Forward operator for polarimetric radio occultation measurements

Author(s):
Hotta, D.; Lonitz, K.; Healy, S.
Publication title: Atmospheric Measurement Techniques
2024
 | Volume: 17 | Issue: 3
2024
DOI: 10.5194/amt-17-1075-2024
Abstract:
Global Navigation Satellite System (GNSS) polarimetric radio occultation (PRO) observations sense the presence of hydrometeor particles along the ray … Global Navigation Satellite System (GNSS) polarimetric radio occultation (PRO) observations sense the presence of hydrometeor particles along the ray path by measuring the difference of excess phases in horizontally and vertically polarised carrier waves. As a first step towards using these observations in data assimilation and model diagnostics, a forward operator for the GNSS-PRO observable φDP (polarimetric differential phase shift) has been implemented by extending the existing two-dimensional forward operator for radio occultation bending-angle observations. Evaluation of heavy-precipitation cases showed that the implemented forward operator can simulate the observed φDP in synoptic-scale atmospheric river (AR) cases very accurately. For tropical cyclone cases it is more challenging to produce reasonable φDP simulations, due to the high sensitivity of φDP with respect to displacement of the position of the tropical cyclones. It was also found that snow is the dominant contributor to the simulated φDP and that the ability to compute the ray paths in two dimensions is essential to accurately simulate φDP. © Copyright: more
Application Atmosphere NWP-SAF Software for CDR development

From Internal Variability to Aerosol Effects: Physical Mechanisms Behind Observed Decadal Trends in Surface Solar Radiation in the Western Pacific Ocean

Author(s):
Correa, L.F.; Folini, D.; Chtirkova, B.; Wild, M.
Publication title: Journal of Geophysical Research: Atmospheres
2024
 | Volume: 129 | Issue: 18
2024
DOI: 10.1029/2024JD041014
Abstract:
The Pacific Ocean, spanning over 30% of the Earth's surface, provides an ideal setting for studying the surface radiative balance due to its relativel… The Pacific Ocean, spanning over 30% of the Earth's surface, provides an ideal setting for studying the surface radiative balance due to its relatively pristine atmospheric conditions, far from anthropogenic emission sources. In this study we investigated the causes for the decadal trends of surface solar radiation (SSR) observed at eight stations scattered across seven islands in the Western Pacific Ocean, and extrapolated the results to the whole Western Pacific region based on the understanding of physical processes. Our results show a contrast between the causes for SSR trends in the northwestern and in the southwestern Pacific. In the Southwestern Pacific region, changes in cloud cover play a major role in the SSR decadal trends and interannual variability. The cloud cover in these areas is strongly associated with sea surface temperature (SST) anomalies, especially those induced by El Nino Southern Oscillation (ENSO) and the Interdecadal Pacific Oscillation (IPO). Modes of variability such as ENSO and IPO affect evaporation and convection, impacting the large-scale dynamics of the atmosphere, therefore influencing the distribution of the regions of deep convection. This consecutively impacts the cloud cover on a regional level and therefore SSR. In the Northern Hemisphere, conversely, a strong influence of these modes on cloudiness and SSR was not found. Instead, indirect evidence suggests that anthropogenic aerosol transported from Eastern Asia plays a major role in the decadal SSR trends. These results contribute to an improved understanding of the physical processes relevant for the long-term SSR trends in remote regions. © 2024 The Author(s). more
Application Atmosphere CM-SAF Climate Data Records

Four decades of global surface albedo estimates in the third edition of the CM SAF cLoud, Albedo and surface Radiation (CLARA) climate data record

