Observations and Implications of Diurnal Climatology and Trends in Direct and Diffuse Solar Radiation Over China

Author(s):
Wang, Y.; Zhang, J.; Trentmann, J.; Fiedler, S.; Yang, S.; Sanchez-Lorenzo, A.; Tanaka, K.; Yuan, W.; Wild, M.
Publication title: Journal of Geophysical Research: Atmospheres
2022
 | Volume: 127 | Issue: 15
2022
DOI: 10.1029/2022JD036769
Abstract:
Solar radiation received at the Earth's surface (Rs) is comprised of two components, the direct radiation (Rd) and the diffuse radiation (Rf). Rd, the… Solar radiation received at the Earth's surface (Rs) is comprised of two components, the direct radiation (Rd) and the diffuse radiation (Rf). Rd, the direct beam from the sun, is essential for concentrated solar power generation. Rf, scattered by atmospheric molecules, aerosols, or cloud droplets, has a fertilization effect on plant photosynthesis. But how Rd and Rf change diurnally is largely unknown owing to the lack of long-term measurements. Taking advantage of 22 years of homogeneous hourly surface observations over China, this study documents the climatological means and evolutions in the diurnal cycles of Rd and Rf since 1993, with an emphasis on their implications for solar power and agricultural production. Over the solar energy resource region, we observe a loss of Rd which is relatively large near sunrise and sunset at low solar elevation angles when the sunrays pass through the atmosphere on a longer pathway. However, the concentrated Rd energy covering an average 10-hr period around noon during a day is relatively unaffected. Over the agricultural crop resource region, the large amounts of clouds and aerosols scattering more of the incoming light result in Rf taking the main proportion of Rs during the whole day. Rf resources and their fertilization effect in the main crop region of China further enhances since 1993 over almost all hours of the day. © 2022. American Geophysical Union. All Rights Reserved. more
Application Atmosphere CM-SAF Climate Data Records

Observations for Reanalyses

Author(s):
Brönnimann, Stefan; Allan, Rob; Atkinson, Christopher; Buizza, Roberto; Bulygina, Olga; Dahlgren, Per; Dee, Dick; Dunn, Robert; Gomes, Pedro; John, Viju O.; Jourdain, Sylvie; Haimberger, Leopold; Hersbach, Hans; Kennedy, John; Poli, Paul; Pulliainen, Jouni; Rayner, Nick; Saunders, Roger; Schulz, Jörg; Sterin, Alexander; Stickler, Alexander; Titchner, Holly; Valente, Maria Antonia; Ventura, Clara; Wilkinson, Clive
Publication title: Bulletin of the American Meteorological Society
2018
 | Volume: 99 | Issue: 9
2018
DOI: 10.1175/BAMS-D-17-0229.1
Abstract:
Abstract Global dynamical reanalyses of the atmosphere and ocean fundamentally rely on observations, not just for the assimilation (i.e., for the defi… Abstract Global dynamical reanalyses of the atmosphere and ocean fundamentally rely on observations, not just for the assimilation (i.e., for the definition of the state of the Earth system components) but also in many other steps along the production chain. Observations are used to constrain the model boundary conditions, for the calibration or uncertainty determination of other observations, and for the evaluation of data products. This requires major efforts, including data rescue (for historical observations), data management (including metadatabases), compilation and quality control, and error estimation. The work on observations ideally occurs one cycle ahead of the generation cycle of reanalyses, allowing the reanalyses to make full use of it. In this paper we describe the activities within ERA-CLIM2, which range from surface, upper-air, and Southern Ocean data rescue to satellite data recalibration and from the generation of snow-cover products to the development of a global station data metadatabase. The project has not produced new data collections. Rather, the data generated has fed into global repositories and will serve future reanalysis projects. The continuation of this effort is first contingent upon the organization of data rescue and also upon a series of targeted research activities to address newly identified in situ and satellite records. more
Application EUM-Secr International cooperation Validation

