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This paper describes the validation of ozone data from the Upper Atmosphere Research Satellite (UARS) Microwave Limb Sounder (MLS). The MLS ozone retrievals are obtained from the calibrated microwave radiances (emission spectra) in two separate bands, at frequencies near 205 and 183 GHz.
Quantifying the global hydrological cycle and its variability across various time scales remains a challenge to the climate community. Direct measurements of evaporation (E), evapotranspiration (ET), and precipitation (P) are not feasible on a global scale, nor is the transport of water vapor over the global oceans and sparsely populated land areas. Expanding satellite data streams have enabled development of various water (and energy) flux products, complementing reanalyses and facilitating observationally constrained modeling. But the evolution of the global observing system has produced additional complications--improvements in satellite sensor resolution and accuracy have resulted in "epochs" of observational quasi-uniformity that can adversely affect reanalysis trends. In this work we focus on vertically integrated moisture flux convergence (VMFC) variations within the period 1979 - present integrated over global land. We show that VMFC in recent reanalyses (e.g. ERA-I, NASA MERRA, NOAA CFSR and JRA55) suffers from observing system changes, though differently in each product. Land Surface Models (LSMs) forced with observations-based precipitation, radiation and near-surface meteorology share closely the interannual P-ET variations of the reanalyses associated with ENSO events. (VMFC over land and P-ET estimates are equivalent quantities since atmospheric storage changes are small on these scales.) But the long-term LSM trend over the period since 1979 is approximately one-fourth that of the reanalyses. Additional reduced observation reanalyses assimilating only surface pressure and /or specifying seasurface temperature also have a much smaller trend in P-ET like the LSMs. We explore the regional manifestation of the reanalysis P-ET / VMFC problems, particularly over land. Both principal component analysis and a simple time series changepoint analysis highlight problems associated with data poor regions such as Equatorial Africa and, for one reanalysis, the Equatorial Andes region. Onset of the availability of passive microwave Special Sensor Microwave Imager (SSMI) moisture data in July 1987 and the transition from the Microwave Sounder Unit (MSU) to an advanced version (AMSU) have significant impacts on VMFC variability. Simple accounting for these errors of leading importance results in modified reanalysis VMFC estimates that agree much better with the LSM results. Regional details of the modified reanalysis VMFC and LSM P-ET are related to changes in Pacific Decadal Variability as manifest in SST changes after the late 1990s.
ECMWF, NCEP, and GMAO routinely assimilate radiosonde and other in-situ observations along with satellite IR and MW Sounder radiance observations. NCEP and GMAO use the NCEP GSI Data Assimilation System (DAS).GSI DAS assimilates AIRS, CrIS, IASI channel radiances Ri on a channel-by-channel, case-by-case basis, only for those channels i thought to be unaffected by cloud cover. This test excludes Ri for most tropospheric sounding channels under partial cloud cover conditions. AIRS Version-6 RiCC is a derived quantity representative of what AIRS channel i would have seen if the AIRS FOR were cloud free. All values of RiCC have case-by-case error estimates RiCC associated with them. Our experiments present to the GSI QCd values of AIRS RiCC in place of AIRS Ri observations. GSI DAS assimilates only those values of RiCC it thinks are cloud free. This potentially allows for better coverage of assimilated QCd values of RiCC as compared to Ri.
The Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats (TROPICS) mission was selected by NASA as part of the Earth Venture-Instrument (EVI-3) program. The overarching goal for TROPICS is to provide nearly all-weather observations of 3D temperature and humidity, as well as cloud ice and precipitation horizontal structure, at high temporal resolution to conduct high-value science investigations of tropical cyclones. TROPICS will provide rapid-refresh microwave measurements (median refresh rate better than 60 min for the baseline mission) which can be used to observe the thermodynamics of the troposphere and precipitation structure for storm systems at the mesoscale and synoptic scale over the entire storm life cycle. TROPICS comprises six Cube-Sats in three low-Earth orbital planes. Each CubeSat will host a high-performance radiometer to provide temperature profiles using seven channels near the 118.75 GHz oxygen absorption line, water vapour profiles using three channels near the 183 GHz water vapour absorption line, imagery in a single channel near 90 GHz for precipitation measurements (when combined with higher-resolution water vapour channels), and a single channel near 205 GHz which is more sensitive to precipitation-sized ice particles. This observing system offers an unprecedented combination of horizontal and temporal resolution to measure environmental and inner-core conditions for tropical cyclones on a nearly global scale and is a major leap forward in the temporal resolution of several key parameters needed for assimilation into advanced data assimilation systems capable of utilizing rapid-update radiance or retrieval data.Launch readiness is currently projected for late 2019.
scene to retrieve their microphysical properties. The Clouds and the Earth's Radiant Energy System (CERES) Project uses the infrared channels (6.72 Âμm, 7.33 Âμm, 13.3 Âμm,13.6 Âμm, 13.9 Âμm, and 14.2 Âμm) available on the Terra and Aqua Moderate Resolution Imaging Spectroradiometers (MODIS) to build its algorithms to retrieval cloud properties. Unfortunately, The Visible Infrared Imaging Radiometer Suite (VIIRS) on board Suomi-NPP (National Polar-Orbiting Partnership) lacks these particular measurements. While conducting research using VIIRS data, it is desirable to bring these data into the VIIRS resolution. The Cross-track Infrared Sounder (CrIS), which is also on board Suomi-NPP, has these infrared channels. This paper describes a method to map the CrIS spectral radiances of CO2 and water vapor to VIIRS, with the mapping software in ATOVS and AVHRR Pre-processing (AAPP) package provided by Satellite Application Facilities for Numerical Weather Prediction (NWP SAF). This method is validated comparing mapped10.763 Âμm from CrIS with M15 from VIIRS. The mapped CO2 and water vapor channels were then created and combined with the conventional VIIRS product, as well as compared against corresponding channels of Aqua MODIS instrument.
Ultra-spectral resolved infrared measurements from aircraft and space-based observations contain information about tropospheric carbon monoxide (CO) and ozone (O3), as well as other trace species. A methodology of retrieving these tropospheric trace species from such remotely sensed spectral data has been developed and validated for the National Airborne Sounder Testbed-Interferometer (NAST-I). The Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) field campaign was conducted during August 2019 to investigate the impact of wildfire and biomass smoke on air quality and weather in the continental United States. NAST-I CO and O3 measurements from the recent FIREX-AQ field campaign are presented herein and used to estimate wildfire plume age. Results show enhanced CO plume evolution and transport away from fire ground site, and its plume age associated with the plume distance in both vertical and horizontal directions from the wildfire location, as enabled by the moderate-vertical and high-horizontal resolution obtained from the NAST-I remotely sensed IR spectrometer onboard NASA ER-2 aircraft. This study advances our knowledge of fire-induced plume with its evolution and age in 3-dimensional space.
Ultra-spectrally resolved infrared measurements from aircraft and space-based observations contain information about tropospheric carbon monoxide (CO) and ozone (O3), as well as other trace species. A methodology for retrieving these tropospheric trace species from such remotely sensed spectral data has been developed and validated for the National Airborne Sounder Testbed-Interferometer (NAST–I). The Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) field campaign was conducted during August 2019 to investigate the impact of wildfire and biomass smoke on air quality and weather in the continental United States. NAST–I CO and O3 measurements from the recent FIREX-AQ field campaign are presented and used to estimate wildfire plume age. Results show enhanced levels of CO in the evolving plume as it is transported away from the fire ground site, and its plume age is associated with the plume distance in both the vertical and horizontal directions from the wildfire location. These results are enabled by the moderate-vertical and high-horizontal resolution obtained from the NAST–I IR spectrometer onboard the NASA ER-2 aircraft. This study advances our knowledge of fire-induced plumes with their evolution and age characterized in three-dimensional space using information from NAST–I retrieved CO and O3 and relative changes in their concentrations.
