfall amount, sea surface temperature, satellite imagery, sounding, and the National Center for Environmental Prediction global <TEX>$1^{\circ}{\times}1^{\circ}$</TEX> reanalysis data. The polar low developed in an area where there was strong baroclinicity in the lower level aided by strong conditional instability due to 925 hPa warm air advection and 700 hPa cold air advection. The development mechanism of polar low is due, in part, to the tropopause folding, which advected stratospheric air increasing potential vorticity in mid-level and inducing cyclonic vorticity and convergence in low-level. Eventually clouds developed and there were snowfall total of 10 cm in Seoul metropolitan area and as much as 20 cm in southern parts of Korea. During the snowfall development, there was a <TEX>$-45^{\circ}C$</TEX> cold core at 500 hPa and shortwave maintained <TEX>$3-5^{\circ}$</TEX> separation with surface trough, which favored the development of polar low located in the warm sector and cyclonic advection area. The height of the dynamical tropopause lowered to 700 hPa during the peak development and increase in potential vorticity allowed strong vertical motion to occur. Overall, there was a close relationship between the development of snowfall and tropopause undulation. The heaviest snowfall occurred east of the tropopause folding where strong cyclonic vorticity, vertical motion, and moisture advection all coincided while the polar low was passing through the Korean peninsula.

The Flatland radar, a VHF wind profiler located near Urbana, Illinois, has been used to study the variability of the tropopause over the period March 1987–April 1988. The vertically directed radar beam provides an indicator of tropopause height as well as measurements of the vertical velocity of the air. The sudden tropopause height changes previously seen in special campaigns are found to be relatively common features. Several case studies made under varying synoptic conditions are used to show that thew discontinuities are associated with tropopause folding events as revealed by cross-section analyses of potential temperature and potential vorticity based on radiosonde data. The vertical velocity in a typical tropopause fold is downward at up to 15 cm s−1. Finally, applications of the continuous data from VHF radars to develop quantitative climatologies of tropopause folding events are presented.

We present a study of the distribution of ozone in the lowermost stratosphere with the goal of characterizing the observed variability. The air in the lowermost stratosphere is divided into two population groups based on Ertel's potential vorticity at 300 hPa. High (low) potential vorticity at 300 hPa indicates that the tropopause is low (high), and the identification of these two groups is made to account for the dynamic variability. Conditional probability distribution functions are used to define the statistics of the ozone distribution from both observations and a three‐dimensional model simulation using winds from the Goddard Earth Observing System Data Assimilation System for transport. Ozone data sets include ozonesonde observations from northern midlatitude stations (1991–1996) and midlatitude observations made by the Halogen Occultation Experiment (HALOE) on the Upper Atmosphere Research Satellite (UARS) (1994–1998). The conditional probability distribution functions are calculated at a series of potential temperature surfaces spanning the domain from the midlatitude tropopause to surfaces higher than the mean tropical tropopause (∼380 K). The probability distribution functions are similar for the two data sources, despite differences in horizontal and vertical resolution and spatial and temporal sampling. Comparisons with the model demonstrate that the model maintains a mix of air in the lowermost stratosphere similar to the observations. The model also simulates a realistic annual cycle. Results show that during summer, much of the observed variability is explained by the height of the tropopause. During the winter and spring, when the tropopause fluctuations are larger, less of the variability is explained by tropopause height. This suggests that more mixing occurs during these seasons. During all seasons, there is a transition zone near the tropopause that contains air characteristic of both the troposphere and the stratosphere. The relevance of the results to the assessment of the environmental impact of aircraft effluence is also discussed.

