Near real-time provision of downwelling shortwave radiation estimates derived from satellite observations

2008 ◽  
Vol 15 (3) ◽  
pp. 411-420 ◽  
Author(s):  
Bernhard Geiger ◽  
Catherine Meurey ◽  
Dulce Lajas ◽  
Laurent Franchistéguy ◽  
Dominique Carrer ◽  
...  
Keyword(s):  
Real Time ◽  
Satellite Observations ◽  
Shortwave Radiation

scholarly journals A regional real-time forecast of marine boundary layers during VOCALS-REx

2011 ◽  
Vol 11 (2) ◽  
pp. 421-437 ◽  
Author(s):  
S. Wang ◽  
L. W. O'Neill ◽  
Q. Jiang ◽  
S. P. de Szoeke ◽  
X. Hong ◽  
...  
Keyword(s):  
Real Time ◽  
Large Scale ◽  
Marine Boundary Layer ◽  
Surface Wind ◽  
Lower Troposphere ◽  
Temporal Distribution ◽  
Satellite Observations ◽  
Naval Research ◽  
Strong Wind

Abstract. This paper presents an evaluation and validation of the Naval Research Laboratory's COAMPS® real-time forecasts during the VOCALS-REx over the area off the west coast of Chile/Peru in the Southeast Pacific during October and November 2008. The analyses focus on the marine boundary layer (MBL) structure. These forecasts are compared with lower troposphere soundings, in situ surface measurements, and satellite observations. The predicted mean MBL cloud and surface wind spatial distributions are in good agreement with the satellite observations. The large-scale longitudinal variation of the MBL structure along 20° S is captured by the forecasts. That is, the MBL height increases westward toward the open ocean, the moisture just above the inversion decreases, and the MBL structure becomes more decoupled offshore. The observed strong wind shear across the cloud-top inversion near 20° S was correctly predicted by the model. The model's cloud spatial and temporal distribution in the 15 km grid mesh is sporadic compared to satellite observations. Our results suggest that this is caused by grid-scale convection likely due to a lack of a shallow cumulus convection parameterization in the model. Both observations and model forecasts show wind speed maxima near the top of MBL along 20° S, which is consistent with the westward upslope of the MBL heights based on the thermal wind relationship. The forecasts produced well-defined diurnal variations in the spatially-averaged MBL structure, although the overall signal is weaker than those derived from the in situ measurements and satellite data. The MBL heights are generally underpredicted in the nearshore area. An analysis of the sensitivity of the MBL height to horizontal and vertical grid resolution suggests that the underprediction is likely associated with overprediction of the mesoscale downward motion and cold advection near the coast.

Oceanography Data Processing Online Using Internet

2017 ◽  
Vol 862 ◽  
pp. 61-66 ◽  
Author(s):  
Suryadhi ◽  
Engki Andri Kisnarti
Keyword(s):  
Data Processing ◽  
Real Time ◽  
Satellite Observations ◽  
The Internet ◽  
Online Data ◽  
Foreign Countries ◽  
Tidal Data ◽  
Global Coverage ◽  
Oceanographic Data ◽  
Coverage Space

The oceanographic data can be obtained by free and online websites of foreign countries. This oceanographic data are obtained from satellite observations result, but this online data is in a coarse resolution with a global coverage space, its usage in certain areas still needs to be combined and validated with the observed data locally or regionally. Thus, this oceanographic data from these local observations some be easily obtained and processed as well as easily accessible by people online, it would require equipments. In this research, the oceanographic data that need to be observed is the speed data, the direction of currents data and the tidal data. The oceanographic data obtained directly from the observed area uses is the sensors that is connected to the microcontroller and sent via a modem. In real time, these data submitted by the microcontroller via the modem that also serves as a gateway SMS directly to the server. From this server, the community can access these data online using the internet.

scholarly journals Characterizing Observed Midtopped Cloud Regimes Associated with Southern Ocean Shortwave Radiation Biases

2014 ◽  
Vol 27 (16) ◽  
pp. 6189-6203 ◽  
Author(s):  
Shannon Mason ◽  
Christian Jakob ◽  
Alain Protat ◽  
Julien Delanoë
Keyword(s):  
Southern Ocean ◽  
High Latitude ◽  
Model Evaluation ◽  
Climate Models ◽  
Evaluation Studies ◽  
Ocean Model ◽  
Satellite Observations ◽  
Shortwave Radiation ◽  
Cloud Regime ◽  
Cloud Regimes

