A comparison of Argo nominal surface and near-surface temperature for validation of AMSR-E SST

AbstractWe explore the decoupling physics of a stratocumulus-topped boundary layer (STBL) moving over cooler water, a situation mimicking the warm air advection (WADV). We simulate an initially well-mixed STBL over a doubly periodic domain with the sea surface temperature decreasing linearly over time using the System for Atmospheric Modeling large-eddy model. Due to the surface cooling, the STBL becomes increasingly stably stratified, manifested as a near-surface temperature inversion topped by a well-mixed cloud-containing layer. Unlike the stably stratified STBL in cold air advection (CADV) that is characterized by cumulus coupling, the stratocumulus deck in the WADV is unambiguously decoupled from the sea surface, manifested as weakly negative buoyancy flux throughout the sub-cloud layer. Without the influxes of buoyancy from the surface, the convective circulation in the well-mixed cloud-containing layer is driven by cloud-top radiative cooling. In such a regime, the downdrafts propel the circulation, in contrast to that in CADV regime for which the cumulus updrafts play a more determinant role. Such a contrast in convection regime explains the difference in many aspects of the STBLs including the entrainment rate, cloud homogeneity, vertical exchanges of heat and moisture, and lifetime of the stratocumulus deck, with the last being subject to a more thorough investigation in part 2. Finally, we investigate under what conditions a secondary stratus near the surface (or fog) can form in the WADV. We found that weaker subsidence favors the formation of fog whereas a more rapid surface cooling rate doesn’t.

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Relative Role of Turbulent and Radiative Flux on the Near-Surface Temperature in a Single-Layer Urban Canopy Model over Houston

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-17-0088.1 ◽

2017 ◽

Vol 56 (8) ◽

pp. 2173-2187 ◽

Cited By ~ 8

Author(s):

James Brownlee ◽

Pallav Ray ◽

Mukul Tewari ◽

Haochen Tan

Keyword(s):

Heat Flux ◽

Surface Temperature ◽

Single Layer ◽

Urban Canopy ◽

Heat Fluxes ◽

Radiative Flux ◽

Hydrological Processes ◽

Urban Canopy Model ◽

Near Surface ◽

Canopy Model

AbstractNumerical simulations without hydrological processes tend to overestimate the near-surface temperatures over urban areas. This is presumably due to underestimation of surface latent heat flux. To test this hypothesis, the existing single-layer urban canopy model (SLUCM) within the Weather Research and Forecasting Model is evaluated over Houston, Texas. Three simulations were conducted during 24–26 August 2000. The simulations include the use of the default “BULK” urban scheme, the SLUCM without hydrological processes, and the SLUCM with hydrological processes. The results show that the BULK scheme was least accurate, and it overestimated the near-surface temperatures and winds over the urban regions. In the presence of urban hydrological processes, the SLUCM underestimates these parameters. An analysis of the surface heat fluxes suggests that the error in the BULK scheme is due to a lack of moisture at the urban surface, whereas the error in the SLUCM with hydrological processes is due to increases in moisture at the urban surface. These results confirm earlier studies in which changes in near-surface temperature were primarily due to the changes in the turbulent (latent and sensible heat) fluxes in the presence of hydrological processes. The contribution from radiative flux was about one-third of that from turbulent flux. In the absence of hydrological processes, however, the results indicate that the changes in radiative flux contribute more to the near-surface temperature changes than the turbulent heat flux. The implications of these results are discussed.

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Investigating the role of dust in ice nucleation within clouds and further effects on the regional weather system over East Asia – Part II: modification of the weather system

10.5194/acp-2017-755 ◽

2017 ◽

Author(s):

Lin Su ◽

Jimmy C.H. Fung

Keyword(s):