Observed and CMIP5-Simulated Radiative Flux Variability Over West Africa

Author(s):
Mackie, A.; Wild, M.; Brindley, H.; Folini, D.; Palmer, P.I.
Publication title: Earth and Space Science
2020
 | Volume: 7 | Issue: 5
2020
DOI: 10.1029/2019EA001017
Abstract:
We explore the ability of general circulation models in the Coupled Model Intercomparison Project (CMIP5) to recreate observed seasonal variability in… We explore the ability of general circulation models in the Coupled Model Intercomparison Project (CMIP5) to recreate observed seasonal variability in top-of-the-atmosphere and surface radiation fluxes over West Africa. This tests CMIP5 models' ability to describe the radiative energy partitioning, which is fundamental to our understanding of the current climate and its future changes. We use 15 years of the monthly Clouds and the Earth's Radiant Energy System Energy Balanced and Filled (EBAF) product, alongside other satellite, reanalysis, and surface station products. We find that the CMIP5 multimodel mean is generally within the reference product range, with annual mean CMIP5 multimodel mean—EBAF of −0.5 W m−2 for top-of-the-atmosphere reflected shortwave radiation, and 4.6 W m−2 in outgoing longwave radiation over West Africa. However, the range in annual mean of the model seasonal cycles is large (37.2 and 34.0 W m−2 for reflected shortwave radiation and outgoing longwave radiation, respectively). We use seasonal and regional contrasts in all-sky fluxes to infer that the representation of the West African monsoon in numerical models affects radiative energy partitioning. Using clear-sky surface fluxes, we find that the models tend to have more downwelling shortwave and less downwelling longwave radiation than EBAF, consistent with past research. We find models that are drier and have lower aerosol loading tend to show the largest differences. We find evidence that aerosol variability has a larger effect in modulating downwelling shortwave radiation than water vapor in EBAF, while the opposite effect is seen in the majority of CMIP5 models. ©2020. The Authors. more
Application Atmosphere CM-SAF Climate Data Records

Observed Temperature Changes in the Troposphere and Stratosphere from 1979 to 2018

Author(s):
Steiner, A. K.; Ladstädter, F.; Randel, W. J.; Maycock, A. C.; Fu, Q.; Claud, C.; Gleisner, H.; Haimberger, L.; Ho, S.-P.; Keckhut, P.; Leblanc, T.; Mears, C.; Polvani, L. M.; Santer, B. D.; Schmidt, T.; Sofieva, V.; Wing, R.; Zou, C.-Z.
Publication title: Journal of Climate
2020
 | Volume: 33 | Issue: 19
2020
DOI: 10.1175/JCLI-D-19-0998.1
Abstract:
Abstract Temperature observations of the upper-air atmosphere are now available for more than 40 years from both ground- and satellite-bas… Abstract Temperature observations of the upper-air atmosphere are now available for more than 40 years from both ground- and satellite-based observing systems. Recent years have seen substantial improvements in reducing long-standing discrepancies among datasets through major reprocessing efforts. The advent of radio occultation (RO) observations in 2001 has led to further improvements in vertically resolved temperature measurements, enabling a detailed analysis of upper-troposphere/lower-stratosphere trends. This paper presents the current state of atmospheric temperature trends from the latest available observational records. We analyze observations from merged operational satellite measurements, radiosondes, lidars, and RO, spanning a vertical range from the lower troposphere to the upper stratosphere. The focus is on assessing climate trends and on identifying the degree of consistency among the observational systems. The results show a robust cooling of the stratosphere of about 1–3 K, and a robust warming of the troposphere of about 0.6–0.8 K over the last four decades (1979–2018). Consistent results are found between the satellite-based layer-average temperatures and vertically resolved radiosonde records. The overall latitude–altitude trend patterns are consistent between RO and radiosonde records. Significant warming of the troposphere is evident in the RO measurements available after 2001, with trends of 0.25–0.35 K per decade. Amplified warming in the tropical upper-troposphere compared to surface trends for 2002–18 is found based on RO and radiosonde records, in approximate agreement with moist adiabatic lapse rate theory. The consistency of trend results from the latest upper-air datasets will help to improve understanding of climate changes and their drivers. more
Application Atmosphere Climate Data Records ROM-SAF

