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Spatial information on climatic characteristics is beneficial in e.g. regional planning, building construction and urban ecology. The possibility to spatially predict urban?Crural temperatures with statistical techniques and small sample sizes was investigated in Turku, SW Finland. Temperature observations from 36 stationary weather stations over a period of 6?years were used in the analyses. Geographical information system (GIS) data on urban land use, hydrology and topography served as explanatory variables. The utilized statistical techniques were generalized linear model and boosted regression tree method. The results demonstrate that temperature variables can be robustly predicted with relatively small sample sizes (n????20?C40). The variability in the temperature data was explained satisfactorily with few accessible GIS variables. Statistically based spatial modelling provides a cost-efficient approach to predict temperature variables on a regional scale. Spatial modelling may aid also in gaining novel insights into the causes and impacts of temperature variability in extensive urbanized areas. 相似文献
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In recent decades, a warming climate likely has accelerated the timing of spring snowmelt in the western United States; however, records of the timing of snowmelt typically only extend to the 1980s. Stream gage data can lengthen records of the timing of snowmelt back to the early 1900s, enhancing understanding of past, current, and future climate change on snowmelt-dominated watersheds and associated ecosystems. We used snowpack telemetry data and historic streamflow records to test reconstructions of final snowmelt dates using Short Time Fourier Transform (STFT) wavelet analysis of hydrographs. STFT reconstructions tested against known final snowmelt dates over the last ~25 years indicate final snowmelt can be determined within ±4 days ~95% of the time and within ±7 days 100% of the time. Comparison of the STFT method with the center of timing method indicates that in addition to reconstructing actual snowmelt dates (as opposed to dates associated with the center of timing of streamflow), the STFT method may limit interpretation errors associated with changes in discharge not related to snowmelt. Reconstructions of final snowmelt dates in the Idaho, U.S. study area show intervals of early snowmelt (1920s–1930s), later and less variable snowmelt (1940s–1970s), and both variable and early snowmelt (~1985–2007). Early and variable snowmelt during the last ~20 years is associated with large wildfires. 相似文献
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Goutami Chattopadhyay Parthasarathi Chakraborthy Surajit Chattopadhyay 《Theoretical and Applied Climatology》2012,110(3):321-328
The present work reports studies on the spatial distribution of tropospheric ozone extending over both southern and northern hemispheres. This study is based on a univariate approach to the spatial data series obtained at regular spatial intervals. Mann?CKendall's (MK) trend analysis has been carried out to discern the trend within the spatial distribution of the tropospheric ozone, and it has been observed that in all seasons, except monsoon (JJAS), there is a linear trend within the spatial distribution. Studying both monthly and seasonal behavior through autoregressive integrated moving average (ARIMA), it has been revealed that ARIMA (0,2,2) can be used as a representative of the spatially distributed tropospheric ozone over southern and northern hemispheres. The representative model has been confirmed through the study of Willmott's index and prediction yield. 相似文献
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José Fernando Pesquero Sin Chan Chou Carlos Afonso Nobre José Antonio Marengo 《Theoretical and Applied Climatology》2010,99(1-2):75-93
This study shows the results from a regional climate simulation of the present-day climate, corresponding to the period 1961–1970 over South America, using the regional Eta Model nested within the HadAM3P model from the UK Hadley Centre. The simulation analysis is focused on assessing the capability of the nested regional model in representing spatial patterns of seasonal mean climate and the annual cycle of precipitation and temperature. The goals of this 10-year run for South America are to verify if the Eta Model can be used in climate-change scenarios and to verify if this model has the ability to generate added value for the South American continent. The Eta Model was chosen because there are few investigations using the Eta Model for long integrations over South America and because the vertical coordinate system used in this model is recommended for use over South America due to the presence of the Andes range. In the present 10-year simulation, the regional model reproduced many of the South American mesoscale climate features and together added new value to the driver model. Value was also added to the driver model by reducing seasonal biases in austral winter relative to austral summer. The regional model also exhibits better performance in the representation of low-level circulation, such as the topographically induced northwesterly flux. 相似文献
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《Dynamics of Atmospheres and Oceans》2007,43(1-4):107-126