Surface Temperature ◽

East Asia ◽

South China ◽

Indirect Effects ◽

Convective Precipitation ◽

Wave Radiation ◽

Direct And Indirect Effects ◽

Weather System ◽

Near Surface ◽

Atmospheric Instability

Abstract. An updated version of the Weather Research and Forecast model coupled with Chemistry (WRF-Chem) was applied to quantify and discuss the full effects of dust on the meteorological field over East Asia during March and April 2012. The performances of the model in simulating the short-wave and long-wave radiation, surface temperature, and precipitation over East Asia are improved by incorporating the effects of dust in the simulations. The radiative forcing induced by the dust-enhanced cloud radiative effect is over one order of magnitude larger than that induced by the direct effect of dust. The semi-direct and indirect effects of dust result in a substantial increase in mid- to high clouds, and a significant reduction in low clouds, leading to a decrease of near-surface temperature and an increase of temperature at the mid- to upper troposphere over East Asia. The spatial redistribution of atmospheric water vapor and modification of the vertical temperature profile over East Asia lead to an inhibition of atmospheric instability over most land areas, but an enhancement of atmospheric instability over South China and the ocean, resulting in a significant inhibition of convective precipitation in areas from central to East China, and a substantial enhancement of convective precipitation over South China. Meanwhile, non-convective precipitation is also reduced significantly over East Asia, as cloud droplets are hindered from growing large enough to form rain droplets, due to the semi-direct and indirect effects of dust. The total precipitation can be reduced or increased by up to 20 % or more.

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Model-dependence of the CO<sub>2</sub> threshold for melting the hard Snowball Earth

Climate of the Past ◽

10.5194/cp-7-17-2011 ◽

2011 ◽

Vol 7 (1) ◽

pp. 17-25 ◽

Cited By ~ 18

Author(s):

Y. Hu ◽

J. Yang ◽

F. Ding ◽

W. R. Peltier

Keyword(s):

Surface Temperature ◽

Greenhouse Effect ◽

Surface Albedo ◽

Snowball Earth ◽

Pressure Broadening ◽

Near Surface ◽

Induced Absorption ◽

Cloud Forcing ◽

Clear Sky ◽

Convective Model

Abstract. One of the critical issues of the Snowball Earth hypothesis is the CO2 threshold for triggering the deglaciation. Using Community Atmospheric Model version 3.0 (CAM3), we study the problem for the CO2 threshold. Our simulations show large differences from previous results (e.g. Pierrehumbert, 2004, 2005; Le Hir et al., 2007). At 0.2 bars of CO2, the January maximum near-surface temperature is about 268 K, about 13 K higher than that in Pierrehumbert (2004, 2005), but lower than the value of 270 K for 0.1 bar of CO2 in Le Hir et al. (2007). It is found that the difference of simulation results is mainly due to model sensitivity of greenhouse effect and longwave cloud forcing to increasing CO2. At 0.2 bars of CO2, CAM3 yields 117 Wm−2 of clear-sky greenhouse effect and 32 Wm−2 of longwave cloud forcing, versus only about 77 Wm−2 and 10.5 Wm−2 in Pierrehumbert (2004, 2005), respectively. CAM3 has comparable clear-sky greenhouse effect to that in Le Hir et al. (2007), but lower longwave cloud forcing. CAM3 also produces much stronger Hadley cells than that in Pierrehumbert (2005). Effects of pressure broadening and collision-induced absorption are also studied using a radiative-convective model and CAM3. Both effects substantially increase surface temperature and thus lower the CO2 threshold. The radiative-convective model yields a CO2 threshold of about 0.21 bars with surface albedo of 0.663. Without considering the effects of pressure broadening and collision-induced absorption, CAM3 yields an approximate CO2 threshold of about 1.0 bar for surface albedo of about 0.6. However, the threshold is lowered to 0.38 bars as both effects are considered.

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Extreme Drought Events over the Amazon Basin: The Perspective from the Reconstruction of South American Hydroclimate

Water ◽

10.3390/w10111594 ◽

2018 ◽

Vol 10 (11) ◽

pp. 1594 ◽

Cited By ~ 6

Author(s):

Beatriz Garcia ◽

Renata Libonati ◽

Ana Nunes

Keyword(s):

Surface Temperature ◽

Extreme Events ◽

General Circulation ◽

Amazon Basin ◽

General Circulation Models ◽

Extreme Drought ◽

Severe Drought ◽

South American ◽

Spatial And Temporal Patterns ◽

Near Surface

The Amazon basin has experienced severe drought events for centuries, mainly associated with climate variability connected to tropical North Atlantic and Pacific sea surface temperature anomalous warming. Recently, these events are becoming more frequent, more intense and widespread. Because of the Amazon droughts environmental and socioeconomic impacts, there is an increased demand for understanding the characteristics of such extreme events in the region. In that regard, regional models instead of the general circulation models provide a promising strategy to generate more detailed climate information of extreme events, seeking better representation of physical processes. Due to uneven spatial distribution and gaps found in station data in tropical South America, and the need of more refined climate assessment in those regions, satellite-enhanced regional downscaling for applied studies (SRDAS) is used in the reconstruction of South American hydroclimate, with hourly to monthly outputs from January 1998. Accordingly, this research focuses on the analyses of recent extreme drought events in the years of 2005 and 2010 in the Amazon Basin, using the SRDAS monthly means of near-surface temperature and relative humidity, precipitation and vertically integrated soil moisture fields. Results from this analysis corroborate spatial and temporal patterns found in previous studies on extreme drought events in the region, displaying the distinctive features of the 2005 and 2010 drought events.