The Fire Influence on Regional to Global Environments and Air Quality (FIREX AQ) field campaign was conducted during August 2019 to investigate the impact of wildfire and biomass smoke on air quality and weather in the continental United States. Ultra-spectral resolved infrared measurements contain information about tropospheric carbon monoxide (CO) and ozone (O3), as well as other trace species. A methodology of retrieving these tropospheric trace species from such remotely sensed spectral data has been developed and validated for the National Airborne Sounder Testbed-Interferometer (NAST I). NAST I CO and O3 measurements from the recent FIREX AQ field campaign are presented herein and used to estimate wildfire plume age. Results show enhanced CO plume evolution and transport away from fire ground site, and its plume age associated with the plume distance in both vertical and horizontal directions from the wildfire location, as enabled by the moderate-vertical and high-horizontal resolution obtained from the NAST I remotely sensed IR spectrometer onboard NASA ER 2 aircraft. This study advances our knowledge of fire-induced plume with its evolution and age in 3-dimensional space.
Tables and figures are presented which show local site observations of cloud fractions, the number of cloud layers, direction of movement, and precipitation data collected during the FIRE (First ISCCP Regional Experiment) Phase 2 Cirrus Intensive Field Observations (IFO) conducted in Coffeyville, Kansas during November and December, 1991. Selected data are also presented at the times of the TIROS Operational Vertical Sounder (TOVS) satellite overpass. Several major scientific projects have used surface-based observations of clouds to compare directly with those being observed from satellites. Characterizing the physical properties of clouds is extremely useful in obtaining a more accurate analysis of the effect of clouds and their movements on weather and climate. It is the purpose of this paper to report data collected during the FIRE Phase 2 IFO experiment and to provide a brief history of such a surface-based system and the technical information required for recording local cloud parameters.
The ionospheric topside sounders of the International Satellites for Ionospheric Studies (ISIS) program were designed as analog systems. More than 16,000 of the original telemetry tapes from three satellites were used to produce topside digital ionograms, via an analog-to-digital (A/D) conversion process, suitable for modern analysis techniques. Unfortunately, many of the resulting digital topside ionogram files could not be auto-processed to produce topside Ne(h) profiles because of problems encountered during the A/D process. Software has been written to resolve these problems and here we report on (1) the first application of this software to a significant portion of the ISIS-1 digital topside-ionogram database, (2) software improvements motivated by this activity, (3) N(sub e)(h) profiles automatically produced from these corrected ISIS-1 digital ionogram files, and (4) the availability via the Virtual Wave Observatory (VWO) of the corrected ISIS-1 digital topside ionogram files for research. We will also demonstrate the use of these N(sub e)(h) profiles for making refinements in the International Reference Ionosphere (IRI) and in the determination of transition heights from Oxygen ion to Hydrogen ion.
It has been recognized for some time that water vapor structure visible in infrared imagery offers a potential for obtaining motion vectors when several images are considered in sequence (Fischer et al., 1981). A study evaluating water vapor winds obtained from the VISSR atmospheric sounder (Stewart et al., 1985) has confirmed the viability of the approach. More recently, 20 data sets have been produced from METEOSAT water vapor imagery for the FGGE period of 10-25 November 1979. Where possible, two data sets were prepared for each day at 0000 and 1200 GMT and compared with rawinsondes over Europe, Africa, and aircraft observations over the oceans. Procedures for obtaining winds were, in general, similar to the earlier study. Motions were detected both by a single pixel tracking and a cross correlation method by using three images individually separated by one hour. A height assignment was determined by matching the measured brightness temperature to the temperature structure represented by the FGGE-IIIB analyses. Results show that the METEOSAT water vapor winds provide uniform horizontal coverage of mid-level flow over the globe with good accuracy.
