CYGNSS Surface Heat Flux Product Development

Ocean surface heat fluxes play a significant role in the genesis and evolution of various marine-based atmospheric phenomena, from the synoptic scale down to the microscale. While in-situ measurements from buoys and flux towers will continue to be the standard in regard to surface heat flux estimates, they commonly have significant gaps in temporal and spatial coverage. Previous and current satellite missions have filled these gaps; though they may not observe the fluxes directly, they can measure the variables needed (wind speed, temperature and humidity) to estimate latent and sensible heat fluxes. However, current remote sensing instruments have their own limitations, such as infrequent coverage, signals attenuated by precipitation or both. The Cyclone Global Navigation Satellite System (CYGNSS) mission overcomes these limitations over the tropical and subtropical oceans by providing improved coverage in nearly all weather conditions. While CYGNSS (Level 2) primarily estimates surface winds, when coupled with observations or estimates of temperature and humidity from reanalysis data, it can provide estimates of latent and sensible heat fluxes along its orbit. This paper describes the development of the Surface Heat Flux Product for the CYGNSS mission, its current results and expected improvements and changes in future releases.

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CYGNSS Surface Heat Flux Product Development

10.20944/preprints201908.0250.v1 ◽

2019 ◽

Author(s):

Juan A. Crespo ◽

Derek J. Posselt ◽

Shakeel Asharaf

Keyword(s):

Heat Flux ◽

Surface Heat Flux ◽

Weather Conditions ◽

Satellite System ◽

Reanalysis Data ◽

Surface Heat ◽

Heat Fluxes ◽

Sensible Heat ◽

Spatial Coverage ◽

Temperature And Humidity

Ocean surface heat fluxes play a significant role in the genesis and evolution of various marine-based atmospheric phenomena, from the synoptic scale down to the microscale. While in-situ measurements from buoys and flux towers will continue to be the standard in regards to surface heat flux estimates, they commonly have significant gaps in temporal and spatial coverage. Previous and current satellite missions have filled these gaps; though they may not observe the fluxes directly, they can measure the variables needed (wind speed, temperature, and humidity) to estimate latent and sensible heat fluxes. However, current remote sensing instruments have their own limitations, such as infrequent coverage, signals attenuated by precipitation, or both. The Cyclone Global Navigation Satellite System (CYGNSS) mission overcomes these limitations over the tropical and subtropical oceans by providing improved coverage in nearly all weather conditions. While CYGNSS (Level 2) primarily estimates surface winds, when coupled with observations or estimates of temperature and humidity from reanalysis data, it can provide estimates of latent and sensible heat fluxes along its orbit. This paper describes the development of the Surface Heat Flux Product for the CYGNSS mission, its current results, and expected improvements and changes in future releases.

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The progress on the observation and modeling of surface heat fluxes and evapotranspiration over heterogeneous landscapes of the Third Pole region

10.5194/egusphere-egu2020-1687 ◽

2020 ◽

Author(s):

Yaoming Ma

Keyword(s):

Heat Flux ◽

Latent Heat Flux ◽

Land Surface ◽

Sensible Heat Flux ◽

Surface Heat ◽

Heat Fluxes ◽

Sensible Heat ◽

Surface Heat Fluxes ◽

The Third ◽

Land Surface Heat Fluxes

<p>The exchange of heat and water vapor between land surface and atmosphere over the Third Pole region (Tibetan Plateau and nearby surrounding region) plays an important role in Asian monsoon, westerlies and the northern hemisphere weather and climate systems. Supported by various agencies in the People&#8217;s Republic of China, a Third Pole Environment (TPE) observation and research Platform (TPEORP) is now implementing over the Third Pole region. The background of the establishment of the TPEORP, the establishing and monitoring plan of long-term scale (5-10 years) of it will be shown firstly. Then the preliminary observational analysis results, such as the characteristics of land surface energy fluxes partitioning and the turbulent characteristics will also been shown in this study. Then, the parameterization methodology based on satellite data and the atmospheric boundary layer (ABL) observations has been proposed and tested for deriving regional distribution of net radiation flux, soil heat flux, sensible heat flux and latent heat flux (evapotranspiration (ET)) and their variation trends over the heterogeneous landscape of the Tibetan Plateau (TP) area. To validate the proposed methodology, the ground measured net radiation flux, soil heat flux, sensible heat flux and latent heat flux of the TPEORP are compared to the derived values. The results showed that the derived land surface heat fluxes over the study areas are in good accordance with the land surface status. These parameters show a wide range due to the strong contrast of surface feature. And the estimated land surface heat fluxes are in good agreement with ground measurements, and all the absolute percent difference in less than 10% in the validation sites. The sensible heat flux has increased slightly and the latent heat flux has decreased from 2001 to 2016 over the TP. It is therefore conclude that the proposed methodology is successful for the retrieval of land surface heat fluxes and ET over heterogeneous landscape of the TP area. Further improvement of the methodology and its applying field over the whole Third Pole region and Pan-Third Pole region were also discussed.</p>