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Near–surface air temperature and snow skin temperature comparison from CREST-SAFE station data with MODIS land surface temperature data

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-12-7665-2015 ◽

2015 ◽

Vol 12 (8) ◽

pp. 7665-7687 ◽

Cited By ~ 2

Author(s):

C. L. Pérez Díaz ◽

T. Lakhankar ◽

P. Romanov ◽

J. Muñoz ◽

R. Khanbilvardi ◽

...

Keyword(s):

Surface Temperature ◽

Skin Temperature ◽

Air Temperature ◽

Land Surface Temperature ◽

Land Surface ◽

Hydrological Cycle ◽

Critical Role ◽

Surface Air Temperature ◽

Balance Model ◽

Near Surface

Abstract. Land Surface Temperature (LST) is a key variable (commonly studied to understand the hydrological cycle) that helps drive the energy balance and water exchange between the Earth's surface and its atmosphere. One observable constituent of much importance in the land surface water balance model is snow. Snow cover plays a critical role in the regional to global scale hydrological cycle because rain-on-snow with warm air temperatures accelerates rapid snow-melt, which is responsible for the majority of the spring floods. Accurate information on near-surface air temperature (T-air) and snow skin temperature (T-skin) helps us comprehend the energy and water balances in the Earth's hydrological cycle. T-skin is critical in estimating latent and sensible heat fluxes over snow covered areas because incoming and outgoing radiation fluxes from the snow mass and the air temperature above make it different from the average snowpack temperature. This study investigates the correlation between MODerate resolution Imaging Spectroradiometer (MODIS) LST data and observed T-air and T-skin data from NOAA-CREST-Snow Analysis and Field Experiment (CREST-SAFE) for the winters of 2013 and 2014. LST satellite validation is imperative because high-latitude regions are significantly affected by climate warming and there is a need to aid existing meteorological station networks with the spatially continuous measurements provided by satellites. Results indicate that near-surface air temperature correlates better than snow skin temperature with MODIS LST data. Additional findings show that there is a negative trend demonstrating that the air minus snow skin temperature difference is inversely proportional to cloud cover. To a lesser extent, it will be examined whether the surface properties at the site are representative for the LST properties within the instrument field of view.

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On the changes in the sea surface temperature in the Benguela upwelling region. Part 1: season cycle

Исследования Земли из космоса ◽

10.31857/s0205-96142019333-44 ◽

2019 ◽

pp. 33-44

Author(s):

A. B. Polonsky ◽

A. N. Serebrennikov

Keyword(s):

Surface Temperature ◽

Seasonal Variability ◽

Surface Wind ◽

Water Layer ◽

Hydrodynamic Characteristics ◽

Entire Area ◽

Near Surface ◽

Sea Level Anomalies ◽

Benguela Upwelling ◽

Upwelling Index

Based on daily ocean surface temperature values for 1982–2017, near-surface wind for 1988–2017. and sea level anomalies for 1993–2017, obtained from satellite data, the seasonal variability of the hydrodynamic characteristics of the upper water layer in the vicinity of the Benguela upwelling is investigated. It is shown that the thermal upwelling index averaged over the entire area with lower temperature values does not give a correct idea on the seasonal course of the water lifting rate in the upwelling zone due to the significant horizontal advection of waters of upwelling origin. The seasonal variations of the vertical velocity of wind origin in the Benguela upwelling zone are characterized by the presence of two extremes from October to March, which is manifested in the predominance of the semiannual harmonic. At the same time, the thermal upwelling index in the zone of distribution of upwelling waters is subject to seasonal variability with an annual period.

