Quality assessment of heterogeneous surface radiation network data

Abstract. The DWD national radiation measurement network comprises 82 automatic sites, 29 manned sites with shaded and unshaded pyranometer and the BSRN station at Lindenberg. The quality assessment routinely applied takes into account the basic astronomical and empirical considerations as well as some interdependencies like total to diffuse flux relation and cross checking with sunshine duration. A more advanced quality assessment approach attempts to routinely utilise timeseries of clear sky radiative transfer simulations for every site. For that purpose a link to cloud coverage obtained from Meteosat second generation geostationary satellite data, highly resolved in time and space, was established. There is a predefined calibration cycle of 30 month for automatic stations. Data analysis on this timescale allows for the detection of sensor degradation, wrong calibration or configuration and other possible local disturbances. Furthermore using satellite cloud mask enables the identification of larger clear sky regions characterized by similar atmospheric conditions. Thus, in a regionalization step correction or recalibration of moderate quality data to a higher level can be considered. The paper provides an overview of DWD surface radiation network and the current activities to improve automatic quality assessment using remotely sensed data and clear sky modeling for the upgrading of radiation data.

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Quality Control of Global Horizontal Irradiance Estimates through BSRN, TOACs and Air Temperature/Sunshine Duration Test Procedures

Climate ◽

10.3390/cli6030069 ◽

2018 ◽

Vol 6 (3) ◽

pp. 69 ◽

Cited By ~ 3

Author(s):

Bikhtiyar Ameen ◽

Heiko Balzter ◽

Claire Jarvis

Keyword(s):

Air Temperature ◽

Sunshine Duration ◽

Test Method ◽

Surface Radiation ◽

Quality Data ◽

Test Procedures ◽

Climate Conditions ◽

Clear Sky ◽

Ground Measurement ◽

Operational Errors

Solar Radiation (SR) data are required for many disciplines and applications. The ground measurement of SR data is hampered by technical and operational errors. Therefore, several approaches have been developed to detect these errors. This study aimed to compare two quality tests of hourly Global Horizontal Irradiance (GHI) estimates through the Baseline Surface Radiation Network (BSRN) of the World Meteorological Organization (WMO) and Top of Atmosphere irradiance and Clear sky (TOACs) on a horizontal plane. Each of these tests has a threshold to pass data, which leads to different results. A newly developed quality test method is presented that uses Sunshine Duration (SD) and Air Temperature (AT) to check hourly GHI and is applied to data from 20 meteorological stations in northeast Iraq. The new method was validated using independent high quality data from six stations in various regions with the same climate regime. The method consists of several tests that compare ground data with upper and lower limits of radiation at the top of the atmosphere, using a clear sky radiation model and the relation between SD and AT with SR to determine data values of dubious quality. The rate of error flags generally range from 1% to 27%. The findings show that SD and AT can be used to support other quality tests and to detect nearly 2% additional dubious data values compared to BSRN and TOACs tests. The SD test tends to work like a consistency check but AT does not work like that according to the validation result. However, AT can be used to test the plausibility of data. The argument for using AT in this study may be impractical for other climate conditions. The results suggest that a combination of tests can lead to a better quality of ground data, especially when the components of SR are unviable. Using climate variables for further checks is another possibility.

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Quality assessment of integrated water vapour measurements at the St. Petersburg site, Russia: FTIR vs. MW and GPS techniques

Atmospheric Measurement Techniques ◽

10.5194/amt-10-4521-2017 ◽

2017 ◽

Vol 10 (11) ◽

pp. 4521-4536 ◽

Cited By ~ 6

Author(s):

Yana A. Virolainen ◽

Yury M. Timofeyev ◽

Vladimir S. Kostsov ◽

Dmitry V. Ionov ◽

Vladislav V. Kalinnikov ◽

...