Rainfall characteristics of the Madden–Julian oscillation (MJO) are analyzed primarily using tropical rainfall measuring mission (TRMM) precipitation radar (PR), TRMM microwave imager (TMI) and lighting imaging sensor (LIS) data. Latent heating structure is also examined using latent heating data estimated with the spectral latent heating (SLH) algorithm.The zonal structure, time evolution, and characteristic stages of the MJO precipitation system are described. Stratiform rain fraction increases with the cloud activity, and the amplitude of stratiform rain variation associated with the MJO is larger than that of convective rain by a factor of 1.7. Maximum peaks of both convective rain and stratiform rain precede the minimum peak of the outgoing longwave radiation (OLR) anomaly which is often used as a proxy for the MJO convection. Stratiform rain remains longer than convective rain until ∼4000 km behind the peak of the mature phase. The stratiform rain contribution results in the top-heavy heating profile of the MJO.Associated with the MJO, there are tri-pole convective rain top heights (RTH) at 10–11, ∼7 and ∼3 km, corresponding to the dominance of afternoon showers, organized systems, and shallow convections, respectively. The stratiform rain is basically organized with convective rain, having similar but slightly lower RTH and slightly lags the convective rain maximum. It is notable that relatively moderate (∼7 km) RTH is dominant in the mature phase of the MJO, while very tall rainfall with RTH over 10 km and lightning frequency increase in the suppressed phase. The rain-yield-per flash (RPF) varies about 20–100% of the mean value of ∼2–10 × 109 kg fl−1 over the tropical warm ocean and that of ∼2–5 × 109 kg fl−1 over the equatorial Islands, between the convectively suppressed phase and the active phase of MJO, in the manner that RPF is smaller in the suppressed phase and larger in the active phase. 相似文献
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Advanced warning of extreme sea level events is an invaluable tool for coastal communities, allowing the implementation of management policies and strategies to minimise loss of life and infrastructure damage. This study is an initial attempt to apply a dynamical coupled ocean–atmosphere model to the prediction of seasonal sea level anomalies (SLA) globally for up to 7 months in advance. We assess the ability of the Australian Bureau of Meteorology’s operational seasonal dynamical forecast system, the Predictive Ocean Atmosphere Model for Australia (POAMA), to predict seasonal SLA, using gridded satellite altimeter observation-based analyses over the period 1993–2010 and model reanalysis over 1981–2010. Hindcasts from POAMA are based on a 33-member ensemble of seasonal forecasts that are initialised once per month for the period 1981–2010. Our results show POAMA demonstrates high skill in the equatorial Pacific basin and consistently exhibits more skill globally than a forecast based on persistence. Model predictability estimates indicate there is scope for improvement in the higher latitudes and in the Atlantic and Southern Oceans. Most characteristics of the asymmetric SLA fields generated by El-Nino/La Nina events are well represented by POAMA, although the forecast amplitude weakens with increasing lead-time. 相似文献
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《大气与海洋》2013,51(3):361-376
Abstract The goal of this study is to evaluate the impact of incorporating the marine surface winds retrieved from the ERS‐2 scatterometer in the Canadian three‐dimensional variational analysis system, (3D‐var). The aspects of the 3D‐var most relevant to the assimilation of surface ‐wind observations and a general method for resolving the directional ambiguity of the retrieved scatterometer ‐winds are first described. A comparison ‐with 6‐h forecasted winds is then made to demonstrate that these data are of high quality, but exhibit a speed bias that can be removed by increasing their amplitudes by about 5%. The analysis increment from a single scatterometer wind observation is calculated to illustrate the response of the 3D‐var to surface wind observations. As a consequence of the forecast error covariance model, the assimilation of surface wind observations produces meteorologically consistent increments for both the rotational and divergent wind components and the mass field. The results from a series of cross‐validation experiments using ship‐based wind data demonstrate a positive impact of assimilating scatterometer winds and the effectiveness of a simple method for estimating and removing the speed bias. The impact of assimilating scatterometer data within a short assimilation cycle is also evaluated. Overall, the results show that including scatterometer data in the analysis decreases the 6‐h forecast error of surface wind by 13%. Over the northern extra‐tropics the improvement is only 4% and for the southern extra‐tropics it is 16%. Results from a series of two‐day forecasts produced using the analyses from the assimilation cycles with and without retrieved scatterometer winds included are also presented. Using radiosonde observations at 850 hPa, 500 hPa, 250 hPa and 100 hPafor verification, the impact on the forecasts is nearly neutral in the northern hemisphere and the tropics. Conversely, a significant positive impact is found on both wind and mass fields in the southern hemisphere over the entire two‐day forecast. 相似文献
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J. Venkata Ratnam Filippo Giorgi Akshara Kaginalkar Stefano Cozzini 《Climate Dynamics》2009,33(1):119-139
A regional coupled atmosphere–ocean model was developed to study the role of air–sea interactions in the simulation of the
Indian summer monsoon. The coupled model includes the regional climate model (RegCM3) as atmospheric component and the regional
ocean modeling system (ROMS) as oceanic component. The two-way coupled model system exchanges sea surface temperature (SST)
from the ocean to the atmospheric model and surface wind stress and energy fluxes from the atmosphere to the ocean model.