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Simulations of Processes Associated with the Fast Warming Rate of the Southern Midlatitude Ocean

Journal of Climate ◽

10.1175/2009jcli3081.1 ◽

2010 ◽

Vol 23 (1) ◽

pp. 197-206 ◽

Cited By ~ 44

Author(s):

Wenju Cai ◽

Tim Cowan ◽

Stuart Godfrey ◽

Susan Wijffels

Keyword(s):

Twentieth Century ◽

Heat Flux ◽

Surface Heat Flux ◽

Heat Content ◽

Surface Heat ◽

Heat Fluxes ◽

Ekman Transport ◽

Content Increase ◽

Intergovernmental Panel ◽

Zonal Distribution

Abstract Significant warming has occurred across many of the world’s oceans throughout the latter part of the twentieth-century. The increase in the oceanic heat content displays a considerable spatial difference, with a maximum in the 35°–50°S midlatitude band. The relative importance of wind and surface heat flux changes in driving the warming pattern is the subject of much debate. Using wind, oceanic temperature, and heat flux outputs from twentieth-century multimodel experiments, conducted for the Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change (IPCC), the authors were able to reproduce the fast, deep warming in the midlatitude band; however, this warming is unable to be accounted for by local heat flux changes. The associated vertical structure and zonal distribution are consistent with a Sverdrup-type response to poleward-strengthening winds, with a poleward shift of the Southern Hemisphere (SH) supergyre and the Antarctic Circumpolar Current. However, the shift is not adiabatic and involves a net oceanic heat content increase over the SH, which can only be forced by changes in the net surface heat flux. Counterintuitively, the heat required for the fast, deep warming is largely derived from the surface heat fluxes south of 50°S, where the surface flux into the ocean is far larger than that of the midlatitude band. The heat south of 50°S is advected northward by an enhanced northward Ekman transport induced by the poleward-strengthening winds and penetrates northward and downward along the outcropping isopycnals to a depth of over 1000 m. However, because none of the models resolve eddies and given that eddy fluxes could offset the increase in the northward Ekman transport, the heat source for the fast, deep warming in the midlatitude band could be rather different in the real world.

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Extratropical cyclone induced sea surface temperature anomalies in the 2013/14 winter

10.5194/wcd-2019-6 ◽

2019 ◽

Author(s):

Helen F. Dacre ◽

Simon A. Josey ◽

Alan L. M. Grant

Keyword(s):

Heat Flux ◽

North Atlantic ◽

Surface Heat Flux ◽

Cold Front ◽

Winter Season ◽

Surface Heat ◽

Heat Fluxes ◽

Sea Surface ◽

Extratropical Cyclones ◽

Sst Cooling

Abstract. The 2013/14 winter averaged sea surface temperature (SST) was anomalously cool in the mid-North Atlantic region. This season was also unusually stormy with extratropical cyclones passing over the mid-North Atlantic every 3 days. However, the processes by which cyclones contribute towards seasonal SST anomalies are not fully understood. In this paper a cyclone identification and tracking method is combined with ECMWF atmosphere and ocean reanalysis fields to calculate cyclone-relative net surface heat flux anomalies and resulting SST changes. Anomalously large negative heat fluxes are located behind the cyclones cold front resulting in anomalous cooling up to 0.2 K/day when the cyclones are at maximum intensity. This extratropical cyclone induced cold wake extends along the cyclones cold front but is small compared to climatological variability. To investigate the potential cumulative effect of the passage of multiple cyclone induced SST cooling in the same location we calculate Earth-relative net surface heat flux anomalies and resulting SST changes for the 2013/2014 winter period. Anomalously large winter averaged negative heat fluxes occur in a zonally orientated band extending across the North Atlantic between 40–60° N. The anomaly associated with cyclones is estimated using a cyclone masking technique which encompasses each cyclone centre and its trailing cold front. North Atlantic extratropical cyclones in the 2013/14 winter season account for 78 % of the observed net surface heat flux in the mid- North Atlantic and net surface heat fluxes in the 2013/14 winter season account for 70 % of the observed cooling in the mid-North Atlantic. Thus extratropical cyclones play a major role in determining the extreme 2013/2014 winter season SST cooling.

