This paper presents coordinated ground-based observations by the NOAA-CREST Lidar Network (CLN) for profiling of aerosols, cloud, water vapor, and wind along the US east coast including Caribbean region at Puerto Rico. The instrumentation, methodology and observation capability are reviewed. The applications to continental and intercontinental-scale transport of smoke and dust plumes, and their large scale regional impact are discussed.

Some applications of data from the Clouds and the Earth's Radiant Energy System (CERES) scanning radiometer require the use of the point response function (PRF), which describes the influence of radiance from each point on the measurement. A radiance source for the measurement of the PRF of the CERES instruments was built and installed into the Radiometric Calibration Facility, in which the CERES instruments have been calibrated. The design and application of the PRF source and the computation of the PRF from these measurements are described. In order to compare the PRF based on measurements with the theoretical PRF, it is necessary to account for the finite size of the beam from the source. The use of the PRF source and the analysis of the data are demonstrated by application to the FM-5 instrument. The measured results compare well with theory for the CERES instruments and are presented for FM-5.

Insufficient suppression of the elastic-scattering signal in the rotational Raman (RR) detection channels can result in a retrieval error particularly when the temperature of a thick cloud is measured using an RR lidar. To solve this problem, a technique is presented to obtain relative transmission factors for the two RR channels' thereby correcting for the influence of residual elastic-signal on the temperature retrieval. The feasibility of this technique is demonstrated by applying the algorithm to the Hampton University (HU) lidar measurements. Intercomparisons of these temperature retrievals from both water-phase and cirrus clouds show good agreement with radiosonde measurements.

An improved method that has the potential to improve the retrieval of aerosol optics properties (backscatter/extinction coefficients) from elastic–Raman lidar data is presented. Aerosol backscatter coefficients can be retrieved by choosing the reference height at near-range rather than conventional far-range when the signal-to-noise ratios are low at the far-range or aloft aerosol layers and clouds appear there. Significant retrieval errors in aerosol backscatter coefficients caused by large uncertainties of the aerosol reference value at far-range can be reduced. To avoid the ill-posed retrievals of aerosol extinction from the conventional Raman method, the new method derives the aerosol extinction and lidar ratio with the constrained Fernald inversions by independent aerosol backscatter coefficients from above proposed method. The numerical simulations demonstrated that the proposed method provides good accuracy and resolution of aerosol profile retrievals. And the method is also applied to elastic–Raman lidar measurements at the Hampton University, Hampton, Virginia.

The vertical stratification and optical characteristics of aloft aerosol plumes are critical to evaluate their influences on climate radiation and air quality. In this study, we demonstrate the synergistic measurements of aloft aerosol plumes by a ground-based NOAA-CREST lidar network (CLN) along the US East Coast, the AERONET-sun/sky radiometer network at lidar sites, and satellite observations. During the plume intrusion period on March 6, 2012, the CLN and AERONET measurements were consistent in illustrating the onset of dust aerosol plumes. We observed two-layers of aerosol located at 1.0 ~ 8.0 km altitude. The column-average volume size distributions show increasing concentration of both fine- and coarse-modes aerosols, but are dominated by the coarse-mode. Direct lidar inversions illustrate that the aerosol plume layers contributed up to 70% of the total AOD. NOAA-HYSPLIT back-trajectories and CALIPSO observations indicate the trans-Pacific transport of Asian-dust at 3 - 8 km altitude to the US East Coast. Meanwhile, the NOAA-HMS fire and smoke products illustrate the transport and possible mixture of dust with fine-mode smoke particles from the middle and southwestern US. The small Angstrom exponents of MODIS/Aqua in the US East Coast imply the dominance of coarse-mode particles. Accordingly, the upper layer of coarse mode aerosols is most likely transported from the East Asia, while the lower layer at 1-3 km altitude probably consists of continental dust particles from the western US mixed with fine-mode smoke particles. In addition, the transport and vertical structure of aerosol are investigated with the NAAPS global aerosol transport model.

This letter describes a lidar retrieval technique that uses the transmittance ratio as a constraint to determine an average lidar ratio as well as extinction and backscatter coefficients of transparent cirrus clouds. The cloud transmittance ratio is directly obtained from two adjacent elastic lidar backscatter signals. The technique can be applied to cirrus measurements where neither the molecular scattering dominant signals above and below the cloud layer are found nor cloudfree reference profiles are available. The technique has been tested with simulated lidar signals and applied to backscatter lidar measurements at Hampton University, Hampton, Virginia.