Abstract Clouds strongly affect the absorption and reflection of shortwave and longwave radiation in the atmosphere. A key bias in climate models is related to excess absorbed shortwave radiation in the high-latitude Southern Ocean. Model evaluation studies attribute these biases in part to midtopped clouds, and observations confirm significant midtopped clouds in the zone of interest. However, it is not yet clear what cloud properties can be attributed to the deficit in modeled clouds. Present approaches using observed cloud regimes do not sufficiently differentiate between potentially distinct types of midtopped clouds and their meteorological contexts. This study presents a refined set of midtopped cloud subregimes for the high-latitude Southern Ocean, which are distinct in their dynamical and thermodynamic background states. Active satellite observations from CloudSat and Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) are used to study the macrophysical structure and microphysical properties of the new cloud regimes. The subgrid-scale variability of cloud structure and microphysics is quantified within the cloud regimes by identifying representative physical cloud profiles at high resolution from the radar–lidar (DARDAR) cloud classification mask. The midtopped cloud subregimes distinguish between stratiform clouds under a high inversion and moderate subsidence; an optically thin cold-air advection cloud regime occurring under weak subsidence and including altostratus over low clouds; optically thick clouds with frequent deep structures under weak ascent and warm midlevel anomalies; and a midlevel convective cloud regime associated with strong ascent and warm advection. The new midtopped cloud regimes for the high-latitude Southern Ocean will provide a refined tool for model evaluation and the attribution of shortwave radiation biases to distinct cloud processes and properties.

scholarly journals Stratosphere-troposphere separation of nitrogen dioxide columns from the TEMPO geostationary satellite instrument

2018 ◽  
Author(s):  
Jeffrey A. Geddes ◽  
Randall V. Martin ◽  
Eric J. Bucsela ◽  
Chris A. McLinden ◽  
Daniel J. M. Cunningham
Keyword(s):  
Real Time ◽  
Time Of Day ◽  
Low Earth Orbit ◽  
Satellite Observations ◽  
Spatial Coverage ◽  
Tropospheric No2 ◽  
Global Coverage ◽  
Factor Ratios ◽  
Small Parts ◽  
Global Algorithm

Abstract. Separating the stratospheric and tropospheric contributions in satellite retrievals of atmospheric NO2 column abundance is a crucial step in the interpretation and application of the satellite observations. A variety of stratosphere-troposphere separation algorithms have been developed for sun-synchronous instruments in low Earth orbit (LEO) that benefit from global coverage, including broad clean regions with negligible tropospheric NO2 compared to stratospheric NO2. These global sun-synchronous algorithms need to be evaluated and refined for forthcoming geostationary instruments focused on continental regions, which lack this global context and require hourly estimates of the stratospheric column. Here we develop and assess a spatial filtering algorithm for the upcoming TEMPO geostationary instrument that will target North America. Developments include using independent satellite observations to identify likely locations of tropospheric enhancements, using independent LEO observations for spatial context, consideration of diurnally-varying partial fields of regard, and a filter based on stratospheric to tropospheric air mass factor ratios. We test the algorithm with LEO observations from the OMI instrument with an afternoon overpass, and from the GOME-2 instrument with a morning overpass. We compare our TEMPO field of regard algorithm against an identical global algorithm to investigate the penalty resulting from the limited spatial coverage in geostationary orbit, and find excellent agreement in the estimated mean daily tropospheric NO2 column densities (R2 = 0.999, slope = 1.009 for July and R2 = 0.998, slope = 0.999 for January). The algorithm performs well even when only small parts of the continent are observed by TEMPO. The algorithm is challenged the most by east coast morning retrievals in the wintertime (e.g. R2 = 0.995, slope = 1.038 at 1400 UTC). We find independent global low Earth observations (corrected for time of day) provide important context near the field-of-regard edges. We also test the performance of the TEMPO algorithm without these supporting global observations. Most of the continent is unaffected (R2 = 0.924 and slope = 0.973 for July and R2 = 0.996 and slope = 1.008 for January), with 90 % of the pixels having differences of less than ±0.2 x 1015 molecules cm−2 between the TEMPO tropospheric NO2 column density and the global algorithm. For near-real-time retrieval, even a climatological estimate of the stratospheric NO2 surrounding the field of regard would improve this agreement. In general, the additional penalty of a limited field of regard from TEMPO introduces no more error than normally expected in most global stratosphere-troposphere separation algorithms. Overall, we conclude that hourly near-real-time stratosphere-troposphere separation for the retrieval of NO2 tropospheric column densities by the TEMPO geostationary instrument is both feasible and robust, regardless of the diurnally-varying limited field of regard.