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Estimation of Land Surface Heat Fluxes Based on Landsat 7 ETM+ Data and Field Measurements over the Northern Tibetan Plateau

Remote Sensing ◽

10.3390/rs11242899 ◽

2019 ◽

Vol 11 (24) ◽

pp. 2899

Author(s):

Nan Ge ◽

Lei Zhong ◽

Yaoming Ma ◽

Meilin Cheng ◽

Xian Wang ◽

...

Keyword(s):

Heat Flux ◽

Latent Heat ◽

Latent Heat Flux ◽

Land Surface ◽

Sensible Heat Flux ◽

Surface Heat ◽

Heat Fluxes ◽

Sensible Heat ◽

Surface Heat Fluxes ◽

Land Surface Heat Fluxes

Land surface heat fluxes consist of the net radiation flux, soil heat flux, sensible heat flux, and latent heat flux. The estimation of these fluxes is essential to the study of energy transfer in land–atmosphere systems. In this paper, Landsat 7 ETM+ SLC-on data were applied to estimate the land surface heat fluxes on the northern Tibetan Plateau using the SEBS (surface energy balance system) model, in combination with the calculation of field measurements at CAMP/Tibet (Coordinated Enhanced Observing Period (CEOP) Asia–Australia Monsoon Project on the Tibetan Plateau) automatic weather stations based on the combinatory method (CM) for comparison. The root mean square errors between the satellite estimations and the CM calculations for the net radiation flux, soil heat flux, sensible heat flux, and latent heat flux were 49.2 W/m2, 46.3 W/m2, 68.2 W/m2, and 54.9 W/m2, respectively. The results reveal that land surface heat fluxes all present significant seasonal variability. Apart from the sensible heat flux, the satellite-estimated net radiation flux, soil heat flux, and latent heat flux exhibited a trend of summer > spring > autumn > winter. In summer, spring, autumn, and winter, respectively, the median values of the net radiation flux (631.8 W/m2, 583.0 W/m2, 404.4 W/m2, 314.3 W/m2), soil heat flux (40.9 W/m2, 37.9 W/m2, 26.1 W/m2, 20.5 W/m2), sensible heat flux (252.7 W/m2, 219.5 W/m2, 221.4 W/m2, 204.8 W/m2), and latent heat flux (320.1 W/m2, 298.3 W/m2, 142.3 W/m2, 75.5 W/m2) exhibited distinct seasonal diversity. From November to April, the in situ sensible heat flux is higher than the latent heat flux; the opposite is true between June and September, leaving May and October as transitional months. For water bodies, alpine meadows and other main underlying surface types, sensible and latent heat flux generally present contrasting and complementary spatial distributions. Due to the 15–60 m resolution of the Landsat 7 ETM+ data, the distribution of land surface heat fluxes can be used as an indicator of complex underlying surface types over the northern Tibetan Plateau.

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Impact of Soil Moisture Data Resolution on Soil Moisture and Surface Heat Flux Estimates through Data Assimilation: A Case Study in the Southern Great Plains

Journal of Hydrometeorology ◽

10.1175/jhm-d-18-0234.1 ◽

2019 ◽

Vol 20 (4) ◽

pp. 715-730 ◽

Cited By ~ 4

Author(s):

Yang Lu ◽

Jianzhi Dong ◽

Susan C. Steele-Dunne

Keyword(s):