We present a method to determine the geometric form factor of a ground-based lidar using simultaneous lidar measurements made from the ground and from space. The theoretical basis is described. The feasibility of the method is demonstrated by applying it to the measurement data acquired by the Cloud Aerosol Lidar Infrared Pathfinder Satellite Observation (CALIPSO) lidar and a ground-based lidar located at the Hampton University (37.02 degrees N, 76.34 degrees W). The geometric factors with different aerosol conditions are retrieved. (C) 2009 Optical Society of America

Continuation of the Earth Radiation Budget (ERB) Climate Data Record (CDR) has been identified as critical in the 2007 NRC Decadal Survey, the Global Climate Observing System WCRP report, and in an assessment titled 'Impacts of NPOESS Nunn-McCurdy Certification on Joint NASA-NOAA Climate Goals'. In response, the final existing CERES Flight Model (FM-5) will fly on the NPP spacecraft for launch in 2010. The CERES FM-5 pre-flight radiometric characterization program has benefited from the operational experience of the CERES EOS sensors. Improvements to the pre-flight program included increased sampling under vacuum conditions and additional tests to characterize the primary and transfer standards in the calibration facilityFuture opportunities for ERB CDR continuity consist of procuring an additional CERES Sensor with modest performance upgrades for flight on the NPOESS C 1 spacecraft in 2013, followed by a new CERES follow-on sensor for flight in 2018 on the NPOESS C3 spacecraft.

From October 1984 through August 2005, the NASA Earth Radiation Budget Satellite (ERBS)/Earth Radiation Budget Experiment (ERBE) nonscanning active cavity radiometers (ACR) were used to monitor long-term changes in the earth radiation budget components of the incoming total solar irradiance (TSI), earth-reflected TSI, and earth-emitted outgoing longwave radiation (OLR). From October 1984 through September 1999, using on-board calibration systems, the ERBS/ERBE ACR sensor response changes, in gains and offsets, were determined from on-orbit calibration sources and from direct observations of the incoming TSI through calibration solar ports at measurement precision levels approaching 0.5 Watts-per-squared-meter, at satellite altitudes. On October 6, 1999, the on-board radiometer calibration system elevation drive failed. Thereafter, special spacecraft maneuvers were performed to observe cold space and the sun in order to define the post-September 1999 geometry of the radiometer measurements, and to determine the October 1999-September 2003 ERBS sensor response changes. Analyses of these special solar and cold space observations indicate that the radiometers were pointing approximately 16 degrees away from the spacecraft nadir and on the anti-solar side of the spacecraft after the elevation drive failure. The special observations indicated that the radiometers' responses were stable at precision levels approaching 0.5 Watts-per-squared-meter. In this paper, determinations of the measurement geometry [sensor pointing direction] and of the radiometers' gain and offset are presented. These determinations will permit the accurate processing of the October 1999 through August 2005 ERBE data products at satellite and top-of-the-atmosphere altitudes.

The CERES Flight Models 1 through 4 instruments were launched aboard NASA's Earth Observing System (EOS) Terra and Aqua Spacecraft into 705 Km sun-synchronous orbits with 10:30 a.m. and 1:30 p.m. equatorial crossing times. These instruments supplement measurements made by the CERES Proto Flight Model (PFM) instrument launched aboard NASA's Tropical Rainfall Measuring Mission (TRMM) spacecraft on November 27, 1997 into a 350 Km, 38-degree mid-inclined orbit. The archived CERES Science data products consist of geolocated and calibrated instantaneous filtered and unfiltered radiances through temporally and spatially averaged TOA, Surface, and Atmospheric fluxes. CERES filtered radiance measurements cover three spectral bands including shortwave (0.3 to 5 micron), total (0.3 to <100 micron) and an atmospheric window channel (8 to 12 micron).Earth Radiation Budget measurements made by the CERES represent a new era in radiation climate data. CERES climate data products realize a factor of 2 to 4 improvement in calibration accuracy and stability over the previous ERBE products. This improvement is derived from two sources: incorporation of lessons learned from the ERBE mission and the development of a rigorous and comprehensive radiometric validation protocol which consists of studies covering different spatial, spectral and temporal time scales on data collected both pre and post launch. This approach has resulted in unprecedented levels of accuracy for radiation budget data products with calibration stability of better than 0.2% and calibration traceability from ground to flight of 0.25%. The current work summarizes the status of the radiometric accuracy and stability of the CERES Edition2 Level 1 data products.