Measurements using the inflatable falling sphere technique have occasionally been used to obtain temperature results from density data and thereby provide comparison with temperature profiles obtained by satellite sounders in the mesosphere and stratosphere. To insure density measurements within narrow time frames and close in space, the inflatable falling sphere is launched within seconds of the nearly overhead satellite pass. Sphere measurements can be used to validate remotely measured temperatures but also have the advantage of measuring small-scale atmospheric features. Even so, with the dearth of remaining falling spheres available (the manufacture of these systems has been discontinued), it may be time to consider whether the remote measurements are mature enough to stand alone. Three field studies are considered, one in 2003 from Northern Sweden, and two in 2010 from the vicinity of Kwajalein Atoll in the South Pacific and from Barking Sands, Hawaii. All three sites are used to compare temperature retrievals between satellite and in situ falling spheres. The major satellite instruments employed are SABER, MLS, and AIRS. The comparisons indicate that remotely measured temperatures mimic the sphere temperature measurements quite well. The data also confirm that satellite retrievals, while not always at the exact location required for detailed studies in space and time, compare sufficiently well to be highly useful. Although the falling sphere will provide a measurement at a specific location and time, satellites only pass a given location daily or less frequently. This report reveals that averaged satellite measurements can provide temperatures and densities comparable to those obtained from the falling sphere, thereby providing a reliable measure of global temperature
The design of the Geostationary Operational Environmental Satellites (GOES) uses newer technology and has expanded capability relative to the predecessor GOES series of satellites. The satellite directly transmits day and night observations of hemispheric-scale weather, hurricanes, and other more localized severe storms and relays processed high-resolution observation data along with weather facsimile (WEFAX) data. Weather observations are generated in the visible and infrared spin scan radiometer (VISSR) atmospheric sounder (VAS). The VAS performs visible and infrared imaging as well as multispectral imaging (MSI) and temperature sounding of the atmosphere. The satellite provides direct interrogation and simultaneous relay transmission between the command data acquisition station (CDAS) and the multiple, widely dispersed data collection platforms (DCP). The satellites also monitor the condition of the earth's magnetic field, energetic particle flux, and X-ray emissions from the sun. The satellite performs all communications functions by means of a multifunction communications system that operates on S-band and uhf frequencies at rates varying from 100 bit/s to 28 megabit/s. An experimental capability for the detection of the emergency locator transmitter beacons is included in the GOES-GH design as a part of the international satellite-aided search and rescue system.
Cross-spectral analysis of low-latitude average Nimbus 7 stratospheric and mesospheric sounder (SAMS) temperature deviations versus Nimbus 7 solar backscattered ultraviolet (SBUV) solar 205 nm flux measurements in the 1-3 mbar pressure range yields significant coherence at periods near 27 and 13 days. This supports earlier correlative evidence that the ozone response to solar ultraviolet variations is supplemented by a coupled temperature response in the upper stratosphere. Comparisons of improved one-dimensional radiative photochemical model calculations with ozone and temperature response measurements at low latitudes yields agreement only in the case of ozone at levels below 3 mbar. An additional, presumably dynamical, component of the upper stratospheric response is suggested. Cross-spectral analysis of low-latitude average SAMS temperature deviations versus higher-latitude temperature fluctuations of opposite sign in the winter hemisphere also yields significant coherency at periods near 27 and 13 days. Latitudinal temperature oscillations of this type result from interference between stationary and traveling wave components at stratospheric heights. It is therefore hypothesized that solar ultraviolet variations may force or modulate traveling waves with periods near 27 and 13 days in the upper stratosphere. The existence of such waves with higher amplitude near solar maximum than near solar minimum may help to explain observed solar cycle variations of zonally averaged winds and temperature in the upper stratosphere.
