Satellite Measurements Of Temperature Research Articles

Rayleigh LIDAR and satellite (HALOE, SABER, CHAMP and COSMIC) measurements of stratosphere-mesosphere temperature over a southern sub-tropical site, Reunion (20.8° S; 55.5° E): climatology and comparison study

Abstract. For the first time, climatology of the middle atmosphere thermal structure is presented, based on 14 years of LIDAR and satellite (HALOE, SABER, CHAMP and COSMIC) temperature measurements. The data is collected over a southern sub-tropical site, Reunion Island (20.8° S; 55.5° E), for the height range between 30 and 60 km. The overall monthly mean temperature shows a maximum of 265–270 K at the stratopause height region from ~44–52 km and peaks during the months of March and November. Furthermore, the temperature profiles are compared with different satellite datasets (HALOE, CHAMP, COSMIC and SABER) and the results are found to be in reasonable agreement with each other, although a relative difference in temperature of ± 5 to 6 K is noticed. In comparison, LIDAR shows higher/lower temperatures for the lower mesosphere/upper stratosphere height region. The differences in temperature measured by the LIDAR and satellite measurements are analogous with previous results available elsewhere. Long-term temperature measurements are used to further study seasonal oscillations, especially annual, semi-annual and quasi-biennial oscillations. In comparison with SAO, the measured spectral amplitudes of AO shows dominant amplitudes in both the upper stratosphere and lower mesosphere height regions. Using LIDAR and the other satellite measurements, the quasi-biennial oscillation was found to be approximately 26 months. The spectral amplitudes are comparable to the results reported earlier by other researchers.

Low latitude 2‐day planetary wave impact on austral polar mesopause temperatures: revealed by a January diminution in PMSE above Davis, Antarctica

A new characteristic of the austral summer polar mesopause as revealed by ground‐based radar and satellite temperature measurements is reported, that is linked to inter‐annual variability of the low‐latitude easterly wind jet. Four consecutive seasons of polar mesosphere summer echoes (PMSE) and mesosphere temperature observations above Davis, Antarctica (68.6°S) show a mid‐January diminution in PMSE occurrence rate that coincides with a minor mesopause warming of several degrees. Spectral analyses of PMSE, Aura Microwave Limb Sounder (MLS) temperatures and radar meridional winds show the presence of ∼4–5‐day planetary waves (PWs) throughout the austral summer in the polar upper mesosphere together with enhanced ∼2‐day PW activity from mid‐January to mid‐February. Analysis of MLS temperatures show that the ∼2‐day PWs have zonal wavenumbers (S) with both westward (S = −2, −3) and eastward (S = +2, +3) components. Although displaying some inter‐annual variation in the peak onset time, the mid‐January mesopause warming coincides with a weakening of the equatorward meridional wind above Davis and enhancement of low‐latitude 2‐day PW activity.

Planetary waves in ozone and temperature in the Northern Hemisphere winters of 2002/2003 and early 2005

Abstract. Temperature and ozone data from the sub-millimetre radiometer (SMR) installed aboard the Odin satellite have been examined to study the relationship between temperature and ozone concentration in the lower and upper stratosphere in winter time. The retrieved ozone and temperature profiles have been considered between the range of 24–46 km during the Northern Hemisphere (NH) winter of December 2002 to March 2003 and January to March 2005. A comparison between the ozone mixing ratio and temperature fields has been made for the zonal means, wavenumber one variations and 5-day planetary waves. The amplitude values in temperature variations are ~5 K in the wavenumber one and 0.5–1 K in the 5-day wave. In ozone mixing ratio, the amplitudes reach ~0.5 ppmv in the wavenumber one and 0.05–0.1 ppmv in the 5-day wave. Several stratospheric warming events were observed during the NH winters of 2002/2003 and early 2005. Along with these warming events, amplification of the amplitude has been detected in wavenumber one (up to 30 K in temperature and 1.25 ppmv in ozone) and partly in the 5-day perturbation (up to 2 K in temperature and 0.2 ppmv in ozone). In general, the results show the expected in-phase behavior between the temperature and ozone fields in the lower stratosphere due to dynamic effects, and an out-of-phase pattern in the upper stratosphere, which is expected as a result of photochemical effects. However, these relationships are not valid for zonal means and wavenumber one components when the wave amplitudes are changing dramatically during the strongest stratospheric warming event (at the end of December 2002/beginning of January 2003). Also, for several shorter intervals, the 5-day perturbations in ozone and temperature are not well-correlated at lower heights, particularly when conditions change rapidly. Odin's basic observation schedule provides stratosphere mode data every third day and to validate the reliability of the 5-day waves extracted from the Odin measurements, additional independent data have been analysed in this study: temperature assimilation data by the European Centre for Medium-range Weather Forecasts (ECMWF) for the NH winter of 2002/2003, and satellite measurements of temperature and ozone by the Microwave Limb Sounder (MLS) on board the Aura satellite for the NH winter in early 2005. Good agreement between the temperature fields from Odin and ECMWF data is found at middle latitude where, in general, the 5-day perturbations from the two data sets coincide in both phase and amplitude throughout the examined interval. Analysis of the wavenumber one and the 5-day wave perturbations in temperature and ozone fields from Odin and from Aura demonstrates that, for the largest part of the examined period, quite similar characteristics are found in the spatial and temporal domain, with slightly larger amplitude values seen by Aura. Hence, the comparison between the Odin data, sampled each third day, and daily data from Aura and the ECMWF shows that the Odin data are sufficiently reliable to estimate the properties of the 5-day oscillations, at least for the locations and time intervals with strong wave activity.