Author(s):
Riihelä, A.; Jääskeläinen, E.; Kallio-Myers, V.
Publication title: Earth System Science Data
2024
 | Volume: 16 | Issue: 2
2024
DOI: 10.5194/essd-16-1007-2024
Abstract:
We present the surface albedo data in the third edition of the CM SAF cLoud, Albedo and surface Radiation (CLARA) data record family. The temporal cov… We present the surface albedo data in the third edition of the CM SAF cLoud, Albedo and surface Radiation (CLARA) data record family. The temporal coverage of this edition is extended from 1979 until the near-present day. The core algorithms and data format remain unchanged from previous editions, but now white- and blue-sky albedo estimates are also available for the first time in CLARA data. We present an overview of the retrieval, followed by an assessment of the accuracy and stability of the data record, based on collocated comparisons with reference surface albedo measurements and intercomparisons with preceding satellite-based albedo data records. Specific attention is paid to addressing the spatial representativeness problem inherent in the "point-to-pixel"validation of satellite-based coarse surface albedo estimates against in situ measurements. We find the CLARA-A3 albedo data to match or improve upon the accuracy and robustness of the predecessor record (CLARA-A2), with good agreement found when compared to in situ measurements. In cases of a large bias, the spatial representativeness of the measurement site typically explains most of the increase. We conclude with a summarizing discussion on the observed strengths and weaknesses of the new data record, including guidance for potential users. The data are available at 10.5676/EUM_SAF_CM/CLARA_AVHRR/V003 (Karlsson et al., 2023b). © Copyright: more
CM-SAF Climate Data Records Land Validation

Generation of Typical Meteorological Sequences to Simulate Growth and Production of Biological Systems

Author(s):
Wane, Ousmane; Zarzalejo, Luis F.; Ferrera-Cobos, Francisco; Navarro, Ana A.; Rodríguez-López, Alberto; Valenzuela, Rita X.
Publication title: Applied Sciences
2023
 | Volume: 13 | Issue: 8
2023
DOI: 10.3390/app13084826
Abstract:
Numerical simulation applied to agriculture or wastewater treatment (WWT) is a complementary tool to understand, a priori, the impact of meteorologica… Numerical simulation applied to agriculture or wastewater treatment (WWT) is a complementary tool to understand, a priori, the impact of meteorological parameters on productivity under limiting environmental conditions or even to guide investments towards other more relevant circular economic objectives. This work proposes a new methodology to calculate Typical Meteorological Sequences (TMS) that could be used as input data to simulate the growth and productivity of photosynthetic organisms in different biological systems, such as a High-Rate Algae Pond (HRAP) for WWT or in agriculture for crops. The TMS was established by applying Finkelstein-Schafer statistics and represents the most likely meteorological sequence in the long term for each meteorological season. In our case study, 18 locations in the Madrid (Spain) region are estimated depending on climate conditions represented by solar irradiance and temperature. The parameters selected for generating TMS were photosynthetically active radiation, solar day length, maximum, minimum, mean, and temperature range. The selection of potential sequences according to the growth period of the organism is performed by resampling the available meteorological data, which, in this case study, increases the number of candidate sequences by 700%. more
Application Atmosphere CM-SAF Climate Data Records

Global and Regional Evaluation of the CERES Edition-4A Surface Solar Radiation and Its Uncertainty Quantification

Author(s):
Zhang, Ke; Zhao, Long; Tang, Wenjun; Yang, Kun; Wang, Jing
Publication title: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
2022
 | Volume: 15
2022
DOI: 10.1109/JSTARS.2022.3164471
Abstract:
This article presents a comprehensive evaluation of the 2000–2018 Clouds and Earth's Radiant Energy System Synoptic 1° Ed4A (CERES SYN1deg Edition 4A)… This article presents a comprehensive evaluation of the 2000–2018 Clouds and Earth's Radiant Energy System Synoptic 1° Ed4A (CERES SYN1deg Edition 4A) surface solar radiation (SSR) product. In particular, the global assessment is conducted over different temporal scales (i.e., hourly, daily, and monthly-average) with special attention given to the impact of clouds, and a regional evaluation is further implemented over the Mainland of China (MC) using SSR measurements from a denser observational network provided by the China Meteorological Administration. Evaluation across all valid station-grid pairs yields mixed performance with |MBE|≤2.8 (6.2) W m−2, RMSE≤89.5 (31.6) W m−2, and R≥0.95 (0.93) over the globe (MC) for different temporal scales, and the monthly CERES SSR, with RMSE≤20 W m−2, is found to hold promise for global numerical weather prediction and climate monitoring. In addition, CERES is found to generally underestimate and overestimate SSR over land and ocean, respectively. Comparison between year-round and cloudy-season suggests that the presence of clouds may potentially impact the SSR retrievals, especially at the hourly temporal scales, with an increase in RMSE values larger than 10 W m−2 for most stations. Further investigation of subgrid heterogeneity suggests that most in situ SSR measurements can reasonably represent the 1° grid average except for some stations with specific geographic deployments, which may raise significant spatial representativeness issues and, therefore, need to be used with great caution. more
Application Atmosphere CM-SAF Climate Data Records Validation