Offline Correction of CMIP6 HighResMIP Simulated Surface Solar Irradiance With 3D Sub-Grid Terrain Radiative Effects

Author(s):
Gu, C.; Huang, A.; Li, X.; Wu, Y.
Publication title: Geophysical Research Letters
2024
 | Volume: 51 | Issue: 10
2024
DOI: 10.1029/2023GL107737
Abstract:
The surface solar irradiance (SSI) is crucial for the land-atmosphere processes and remarkably affected by the topography over the rugged areas. Howev… The surface solar irradiance (SSI) is crucial for the land-atmosphere processes and remarkably affected by the topography over the rugged areas. However, the Coupled Model Intercomparison Project Phase 6 (CMIP6) HighResMIP models adopting the parallel-plane radiative scheme without considering the sub-grid terrain solar radiative effects (3DSTSRE) overestimate the SSI in the rugged areas and the overestimation increases with the sub-grid terrain complexity. To reduce the biases of the SSI simulations, this study offline corrects the SSI simulations of CMIP6 HighResMIP models by a 3DSTSRE scheme. Results show that the SSI biases produced by the HighResMIP models in the rugged regions can be significantly reduced by adopting the 3DSTSRE offline correction, and the improvements increase with the sub-grid terrain complexity, indicating that considering the 3DSTSRE in the climate models to improve the SSI simulations over rugged areas is necessary. © 2024. The Author(s). more
Application Atmosphere CM-SAF Climate Data Records Validation

Observing the evolution of summer melt on multiyear sea ice with ICESat-2 and Sentinel-2

Author(s):
Buckley, E.M.; Farrell, S.L.; Herzfeld, U.C.; Webster, M.A.; Trantow, T.; Baney, O.N.; Duncan, K.A.; Han, H.; Lawson, M.
Publication title: Cryosphere
2023
 | Volume: 17 | Issue: 9
2023
DOI: 10.5194/tc-17-3695-2023
Abstract:
We investigate sea ice conditions during the 2020 melt season, when warm air temperature anomalies in spring led to early melt onset, an extended melt… We investigate sea ice conditions during the 2020 melt season, when warm air temperature anomalies in spring led to early melt onset, an extended melt season, and the second-lowest September minimum Arctic ice extent observed. We focus on the region of the most persistent ice cover and examine melt pond depth retrieved from Ice, Cloud, and land Elevation Satellite-2 (ICESat-2) using two distinct algorithms in concert with a time series of melt pond fraction and ice concentration derived from Sentinel-2 imagery to obtain insights about the melting ice surface in three dimensions. We find the melt pond fraction derived from Sentinel-2 in the study region increased rapidly in June, with the mean melt pond fraction peaking at 16 % ± 6 % on 24 June 2020, followed by a slow decrease to 8 % ± 6 % by 3 July, and remained below 10 % for the remainder of the season through 15 September. Sea ice concentration was consistently high (>95 %) at the beginning of the melt season until 4 July, and as floes disintegrated, it decreased to a minimum of 70 % on 30 July and then became more variable, ranging from 75 % to 90 % for the remainder of the melt season. Pond depth increased steadily from a median depth of 0.40 m ± 0.17 m in early June and peaked at 0.97 m ± 0.51 m on 16 July, even as melt pond fraction had already started to decrease. Our results demonstrate that by combining high-resolution passive and active remote sensing we now have the ability to track evolving melt conditions and observe changes in the sea ice cover throughout the summer season. © Copyright: more
Application Climate Data Records Cryosphere OSI-SAF Ocean