Comparative analyses of ground based and satellite temperature measurements on the territory of Serbia

In this paper the air temperature changes on the territory of Serbia were investigated, on the basis of data from ground-based and satellite measurements, for the period 1979-2006. The trend analysis has shown that there is no amplification of trend of air temperature increase with altitude. The conclusion imposes itself that the air temperature increase in the researched area as well as on the Earth can not be only explained by models which presume domination of anthropogenic greenhouse effect.

First complete season of PMSE observations above Davis, Antarctica, and their relation to winds and temperatures

A comprehensive account of the properties of southern hemisphere (SH) Polar Mesosphere Summer Echoes (PMSE) has been constrained by the lack of deployment of atmospheric radars. Here we present the first complete season of PMSE detected above the high‐latitude station Davis, Antarctica (78.0°E, 68.6°S) using a 55‐MHz atmospheric radar for the 2004–2005 austral summer. We present the characteristics and morphology of SH PMSE events observed during the interval 23 November 2004–18 February 2005. Coincident Aura satellite temperature measurements (T) and ground MF‐radar partial reflection observations are used to investigate the thermal and dynamical state of the polar mesosphere during conditions of PMSE occurrence. We find that the seasonal envelope of PMSE corresponds remarkably well with the seasonal envelope of temperature or more precisely when T − Tfp < 0 K (Tfp = frost point temperature). Furthermore, we show that PMSE are linked with the typical summer equatorward flow of the mesosphere meridional wind, but were perturbed while this wind flowed poleward.

Climate analysis with satellite versus weather station data

This paper compares how well satellite versus weather station measurements of climate predict agricultural performance in Brazil, India, and the United States. Although weather stations give accurate measures of ground conditions, they entail sporadic observations that require interpolation where observations are missing. In contrast, satellites have trouble measuring some ground phenomenon such as precipitation but they provide complete spatial coverage of various parameters over a landscape. The satellite temperature measurements slightly outperform the interpolated ground station data but the precipitation ground measurements generally outperform the satellite surface wetness index. In India, the surface wetness index outperforms station precipitation but this may be reflecting irrigation, not climate. The results suggest that satellites provide promising measures of temperature but that ground station data may still be preferred for measuring precipitation in rural settings.

Gravity wave drag estimation from global analyses using variational data assimilation principles. I: Theory and implementation

AbstractA novel technique to estimate gravity wave drag from global‐scale analyses is presented. It is based on the principles of four‐dimensional variational data assimilation, using a dynamical model of the middle atmosphere and its adjoint. The global analyses are treated as observations. A cost function that measures the mismatch between the model state and observations is defined. The control variables are the components of the three‐dimensional gravity wave drag field, so that minimization of the cost function gives the optimal gravity wave drag field. The minimization is performed using a conjugate gradient method, with the adjoint model used to calculate the gradient of the cost function.In this work, we present the theory behind the new technique and evaluate extensively the ability of the technique to estimate the gravity wave drag using so‐called twin experiments, in which the ‘observations’ are given by the evolution of the dynamical model with a prescribed gravity wave drag. The results show that the technique can estimate accurately the prescribed gravity wave drag. When the cost function is suitably defined, there is good convergence of the minimization scheme under realistic atmospheric conditions. We also show that the cost function gradient is well approximated taking into account only adiabatic processes. We note some limitations of the technique for estimating gravity wave drag in tropical regions if satellite temperature measurements are the only observational information available. Copyright © 2005 Royal Meteorological Society.