Keyword(s):

Quality Assessment ◽

Water Vapour ◽

Measurement Errors ◽

Microwave Radiometer ◽

Reference Method ◽

Atmospheric Conditions ◽

Assessment Protocol ◽

Clear Sky ◽

Integrated Water Vapour ◽

Sky Conditions

Abstract. The cross-comparison of different techniques for atmospheric integrated water vapour (IWV) measurements is the essential part of their quality assessment protocol. We inter-compare the synchronised data sets of IWV values measured by the Bruker 125 HR Fourier-transform infrared spectrometer (FTIR), RPG-HATPRO microwave radiometer (MW), and Novatel ProPak-V3 global navigation satellite system receiver (GPS) at the St. Petersburg site between August 2014 and October 2016. As the result of accurate spatial and temporal matching of different IWV measurements, all three techniques agree well with each other except for small IWV values. We show that GPS and MW data quality depends on the atmospheric conditions; in dry atmosphere (IWV smaller than 6 mm), these techniques are less reliable at the St. Petersburg site than the FTIR method. We evaluate the upper bound of statistical measurement errors for clear-sky conditions as 0.29 ± 0.02 mm (1.6 ± 0.3 %), 0.55 ± 0.02 mm (4.7 ± 0.4 %), and 0.76 ± 0.04 mm (6.3 ± 0.8 %) for FTIR, GPS, and MW methods, respectively. We propose the use of FTIR as a reference method under clear-sky conditions since it is reliable on all scales of IWV variability.

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Retrieval and Validation of Cloud Top Temperature from the Geostationary Satellite INSAT-3D

Remote Sensing ◽

10.3390/rs11232811 ◽

2019 ◽

Vol 11 (23) ◽

pp. 2811 ◽

Cited By ~ 1

Author(s):

Lima ◽

Prijith ◽

Sesha Sai ◽

Rao ◽

Niranjan ◽

...

Keyword(s):

Geostationary Satellite ◽

Probability Of Detection ◽

Quality Data ◽

Orthogonal Polarization ◽

Cloud Detection ◽

Pixel Resolution ◽

Clear Sky ◽

Hit Rate ◽

Cloud Mask ◽

Cloud Top Temperature

Investigation of cloud top temperature (CTT) and its diurnal variation is highly reliant on high spatial and temporal resolution satellite data, which is lacking over the Indian region. An algorithm has been developed for detection of clouds and retrieval of CTT from the geostationary satellite INSAT-3D. These retrievals are validated (inter-compared) with collocated in-situ (satellite) measurements with specific intent to generate climate-quality data. The cloud detection algorithm employs nine different tests, in accordance with solar illumination, satellite angle and surface type conditions to generate pixel-resolution cloud mask. Validation of cloud mask with cloud-aerosol lidar with orthogonal polarization (CALIOP) shows that probability of detection (POD) of cloudy (clear) sky is 81% (85%), with 83% hit rate. The algorithm is also implemented on similar channels of moderate resolution imaging spectroradiometer (MODIS), which provides 88% (83%) POD of cloudy (clear) sky, with 86% hit rate. CTT retrieval is done at the pixel level, for all cloud pixels, by employing appropriate methods for various types of clouds. Comparison of CTT with radiosonde and cloud-aerosol lidar and infrared pathfinder satellite observations (CALIPSO) shows mean absolute error less than 3%. The study also examines sensitivity of retrieved CTT to the cloud classification scheme and retrieval criteria. Validation results and their close agreements with those of similar satellites demonstrate the reliability of the retrieved product for climate studies.

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Long-term series of surface solar radiation at Athens, Greece

10.5194/acp-2017-48 ◽

2017 ◽

Author(s):

Stelios Kazadzis ◽

Dimitra Founda ◽

Bill Psiloglou ◽

Haralambos Kambezidis ◽

Nikolaos Mihalopoulos ◽

...

