Studies of the radiation budget anomalies over Antarctica during 1974–1983, and their possible relationship to climatic variations

We present the results of a study of anomalies, which are defined as differences of seasonal means from the data set seasonal means, in the Earth's radiation budget from the analysis of nine years of ten day mean observations derived from the NOAA polar orbiter satellites for the period, 1974–1983. We estimate that the standard deviation in the outgoing longwave flux for this period is less than 12 Wm^?2 and typically 7 Wm^?2. The results show that there are several geographical areas for which the standard deviation is in excess of 20 Wm^?2; in such regions the radiation budget anomalies exceeded these due to natural atmospheric variability. In this paper we discuss the relationship of these anomalies with climatic change.     

Climatic variations in the outgoing longwave radiation of the past decade as observed from NOAA polar orbiting satellites

Components of the earth radiation budget have been calculated on a regular basis since June 1974 (except for a 10 month gap in data in 1978) based on measurements by the scanning radiometers and the advanced very high resolution radiometers on the operational NOAA polar orbiting satellites. A new base set of monthly and seasonal averages of outgoing longwave radiation has been prepared by NOAA's Climate Analysis Center (CAC) for the entire period of record through November 1983. Anomalies relative to these new normals have now been constructed for each month and season in the entire record.In this presentation, some of the more prominent anomalies of outgoing longwave radiation over the past decade are discussed. A major concentration is on the tropics and subtropics where there have been very substantial radiation variations associated with major shifts in convective cloudiness accompanying El Niño/Southern Oscillation events.     

The sensitivity of the earth's radiation budget to changes in cloudiness

Cloudiness modulates the radiation budget at the top of the Earth-atmosphere system. For radiation balance studies, for climate diagnostic studies, and for climate modeling studies, it is important to know the sensitivity of both the outgoing longwave radiation and the net (absorbed solar minus outgoing longwave) radiation of the system to changes in cloudiness on a global basis. Based on a 45 month series of NOAA satellite scanning radiometer observations, estimates of the global distribution of these sensitivity parameters are obtained.     

Verification of satellite observations of stratospheric minor constituents

The TIROS-N operational meteorological satellite observing system will have the capability of determining global ozone amounts from two instruments by 1985. The TIROS Operational Vertical Sounder (TOVS) yields total ozone amounts through measurements of atmospheric infrared radiances. The Solar Backscatter Ultraviolet (SBUV/2) spectrometer yields total ozone amounts and vertical ozone profiles through measurements of the solar ultraviolet radiation backscattered by the atmosphere. The current operations plan calls for single satellites containing both instruments system with local afternoon equator crossing times. They will be launched at approximately 18 month intervals.The satellite ozone products will require verification using commonly accepted references. For total ozone, Dobson spectrophotometer determinations are to be used. For vertical profiles, no clear choice now exists among balloon-launched chemical sondes, rocket-launched optical sondes or Dobson Umkehr measurements. The applicability and use of these measurement systems are discussed with emphasis on the need for the verification data consistent with the operational satellite lifetimes.Another major source of data for verification is other satellite systems. Comparisons of vertical ozone profiles from several concurrent satellites is discussed. This includes results from SAGE, LIMS and SBUV.     

An examination of a technique for estimating the longwave radiation budget from satellite radiance observations

Intercomparisons of the zonally averaged outgoing longwave fluxes estimated from 10 μm radiance observations on NOAA polar orbiters and flat plate observations on the Nimbus 6 ERB experiment have shown the NOAA estimates to be higher than the ERB measurements. Our analysis shows that the operational technique systematically overestimates calculated fluxes for middle and high cloud conditions. A different radiative transfer model and new assumptions concerning clouds reduce the NOAA-ERB flux difference by approximately 35%.     

The United States operational polar-orbiting satellite series,TIROS-N

The U.S. launched the first of its new series of polar-orbiting, operational satellites, named TIROS-N, on 13 October 1978. The second, named NOAA-A, was launched on 27 June 1979. Together they comprise the operational system since from an average altitude of 840 km two satellites are required to provide global coverage in the equatorial zone. Operational products for FGGE (atmospheric temperature profiles, sea surface temperature analysis, and other data) are discussed and compared with prior performance. New uses in support of oceanology (Service ARGOS) are described.     