Contemporary Earth and space science relies on complex infrastructures that connect observations, data transmission, processing systems and digital services. A critical but often under-recognized component of this system is access to radio-frequency spectrum, which enables both the acquisition of observations and the real-time exchange of data from meteorological satellites, weather radars, radiosondes, space weather sensors and other Earth observation systems. The radio-frequency spectrum is a physically limited and increasingly contested resource.The World Meteorological Organization (WMO), a specialized agency of the United Nations with 193 Members, provides the global coordination framework for observing and data systems through the WMO Integrated Global Observing System (WIGOS), the WMO Information System (WIS) and the WMO Integrated Processing and Prediction System (WIPPS). These systems support standardized observations, global data exchange and the delivery of operational services that underpin numerical weather prediction, climate monitoring, hydrology and environmental applications worldwide.Within this framework, the WMO Space Programme coordinates international activities related to the availability and use of satellite data and products, capacity development, space weather coordination, and cooperation on radio-frequency spectrum use. This includes engagement with scientific and regulatory communities through the Expert Team on Radio-Frequency Coordination, contributions to international technical studies, development of joint guidance (e.g., WMO–International Telecommunication Union (ITU) handbooks), and coordinated preparations for the World Radiocommunication Conference 2027 (WRC-27).This presentation frames spectrum coordination as a core element of Earth observation data systems and highlights its role in maximizing the economic, social and environmental value of global meteorological infrastructures, including societally critical initiatives such as Early Warnings for All (EW4All).

Accurate long-term temperature and precipitation estimates at high spatial and temporal resolutions are vital for a wide variety of climatological studies. We have produced a new, publicly available, daily, gridded maximum temperature, minimum temperature, and precipitation dataset for China with a high spatial resolution of 1 km and over a long-term period (1961 to 2019). It has been named the HRLT and the dataset is publicly available at https://doi.org/10.1594/PANGAEA.941329 (Qin and Zhang, 2022). In this study, the daily gridded data were interpolated using comprehensive statistical analyses, which included machine learning, the generalized additive model, and thin plate splines. It is based on the 0.5° × 0.5° grid dataset from the China Meteorological Administration, together with covariates for elevation, aspect, slope, topographic wetness index, latitude, and longitude. The accuracy of the HRLT daily dataset was assessed using observation data from meteorological stations across China. The maximum and minimum temperature estimates were more accurate than the precipitation estimates. For maximum temperature, the mean absolute error (MAE), root mean square error (RMSE), Pearson’s correlation coefficient (Cor), coefficient of determination after adjustment (R2), and Nash-Sutcliffe modeling efficiency (NSE) were 1.07 °C, 1.62 °C, 0.99, 0.98, and 0.98, respectively. For minimum temperature, the MAE, RMSE, Cor, R2, and NSE were 1.08 °C, 1.53 °C, 0.99, 0.99, and 0.99, respectively. For precipitation, the MAE, RMSE, Cor, R2, and NSE were 1.30 mm, 4.78 mm, 0.84, 0.71, and 0.70, respectively. The accuracy of the HRLT was compared to those of the other three existing datasets and its accuracy was either greater than the others, especially for precipitation, or comparable in accuracy, but with higher spatial resolution or over a longer time period. In summary, the HRLT dataset, which has a high spatial resolution, covers a longer period of time and has reliable accuracy, is suitable for future environmental analyses, especially the effects of extreme weather.

The three-dimensional connections between Eurasian cooling and Arctic warming since 1979 were investigated using potential vorticity (PV) dynamics. We found that Eurasian cooling can be regulated by Arctic warming through PV adaptation and PV advection. Here, PV adaptation refers to the adaptation of PV to forcing and coherent dynamic–thermodynamic adaptation to PV change. In a PV perspective, first, the anticyclonic circulation change over the Arctic is produced by a negative PV change through PV adaptation, in which the change means the linear trend from 1979 to 2017. The negative PV change is directly regulated by Arctic warming because the vertical structure of Arctic warming is stronger at lower levels, which generates a negative PV change through the diabatic heating effect. Second, the circulation change produces a change in horizontal PV advection due to the existence of climatological PV gradients. Thus, as a balanced result, both the circulation change and PV change extend to the midlatitudes through horizontal PV advection and PV adaptation. Eventually, Eurasian cooling at the surface and in the lower troposphere is dominated by PV changes at the surface through PV adaptation. Meanwhile, enhanced Eurasian cooling in the middle troposphere is dominated by top-down influences of upper-level PV change through PV adaptation. Nevertheless, the upper-level PV changes are still contributed to by horizontal PV advection associated with Arctic warming. Overall, the general dynamics connecting Eurasian cooling with Arctic warming are demonstrated in a PV view.