Global evaluation of fast radiative transfer model coefficients for early meteorological satellite sensors

Author(s):
Silveira, B.B.; Turner, E.C.; Vidot, J.
Publication title: Atmospheric Measurement Techniques
2024
 | Volume: 17 | Issue: 4
2024
DOI: 10.5194/amt-17-1279-2024
Abstract:
RTTOV (the Radiative Transfer for TOVS code, where TOVS is the TIROS Operational Vertical Sounder) coefficients are evaluated using a large, independe… RTTOV (the Radiative Transfer for TOVS code, where TOVS is the TIROS Operational Vertical Sounder) coefficients are evaluated using a large, independent dataset of 25000 atmospheric model profiles as a robust test of the diverse 83 training profiles typically used. The study is carried out for nine historical satellite instruments: the InfraRed Interferometer Spectrometer D (IRIS-D), Satellite Infrared Spectrometer B (SIRS-B), Medium Resolution Infrared Radiometer (MRIR) and High Resolution Infrared Radiometer (HRIR) for the infrared part of the spectrum, and the Microwave Sounding Unit (MSU), Special Sensor Microwave Imager (SSM/I), Special Sensor Microwave - Humidity (SSM/T-2), Scanning Multichannel Microwave Radiometer (SMMR) and Special Sensor Microwave Imager/Sounder (SSMI/S) for the microwave. Simulated channel brightness temperatures show similar statistics for both the independent and the 83-profile datasets, confirming that it is acceptable to validate the RTTOV coefficients with the same profiles used to generate the coefficients. Differences between the RTTOV and the line-by-line models are highest in water vapour channels, where mean values can reach up to 0.4±0.2K for the infrared and 0.04±0.13K for the microwave. Examination of the latitudinal dependence of the bias reveals different patterns of variability for similar channels on different instruments, such as the channel centred at 679cm-1 on both IRIS-D and SIRS-B, showing the importance of the specification of the instrumental spectral response functions (ISRFs). Maximum differences of up to several kelvin are associated with extremely non-typical profiles, such as those in polar or very hot regions. © Copyright: more
Atmosphere NWP-SAF Software for CDR development Validation

Global Cloudiness and Cloud Top Information from AVHRR in the 42-Year CLARA-A3 Climate Data Record Covering the Period 1979–2020

Author(s):
Karlsson, Karl-Göran; Devasthale, Abhay; Eliasson, Salomon
Publication title: Remote Sensing
2023
 | Volume: 15 | Issue: 12
2023
DOI: 10.3390/rs15123044
Abstract:
This paper investigates the quality of global cloud fraction and cloud-top height products provided by the third edition of the CM SAF cLoud, Albedo a… This paper investigates the quality of global cloud fraction and cloud-top height products provided by the third edition of the CM SAF cLoud, Albedo and surface RAdiation dataset from the AVHRR data (CLARA-A3) climate data record (CDR) produced by the EUMETSAT Climate Monitoring Satellite Application Facility (CM SAF). Compared with with CALIPSO–CALIOP cloud lidar data and six other cloud CDRs, including the predecessor CLARA-A2, CLARA-A3 has improved cloud detection, especially over ocean surfaces, and improved geographical variation and cloud detection efficiency. In addition, CLARA-A3 exhibits remarkable improvements in the accuracy of its global cloud-top height measurements. For example, in tropical regions, previous underestimations for high-level clouds are reduced by more than 2 km. By taking advantage of more realistic descriptions of global cloudiness, this study attempted to estimate trends in the observable fraction of low-level clouds, acknowledging their importance in producing a net climate cooling effect. The results were generally inconclusive in the tropics, mainly due to the interference of El Nino modes during the period under study. However, the analysis found small negative trends over oceanic surfaces outside the core tropical region. Further studies are needed to verify the significance of these results. more
Atmosphere CM-SAF Climate Data Records Validation