On the derivation of radiation budget parameters at the surface from satellite measurements

The modelling of climate and circulation processes requires more than ever before accurate data on the energy exchange between the earth's surface and the atmosphere. Accuracies are estimated to range between 2–20 Wm^?2 for global and monthly averages. The four components of the radiation budget at ground can still not at all be derived with sufficient accuracy from satellite measurements and from correlative data of conventional surface based origin. In this paper are discussed the general possibilities. Basic research is still required to establish a reliable error budget, and ground truth is essential.     

Clouds and Earth Radiant Energy System (CERES), a review: Past,present and future

The Clouds and Earth Radiant Energy System (CERES) project’s objectives are to measure the reflected solar radiance (shortwave) and Earth-emitted (longwave) radiances and from these measurements to compute the shortwave and longwave radiation fluxes at the top of the atmosphere (TOA) and the surface and radiation divergence within the atmosphere. The fluxes at TOA are to be retrieved to an accuracy of 2%. Improved bidirectional reflectance distribution functions (BRDFs) have been developed to compute the fluxes at TOA from the measured radiances with errors reduced from ERBE by a factor of two or more. Instruments aboard the Terra and Aqua spacecraft provide sampling at four local times. In order to further reduce temporal sampling errors, data are used from the geostationary meteorological satellites to account for changes of scenes between observations by the CERES radiometers.     

An attempt for objective analysis of TIROS-N images

An attempt for digital processing of analog images taken in the infrared channel (10.5–11.5 μm) from TIROS-N is presented. The data digitized to 8-bits are normalized by using SR Data Manipulator. The investigated period is November 3–4, 1979. The geographic rectification moves the data into a polar stereographic map. To estimate the cloud heights empirical relationships are applied. The following characteristics of the cloud field are produced: the cloud amount, the dominant cloud-type, the daily variation of IR brightness temperature and the cloud texture. The results are visualized on a colour display.     

Cloudiness over the Eastern Equatorial Pacific for summer 1983 from geostationary satellite data

The extraordinary El-Nino event of 1982–83 started to fade out in the late spring of 1983. However the sea surface temperature of the Eastern Equatorial Pacific still remained warmer than normal in the following summer. To investigate the characteristics of this late transition phase of the 1982–83 El-Nino, the GOES-West satellite data of July and August of 1983 are analyzed. The outgoing longwave radiation field and the distribution of cloudiness, which was derived by using a new threshold technique, are obtained. The longwave radiation field is compared to monthly average climatic indices commonly used at the Climatic Analysis Center. The results of cloud analysis showed some interesting features during the decaying phase of the 1982–83 El-Nino. The diurnal variation of cloudiness indicates that total cloud amounts decrease from 8 GMT to 20 GMT over most of the area. This overall study demonstrates preliminary results of the International Satellite Cloud Climatology Project of the World Climate Research Program.     

Is there an abnormal enhancement of atmospheric aerosol before the 2008 Wenchuan earthquake?

There are extensive reports of ionospheric disturbances before the great 2008 Wenchuan earthquake, which are possibly explained by seismogenic electric field hypotheses linked with the aerosols injected in atmosphere. This paper attempts to investigate the possible change of atmospheric aerosol optical depth (AOD) associated with this earthquake by using MODIS data from both Terra and Aqua satellites. The result shows a clear enhancement of AOD along the Longmenshan faults 7 days before the quake, which is 1 day and 4 days earlier than the reported negative and positive ionospheric disturbances, respectively, and is 1 day earlier than or quasi-synchronism with other reported atmospheric anomalies including air temperature, outgoing longwave radiation and relative humidity. Particularly, the spatial distribution of AOD enhancement is very local and it is correlated well with the active faults and surface ruptures. We suggest that this unique enhancement could be associated with the Lithosphere–Atmosphere–Ionosphere coupling process during the preparation of the Wenchuan earthquake.     