Abstract This paper gives an update on the observed decadal variability of the earth radiation budget (ERB) using the latest altitude-corrected Earth Radiation Budget Experiment (ERBE)/Earth Radiation Budget Satellite (ERBS) Nonscanner Wide Field of View (WFOV) instrument Edition3 dataset. The effects of the altitude correction are to modify the original reported decadal changes in tropical mean (20°N to 20°S) longwave (LW), shortwave (SW), and net radiation between the 1980s and the 1990s from 3.1, −2.4, and −0.7 to 1.6, −3.0, and 1.4 W m−2, respectively. In addition, a small SW instrument drift over the 15-yr period was discovered during the validation of the WFOV Edition3 dataset. A correction was developed and applied to the Edition3 dataset at the data user level to produce the WFOV Edition3_Rev1 dataset. With this final correction, the ERBS Nonscanner-observed decadal changes in tropical mean LW, SW, and net radiation between the 1980s and the 1990s now stand at 0.7, −2.1, and 1.4 W m−2, respectivel...

Successive radiometers have been flown on spacecraft for measurement of the radiation budget of the Earth and to date have provided data sets which overlap in time over a 25‐year period. Together these data sets cover two cycles of any decadal oscillation and are useful for climate research. However, before multiple data sets can be used, it is necessary first to establish precisions and relative biases of the data sets. Although these instruments were all calibrated with great care, inevitably there are differences between the instruments. Also, instruments change while in orbit due to degradation of optical elements and changes of the detectors. A number of studies have compared measurements between pairs of radiometers in order to establish these differences. In this paper we compile these results and by use of a bar chart demonstrate the traceability of calibration of satellite radiation budget instruments over these two decades. Using this compilation the differences are computed for any two instruments listed. The instruments considered here include the ERBE scanning and nonscanning radiometers, ScaRaB I and II, and the CERES instruments aboard the TRMM, Terra, and Aqua spacecraft. These results are a prerequisite to use of multiple data sets for long‐term studies of climate process. The largest biases are between the ERBS scanning and non‐scanning radiometers, which at the “top of the atmosphere” differ by 5.4 W m −2 for shortwave fluxes and by 5.8 W m −2 for daytime longwave fluxes. The standard deviations of the biases, which define how well the data sets can be connected, are less than 1 W m −2 for longwave and between 1 and 2 W m −2 for shortwave fluxes.

The NASA Earth Radiation Budget Experiment (ERBE) missions were designed to monitor long-term changes in the earth radiation budget components which may cause climate changes. During the October 1984 through September 2004 period, the NASA Earth Radiation Budget Satellite (ERBS)/ERBE nonscanning active cavity radiometers (ACR) were used to monitor long-term changes in the earth radiation budget components of the incoming total solar irradiance (TSI), earth-reflected TSI, and earth-emitted outgoing longwave radiation (OLR). The earth-reflected total solar irradiances were measured using broadband shortwave fused, waterless quartz (Suprasil) filters and ACR's that were covered with a black paint absorbing surface. Using on-board calibration systems, 1984 through 1999, long-term ERBS/ERBE ACR sensor response changes were determined from direct observations of the incoming TSI in the 0.2-5 micrometer shortwave broadband spectral region. During the October 1984 through September 1999 period, the ERBS shortwave sensor responses were found to decrease as much as 8.8% when the quartz filter transmittances decreased due to direct exposure to TSI. On October 6, 1999, the on-board ERBS calibration systems failed. To estimate the 19992004, ERBS sensor response changes, the 1984-1997 NOAA-9, and 1986-1995 NOAA-10 Spacecraft ERBE ACR responses were used to characterize response changes as a function of exposure time. The NOAA-9 and NOAA-10 ACR responses decreased as much as 10% due to higher integrated TSI exposure times. In this paper, for each of the ERBS, NOAA-9, and NOAA-10 Spacecraft platforms, the solar calibrations of the ERBE sensor responses are described as well as the derived ERBE sensor response changes as a function of TSI exposure time. For the 1984-2003 ERBS data sets, it is estimated that the calibrated ERBE earth-reflected TSI measurements have precisions approaching 0.2 Watts-per-squared-meter at satellite altitudes.