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Determination of the united quality latent index of adaptability (UQLIA) and contribution of some environmental parameters to it for Deschampsia antarctica populations, Galindez island (Maritime Antarctic) season 2017/2018

Visnik ukrains'kogo tovaristva genetikiv i selekcioneriv ◽

10.7124/visnyk.utgis.16.2.1057 ◽

2019 ◽

Vol 16 (2) ◽

pp. 190-202

Author(s):

I. Y. Parnikoza ◽

N. Y. Miryuta ◽

V. Y. Ivanets ◽

E. O. Dykyi

Keyword(s):

Surface Temperature ◽

Pairwise Comparison ◽

Environmental Parameters ◽

Soil Surface ◽

Deschampsia Antarctica ◽

Near Surface ◽

Soil Surface Temperature ◽

Experimental Populations ◽

The Individual

The purpose of our work has been to determine the indicator of complex adaptability — the United Quality Latent Index of Adaptability (UQLIA) for the experimental populations of Deschampsia antarctica É. Desv. and study the contribution to it of some environmental factors such as the near soil surface temperature and organogens content. Materials and methods. The determination of UQLIA was based on a pairwise comparison of the differences between investigated parameters of populations by mathematical regression techniques. The soil surface temperature was measured by loggers installed near plants in each locus during April 2017 – April 2018. Results and conclusions. Temperature fluctuations were described during December 2017 – February 2018 for twelve experimental populations of D. antarctica and one control fragment of moss turf subformation from Galindez Island. Significant variations in average daily near surface temperature were observed during the study period between populations, especially in December and January. The UQLIA of D. antarctica for this season was calculated on the basis of the projective cover, biometric indices of generative plants and the content of protective and reserve proteins in seeds for the eleven populations. The values of the United Soil Surface Temperature Influence Index (UTII) for the season summer months and the United Organogens Content in Soil Influence Index (UOCSII) have been calculated for the individual parameters of D. antarctica plants adaptability. The reliable contribution of UTII to ULIA has been shown for December and January, at the moment of the greatest variation of soil surface temperature. UOCSII provided a reliable contribution to the ULIA only in the amount of UTII. Keywords: Deschampsia antarctica, United Quality Latent Index of Adaptability (UQLIA), contribution of soil surface temperature and organogens content to complex adaptability.

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The Predictability of Soil Moisture and Near-Surface Temperature in Hindcasts of the NCEP Seasonal Forecast Model

Journal of Climate ◽

10.1175/1520-0442(2003)016<0510:tposma>2.0.co;2 ◽

2003 ◽

Vol 16 (3) ◽

pp. 510-521 ◽

Cited By ~ 35

Author(s):

Masao Kanamitsu ◽

Cheng-Hsuan Lu ◽

Jae Schemm ◽

Wesley Ebisuzaki

Keyword(s):

Soil Moisture ◽

Surface Temperature ◽

Forecast Model ◽

Seasonal Forecast ◽

Near Surface

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The influence of the forest on night-time snow surface temperature

Annals of Glaciology ◽

10.3189/172756401781819256 ◽

2001 ◽

Vol 32 ◽

pp. 217-222 ◽

Cited By ~ 7

Author(s):

Peter Höller

Keyword(s):

Surface Temperature ◽

Open Field ◽

Air Temperature ◽

Forest Canopy ◽

Small Range ◽

Snow Surface ◽

Net Radiation ◽

Night Time ◽

Near Surface ◽

Snow Surface Temperature

AbstractSnow surface temperature (Ts) plays an important role in the formation of surface hoar or near-surface faceted crystals The goal of this study was to obtain detailed information on Ts in different forest stands nelr the timberline. The investigations were conducted during clear nights and showed that the snow surface temperature is influenced very strongly by the forest canopy. While the air temperature was very similar on the different experimental sites, Ts was higher in the forest than in the open field; on the south-facing slope the difference between the forest and the open field was 3–4.5°C, and on the north-facing slope approximately 3–7°C. Taking into account that εair is 0.7 and εtree is 0.94, the incoming radiation (I ↓) for the different experimental sites was calculated by the equation of Brunt (the canopy density was estimated using photographs taken with an 8 mm fish-eye). To calculate Ts, air temperature and averaged values of the net radiation (because the net radiation (I) has only a small range of variation during clear nights) were used. The results show that the calculated values were higher than the measured values (by approximately 2°C). However, a better correlation was found by using lower values of the emissivity (εair0.67 and εtree0.91).

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