The coupled model is run for four years 1997, 1998, 2002 and 2003 and the results are compared with observations and atmosphere-only
model runs employing Reynolds SSTs as lower boundary condition. It is found that the coupled model captures the main features
of the Indian monsoon and simulates a substantially more realistic spatial and temporal distribution of monsoon rainfall compared
to the uncoupled atmosphere-only model. The intraseasonal oscillations are also better simulated in the coupled model compared
to the atmosphere-only model. These improvements are due to a better representation of the feedbacks between the SST and convection
and highlight the importance of air–sea coupling in the simulation of the Indian monsoon. 相似文献
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Theoretical and Applied Climatology - Historical Chinese surface meteorological records provided by the special fund for basic meteorological data from the National Meteorological Information... 相似文献
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Yoo-Geun Ham Jong-Seong Kug In-Sik Kang Fei-Fei Jin Axel Timmermann 《Climate Dynamics》2010,34(6):905-917
The impacts of diurnal atmosphere–ocean (air–sea) coupling on tropical climate simulations are investigated using the SNU
coupled GCM. To investigate the effect of the atmospheric and oceanic diurnal cycles on a climate simulation, a 1-day air–sea
coupling interval experiment is compared to a 2-h coupling experiment. As previous studies have suggested, cold temperature
biases over equatorial western Pacific regions are significantly reduced when diurnal air–sea coupling strategy is implemented.
This warming is initiated by diurnal rectification and amplified further by the air–sea coupled feedbacks. In addition to
its effect on the mean climatology, the diurnal coupling has also a distinctive impact on the amplitude of the El Nino-Southern
Oscillation (ENSO). It is demonstrated that a weakening of the ENSO magnitude is caused by reduced (increased) surface net
heat fluxes into the ocean during El Nino (La Nina) events. Primarily, decreased (increased) incoming shortwave radiation
during El Nino (La Nina) due to cloud shading is responsible for the net heat fluxes associated with ENSO. 相似文献
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Lazar Lazić 《Meteorology and Atmospheric Physics》2000,75(1-2):121-130
Summary Following a recent approach of Fox-Rabinovitz an iterative Matsuno or a “Super-Matsuno” style scheme is applied as a filter
in the Eta Model. In contrast to Fox-Rabinovitz, we however apply the scheme not for all of the model’s time-differencing
but for its adjustment terms only. These distinctions compared to the original Fox-Rabinovitz’-method are made easy to implement
by the split time differencing approach of the Eta, and at the same time would appear clearly appropriate for the “initialization”
purpose. In addition, while Fox-Rabinovitz emphasizes the use of the method within a long time-scale data assimilation framework,
we are focusing on the impact of the method in a short-range forecasting environment/time-scale.
