Verification of quality of GPS based radiosonde data

Abstract. Water vapor plays an important role in meteorological applications; GeoForschungsZentrum (GFZ) therefore developed a tomographic system to derive 3-D distributions of the tropospheric water vapor above Germany using GPS data from about 300 ground stations. Input data for the tomographic reconstructions are generated by the Earth Parameter and Orbit determination System (EPOS) software of the GFZ, which provides zenith total delay (ZTD), integrated water vapor (IWV) and slant total delay (STD) data operationally with a temporal resolution of 2.5 min (STD) and 15 min (ZTD, IWV). The water vapor distribution in the atmosphere is derived by tomographic reconstruction techniques. The quality of the solution is dependent on many factors such as the spatial coverage of the atmosphere with slant paths, the spatial distribution of their intersections and the accuracy of the input observations. Independent observations are required to validate the tomographic reconstructions and to get precise information on the accuracy of the derived 3-D water vapor fields. To determine the quality of the GPS tomography, more than 8000 vertical water vapor profiles at 13 German radiosonde stations were used for the comparison. The radiosondes were launched twice a day (at 00:00 UTC and 12:00 UTC) in 2007. In this paper, parameters of the entire profiles such as the wet refractivity, and the zenith wet delay have been compared. Before the validation the temporal and spatial distribution of the slant paths, serving as a basis for tomographic reconstruction, as well as their angular distribution were studied. The mean wet refractivity differences between tomography and radiosonde data for all points vary from −1.3 to 0.3, and the root mean square is within the range of 6.5–9. About 32% of 6803 profiles match well, 23% match badly and 45% are difficult to classify as they match only in parts.

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Integrated Precipitable Water Vapour Measurements At Polish Polar Station Hornsund From GPS Observations Verified By Aerological Techniques

Reports on Geodesy and Geoinformatics ◽

10.2478/rgg-2015-0001 ◽

2015 ◽

Vol 98 (1) ◽

pp. 1-17 ◽

Cited By ~ 3

Author(s):

Michał Kruczyk ◽

Tomasz Liwosz

Keyword(s):

Meteorological Parameter ◽

Precipitable Water ◽

Atmospheric Temperature ◽

Systematic Difference ◽

Radiosonde Data ◽

Tropospheric Delay ◽

Precipitable Water Vapour ◽

Retrieval Technique

AbstractWe present results of the comparison of integrated precipitable water measurements from GPS solution and aerological techniques: CIMEL-318 sun-photometer and radiosoundings (RAOB). Integrated Precipitable Water (IPW) - important meteorological parameter is derived from GPS tropospheric solutions by known procedure for GPS station at Polish Polar Station, Hornsund (Svalbard). The relation between 2 m temperature and the mean temperature of atmosphere above, used to convert from wet part of tropospheric delay (ZWD) to IPW, has been derived using local radiosonde data at Ny Alesund. Sunphotometer data have been provided by AERONET. Quality of dedicated tropospheric solutions has been verified by comparison with EPN tropospheric combined product. Several IPW comparisons and analyses lead to determination of systematic difference between techniques: GPS IPW and sunphotometer data (not present in case of RAOBs). IPW measured by CIMEL is on average 5% bigger (0.5 mm) than IPW from GPS. This bias changes seasonally and is a function of atmospheric temperature what signals some systematic deficiencies in solar photometry as IPW retrieval technique. CIMEL IPW show some temperature dependent bias also in relation to radiosoundings.

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An Assessment of the Temperature and Humidity of Atmospheric Infrared Sounder (AIRS) v6 Profiles Using Radiosonde Data in the Lee of the Tibetan Plateau

Atmosphere ◽

10.3390/atmos10070394 ◽

2019 ◽

Vol 10 (7) ◽

pp. 394 ◽

Cited By ~ 1

Author(s):

Zhiwei Heng ◽

Xingwen Jiang

Keyword(s):

Tibetan Plateau ◽

Weather Prediction ◽

Radiosonde Data ◽

Cold Bias ◽

The Tibetan Plateau ◽

Atmospheric Infrared Sounder ◽

Near Surface ◽

Climate Monitoring ◽

Radiosonde Observation

Atmospheric Infrared Sounder (AIRS) products are important for weather prediction and climate monitoring in the lee of the Tibetan Plateau (TP), where the terrain is complex. However, the quality of the AIRS products in this region remains unclear due to the unavailability of upper-air observation. In this study, for the first time, we use an 8-year intensive radiosonde observation dataset from 11 sites to assess the quality of the AIRS version 6 products in the lee of the TP at both daytime and nighttime. The results indicate that, overall, the AIRS products have a dry and cold bias in the lee of the TP, and larger biases over the sites of higher altitude. AIRS temperature retrieval has a larger deficiency in low levels at nighttime, while a better representation of moisture is found below 600 hPa over the low-altitude sites. In the lee of the TP, the quality control flags for temperature and moisture should be considered individually. The AIRS profile products could be useful for synoptic analysis of air temperature, moisture, and climate monitoring in this region, and further improvements are needed in the near-surface and nighttime retrieval processes.