Keyword(s):

Lower Limit ◽

Sunshine Duration ◽

Mediterranean Area ◽

Surface Radiation ◽

Linear Change ◽

Surface Solar Radiation ◽

Clear Sky ◽

Ssr Analysis ◽

The Difference

Abstract. We present a long-term series of solar surface radiation (SSR) for the city of Athens, Greece. The SSR measurements were performed from 1953 to 2012, and before that (1900–1952) sunshine duration (SD) records have been used in order to reconstruct monthly SSR. Analysis from the whole dataset (1900–2012) mainly showed: a decrease of 2.9 % per decade in SSR from 1910 to 1940 assuming a linear change in SSR. For the dimming period (1955–1980), a −2 % change per decade has been observed, that matches various European long-term SSR measurement related studies. This percentage for Athens is in the lower limit, compared to other studies for the Mediterranean area. For the brightening period (1980–2012) we have calculated a +1.5 % per decade which is also in the lower limit of the reported positive changes in SSR around Europe. Comparing the 30-year periods (1954–1983 and 1983–2012) we have found a difference of 4.5 %. The difference was observed for all seasons except winter. Using an analysis of SSR calculations of all sky and clear sky (cloudless) conditions/days, we report that most of the observed changes in SSR after 1954 can be attributed partly to cloudiness and mostly to aerosol load changes.

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Synergistic use of Imager Window observations for Cloud Clearing of Sounder Observation for INSAT-3D

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprsarchives-xl-8-315-2014 ◽

2014 ◽

Vol XL-8 ◽

pp. 315-320 ◽

Cited By ~ 2

Author(s):

J. Satapathy ◽

P. K. Thapliyal ◽

M. V. Shukla ◽

C. M. Kishtawal

Keyword(s):

Statistical Analysis ◽

High Resolution ◽

Spatial Resolution ◽

Atmospheric Temperature ◽

Indian Region ◽

Supplementary Information ◽

Atmospheric Conditions ◽

Clear Sky ◽

Fractional Cloud ◽

Cloud Mask

The retrieval of atmospheric temperature and water vapor profiles from infrared Sounder are severely limited by the presence of cloud. Therefore, retrieval from infrared sounding observations is performed only over clear-sky atmospheric conditions. The probability of finding a clear-sky pixel at spatial resolution of 10 km is found to be very small globally. This study presents a quantitative analysis of the clear-sky probability that is carried out for different months over the Indian region for INSAT-3D Sounder. The probability of a clear-sky is found to be ~7 % for the field of view of 10 km corresponding to the INSAT-3D Sounder. This statistical analysis is established using MODIS cloud mask having 95 % confidence level at 1 km resolution spread in the region between 50E–110E and 30S–30N. This necessitates cloud clearing to remove the effect of partial clouds in the Sounder FOV to provide a clear-sky equivalent sounding retrieval. Various methods were explored to derive the cloud-cleared radiances using supplementary information such as high resolution infrared or microwave observations. This study presents an effort to use the existing traditional method to derive optimal cloudcleared radiances for INSAT-3D Sounder, by estimating the fractional cloud cover using collocated high resolution INSAT-3D Imager window channel observation. The final Sounder cloud-cleared radiances have been validated with the operational AIRS L2 cloud-cleared radiance products. Nevertheless, the statistical analysis of clear-sky probability over Indian region also provides a significant insight towards the dependency of spatial resolution and the considerable field-of-regard (FOR) in obtaining the clear-sky area in the satellite observations. This, in a way, necessitates the cloud-clearing for coarser resolution sensors and at the same time, states the benefits of using very high resolution sensors. It has been observed that FOV of 1km and by choosing a reasonably good FOR can eliminate the cloudy-sky hindrances by increasing the probability of clear-sky from 5 % to 50 %.

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Radiative cooling by clouds affects the precipitation - temperature scaling derived from observations

10.5194/ems2021-108 ◽

2021 ◽

Author(s):

Sarosh Alam Ghausi ◽

Axel Kleidon ◽

Subimal Ghosh

Keyword(s):