A Loop Current Intrusion Case Study on the West Florida Shelf*

The Gulf of Mexico Loop Current intruded upon the West Florida continental shelf in June 2000. In situ currents and hydrography along with satellite temperature and altimetry measurements are used to describe this event and its effects on the shelf. A strong southward current is observed to flow along the shelf slope seaward of the intruded water boundary. This current transported cold, nutrient-rich water from the north, thereby producing anomalous hydrographic features near the shelf break (80-m isobath). An array of moored velocity profilers reveals that the currents landward of the intruded water are independent of the Loop Current and primarily driven by local winds. A series of idealized numerical model simulations inclusive of forcing by both the Loop Current and local winds confirm the observational findings that the shelfbreak currents are largely Loop Current controlled while the shelf currents are largely controlled by the local winds.

Temporal Homogenization of Monthly Radiosonde Temperature Data. Part II: Trends, Sensitivities, and MSU Comparison

Trends in radiosonde-based temperatures and lower-tropospheric lapse rates are presented for the time periods 1959‐97 and 1979‐97, including their vertical, horizontal, and seasonal variations. A novel aspect is that estimates are made globally of the effects of artificial (instrumental or procedural) changes on the derived trends using data homogenization procedures introduced in a companion paper (Part I). Credibility of the data homogenization scheme is established by comparison with independent satellite temperature measurements derived from the microwave sounding unit (MSU) instruments for 1979‐97. The various analyses are performed using monthly mean temperatures from a near‐globally distributed network of 87 radiosonde stations. The severity of instrument-related problems, which varies markedly by geographic region, was found, in general, to increase from the lower troposphere to the lower stratosphere, although surface data were found to be as problematic as data from the stratosphere. Except for the surface, there is a tendency for changes in instruments to artificially lower temperature readings with time, so that adjusting the data to account for this results in increased tropospheric warming and decreased stratospheric cooling. Furthermore, the adjustments tend to enhance warming in the upper troposphere more than in the lower troposphere; such sensitivity may have implications for ‘‘fingerprint’’ assessments of climate change. However, the most sensitive part of the vertical profile with regard to its shape was near the surface, particularly at regional scales. In particular, the lower-tropospheric lapse rate was found to be especially sensitive to adjustment as well as spatial sampling. In the lower stratosphere, instrument-related biases were found to artificially inflate latitudinal differences, leading to statistically significantly more cooling in the Tropics than elsewhere. After adjustment there were no significant differences between the latitude zones.

Improved Treatment of Surface Evapotranspiration in a Mesoscale Numerical Model Part II: Via the Assimilation of Satellite Mesurements

In part I of this research, it was shown that the simplified bucket method in the PSU/NCAR MM4 system had an apparent tendency to overestimate surface evapotranspiration (ET) when the long-term observational data from the Atmospheric Radiation Measurement program are used for verification. It was demonstrated that a Penman-Monteith (PM) method could effectively reduce the degree of overestimating surface ET. An examination of the impact of satellite data insertion, using a variational Four-Dimensional Data Assimilation (FDDA) technique proposed by Gal-Chen (1983, 1986), on the model's estimation of surface ET is performed in the second part of this research. It shows that when the bucket method is in use the assimilation of the Geostationary Operational Environmental Satellite (GOES) temperature measurements helps the model make better estimation of surface ET owing to a significant decrease of potential ET resulting from a pronounced decrease of skin temperature and the associated moisture gradient at the ground surface. When the PM method is in use, the assimilation of GOES data tends to decrease the temperature and the associated mixing ratio depression at the lowest model level during the data assimilation period, and thus, the potential ET is decreased during the succeeding simulation period. Therefore, the model using the PM method is able to more correctly estimate latent heat flux after the data assimilation period. It reveals that Gal-Chen's FDDA algorithm of assimilating GOES data provides the model with the PM method a greater possibility of yielding the most accurate estimation of surface ET. The GOES data insertion would allow the model using the bucket method to gain a higher probability of making a more accurate estimation of latent heat flux than the model using the PM method without GOES data insertion. Even only satellite data insertion will enable the model to show a better estimation of surface ET. A nudging technique is shown to enhance the advantages of the proposed FDDA algorithm by making the model generate a more realistic estimation of surface ET. The nudging technique results in a further decrease of the skin temperature, temperature at the lowest model level and the accompanying moisture content at the ground surface and at the lowest model level during the data assimilation period.