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Evaluation and Improvement of the Quality of Ground-Based Microwave Radiometer Clear-Sky Data

Atmosphere ◽

10.3390/atmos12040435 ◽

2021 ◽

Vol 12 (4) ◽

pp. 435

Author(s):

Qing Li ◽

Ming Wei ◽

Zhenhui Wang ◽

Yanli Chu

Keyword(s):

Water Vapor ◽

Temperature Inversion ◽

Atmospheric Temperature ◽

Radiosonde Data ◽

Vapor Density ◽

Clear Sky ◽

Brightness Temperatures ◽

Temperature And Humidity ◽

Humidity Profiles

To assess the quality of the retrieved products from ground-based microwave radiometers, the “clear-sky” Level-2 data (LV2) products (profiles of atmospheric temperature and humidity) filtered through a radiometer in Beijing during the 24 months from January 2010 to December 2011 were compared with radiosonde data. Evident differences were revealed. Therefore, this paper investigated an approach to calibrate the observed brightness temperatures by using the model-simulated brightness temperatures as a reference under clear-sky conditions. The simulation was completed with a radiative transfer model and National Centers for Environmental Prediction final analysis (NCEP FNL) data that are independent of the radiometer system. Then, the least-squares method was used to invert the calibrated brightness temperatures to the atmospheric temperature and humidity profiles. A comparison between the retrievals and radiosonde data showed that the calibration of the brightness temperature observations is necessary, and can improve the inversion of temperature and humidity profiles compared with the original LV2 products. Specifically, the consistency with radiosonde was clearly improved: the correlation coefficients are increased, especially, the correlation coefficient for water vapor density increased from 0.2 to 0.9 around the 3 km height; the bias decreased to nearly zero at each height; the RMSE (root of mean squared error) for temperature profile was decreased by more than 1 degree at most heights; the RMSE for water vapor density was decreased from greater than 4 g/m3 to less than 1.5 g/m3 at 1 km height; and the decrease at all other heights were also noticeable. In this paper, the evolution of a temperature inversion process is given as an example, using the high-temporal-resolution brightness temperature after quality control to obtain a temperature and humidity profile every two minutes. Therefore, the characteristics of temperature inversion that cannot be seen by conventional radiosonde data (twice daily) were obtained by radiometer. This greatly compensates for the limited temporal coverage of radiosonde data. The approach presented by this paper is a valuable reference for the reprocessing of the historical observations, which have been accumulated for years by less-calibrated radiometers.

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Nimbus-6 Temperature Soundings Obtained Using Interactive Video-Graphics Computer Techniques

Bulletin of the American Meteorological Society ◽

10.1175/1520-0477-62.9.1308 ◽

1981 ◽

Vol 62 (9) ◽

pp. 1308-1318 ◽

Cited By ~ 2

Author(s):

Byron A. Paulson ◽

Lyle H. Horn

Keyword(s):

Interactive Video ◽

Data Access ◽

Temperature Fields ◽

Radiosonde Data ◽

Single Spot ◽

University Of Wisconsin ◽

Level Data ◽

The Individual ◽

The University

In an attempt to improve the quality of Nimbus-6 soundings, the Man-computer Interactive Data Access System (McIDAS) at the University of Wisconsin is used to manually edit individual (scan spot) High-resolution Infrared Sounder (HIRS) soundings. Unlike the Nimbus-6 Data System Test (DST) soundings that are derived from averages of up to 84 spot radiance measurements and the TIROS-N and NOAA-6 operational soundings that can involve averages of up to 63 spot measurements, the HIRS soundings used in this study were derived from single spot radiances or averages of five single spot soundings. Also, unlike the DST soundings, the HIRS McIDAS retrievals used contemporary surface (instrument shelter) temperatures as a pseudoinfrared window channel to aid in cloud filtering. These McIDAS-generated soundings were used to analyze 1) level temperature fields at 850, 500, and 300 mb; 2) the 850–300 mb thickness field; and 3) the 500 mb height field over eastern Europe for a 20 August 1975 case. The excellent radiosonde network in this area is used for verification purposes. While the individual spot soundings offer little improvement over the DST data, the averages of five of these soundings provide analyses that are distinctly superior to the operational DST soundings. Although improvement is noted in the root mean square and bias scores, the largest improvements are found in the S1 score, which is a measure of gradient comparison. The radiosonde verification data are partitioned into subsets and in some tests are combined with the HIRS soundings. Other tests involve comparisons in which the radiosonde data consist of only mandatory-level data. The various tests indicate that the edited HIRS soundings averaged in small groups are comparable to mandatory-level radiosonde data in constructing 500 mb height analyses.