Extreme Precipitation ◽

Surface Radiation ◽

Balance Model ◽

Atmospheric Conditions ◽

Precipitation Temperature ◽

Clear Sky ◽

Scaling Relationships ◽

Precipitation Response ◽

Temperature Scaling ◽

Precipitation Events

One direct effect of climate warming on hydrology is the increase in moisture holding capacity of atmosphere at the rate of 7%/&#176;C as suggested by the Clausius Clapeyron equation. Extreme precipitation largely depends on the amount of precipitable water in the atmospheric column and is thus expected to scale with temperature at the same rate. Observations, however, show significant variability in precipitation - temperature scaling rates, with negative scaling dominating in the tropical regions. These scaling relationships assume a one way causality, i.e. temperature is independent of precipitation. However, we show here that temperatures strongly co-vary with precipitation through the effect that clouds have on surface radiation. The presence of clouds associated with precipitation events result in lower solar isolation at the surface, further leading to reduced temperatures. This induces a two-way causality and thus temperature is no longer independent of precipitation. To remove this cooling effect of clouds, we used a surface energy balance model with a thermodynamic constraint to derive clear sky temperatures during precipitation events. We then show using observations from India, that extreme precipitation scaled with clear sky temperatures shows an increase consistent with the CC rate. On contrary, the negative scaling obtained using observed temperatures misrepresent the precipitation response to warming as a result of the co-variation with the cloud radiative effect. Our findings reveal that scaling relationships not only show how precipitation changes with temperature but also how atmospheric conditions associated with precipitation affect temperature. Thus, this covariation needs to be taken into account when using observations to derive scaling relationships that are then used to infer the extreme precipitation response to climate change.

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Estimation of Daily Mean Photosynthetically Active Radiation under All-Sky Conditions Based on Relative Sunshine Data

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-10-05018.1 ◽

2012 ◽

Vol 51 (1) ◽

pp. 150-160 ◽

Cited By ~ 22

Author(s):

Jun Qin ◽

Kun Yang ◽

Shunlin Liang ◽

Wenjun Tang

Keyword(s):

Photosynthetically Active Radiation ◽

Sunshine Duration ◽

Surface Radiation ◽

Radiation Budget ◽

Mean Bias Error ◽

Bias Error ◽

Active Radiation ◽

Clear Sky ◽

Surface Radiation Budget ◽

Sky Conditions

AbstractPhotosynthetically active radiation (PAR) is absorbed by plants to carry out photosynthesis. Its estimation is important for many applications such as ecological modeling. In this study, a broadband transmittance scheme for solar radiation at the PAR band is developed to estimate clear-sky PAR values. The influence of clouds is subsequently taken into account through sunshine-duration data. This scheme is examined without local calibration against the observed PAR values under both clear- and cloudy-sky conditions at seven widely distributed Surface Radiation Budget Network (SURFRAD) stations. The results indicate that the scheme can estimate the daily mean PAR at these seven stations under all-sky conditions with root-mean-square error and mean bias error values ranging from 6.03 to 6.83 W m−2 and from −2.86 to 1.03 W m−2, respectively. Further analyses indicate that the scheme can estimate PAR values well with globally available aerosol and ozone datasets. This suggests that the scheme can be applied to regions for which observed aerosol and ozone data are not available.

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Quality assessment of Izaña's upper-air water vapour measurement techniques: FTIR, Cimel, MFRSR, GPS, and Vaisala RS92

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-2-1625-2009 ◽

2009 ◽

Vol 2 (4) ◽

pp. 1625-1662 ◽

Cited By ~ 7

Author(s):

M. Schneider ◽

P. M. Romero ◽

F. Hase ◽

T. Blumenstock ◽

E. Cuevas ◽

...

Keyword(s):

Quality Assessment ◽

Water Vapour ◽

Measurement Techniques ◽

Precipitable Water ◽

Research Centre ◽

Atmospheric Conditions ◽

Precipitable Water Vapour ◽

Clear Sky ◽

Large Water

Abstract. At the Izaña Atmospheric Research Centre water vapour amounts are measured routinely by different techniques since many years. We intercompare the total precipitable water vapour amounts measured between 2005 and 2009 by a Fourier Transform Infrared (FTIR) spectrometer, a Multifilter rotating shadow-band radiometer (MFRSR), a Cimel sunphotometer, a Global Positioning System (GPS) receiver, and daily radiosondes (Vaisala RS92). In addition we intercompare the water vapor profiles measured by the FTIR and the radiosondes. The long-term intercomparison assures that our study well represents the large water vapour variabilities that occur in the troposphere and allows a reliable empirical quality assessment for the different water vapour dataset. We examine how the data quality of the different techniques depends on atmospheric conditions and estimate the dry bias of the techniques which are restricted to clear sky observations.

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