Although the Polar Weather Research and Forecasting (PWRF) model has been developed for polar environments, simulations of atmospheric states in the polar region still have large uncertainties. Therefore, the effects of data assimilation (DA) to improve forecasts in the polar region were investigated for September 2017 using PWRF and the three-dimensional variational (3DVAR) DA method. The experiments without DA and those with DA assimilating only conventional observations and both conventional observations and satellite radiance data were performed. The forecasts from all experiments both without and with DA underestimated (overestimated) the downward longwave (shortwave) radiation flux due to the underestimation of the amount of Arctic clouds. When satellite radiance data (i.e., the Advanced Microwave Sounding Unit-A (AMSU-A) and Microwave Humidity Sounder (MHS)) were assimilated in addition to conventional observations in the PWRF, the distribution and amount of water vapor became closer to observations, which improves cloud liquid water forecasts. Therefore, when both conventional observations and radiance data were assimilated, the 25–30 h forecast errors of the downward longwave and shortwave radiation fluxes and sensible and latent heat fluxes decreased by 12.7%, 8.1%, 3.2%, and 7.8% with the WSM5 scheme and by 17.1%, 4.7%, 2.5%, and 3.1% with the 2-moment Morrison scheme, respectively, compared to those in the experiments without DA. The forecast errors of the 10 m wind and 2 m temperature with DA were smaller than those without DA at most observation stations. Therefore, the uncertainties of the Arctic forecasts in the PWRF decreased when using DA. To further improve Arctic forecasts, the assimilation of various additional satellite data is necessary.
During the cooperative convective precipitation experiment, eight times were selected as VISSR atmospheric sounder (VAS) observation periods. A synoptic analysis of the surface and the 850, 700, 500, 300, and 200 maps for those eight periods. The satellite and radar data for those periods are included with the analyses. There were five rawinsonde stations in eastern Montana which made extra soundings for the VAS periods.
The CO2 slicing method is generally recognized as the most accurate means of inferring cloud altitude from passive infrared radiance observations. The method is applicable to semi-transparent and broken clouds. During the cirrus FIRE and COHMEX field experiments, CO2 channel radiance data suitable for cloud altitude specification were achieved from moderate spectral resolution satellite sounders (NOAA-TOVS and GOES-VAS) and from a High spectral resolution Interferometer Spectrometer (HIS) flown on the NASA U2/ER2 aircraft. Also aboard the ER2 was a down-looking active lidar unit capable of providing cloud top pressure verifications with high accuracy. A third instrument, the Multispectral Atmospheric Mapping Sensor (MAMS) provided 50 meter resolution infrared window data which is used wtih radiosonde data to verify the heights of middle and low level clouds. Comparisons of lidar and MAMS/radiosonde ground truth cloud heights are made with those determined from: high resolution (0.5/cm) HIS spectra, HIS spectra degraded to the moderate resolution (15/cm) of the VAS/TOVS instruments, and spectrally averaged HIS radiances for individual pairs of VAS spectral channels. The results show that the best results are achieved from high resolution spectra; the RMS difference with the ground truth is 23 mb. The RMS differences between the infrared radiance determination and ground truth increase by 35 percent when the spectral resolution is degraded to the moderate spectral resolution of the VAS/TOVS instruments and by 52 to 183 percent, depending upon channel combinations, when only two spectral channels at VAS/TOVS spectral resolution are used.
Monthly zonal mean observations of H2O and CH4 made by the limb infrared monitor of the stratosphere and the stratospheric and mesospheric sounder instruments on Nimbus 7 have been used to investigate whether the H2O mixing ratios in the stratosphere are consistent with a source via the oxidation of CH4. While both sets of data show considerable seasonally varying structure, total hydrogen (neglecting molecular hydrogen) is relatively featureless with a mean value over the stratosphere of 6.0 + or - 0.35 ppmm(1sigma) for the five-month period studied. The uniformity of the total hydrogen fields points to the validity of the CH4 oxidation hypothesis. The derived fields of total hydrogen are used to deduce a mean H2O mixing ratio for air as it enters the stratosphere of 2.7 + or - 0.35 ppmv (1sigma) from which a desiccation temperature may be deduced.