Oceanic cloud trends during the satellite era and their radiative signatures

Author(s):
Tselioudis, George; Rossow, William B.; Bender, Frida; Oreopoulos, Lazaros; Remillard, Jasmine
Publication title: Climate Dynamics
2024
 | Volume: 62 | Issue: 9
2024
DOI: 10.1007/s00382-024-07396-8
Abstract:
The present study analyzes zonal mean cloud and radiation trends over the global oceans for the past 35 years from a suite of satellite datasets cover… The present study analyzes zonal mean cloud and radiation trends over the global oceans for the past 35 years from a suite of satellite datasets covering two periods. In the longer period (1984–2018) cloud properties come from the ISCCP-H, CLARA-A3, and PATMOS-x datasets and radiative properties from the ISCCP-FH dataset, while for the shorter period (2000–2018) cloud data from MODIS and CloudSat/CALIPSO and radiative fluxes from CERES-EBAF are added. Zonal mean total cloud cover (TCC) trend plots show an expansion of the subtropical dry zone, a poleward displacement of the midlatitude storm zone and a narrowing of the tropical intertropical convergence zone (ITCZ) region over the 1984–2018 period. This expansion of the ‘low cloud cover curtain’ and the contraction of the ITCZ rearrange the boundaries and extents of all major climate zones, producing a more poleward and narrower midlatitude storm zone and a wider subtropical zone. Zonal mean oceanic cloud cover trends are examined for three latitude zones, two poleward of 50 ° and one bounded within 50oS and 50oN, and show upward or near-zero cloud cover trends in the high latitude zones and consistent downward trends in the low latitude zone. The latter dominate in the global average resulting in TCC decreases that range from 0.72% per decade to 0.17% per decade depending on dataset and period. These contrasting cloud cover changes between the high and low latitude zones produce contrasting low latitude cloud radiative warming and high latitude cloud radiative cooling effects, present in both the ISCCP-FH and CERES-EBAF datasets. The global ocean mean trend of the short wave cloud radiative effect (SWCRE) depends on the balance between these contrasting trends, which in the CERES dataset materializes as a SW cloud radiative warming trend of 0.12 W/m2/decade coming from the dominance of the low-latitude positive SWCRE trends while in the ISCCP-FH dataset it manifests as a 0.3 W/m2/decade SW cloud radiative cooling trend coming from the dominance of the high latitude negative SWCRE trends. The CERES cloud radiative warming trend doubles in magnitude to 0.24 W/m2/decade when the period is extended from 2016 to 2022, implying a strong cloud radiative heating in the past 6 years coming from the low latitude zone. more
Atmosphere CM-SAF Climate Data Records Validation

On the Accuracy of Vaisala RS41 versus RS92 Upper-Air Temperature Observations

Author(s):
Sun, Bomin; Reale, Tony; Schroeder, Steven; Pettey, Michael; Smith, Ryan
Publication title: Journal of Atmospheric and Oceanic Technology
2019
 | Volume: 36 | Issue: 4
2019
DOI: 10.1175/JTECH-D-18-0081.1
Abstract:
The accuracy of Vaisala RS92 versus RS41 global radiosonde soundings, emphasizing stratospheric temperature, is assessed from January 2015 to June 201… The accuracy of Vaisala RS92 versus RS41 global radiosonde soundings, emphasizing stratospheric temperature, is assessed from January 2015 to June 2017 using ~311 500 RS92 and ~65 800 RS41 profiles and three different reference data sources. First, numerical weather prediction (NWP) model outputs are used as a transfer medium to produce relative RS92 and RS41 comparisons by analyzing observation minus NWP model background (OB–BG) and observation minus analysis (OB–AN) differences using the NOAA Climate Forecast System Reanalysis (CFSR; both comparisons) and the operational European Centre for Medium-Range Weather Forecasts (ECMWF) model (OB–AN comparison only). Second, GPS radio occultation (GPSRO) dry temperature profiles are directly compared with radiosondes, using GPSRO data from the University Corporation for Atmospheric Research (UCAR) Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) and EUMETSAT Radio Occultation Meteorology (ROM) Satellite Application Facility (SAF). Third, dual launches (RS92 and RS41 suspended from the same balloon) at five sites allow direct assessments. Comparisons of RS92 versus RS41 from all reference data sources are basically consistent. These two sondes agree well with global average temperature differences more
Application Atmosphere Climate Data Records ROM-SAF