Surface air temperature and its changes over the past 150 years

We review the surface air temperature record of the past 150 years, considering the homogeneity of the basic data and the standard errors of estimation of the average hemispheric and global estimates. We present global fields of surface temperature change over the two 20‐year periods of greatest warming this century, 1925–1944 and 1978–1997. Over these periods, global temperatures rose by 0.37° and 0.32°C, respectively. The twentieth‐century warming has been accompanied by a decrease in those areas of the world affected by exceptionally cool temperatures and to a lesser extent by increases in areas affected by exceptionally warm temperatures. In recent decades there have been much greater increases in night minimum temperatures than in day maximum temperatures, so that over 1950–1993 the diurnal temperature range has decreased by 0.08°C per decade. We discuss the recent divergence of surface and satellite temperature measurements of the lower troposphere and consider the last 150 years in the context of the last millennium. We then provide a globally complete absolute surface air temperature climatology on a 1° × 1° grid. This is primarily based on data for 1961–1990. Extensive interpolation had to be undertaken over both polar regions and in a few other regions where basic data are scarce, but we believe the climatology is the most consistent and reliable of absolute surface air temperature conditions over the world. The climatology indicates that the annual average surface temperature of the world is 14.0°C (14.6°C in the Northern Hemisphere (NH) and 13.4°C for the Southern Hemisphere). The annual cycle of global mean temperatures follows that of the land‐dominated NH, with a maximum in July of 15.9°C and a minimum in January of 12.2°C.

Lidar measurements of stratospheric temperature during STOIC

Measurements of stratospheric temperature and density were acquired by the NASA/GSFC lidar during the Stratospheric Ozone Intercomparison Campaign (STOIC) experiment at the Jet Propulsion Laboratory Table Mountain Facility (TMF) (34.4°N, 117.7°W) in July and August 1989. Lidar temperatures, obtained on 21 nights preceding and during this experiment, are compared with temperatures derived by radiosondes, datasondes, Stratospheric Aerosol and Gas Experiment (SAGE II) satellite experiment, and National Meteorological Center (NMC) analyses. Radiosondes were flown from the TMF site as well as from San Nicholas Island (33.2°N, 119.5°W) located about 225 km southwest of TMF. Datasondes were deployed from Super‐Loki rockets also launched at San Nicholas Island. SAGE II satellite temperature measurements were made within 1000 km of the Table Mountain site. NMC temperature analyses derived from the NOAA satellite measurements were interpolated to coincide in space and time with the lidar measurements. The lidar temperatures, which were derived for altitudes between 30 and 65 km, were within 2–3 K of the temperatures measured by the other sensors in the altitude range 30–45 km. Between 30 and 35 km, lidar temperatures were about 2 K cooler than those obtained from the datasondes and the NMC analyses but were about 1–2 K warmer than those obtained from the radiosonde. These differences may be due to the time difference between the measurements as well as possible nonnegligible aerosol scattering near 30 km. Near and above the stratopause the temperature differences increased to 3–8 K. Lidar temperature profiles also show small‐scale variations possibly caused by wave activity.

Land surface temperatures derived from the advanced very high resolution radiometer and the along‐track scanning radiometer: 2. Experimental results and validation of AVHRR algorithms