Global long-term monitoring of the ozone layer – a prerequisite for predictions

Author(s):
Loyola, D. G.; Coldewey-Egbers, R. M.; Dameris, M.; Garny, H.; Stenke, A.; Van Roozendael, M.; Lerot, C.; Balis, D.; Koukouli, M.
Publication title: International Journal of Remote Sensing
2009
 | Volume: 30 | Issue: 15-16
2009
DOI: 10.1080/01431160902825016
Abstract:
Although the Montreal Protocol now controls the production and emission of ozone depleting substances, the timing of ozone recovery is unclear. There … Although the Montreal Protocol now controls the production and emission of ozone depleting substances, the timing of ozone recovery is unclear. There are many other factors affecting the ozone layer, in particular climate change is expected to modify the speed of re-creation of the ozone layer. Therefore, long-term observations are needed to monitor the further evolution of the stratospheric ozone layer. Measurements from satellite instruments provide global coverage and are supplementary to selective ground-based observations. The combination of data derived from different space-borne instruments is needed to produce homogeneous and consistent long-term data records. They are required for robust investigations including trend analysis. For the first time global total ozone columns from three European satellite sensors GOME (ERS-2), SCIAMACHY (ENVISAT), and GOME-2 (METOP-A) are combined and added up to a continuous time series starting in June 1995. On the one hand it is important to monitor the consequences of the Montreal Protocol and its amendments; on the other hand multi-year observations provide the basis for the evaluation of numerical models describing atmospheric processes, which are also used for prognostic studies to assess the future development. This paper gives some examples of how to use satellite data products to evaluate model results with respective data derived from observations, and to disclose the abilities and deficiencies of atmospheric models. In particular, multi-year mean values derived from the Chemistry-Climate Model E39C-A are used to check climatological values and the respective standard deviations. more
AC-SAF Atmosphere Climate Data Records Validation

Global Ozone Monitoring Experiment-2 (GOME-2) daily and monthly level-3 products of atmospheric trace gas columns

Author(s):
Chan, K.L.; Valks, P.; Heue, K.-P.; Lutz, R.; Hedelt, P.; Loyola, D.; Pinardi, G.; Van Roozendael, M.; Hendrick, F.; Wagner, T.; Kumar, V.; Bais, A.; Piters, A.; Irie, H.; Takashima, H.; Kanaya, Y.; Choi, Y.; Park, K.; Chong, J.; Cede, A.; Frieß, U.; Richter, A.; Ma, J.; Benavent, N.; Holla, R.; Postylyakov, O.; Rivera Cárdenas, C.; Wenig, M.
Publication title: Earth System Science Data
2023
 | Volume: 15 | Issue: 4
2023
DOI: 10.5194/essd-15-1831-2023
Abstract:
We introduce the new Global Ozone Monitoring Experiment-2 (GOME-2) daily and monthly level-3 product of total column ozone (O3), total and tropospheri… We introduce the new Global Ozone Monitoring Experiment-2 (GOME-2) daily and monthly level-3 product of total column ozone (O3), total and tropospheric column nitrogen dioxide (NO2), total column water vapour, total column bromine oxide (BrO), total column formaldehyde (HCHO), and total column sulfur dioxide (SO2) (daily products 10.15770/EUM-SAF-AC-0048, ; monthly products 10.15770/EUM-SAF-AC-0049, ). The GOME-2 level-3 products aim to provide easily translatable and user-friendly data sets to the scientific community for scientific progress as well as to satisfy public interest. The purpose of this paper is to present the theoretical basis as well as the verification and validation of the GOME-2 daily and monthly level-3 products. The GOME-2 level-3 products are produced using the overlapping area-weighting method. Details of the gridding algorithm are presented. The spatial resolution of the GOME-2 level-3 products is selected based on the sensitivity study. The consistency of the resulting level-3 products among three GOME-2 sensors is investigated through time series of global averages, zonal averages, and bias. The accuracy of the products is validated by comparison to ground-based observations. The verification and validation results show that the GOME-2 level-3 products are consistent with the level-2 data. Small discrepancies are found among three GOME-2 sensors, which are mainly caused by the differences in the instrument characteristic and level-2 processor. The comparison of GOME-2 level-3 products to ground-based observations in general shows very good agreement, indicating that the products are consistent and fulfil the requirements to serve the scientific community and general public. © Copyright: more
AC-SAF Atmosphere Climate Data Records Validation