From October 1984 until September 30, 1999, on-orbit, the Earth Radiation Budget Satellite (ERBS)/Earth Radiation Budget Experiment (ERBE) nonscanning, active cavity radiometers (ACR) were calibrated using observations of the incoming total solar irradiance, and of reference irradiances from an on-board tungsten lamp and blackbodies in order to determine drifts and shifts in the ACR responses. On October 7, 1999, the ERBE elevation drive system failed near the earth nadir viewing configuration. Thereafter, the elevation failure prevented observations of the on-board, built-in calibration systems. On July 23, August 8, and December 10, 2002, the ERBS was pitched 180 degrees to observe cold space, representative of a 3 Kelvin blackbody, in order to determine the ACR's zero-irradiance offsets. On December 4, 2002, the ERBS was pitched 180 degrees away from the earth in order to observe the sun, and to determine the ACR's gains. In this paper, the 2002, 180-degree pitch calibrations are compared with the earlier 1984-1999, calibrations which were obtained using the on-orbit, built-in calibration systems. In addition, the 2002 calibrations are compared with earlier scheduled November 21, 1984, and October 20, 1985, 180-degree pitch calibrations, as well as with deep space calibrations from unscheduled July 2, 1987, January 16, 1999, and November 16, 2000, ERBS spacecraft tumbles. The 2002 ACR offsets were found to be consistent with 1984-2000 offsets at the 1.0 Wm(-2). 1984-1999, ERBE top-of-the-atmosphere (TOA), and satellite altitude (SA) earth irradiances are presented. Analyses of the TOA ERBE earth irradiances indicate that the TOA irradiance time series exhibited a 1.7 Wm(-2) increase as a result of 1988-1992, and 1998-2002 satellite altitudinal decreases during periods of maximum solar magnetic activity.

Long-term, incoming total solar irradiance (TSI) measurement trends were validated using proxy TSI values, derived from indices of solar magnetic activity. Spacecraft active cavity radiometers (ACR) are being used to measure longterm TSI variability, which may trigger global climate changes. The TSI, typically referred to as the "solar constant", was normalized to the mean earth-sun distance. Studies of spacecraft TSI data sets confirmed the existence of a 0.1 %, long-term TSI variability component within a 10-year period. The 0.1 % TSI variability component is clearly present in the spacecraft data sets from the 1984-2004 time frame. Typically, three overlapping spacecraft data sets were used to validate long-term TSI variability trends. However, during the years of 1978-1984, 1989-1991, and 1993-1996, three overlapping spacecraft data sets were not available in order to validate TSI trends. The TSI was found to vary with indices of solar magnetic activity associated with recent 10-year sunspot cycles. Proxy TSI values were derived from least squares analyses of the measured TSI variability with the solar indices of 10.7-cm solar fluxes, and with limbdarked sunspot fluxes. The resulting proxy TSI values were compared to the spacecraft ACR measurements of TSI variability to detect ACR instrument degradation, which may be interpreted as TSI variability. Analyses of ACR measurements and TSI proxies are presented primarily for the 1984-2004, Earth Radiation Budget Experiment (ERBE) ACR solar monitor data set. Differences in proxy and spacecraft measurement data sets suggest the existence of another TSI variability component with an amplitude greater than or equal to 0.5 Wm-2 (0.04%), and with a cycle of 20 years or more.

The CERES instruments obtain their measurements from three scanning thermistor bolometers: the total channel which measures radiation in the 0.3 - 100 mum spectral region; the water vapor window channel which measures longwave radiation from 8 - 12 mum; and the shortwave channel which measures the reflected solar energy from 0.3 - 5.0 mum. The Aqua spacecraft, which is dedicated to advancing our understanding of Earth's water cycle and our environment, was launched on May 4, 2002. The Aqua CERES internal calibration module uses operations similar to previous CERES instruments (Flight Model 1 (FM1) and Flight Model 2 (FM2)) that were launched on the Terra spacecraft in December 1999. The internal calibration mechanism and the resulting data for Flight Model 3 (FM3) and Flight Model 4 (FM4) instruments are critical in determining the stability of both instruments as referenced to ground-based calibration. In this paper, the internal calibration procedure and the results will be presented. Both the FM3 and FM4 instruments were found stable within 0.3% on orbit. Results for the FM1 and FM2 instruments will also be discussed.

The Geostationary Earth Radiation Budget (GERB) instrument aboard the Meteosat Second Generation Satellite has 256 channels which measure total radiance and 256 channels which measure solar radiation reflected from the Earth. In order to validate the calibration of these channels, the Clouds and Earth Radiant Energy System (CERES) instrument aboard the Terra spacecraft is operated in such a way as to view Earth scenes from the same direction as the GERB, so as to measure the same total and reflected solar radiances. The method uses the capability to program the azimuth of the CERES scan plane, such that the scan plane includes the GERB.