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Skills of Thunderstorm Prediction by Convective Indices over a Metropolitan Area: Comparison of Microwave and Radiosonde Data

Remote Sensing ◽

10.3390/rs12040604 ◽

2020 ◽

Vol 12 (4) ◽

pp. 604

Author(s):

Mikhail Yu. Kulikov ◽

Mikhail V. Belikovich ◽

Natalya K. Skalyga ◽

Maria V. Shatalina ◽

Svetlana O. Dementyeva ◽

...

Keyword(s):

Lead Time ◽

Convective Available Potential Energy ◽

Skill Score ◽

Radiosonde Data ◽

Moderate Correlation ◽

K Index ◽

Heidke Skill Score ◽

Points Of View ◽

Better Than

In this work, we compare the values of 15 convective indices obtained from radiosonde and microwave temperature and water vapor profiles simultaneously measured over Nizhny Novgorod (56.2°N, 44°E) during 5 convective seasons of 2014–2018. A good or moderate correlation (with coefficients of ~0.7–0.85) is found for most indices. We assess the thunderstorm prediction skills with a lead time of 12 h for each radiosonde and microwave index. It is revealed that the effectiveness of thunderstorm prediction by microwave indices is much better than by radiosonde ones. Moreover, a good correlation between radiosonde and microwave values of a certain index does not necessarily correspond to similar prediction skills. Eight indices (Showalter Index, Maximum Unstable Convective Available Potential Energy (CAPE), Total Totals index, TQ index, Jefferson Index, S index, K index, and Thompson index) are regarded to be the best predictors from both the true skill statistics (TSS) maximum and Heidke skill score (HSS) maximum points of view. In the case of radiosonde data, the best indices are the Jefferson Index, K index, S index, and Thompson index. Only TSS and HSS maxima for these indices are close to the microwave ones, whereas the prediction skills of other radiosonde indices are essentially worse than in the case of microwave data. The analysis suggests that the main possible reason of this discrepancy is an unexpectedly low quality of radiosonde data.

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Annotation: Class Size and the Quality of Educational Outcomes

Journal of Child Psychology and Psychiatry ◽

10.1017/s0021963098002819 ◽

1998 ◽

Vol 39 (6) ◽

pp. 797-804 ◽

Cited By ~ 8

Author(s):

Neville Bennett

Keyword(s):

Educational Outcomes ◽

Class Size

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Immunoferritin localization of intracellular antigens in positively stained frozen sections

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010008170x ◽

1978 ◽

Vol 36 (2) ◽

pp. 168-169

Author(s):

K. T. Tokuyasu

Keyword(s):

Surface Tension ◽

Water Surface ◽

Thin Layers ◽

The Other ◽

Positive Staining ◽

Frozen Sections ◽

The Past ◽

Ultrathin Frozen Sections ◽

Definition Of

During the past investigations of immunoferritin localization of intracellular antigens in ultrathin frozen sections, we found that the degree of negative staining required to delineate u1trastructural details was often too dense for the recognition of ferritin particles. The quality of positive staining of ultrathin frozen sections, on the other hand, has generally been far inferior to that attainable in conventional plastic embedded sections, particularly in the definition of membranes. As we discussed before, a main cause of this difficulty seemed to be the vulnerability of frozen sections to the damaging effects of air-water surface tension at the time of drying of the sections.Indeed, we found that the quality of positive staining is greatly improved when positively stained frozen sections are protected against the effects of surface tension by embedding them in thin layers of mechanically stable materials at the time of drying (unpublished).

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Lithography below 100 nm

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100074367 ◽

1983 ◽

Vol 41 ◽

pp. 96-99

Author(s):

L. D. Jackel

Keyword(s):

Spatial Distribution ◽

Electron Beam ◽

Electron Scattering ◽

Electron Beam Lithography ◽

Substrate Material ◽

Local Electron ◽

Electron Dose ◽

Positive Resist ◽

Exposure Process

Most production electron beam lithography systems can pattern minimum features a few tenths of a micron across. Linewidth in these systems is usually limited by the quality of the exposing beam and by electron scattering in the resist and substrate. By using a smaller spot along with exposure techniques that minimize scattering and its effects, laboratory e-beam lithography systems can now make features hundredths of a micron wide on standard substrate material. This talk will outline sane of these high- resolution e-beam lithography techniques.We first consider parameters of the exposure process that limit resolution in organic resists. For concreteness suppose that we have a “positive” resist in which exposing electrons break bonds in the resist molecules thus increasing the exposed resist's solubility in a developer. Ihe attainable resolution is obviously limited by the overall width of the exposing beam, but the spatial distribution of the beam intensity, the beam “profile” , also contributes to the resolution. Depending on the local electron dose, more or less resist bonds are broken resulting in slower or faster dissolution in the developer.

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