: A physical distinction between stratosphere and troposphere can be made in terms of potential vorticity or ozone. The World Meteorological Organization (WMO) tropopause, based only on thermal stability, does not always separate the different physical properties of the two regions. It is the purpose of this paper to show that the altitude in a vertical ozone profile at which ozone, and therefore potential vorticity, begins to increase rapidly is determinable from the temperature profile alone. The tropopause definition developed here reduces the WMO temperature gradient and thickness criteria and relies on the relative change of temperature lapse rate. The new definition determines heights of the tropopause that are in excellent agreement with ozone profile information. The proposed tropopause definition was applied to an archived ten-year global radiosonde data set to prepare a climatology. The definition was also applied to an archived set of several thousand ozonesonde temperature profiles to prepare a climatology of vertical ozone gradient at the tropopause. (Author)

Vertical cross sections of potential vorticity, computed and contoured by band, and hemispheric distributions of potential vorticity, computed and contoured by machine, are compared to both discrete and continuous measurements of radioactivity made during Project Springfield. Comparisons made in the upper troposphere and lower stratosphere show a positive correlation between potential vorticity and radioactivity of stratospheric origin. The radioactivity measurements and machine-computed isentropic trajectories prove that stratospheric air from high latitudes is transported southward and downward into the troposphere as the tropopause folds. Changes in potential vorticity and the concentration of radioactivity along the trajectories also prove that subsynoptic-scale mixing destroys the extruded stratospheric layer in the troposphere. The mass outflow from stratosphere to troposphere associated with tropopause folding is compensated by a quasi-steady inflow along the tropopause. This inflow is nec...

The global variation characteristics of tropopause are shown by analyzing the data of temperature profiles from Radio Occultation (RO) observations aboard the satellites of COSMIC. These satellites have excellent explorations with global coverage and vertical resolution. The accurate and high vertical resolution temperature profiles from RO/COSMIC provide a unique opportunity to study the global structure and variability of tropopause. The daily mean temperature data from the day 111 of 2006 to the day 295 of 2007 are chosen for the analysis in this paper. The global distributions of tropopause height and temperature and their temporal variation depending on latitude, by using the method of Lapse Rate Tropopause (LRT), are discussed. These results indicate that the global distributions of tropopause temperature and height are consistent with the investigation by some radiosondes and the reanalyses data of the European Centre for Medium-Range Weather Forecasts (ECMWF). There are three important characteristics in the present study: (1) the obvious seasonal variation of tropopause height and temperature, (2) the reversed phase variability of tropopause height between the equatorial, lower latitude and the higher latitude, and (3) the North-South asymmetry of the annual variation of tropopause temperature and height.

Annual and interannual variations of ozone in the upper troposphere and lower stratosphere (UTLS) region have been studied using ozonesonde data collected between 1994 and 2001 at several northern European stations. The climatology of ozone exhibits a prominent annual cycle in the UTLS region. The observed change in the phase of the annual cycle from late spring‐early summer at 500 hPa to spring at 200 hPa and to winter‐early spring at 100 hPa shows the switching of the ozone control from photochemical to dynamical. Traces of interannual variation in the lower stratosphere are seen not only in the upper troposphere but also in the middle troposphere (not necessarily always) indicating the dynamical influence on tropospheric ozone budget. Further, the correlation between ozone mixing ratio and potential vorticity (PV) is studied at three northern high‐latitude stations. As expected, a good correlation is found in the lower stratosphere, while the correlation is fair in the middle troposphere, except during summer over the European Arctic. This weak correlation at high latitudes indicates the dominance of photochemistry over dynamics in the presence of prolonged hours of solar illumination. The correlation coefficients derived at high latitudes are smaller than those reported at midlatitudes. This could be due to the greater number of tropopause folds at midlatitudes than at high latitudes and this eventually leads to the conclusion that the downward cross‐tropopause flux is greater at midlatitudes than at high latitudes. Absence of a significant north‐south gradient in the ozone/PV ratio in the lower stratosphere suggests that a single ozone/PV ratio (however, the ratio varies with month) can be used to convert global PV fluxes to ozone fluxes. A few cases of tropopause folds (only one case study is reported in the present study) are selected and studied in detail with the help of a very high frequency radar and meteorological analysis. The ratio between ozone and PV for these case studies agrees reasonably well with the climatological ratios.