On the determination of coherent solar climates over a tropical island with a complex topography

Author(s):
Mialhe, Pauline; Pohl, Benjamin; Morel, Béatrice; Trentmann, Jörg; Jumaux, Guillaume; Bonnardot, François; Bessafi, Miloud; Chabriat, Jean-Pierre
Publication title: Solar Energy
2020
 | Volume: 206
2020
DOI: 10.1016/j.solener.2020.04.049
Abstract:
Many tropical islands aim at developing a greener self-sufficient energy production systems based on renewable energy, notably solar-generated electri… Many tropical islands aim at developing a greener self-sufficient energy production systems based on renewable energy, notably solar-generated electricity. This work explores the mean diurnal and annual solar cycles over La Réunion island (southwest Indian Ocean: 21°S, 55.5°E), and their spatial behavior, using the Solar surfAce RAdiation Heliosat – East (SARAH-E) satellite-derived data at high spatial (0.05°×0.05°) and time (hourly) resolutions over period 1999–2016. Comparisons of the SARAH-E data with ground-based measurements over the period 2011–2015 show differences of ~15% for diurnal-seasonal variations. The solar resource over the island displays strong spatial variability, with differences larger than 100 Wm-2 between coastal and mountainous zones. The mean solar resource is lower on the island than on the nearby sea by ~20%. The strongest interactions between the diurnal and annual cycles are found at the windward mid-slopes and near the active volcano, in line with the well-known cloud processes encountered there. A clustering of solar zones, based on diurnal-seasonal cycles, structures the island into a dipole that opposes the western to the eastern side of the island. more
Application Atmosphere CM-SAF Climate Data Records

On the land-sea contrast in the surface solar radiation (Ssr) in the baltic region

Author(s):
Lindfors, A.V.; Hertsberg, A.; Riihelä, A.; Carlund, T.; Trentmann, J.; Müller, R.
Publication title: Remote Sensing
2020
 | Volume: 12 | Issue: 21
2020
DOI: 10.3390/rs12213509
Abstract:
The climatological surface solar radiation (SSR; also called global radiation), which is largely dependent on cloud conditions, is an important indica… The climatological surface solar radiation (SSR; also called global radiation), which is largely dependent on cloud conditions, is an important indicator of the solar energy production potential. In the Baltic area, previous studies have indicated lower cloud amounts over seas than over land, in particular during the summer. However, the existing literature on the SSR climate or how it translates into solar energy potential has not paid much attention to how the SSR behaves quantitatively in relation to the coastline. In this paper, we have studied the climatological land–sea contrast of the SSR over the Baltic area. For this, we used two satellite climate data records, CLARA-A2 and SARAH-2, together with a coastline data base and ground-based pyranometer measurements of the SSR. We analyzed the behaviour of the climatological mean SSR over the period 2003–2013 as a function of the distance to the coastline. The results show that off-shore locations on average receive higher SSR than inland areas and that the land–sea contrast in the SSR is strongest during the summer. Furthermore, the land–sea contrast in the summer time SSR exhibits similar behavior in various parts of the Baltic. For CLARA-A2, which shows better agreement with the ground-based measurements than SARAH-2, the annual SSR is 8% higher 20 km off the coastline than 20 km inland. For summer, i.e., June–August, this difference is 10%. The observed land–sea contrast in the SSR is further shown to correspond closely to the behavior of clouds. Here, convective clouds play an important role as they tend to form over inland areas rather than over the seas during the summer part of the year. © 2020 by the authors. Licensee MDPI, Basel, Switzerland. more
Application Atmosphere CM-SAF Climate Data Records Validation
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