Estimating surface longwave radiative fluxes from satellites utilizing artificial neural networks

Nussbaumer, E.; Pinker, R. T.

doi:10.1029/2011jd017141

Cited by 23 publications

(17 citation statements)

References 52 publications

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“…Earlier estimates of E l↓ were based on surface measurements of air temperature and humidity and observations of cloud cover (Brunt, ) justified by the fact that the greater part of the down‐welling long‐wave flux is emitted from the near surface layers of the atmosphere (Elsasser, , Nussbaumer and Pinker, ). Recent studies have confirmed that surface measurements of air temperature and humidity when combined as specific humidity provide an accurate proxy for measurements of E l↓ under all sky conditions and over a wide range of climates.…”

Section: Introductionmentioning

confidence: 94%

Estimating long‐wave radiation at the Earth's surface from measurements of specific humidity

Rosa

Stanhill

2013

Intl Journal of Climatology

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ABSTRACT:The relationship between specific humidity (q) and down-welling long-wave radiation (E l↓ ) was investigated on a daily, monthly and annual basis for 39 widely distributed sites of the Baseline Surface Radiation Network (BSRN) and validated using two additional BSRN sites. A power relationship between E l↓ and q was fitted to the data for each site; the constant did not change significantly with time and geographic location. Neither the mean value of q nor the residual value of E l↓ changed significantly between 1998 and 2011, suggesting the applicability of the relationship over periods without large changes in the Earth's temperature and/or concentration of H 2 O. The root mean square error for both the calibration and validation sites was comparable to that reported for both direct measurements and satellite-derived estimates for daily, monthly and annual periods. The power relationships were weaker for three tropical sites located in the Pacific Ocean, where the seasonal variation in q was smaller than at the other sites. For the remaining stations, a common power relationship, E l↓ = 212.64 q 0.22 , enabled monthly values of E l↓ to be accurately estimated from widely available measurements of air temperature, humidity and pressure at the Earth's surface.KEY WORDS surface long-wave radiation from specific humidity; temporal and spatial variations

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Section: Introductionmentioning

confidence: 94%

Estimating long‐wave radiation at the Earth's surface from measurements of specific humidity

Rosa

Stanhill

2013

Intl Journal of Climatology

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“…The fluxes are derived globally and gridded to 0.5° at 3 hourly time scale from July 1983 to December 2009; they include both SW↓ [ Ma and Pinker , ] and LW↓ [ Nussbaumer and Pinker , ] flux components. For the period from January 2002 to December 2012, using an inference scheme labeled as UMD_MODIS_SW for SW↓ [ Wang and Pinker , ] and UMD_MODIS_LW for LW↓ [ Nussbaumer and Pinker , ], they are implemented globally with products from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor both on Aqua and Terra [ King et al ., ] at 1° spatial resolution at daily time scale (additional details on the ISCCP DX‐based data are presented in Appendix ). Methodology how to homogenize the satellite estimates from the two independent sources, namely, ISCCP DX and Modis, is described in Appendix . ERA‐Interim (ERA‐I) [ Berrisford et al ., ; Dee et al ., ] data as downloaded from http://rda.ucar.edu.…”

Section: Data To Be Usedmentioning

confidence: 99%

The net energy budget at the ocean‐atmosphere interface of the “Cold Tongue” region

et al. 2017

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Pacific “Cold Tongue” (PCT) sea surface temperature (SST) experiences significant (>0.5°C) interannual variations forced by the El‐Nino Southern Oscillations (ENSO) with global impacts on the Earth climate. In this study, we estimate the PCT net heat budget known to be difficult to derive using numerical models. The main goal is to determine how accurately the net heat flux across the surface/atmosphere interface can currently be determined primarily, from satellite observations; these are first evaluated against the nearest available observations inside and outside the PCT of the Tropical Pacific Ocean, using buoy arrays such as the Tropical Atmosphere Ocean/Triangle Trans‐Ocean Buoy Network (TAO/TRITON). It was found that the satellite‐based estimates of both turbulent and radiative fluxes are in better agreement with the observations than similar estimates from leading numerical models. The monthly mean satellite estimates of PCT SW↓ during January/July 2009 were 273.07/170.14, for LW↓, latent heat and sensible heat they were 378.79/365.54, 95.52/130.31, 9.89/20.67, respectively (all in W/m2). The estimated standard deviations for PCT SW↓ were in the range of 7.2–7.8% of the mean and in the range of 2.0–2.5% for LW↓, at daily time scale. Satellite estimates of both PCT LHF and SHF exhibit much higher variability, characterized by standard deviations of 50% from the mean values.

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“…Methodologies to derive radiative fluxes from long‐term satellite observations are described, for example, in Zhang et al . [] and Ma and Pinker [], methods that use more recent satellite observations (as also used in this study) are described in Wang and Pinker [] and Nussbaumer and Pinker []. The methodologies how the various fluxes were computed will be summarized in section 2.…”

Section: Introductionmentioning

confidence: 99%

Estimates of net heat fluxes over the Atlantic Ocean

et al. 2014

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[1] Many studies have been undertaken to evaluate turbulent heat fluxes at the oceanatmosphere interface; less was done on the total net heat flux. We will compare heat budgets at the ocean-atmosphere interface as derived from satellites and from blended products, compare them to in situ observations, identify the location of largest differences, and attempt to explain reasons for these differences. The results over the Atlantic Sector (50 S-50 N) for a 3 year period show that differences in the turbulent fluxes among two widely used approaches are overshadowed by differences in the radiative fluxes. While the maximum difference in sensible and latent heat fluxes can be about 30 W/m 2 , the mean values for latent heat fluxes are 22.27 W/m 2 for January and 5.40 W/m 2 for July. For sensible heat, they are 2.82 W/m 2 for January and 5.64 W/m 2 for July. We show that the maximum difference in net radiative fluxes can be as high as 55 W/m 2 , for January, the mean difference in net SW is 6.31 W/m 2 and in net LW it is 12.14 W/m 2 . For July, the respective differences are 29.99 W/m 2 for the SW and 14.31 W/m 2 for the LW. Relationships between the fluxes and satellite derived surface wind speed, total precipitable water, and cloud cover provide insight on the dominant processes that control the net heat flux. This study is intended to present an estimate of uncertainties that still exist in the net heat flux at the ocean-atmosphere interface.

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Estimating surface longwave radiative fluxes from satellites utilizing artificial neural networks

Cited by 23 publications

References 52 publications

Estimating long‐wave radiation at the Earth's surface from measurements of specific humidity

Estimating long‐wave radiation at the Earth's surface from measurements of specific humidity

The net energy budget at the ocean‐atmosphere interface of the “Cold Tongue” region

Estimates of net heat fluxes over the Atlantic Ocean

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