CM-SAF surface radiation budget: First results with AVHRR data

In the phase of redefinition of the EUMETSAT ground segment seven so called Satellite Application Facilities (SAF) each of them serving dedicated user groups have been established in Europe. The SAF on climate monitoring (CM-SAF) will deliver a comprehensive set of climate variables, including from different cloud products, radiation budget at the top of the atmosphere, surface radiation budget and tropospheric humidity. A consistent dataset of cloud and radiation products in a high spatial resolution on a uniform grid is derived. The CM-SAF is a joint project of the German Meteorological Service, EUMETSAT and five other European Meteorological Services. It is dedicated to produce climate datasets using data from instruments onboard of METEOSAT Second Generation and polar orbiting satellites NOAA and METOP. After the development phase, the CM-SAF has started its initial operational phase in the end of 2003. In this context, the algorithms have been implemented at the processing centres and the processing of satellite data from the polar orbiting satellites of NOAA has commenced. This paper gives an overview of the first products of surface radiative fluxes and their validation with selected surface sites.     

Surface temperatures at the nearside of the Moon as a record of the radiation budget of Earth’s climate system

Understanding the balance between incoming radiation from the Sun and outgoing radiation from Earth is of critical importance in the study of climate change on Earth. As the only natural satellite of Earth, the Moon is a unique platform for the study of the disk-wide radiation budget of Earth. There are no complications from atmosphere, hydrosphere, or biosphere on the Moon. The nearside of the Moon allows for a focus on the solar radiation during its daytime, and on terrestrial radiation during its nighttime. Additionally, lunar regolith temperature is an amplifier of the terrestrial radiation signal because lunar temperature is proportional to the fourth square root of radiation as such is much more sensitive to the weak terrestrial radiation in nighttime than the strong solar radiation in daytime. Indeed, the long-term lunar surface temperature time series obtained inadvertently by the Heat Flow Experiment at the Apollo 15 landing site three decades ago may be the first important observation from deep space of both incoming and outgoing radiation of the terrestrial climate system. A revisit of the lunar surface temperature time series reveals distinct characteristics in lunar surface daytime and nighttime temperature variations, governed respectively by solar and terrestrial radiation.     

Short-term periodicities in the downward longwave radiation and their associations with cosmic ray and solar interplanetary data

In this study downward longwave (LW) atmospheric radiation data for the period of 2014–2020 were used to search for short-term periodicities using fast Fourier transform (FFT). Several local peaks in the power spectrum density were found and established. The time series exhibits a series of significant peaks (exceeding the 95% confidence limit), such as at 273 days, 227 days, 200 days, 178 days, 157 days, 110 days, 120 days, 87 days, 73 days, 53–56 days, 35–30 days, 25–27 days, 21 days, 13 days, and 9–10 days.Moreover, cosmic ray data from KACST muon detector and the Oulu neutron monitor, as well as the data for the solar radio flux at 10.7 cm (F10.7 cm), Dst index, and solar wind speed for the same period as the LW data, were used to look for common cyclic variations and periodicities matching those found in the LW radiation. This was done to investigate the possible effect of the solar activity parameters on LW radiation. Several common periodicities were observed in the spectra of all the variables considered, such as 227 days, 154–157 days, 25–27 days, and 21 days. Some of the periodicities found in the LW radiation spectrum can be attributed to the modulation of the cosmic ray intensity by solar activity. Others are attributed to the disturbances in the interplanetary magnetic field. Based on the spectral results, we suggest that the solar signals may directly or indirectly affect the variations of the downward longwave radiation, which in turn may affect climate change.     