scholarly journals Improved Mitigation Method for the Multipath Delays of BDS-3 Code Observations with the Aid of a Sparse Modeling Algorithm

2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Chao Hu ◽  
Qianxin Wang ◽  
Alberto Hernandez Moraleda
Keyword(s):  
Real Time ◽  
Satellite Observations ◽  
Global Navigation Satellite Systems ◽  
Single Frequency ◽  
Sparse Modeling ◽  
Satellite Systems ◽  
Station Coordinates ◽  
Point Positioning ◽  
Modeling Algorithm ◽  
Multipath Delay

Global navigation satellite systems are essential for positioning, navigation, and timing services. The quality and reliability of satellite observations determine the system performance, especially in the case of the newly launched global BDS-3 service. However, analyses of multipath delays in BDS-3 satellite observations suggest that there are appreciable errors at different frequencies. Improvement of the accuracy and precision of positioning, navigation, and timing services provided by BDS-3 requires the mitigation of multipath delays of the satellite observations. This paper models the multipath delays of BDS-3 observations using a least-squares combined autoregressive method. Furthermore, a sparse modeling algorithm is proposed to obtain a multipath delay series using total variation and elastic net terms for denoising and eliminating the effect of limited original observations. The estimated coefficients of multipath delays are then set as prior information to correct the next-arc code observations, where the square-root information filter is used in the coefficient estimation. Moreover, four groups of experiments are conducted to analyze the results of modeling the BDS-3 multipath delay using the proposed methods, with single-frequency precise point positioning (PPP) and real-time PPP solutions being selected to test the correction of multipath delays in BDS-3 code observations. The residuals of iGMAS and MGEX station coordinates indicate improvements in eastward, northward, and upward directions of at least 4.1%, 9.6%, and 1.2%, respectively, for the frequency B1I; 6.6%, 5.3%, and 0.2%, respectively, for B3I, 12.5%, 14.3%, and 3.8%, respectively, for B1C; and 5.9%, 7.4%, and 18.1%, respectively, for B2a relative to the use of the traditional method in BDS-3 single-frequency PPP. Furthermore, the real-time double-frequency PPP is optimized by at least 10% for B 1 I + B 3 I and B 1 C + B 2 a . An improved result was obtained with the proposed strategy in a standard point positioning experiment. The proposed multipath delay mitigation method is therefore effective in improving BDS-3 satellite code observations.

scholarly journals A regional real-time forecast of marine boundary layers during VOCALS-Rex

2010 ◽  
Vol 10 (8) ◽  
pp. 18419-18466 ◽  
Author(s):  
S. Wang ◽  
L. W. O'Neill ◽  
Q. Jiang ◽  
S. P. de Szoeke ◽  
X. Hong ◽  
...  
Keyword(s):  
Real Time ◽  
Large Scale ◽  
Marine Boundary Layer ◽  
Surface Wind ◽  
Lower Troposphere ◽  
Temporal Distribution ◽  
Satellite Observations ◽  
Naval Research ◽  
Strong Wind ◽  
The West

Abstract. This paper presents an evaluation and validation of the Naval Research Laboratory's COAMPS real-time forecasts during the VOCALS-Rex over the area off the west coast of Chile/Peru in the Southeast Pacific during October and November 2008. The analyses focus on the marine boundary layer (MBL) structure. These forecasts are compared with lower troposphere soundings, surface measurements, and satellite observations. The predicted mean MBL cloud and surface wind spatial distributions are in good agreement with the satellite observations. The large-scale longitudinal variation of the MBL structure along 20° S is captured by the forecasts. That is, the MBL heights increase toward the open ocean, the moisture just above the inversion decreases, and the MBL structure becomes more decoupled offshore. The observed strong wind shear across the cloud-top inversion in coastal area at 20° S was correctly predicted by the model. Our results show that the sporadic cloud spatial and temporal distribution in the 15 km grid mesh is caused by grid-scale convection likely due to a lack of a shallow cumulus convection parameterization in the model. Both observations and model forecasts show wind speed maxima near the top of MBL along 20° S, which is consistent with the west-ward upslope of the MBL heights based on the thermal wind relationship. The forecasts produced well-defined diurnal variations in the spatially averaged MBL structure, although the overall signal is weaker than those derived from the in situ measurements and satellite data. The MBL heights are generally underpredicted in the nearshore area. The analysis of the sensitivity simulations with regard to grid resolution suggests that the under-prediction is likely associated with over-prediction of the mesoscale downward motion and cold advection along the coast.

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