After a short one hour “initialization” procedure is completed, standard model integration is continued, now very much free
of noise. The Super-Matsuno style scheme is found to balance initially unbalanced external and internal modes and to significantly
reduce the high-frequency noise during the first 6 time steps. In a control case noise also reduces in amplitude as integration
proceeds, but at a much slower rate. The model integration results with and without “initialization” after 6 hours are however
very similar. Even so, it is to be expected that small differences, given that they have resulted from the removal of spurious
initial noise, have to be beneficial.
Received July 5, 1999/Revised January 11, 2000 相似文献
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《大气与海洋》2013,51(3):169-183
Abstract Ice‐band characteristics for the region off East Queen Maud Land in Antarctica were examined and their relationship with the wind conditions was assessed using a large number of Marine Observation Satellite (MOS) Multispectral Electronic Self Scanning Radiometer (MESSR) images received at Syowa Station during the period 1989–93. Analyses from 43 examples of bands captured from August to December suggest that ice‐band formation and band scale are affected by both wind speed and direction over approximately the preceding four days (defined as the effective wind). Ice‐band width and spacing are significantly correlated with the effective wind speed and the maximum wind speed during that period. The long axis of ice bands tends to be oriented at 70°‐90° (mean of 75°) to the right of the effective wind direction. The band scales decrease from winter (August) to summer (December) with typical band spacing of 4–6 km in winter and 1–2 km in summer. This seems to be primarily due to a decrease in ice floe size and partly due to a decrease in the effective wind speed from winter to summer. Band scale decreases from the ice interior to the ice edge under conditions of off‐ice winds. 相似文献
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Assessing protected area’s carbon stocks and ecological structure at regional-scale using GEDI lidar
Protected areas (PAs) serve as a critical strategy for protecting natural resources, conserving biodiversity, and mitigating climate change. While there is a critical need to guide area-based conservation efforts, a systematic assessment of PA effectiveness for storing carbon stocks has not been possible due to the lack of globally consistent forest biomass data. In this study, we present a new methodology utilizing forest structural information and aboveground biomass density (AGBD) obtained from the Global Ecosystem Dynamics Investigation (GEDI) mission. We compare PAs with similar, unprotected forests obtained through statistical matching to assess differences in carbon storage and forest structure. We also assess matching outcomes for a robust and minimally biased way to quantify PA efficacy. We find that all analyzed PAs in Tanzania possess higher biomass densities than their unprotected counterfactuals (24.4% higher on average). This is also true for other forest structure metrics, including tree height, canopy cover, and plant area index (PAI). We also find that community-governed PAs are the most effective category of PAs at preserving forest structure and AGBD – often outperforming those managed by international or national entities. In addition, PAs designated under more than one entity perform better than the PAs with a single designation, especially those with multiple international designations. Finally, our findings suggest that smaller PAs may be more effective for conservation, depending on levels of connectivity. Taken together, these findings support the designation of PAs as an effective means for forest management with considerable potential to protect forest ecosystems and achieve long-term climate goals. 相似文献
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Branislav Bajat Milutin Pejović Jelena Luković Predrag Manojlović Vladan Ducić Sanja Mustafić 《Theoretical and Applied Climatology》2013,112(1-2):1-13
The appearence of geostatistics and geographical information systems has made it possible to analyze complex spatial patterns of meteorological elements over large areas in the applied climatology. The objective of this study is to use geostatistics to characterize the spatial structure and map the spatial variation of average values of precipitation for a 30-year period in Serbia. New, recently introduced, geostatistical algorithms facilitate utilization of auxiliary variables especially remote sensing data or freely available global datasets. The data from Advanced Spaceborn Thermal Emission and Reflection Radiometer global digital elevation model are incorporated as ancillary variables into spatial prediction of average annual precipitation using geostatistical method known as regression kriging. The R 2 value of 0.842 proves high performance result of the prediction of the proposed method. 相似文献
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Silva Karita Almeida de Souza Rolim Glauco de Oliveira Aparecido Lucas Eduardo 《Theoretical and Applied Climatology》2022,148(3-4):1279-1288
Theoretical and Applied Climatology - The El Niño-Southern Oscillation (ENSO) phenomenon affects the global climate by changing temperature and precipitation patterns mainly in tropical... 相似文献