Global scale error assessments of soil moisture estimates from microwave-based active and passive satellites and land surface models over forest and mixed irrigated/dryland agriculture regions

Author(s):
Kim, Hyunglok; Wigneron, Jean-Pierre; Kumar, Sujay; Dong, Jianzhi; Wagner, Wolfgang; Cosh, Michael H.; Bosch, David D.; Collins, Chandra Holifield; Starks, Patrick J.; Seyfried, Mark; Lakshmi, Venkataraman
Publication title: Remote Sensing of Environment
2020
 | Volume: 251
2020
DOI: 10.1016/j.rse.2020.112052
Abstract:
Over the past four decades, satellite systems and land surface models have been used to estimate global-scale surface soil moisture (SSM). However, in… Over the past four decades, satellite systems and land surface models have been used to estimate global-scale surface soil moisture (SSM). However, in areas such as densely vegetated and irrigated regions, obtaining accurate SSM remains challenging. Before using satellite and model-based SSM estimates over these areas, we should understand the accuracy and error characteristics of various SSM products. Thus, this study aimed to compare the error characteristics of global-scale SSM over vegetated and irrigated areas as obtained from active and passive satellites and model-based data: Advanced Scatterometer (ASCAT), Soil Moisture and Ocean Salinity (SMOS), Advanced Microwave Scanning Radiometer 2 (AMSR2), Soil Moisture Active Passive (SMAP), European Centre for Medium-Range Weather Forecasts Reanalysis 5 (ERA5), and Global Land Data Assimilation System (GLDAS). We employed triple collocation analysis (TCA) and caluclated conventional error metrics from in-situ SSM measurements. We also considered all possible triplets from 6 different products and showed the viability of considering the standard deviation of TCA-based numbers in producing robust results. Over forested areas, it was expected that model-based SSM data might provide more accurate SSM estimates than satellites due to the intrinsic limitations of microwave-based systems. Alternately, over irrigated regions, observation-based SSM data were expected to be more accurate than model-based products because land surface models (LSMs) cannot capture irrigation signals caused by human activities. Contrary to these expectations, satellite-based SSM estimates from ASCAT, SMAP, and SMOS showed fewer errors than ERA5 and GLDAS SSM products over vegetated conditions. Furthermore, over irrigated areas, ASCAT, SMOS, and SMAP outperformed other SSM products; however, model-based data from ERA5 and GLDAS outperformed AMSR2. Our results emphasize that, over irrgated areas, considering satellite-based SSM data as alternatives to model-based SSM data sometimes produces misleading results; and considering model-based data as alternatives to satellite-based SSM data in forested areas can also sometimes be misleading. In addition, we discovered that no products showed much degradation in TCA-based errors under different vegetated conditions, while different irrigation conditions impacted both satellite and model-based SSM data sets. The present research demonstrates that limitations in satellite and modeled SSM data can be overcome in many areas through the synergistic use of satellite and model-based SSM products, excluding areas where satellite-based data are masked out. In fact, when four satellite and model data sets are used selectively, the probability of obtaining SSM with stronger signal than noise can be close to 100%. more
Climate Data Records H-SAF Land Validation
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