scholarly journals Relative Roles of Eurasian Snow Depth and Sea Surface Temperature in Indian and Korean Summer Monsoons Based on GME Model Simulations

2020 ◽  
Vol 7 (8) ◽  
Author(s):  
S. K. Panda ◽  
Mi‐Jin Hong ◽  
S. K. Dash ◽  
Jai‐Ho Oh ◽  
K. C. Pattnayak
2015 ◽  
Vol 30 (1) ◽  
pp. 197-205 ◽  
Author(s):  
Baoqiang Tian ◽  
Ke Fan

Abstract A new statistical forecast scheme, referred to as scheme 1, is developed using observed autumn Atlantic sea surface temperature (SST) and Eurasian snow cover in the preceding autumn to predict the upcoming winter North Atlantic Oscillation (NAO) using the year-to-year increment prediction approach (i.e., DY approach). Two predictors for the year-to-year increment are identified that are available in the preceding autumn. Cross-validation tests for the period 1950–2011 and independent hindcasts for the period 1990–2011 are performed to validate the prediction ability of the proposed technique. The cross-validation test results for 1950–2011 reveal a high correlation coefficient of 0.52 (0.58) between the predicted and observed NAO indices (DY of the NAO). The model also successfully predicts the independent hindcasts for the period 1990–2011 with a correlation coefficient of 0.55 (0.74). In addition, scheme 0 (i.e., anomaly approach) is established using the SST and snow cover anomalies during the preceding autumn. Compared with scheme 0, this new prediction model has higher predictive skill in reproducing the interdecadal variability of NAO. Therefore, this study provides an effective climate prediction scheme for the interannual and interdecadal variability of NAO in boreal winter.


2012 ◽  
Vol 25 (4) ◽  
pp. 1340-1348 ◽  
Author(s):  
Zhengzhao Johnny Luo ◽  
Dieter Kley ◽  
Richard H. Johnson ◽  
G. Y. Liu ◽  
Susanne Nawrath ◽  
...  

Abstract Multiple years of measurements of tropical upper-tropospheric temperature and humidity by the Measurement of Ozone and Water Vapor by Airbus In-Service Aircraft (MOZAIC) project are analyzed in the vicinity of deep convective outflow to study the variations of temperature and humidity and to investigate the influence of the sea surface temperature (SST) on the outflow air properties. The principal findings are the following. 1) The distribution of relative humidity with respect to ice (RHi) depends on where a convective system is sampled by the MOZAIC aircraft: deep inside the system, RHi is unimodal with the mode at ~114%; near the outskirts of the system, bimodal distribution of RHi starts to emerge with a dry mode at around 40% and a moist mode at 100%. The results are compared with previous studies using in situ measurements and model simulations. It is suggested that the difference in the RHi distribution can be explained by the variation of vertical motions associated with a convective system. 2) Analysis of MOZAIC data shows that a fractional increase of specific humidity with SST, q−1 dq/dSTT, near the convective outflow is about 0.16–0.18 K−1. These values agree well with previous studies using satellite data. Because MOZAIC measurements of temperature and humidity are independent, the authors further analyze the SST dependence of RHi and temperature individually. Temperature increases with SST for both prevalent flight levels (238 and 262 hPa); RHi stays close to constant with respect to SST for 238 hPa but shows an increasing trend for the 262-hPa level. Analysis conducted in this study represents a unique observational basis against which model simulations of upper-tropospheric humidity and its connection to deep convection and SST can be evaluated.


2012 ◽  
Vol 8 (2) ◽  
pp. 1005-1056 ◽  
Author(s):  
G. Lohmann ◽  
M. Pfeiffer ◽  
T. Laepple ◽  
G. Leduc ◽  
J.-H. Kim

Abstract. We compare the ocean temperature evolution of the Holocene as simulated by climate models and reconstructed from marine temperature proxies. We use transient simulations from a coupled atmosphere-ocean general circulation model, as well as an ensemble of time slice simulations from the Paleoclimate Modelling Intercomparison Project. The proxy dataset comprises a global compilation of marine alkenone- and Mg/Ca-derived sea surface temperature (SST) estimates. Independently of the choice of the climate model, we observe significant mismatches between modelled and estimated SST amplitudes in the trends for the last 6000 yr. Alkenone-based SST records show a similar pattern as the simulated annual mean SSTs, but the simulated SST trends underestimate the alkenone-based SST trends by a factor of two to five. For Mg/Ca, no significant relationship between model simulations and proxy reconstructions can be detected. We tested if such discrepancies can be caused by too simplistic interpretations of the proxy data. We therefore considered the additional environmental factor changes in the planktonic organisms' habitat depth and a time-shift in the recording season to diagnose whether invoking those environmental factors can help reconciling the proxy records and the model simulations. We find that invoking shifts in the living season and habitat depth can remove some of the model-data discrepancies in SST trends. Regardless whether such adjustments in the environmental parameters during the Holocene are realistic, they indicate that when modeled temperature trends are set up to allow drastic shifts in the ecological behavior of planktonic organisms, they do not capture the full range of reconstructed SST trends. These findings challenge the quantitative comparability of climate model sensitivity and reconstructed temperature trends from proxy data.


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