Heat Flux ◽

Soil Moisture ◽

Spatial Resolution ◽

Surface Heat Flux ◽

Root Zone ◽

Sampling Frequency ◽

Surface Heat ◽

Heat Fluxes ◽

Soil Moisture Data ◽

Temporal Sampling

Abstract The spatial heterogeneity and temporal variation of soil moisture and surface heat fluxes are key to many geophysical and environmental studies. It has been demonstrated that they can be mapped by assimilating soil thermal and wetness information into surface energy balance models. The aim of this work is to determine whether enhancing the spatial resolution or temporal sampling frequency of soil moisture data could improve soil moisture or surface heat flux estimates. Two experiments are conducted in an area mainly covered by grassland, and land surface temperature (LST) observations from the Geostationary Operational Environmental Satellite (GOES) mission are assimilated together with either an enhanced L-band passive soil moisture product (9 km, 2–3 days) from the Soil Moisture Active Passive (SMAP) mission or a merged product (36 km, quasi-daily) from the SMAP and the Soil Moisture Ocean Salinity (SMOS) mission. The results suggest that the availability of soil moisture observations is increased by 41% after merging data from the SMAP and the SMOS missions. A comparison with results from a previous study that assimilated a coarser SMAP soil moisture product (36 km, 2–3 days) suggests that enhancing the temporal sampling frequency of soil moisture observations leads to improved soil moisture estimates at both the surface and root zone, and the largest improvement is seen in the bias metric (0.008 and 0.007 m3 m−3 on average at the surface and root zone, respectively). Enhancing the spatial resolution, however, does not significantly improve soil moisture estimates, particularly at the surface. Surface heat flux estimates from assimilating soil moisture data of different spatial or temporal resolutions are very similar.

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On the relationship between CYGNSS surface heat fluxes and the lifecycle of low-latitude ocean extratropical cyclones

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-21-0074.1 ◽

2021 ◽

Author(s):

Catherine M. Naud ◽

Juan A. Crespo ◽

Derek J. Posselt

Keyword(s):

Heat Flux ◽

Surface Heat ◽

Heat Fluxes ◽

Extratropical Cyclone ◽

Extratropical Cyclones ◽

Sensible Heat ◽

Low Latitude ◽

Surface Heat Fluxes ◽

Cold Fronts ◽

Warm Sector

AbstractSurface latent and sensible heat fluxes are important for extratropical cyclone evolution and intensification. Because extratropical cyclone genesis often occurs at low-latitude, CYGNSS surface latent and sensible heat flux retrievals are composited to provide a mean picture of their spatial distribution in low-latitude oceanic extratropical cyclones. CYGNSS heat fluxes are not affected by heavy precipitation and offer observations of storms with frequent revisit times. Consistent with prior results obtained for cyclones in the Gulf Stream region, the fluxes are strongest in the wake of the cold fronts, and weakest to negative in the warm sector in advance of the cold fronts. As cyclone strength increases, or mean precipitable water decreases, the maximum in surface heat fluxes increases while the minimum decreases. This impacts the changes in fluxes during cyclone intensification: the post-cold frontal surface heat flux maximum increases due to the increase in near surface winds. During cyclone dissipation, the fluxes in this sector decrease, due to the decrease in winds and in temperature and humidity contrast. The warm sector minimum decreases throughout the entire cyclone lifetime and is mostly driven by sea-air temperature and humidity contrast changes. However, during cyclone dissipation, the surface heat fluxes increase along the cold front in a narrow band to the east, independently from changes in the cyclone characteristics. This suggests that, during cyclone dissipation, energy transfers from the ocean to the atmosphere are linked to frontal in addition to synoptic-scale processes.

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The Measurement of Surface Heat Flux Using the Peltier Effect

Journal of Heat Transfer ◽

10.1115/1.3250754 ◽

1989 ◽

Vol 111 (3) ◽

pp. 798-803 ◽

Cited By ~ 12

Author(s):

E. C. Shewen ◽

K. G. T. Hollands ◽

G. D. Raithby

Keyword(s):

Heat Transfer ◽

Heat Flux ◽

Surface Heat Flux ◽

Surface Heat ◽

Heat Fluxes ◽

Physical Models ◽

Peltier Effect ◽

Absolute Accuracy ◽

Measuring Surface ◽

Wide Range

Calorimetric methods for measuring surface heat flux use Joulean heating to keep the surface isothermal. This limits them to measuring the heat flux of surfaces that are hotter than their surroundings. Presented in this paper is a method whereby reversible Peltier effect heat transfer is used to maintain this isothermality, making it suitable for surfaces that are either hotter or colder than the surroundings. The paper outlines the theory for the method and describes physical models that have been constructed, calibrated, and tested. The tested physical models were found capable of measuring heat fluxes with an absolute accuracy of 1 percent over a wide range of temperature (5–50°C) and heat flux (15–500 W/m2), while maintaining isothermality to within 0.03 K. A drawback of the method is that it appears to be suited only for measuring the heat flux from thick metallic plates.