Sea surface temperature measurement from satellites: Validation and accuracy

A review of the latest published results concerning the accuracy of satellite derived sea surface temperature (SST) estimation is presented. Two types of platforms are considered : orbiting satellites and geosynchronous satellites and the accuracies that may now be expected from such systems are reported. This review emphasizes the impressive improvement in global mapping of SST obtained from the Advanced Very High Resolution Radiometer (AVHRR) on NOAA's operational polar satellites. Tests of the AVHRR SST's against a high reliability data set consisting of buoys, bathythermographs and research ship reports indicate biases of < 0.1°C and RMS differences of < 0.75°C (McClain [1]). Particular attention is also paid to a method adding along track scanning capability to the present multichannel AVHRR technique. This method is demonstrated owing to the coupling of an orbiting satellite (TIROS-N) and a geosynchronous satellite (METEOSAT). Another type of coupling of two such platforms is also presented in connection with the advent of geostationary satellites equipped with a vertical sounding capability, such as GOES-4.     

Determination of Angular Distribution Models for Indian desert scene: Comparison with other desert models

In this paper, the shortwave and longwave anisotropy for clear sky Indian desert scene has been estimated using long-term surface data, radiative transfer calculations and Helmholtz reciprocity for missing values. This study is important in the perspective of the low inclination satellites like Megha–Tropiques (MT) mission, carrying Scanner for Radiation Budget (ScaRaB) payload, which will provide broadband radiative fluxes at the top of the atmosphere (TOA). Due to low inclination angle, the angular models for clear sky land scenes for the MT-ScaRaB orbits will be dominated by desert points.The Angular Distribution Models (ADMs) determined in this study were compared with existing desert models. It is observed that for longwave radiation, the largest disagreement is observed for higher values of viewing zenith angle, especially for the summer season, where the difference in flux can reach up to 13 W/m². For the shortwave radiation, higher values of both solar zenith angle and viewing zenith angle cause largest incongruity in the computed albedo from the different models, suggesting the need of caution in interpretation of the flux computations from these bins. In fact at the higher solar zenith angle bin, the disparity in albedo can go up to 6.4%.     

The interannual variability of the earth's radiation budget components as observed from space

Based on the 1974–78 NOAA data, characteristic features of the variability of the Earth's radiation budget and its components over the area of the Northern Atlantic have been analyzed. Calculations of the mean square deviation for the ERB and its components have let to the conclusions that anomalous regions of maximum variability may be considered as energy-active zones.     

The role of space techniques in FGGE

The space-based sub-system of the composite observing system, operated during the Operational Year of the Global Weather Experiment, played an indispensable role in the acquisition of data and in transmitting data from surface-based and airborne observational platforms to data-processing centres. The sub-system comprised both geostationary and near-polar orbiting meteorological satellites and special efforts were undertaken to keep the performance of the system as close as possible to that which had been anticipated during the planning stage of the Experiment.Five geostationary satellites were spaced at approximately uniform intervals around the equator. They were used primarily to derive wind vectors by measuring the displacement of clouds. The satellites also provided communication support for the Aircraft to Satellite Data Relay system, by which flight level meteorological data were automatically transmitted to ground receiving stations.Three polar orbiting satellites provided data simultaneously during the whole Operational Year. Vertical temperature soundings, clear-radiance data, sea-surface temperature and wind speed data, and total atmospheric water vapour data were produced for inclusion in the research data set of the Experiment. Two of these satellites /TIROS-N and NOAA-6/ carried a new data collection and platform location system, a basic component of the Tropical Constant Level Balloon System and the Drifting Buoy System of FGGE.     

Early results based on the stratospheric channels of TOVS on the TIROS-N series of operational satellites

TOVS (TIROS Operational Vertical Sounder) comprises the three radiometers HIRS-2 (High resolution Infra Red Sounder Mod 2), MSU (Microwave Sounding Unit) and SSU (Stratospheric Sounding Unit) mounted on the TIROS-N series of operational spacecraft. Data from these sounders have been available since October 1978 and the series should continue to beyond 1985. The derivation and assessment of stratospheric geopotential height fields from these sounders, with particular reference to the SSU, are described. Measurements of stratospheric diurnal temperature effects and plots of zonally meaned brightness temperatures over a 450 day period are also presented.