Abstract. Warm conveyor belts (WCBs) are dynamically important, strongly ascending and mostly stratiform cloud-forming airstreams in extratropical cyclones. Despite the predominantly stratiform character of the WCB's large-scale cloud band, convective clouds can be embedded in it. This embedded convection leads to a heterogeneously structured cloud band with locally enhanced hydrometeor content, intense surface precipitation and substantial amounts of graupel in the middle troposphere. Recent studies showed that embedded convection forms dynamically relevant quasi-horizontal potential vorticity (PV) dipoles in the upper troposphere. Thereby one pole can reach strongly negative PV values associated with inertial or symmetric instability near the upper-level PV waveguide, where it can interact with and modify the upper-level jet. This study analyzes the characteristics of embedded convection in the WCB of cyclone Sanchez based on WCB online trajectories from a convection-permitting simulation and airborne radar observations during the North Atlantic Waveguide and Downstream Impact Experiment (NAWDEX) field campaign (intense observation periods, IOPs, 10 and 11). In the first part, we present the radar reflectivity structure of the WCB and corroborate its heterogeneous cloud structure and the occurrence of embedded convection. Radar observations in three different sub-regions of the WCB cloud band reveal the differing intensity of its embedded convection, which is qualitatively confirmed by the ascent rates of the online WCB trajectories. The detailed ascent behavior of the WCB trajectories reveals that very intense convection with ascent rates of 600 hPa in 30–60 min occurs, in addition to comparatively moderate convection with slower ascent velocities as reported in previous case studies. In the second part of this study, a systematic Lagrangian composite analysis based on online trajectories for two sub-categories of WCB-embedded convection – moderate and intense convection – is performed. Composites of the cloud and precipitation structure confirm the large influence of embedded convection: intense convection produces very intense local surface precipitation with peak values exceeding 6 mm in 15 min and large amounts of graupel of up to 2.8 g kg−1 in the middle troposphere (compared to 3.9 mm and 1.0 g kg−1 for the moderate convective WCB sub-category). In the upper troposphere, both convective WCB trajectory sub-categories form a small-scale and weak PV dipole, with one pole reaching weakly negative PV values. However, for this WCB case study – in contrast to previous case studies reporting convective PV dipoles in the WCB ascent region with the negative PV pole near the upper-level jet – the negative PV pole is located east of the convective ascent region, i.e., away from the upper-level jet. Moreover, the PV dipole formed by the intense convective WCB trajectories is weaker and has a smaller horizontal and vertical extent compared to a previous NAWDEX case study of WCB-embedded convection, despite faster ascent rates in this case. The absence of a strong upper-level jet and the weak vertical shear of the ambient wind in cyclone Sanchez are accountable for the weak diabatic PV modification in the upper troposphere. This implies that the strength of embedded convection alone is not a reliable measure for the effect of embedded convection on upper-level PV modification and its impact on the upper-level jet. Instead, the profile of vertical wind shear and the alignment of embedded convection with a strong upper-level jet play a key role for the formation of coherent negative PV features near the jet. Finally, these results highlight the large case-to-case variability of embedded convection not only in terms of frequency and intensity of embedded convection in WCBs but also in terms of its dynamical implications.

Extreme weather occurs when meteorological conditions in a specific location are unusually lower or higher than the average pattern, for example, tropical cyclones and extreme rain events. The southern margin of Yogyakarta, a province in Indonesia, abuts the Indian Ocean as one of the active tropical cyclone basins on Earth. Therefore, tropical cyclones potentially affect the rainfall characteristics in the region. This study aimed to ascertain the threshold values and frequencies of extreme rainfall and the impact of tropical cyclones on daily rainfall in Yogyakarta. It used 30-year rainfall data (1991‒2020) from the Climate Hazards Group InfraRed Precipitation with Station (CHIRPS) and three methods for determining extremes: the percentile method and two fixed thresholds set by Indonesia’s Meteorological, Climatological, and Geophysical Agency (BMKG) and World Meteorological Organization (WMO). Details on tropical cyclone occurrences were obtained from Australia’s Bureau of Meteorology. The results showed that the 99th percentile made the nearest threshold values to the fixed ones set for extreme rainfall by WMO and heavy rain by BMKG (R50mm). Extreme rainfall occurred in the west more often than in other parts of the province. In 1991‒2020, four tropical cyclones entered the Yogyakarta area, including Tropical Cyclone Cempaka on November 28, 2017, which induced inordinately high rainfall that exceeded the percentile threshold and the WMO’s fixed threshold of 50 mm (R50mm) for extremes and fell in the category Heavy Rainfall by the BMKG standard.