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Dynamic Calibration of a Coaxial Thermocouples for Short Duration Transient Measurements

Journal of Heat Transfer ◽

10.1115/1.4024593 ◽

2013 ◽

Vol 135 (12) ◽

Cited By ~ 17

Author(s):

Rakesh Kumar ◽

Niranjan Sahoo

Keyword(s):

Heat Flux ◽

Finite Element ◽

Heat Conduction ◽

Surface Heat Flux ◽

Surface Heat ◽

Heat Fluxes ◽

Dynamic Calibration ◽

One Dimensional ◽

Surface Heat Fluxes ◽

Heat Loads

Coaxial thermocouple sensors are suitable for measuring highly transient surface heat fluxes because the response times of these sensors are very small (∼0.1 ms). These robust sensors have the flexibility of mounting them directly on the surface of any geometry. So, they have been routinely used in ground-based impulse facilities as temperature sensors where rapid changes in heat loads are expected on aerodynamic models. Subsequently, the surface heat fluxes are predicted from the transient temperatures by appropriate one-dimensional heat conduction modeling for semi-infinite body. In this backdrop, the purpose of this work is to design and fabricate K-type coaxial thermocouples in-house and calibrate them under similar nature of heat loads by using simple laboratory instruments. Here, two methods of dynamic calibration of coaxial thermocouples have been discussed, where the known step loads are applied through radiation and conduction modes of heat transfer. Using appropriate one dimensional heat conduction modeling, the surface heat fluxes are predicted from the measured temperature histories and subsequently compared with the input heat loads. The recovery of surface heat flux from laser based calibration experiment under-predicts by 4% from its true input heat load. Similarly, recovery of surface heat flux from the conduction mode calibration experiments under-predicts 6% from its true input value. Further, finite-element based numerical study is performed on the coaxial thermocouple model to obtain surface temperatures with same heat loads as used in the experiments. The recovery of surface temperatures from finite element simulation is achieved within an accuracy of ±0.3% from the experiment.

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Measurements of Burnout Conditions for Flow of Boiling Water in a Vertical Annulus

Journal of Heat Transfer ◽

10.1115/1.3688706 ◽

1964 ◽

Vol 86 (3) ◽

pp. 393-404 ◽

Cited By ~ 6

Author(s):

K. M. Becker ◽

G. Hernborg

Keyword(s):

Heat Flux ◽

Surface Heat Flux ◽

Flow Model ◽

Film Flow ◽

Surface Heat ◽

Heat Fluxes ◽

Nonuniform Heating ◽

Steam Quality ◽

Internal Heating ◽

Inner Surface

The present paper deals with measurements of burnout conditions for flow of boiling water in an annulus with an inner diameter of 9.92 mm, an outer diameter of 17.42 mm, and a heated length of 608 mm. Data were obtained in respect of external heating only, internal heating only, and dual uniform and nonuniform heating. The following ranges of variables were studied and 978 burnout measurements were obtained. Pressure: 8.5 < p < 37.5 kg/cm2; Inlet subcooling: 60 < Δtsub < 205 deg C; Steam quality: 0.10 < x < 0.91; Inner surface heat flux: 0 < (q/A)i < 303 W/cm2; Outer surface heat flux: 0 < (q/A)0 < 374 W/cm2; Mass velocity: 71 < m˙/F < 961 kg/m2sec. The results are presented in diagrams where the burnout steam qualities, xBO, were plotted against the pressure with the surface heat fluxes as parameters. The data have been correlated by curves. The scatter of the data around the curves is less than ±5 percent. In the case of equal heat fluxes on both walls of the annulus, burnout always occurred on the inner wall, and the data compared rather well with round duct data. When the annulus was heated internally only, the data showed very low burnout values in comparison with the results for dual heating and round ducts. This disagreement was explained by considering the climbing film flow model and by the fact that only a fraction of the channel perimeter was heated. For external heating the data are somewhat lower than corresponding round duct data, but rather high in comparison with internal heating. The climbing film flow model was also used to interpret this observation. For dual nonuniform heating it was found that the outer surface may be overloaded from 30 to 70 percent compared with the inner surface without reducing the margin of safety in respect to burnout for the annulus. It was further observed that when the heat flux for the wall on which burnout occurs is increased, the burnout steam quality for the channel decreases. If, however, the heat flux for the opposite wall is increased, the burnout steam quality also increases. It was also observed that the highest burnout values are obtained when burnout occurs simultaneously on both cylinders. Finally, the results have been compared with annuli and rod cluster data in published works, and a method for predicting burnout conditions in rod clusters has been proposed.

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