This is the second paper in a series of three papers which discuss the problem of deriving accurate land surface temperatures (LSTs) from infrared radiometers on board satellites, such as the NOAA advanced very high resolution radiometer (AVHRR) and the ERS 1 along‐track scanning radiometer (ATSR). In the first part a detailed description of a theoretical model for deriving LSTs based on linearization of the radiative transfer equation was given. This paper focuses on an experimental investigation aimed at establishing the validity and accuracy of the so‐called split‐window technique applied to the land surface. The paper concentrates on the use of AVHRR data for LST estimation; the third part of this series will discuss ATSR data. Because of the lack of good ground‐truth data, an appropriate method has been devised to create an LST validation data set suitable for comparison with the AVHRR or ATSR infrared measurements. Multiple regression relations between satellite temperature measurements and areal averages of in situ temperatures are presented for several surface types from two field sites. Root‐mean‐square differences of about ±1.5°C are obtained for all of the surface types and the correlations are extremely good (r2 ≥ 0.95). These results are considered to represent the limiting accuracies that can be expected from the split‐window formulation applied to high‐resolution AVHRR measurements. Results are also presented for dual‐channel and triple‐window algorithms. The effects of spatial variability and viewing geometry on surface temperature retrieval are discussed. It is found that for the vegetated surfaces studied, emissivity effects are minimized by cavity effects and angular effects are only important for structured vegetation (e.g., row crops) and certain viewing geometries. The spatial temperature variability is large at scales below 1 km2 (>3°C), is small at a scale of 1–10 km2 (<1°C), and increases only slowly with spatial scale beyond scales of 10 km2 or so. Comparisons between the LST algorithms given in part 1, published algorithms by other authors and the in situ data indicate that for these when used with climatological atmospheres and laboratory measured emissivities.

Patchiness in satellite derived sea surface temperature

Patchiness, indicated by ship measurements from the International Indian Ocean Expedition, was checked against the most advanced sea surface temperature program based on satellite observations. The statistical analysis of structures observed with sea surface temperature measurements showed that they are highly correlated with the time span of observations; i. e., structures or patches in the temperature field can be artificially created by the “age” of temperature observations. Simulated multi-ship observations, based on satellite temperature measurements over a time frame of several weeks, show patches that were created by the time span during which the measurements were taken.

Satellite Estimation of the Surface Energy Balance, Moisture Availability and Thermal Inertia

A method for inferring the distribution of surface heat and evaporative fluxes and the ground moisture availability and thermal inertia (ground conductive capacity) is used to analyze two urbanized areas, Los Angeles and St. Louis. The technique employs infrared satellite temperature measurements in conjunction with a one-dimensional boundary-layer model. Results show that there is a marked reduction of evaporation and moisture availability and a corresponding elevation of sensible heat flux over urbanized areas and over cropped areas with low vegetative cover. Conversely, low heat flux and high evaporation characterize vegetated and, especially, forested areas. Warm urban centers appear directly related to a reduction in vegetation, which normally allows for a greater fraction of available radiant energy to be converted into latent heat flux. The distribution of thermal inertia was surprisingly ill-defined and its variation between urban and rural areas was quite small. Thus, the increased heat storage within the urban fabric, which has been proposed as the underlying cause of the nocturnal heat island, may be caused mainly by enhanced daytime surface heating which occurs because of surface dryness, rather than by large spatial variations in the conductivity of the surface.

Thermospheric temperature variations inferred from incoherent scatter observations

Radar-based values of the neutral exospheric temperature Tn obtained at 12°S on 127 nights in 1967 and 1968 are presented and discussed. The dominant effect is an annual variation of approximately ±5%, warmer in summer than in winter. Previous radar-based maps of the diurnal temperature bulge show similar seasonal variations of Tn at night. Model atmosphere maps show smaller Tn variations, but since the Tn value of the model is a parameter defining the average distribution of the neutral density, both the radar and model atmosphere maps may be correct. In addition to the annual variation, a semiannual variation and geomagnetic heating effects are also observed. The data indicate that the electron temperature Te is often less than 20°K above Tn at night, although it appears that (Te - Tn) may occasionally be 50°K or more. Because of the apparent near equality of Te, Ti, and Tn, data presented here are suitable for comparison with satellite and other temperature measurements. Agreement is found with an empirical law for Tn based on incoherent scatter at 45°N. Temperatures measured with a retarding potential analyzer (RPA) on Ogo 4 sometimes agree with and sometimes are ∼50% higher than nearly overlapping radar temperatures presented here. The Ogo 4 data imply that the ion-neutral heating rate is sometimes much higher than that inferred from radar observations. However, Ti values from the RPA on Ogo 6 are consistent with the radar data presented herein.

CoincidentF-region temperature determinations from incoherent backscatter and Doppler broadening of [O I] 6300 A

Summary. A Fabry-Perot spectrometer has been used at Arecibo, Puerto Rico, for measurement of the Doppler line width of [O I] 6300-A emission in the night airglow. The temperature of the nighttime F region was obtained simultaneously from this technique and from analysis of data from incoherent scatter radar. In a series of experiments the two methods gave results that agree to within ±15% rms. This agreement is closer than that usually obtained when incoherent scatter and satellite measurements of temperature are compared.