On the Upper Oceanic Heat Budget in the South China Sea:Annual Cycle

The upper oceanic heat budget in the South China Sea (SCS) is studied on the basis of ocean surface heat flux, upper sea heat storage and horizontal oceanic heat transport calculated from Comprehensive Ocean and Atmosphere Data Set. Several useful conclusions can be obtained and they are helpful for us to understand the climatologically thermal condition in the SCS. The annual variation of net heat budget reflects the adjustment and sudden change of the monsoon circulation over the SCS. The variation of upper oceanic heat storage of the SCS is tightly connected with the oceanic heat transport as well as the vertical movement in the SCS and so on.

Seasonal evolution of the dominant modes of the Eurasian snowpack and atmospheric circulation from autumn to the subsequent spring and the associated surface heat budget

This study investigates the seasonal evolution of the dominant modes of the Eurasian snowpack and atmospheric circulation from autumn to the subsequent spring using snow water equivalent （SWE）, snow cover frequency （SCF）, and 500 hPa geopotential height data. It is found that the Eurasian SWE/SCF and circulation dominant modes are stably coupled from autumn to the subsequent spring.The temporal coherence of the seasonal evolution of the dominant modes is examined.The seasonal evolution of the Eurasian circulation and SWE dominant modes exhibit good coherence, whereas the evolution of the Eurasian SCF dominant mode is incoherent during the autumn-winter transition season. This incoherence is associated with a sign-change in the SCF anomalies in Europe during the autumn-winter transition season, which is related to the wind anomalies over Europe. In addition, the surface heat budget associated with the Eurasian SWE/SCF and circulation dominant modes is analyzed. The sensible heat flux （SHF） related to the wind-induced thermal advection dominates the surface heat budget from autumn to the subsequent spring, with the largest effect during winter. The surface net shortwave radiation is mainly modulated by snow cover rather than cloud cover, which is estimated to be as important as, or likely superior to, the SHF for the surface heat budget during spring.The NCEP-NCAR surface heat flux reanalysis data demonstrate a consistency with the SWE/SCF and air temperature observational data, indicating a good capability for snow-atmosphere interaction analysis.

A Heat Budget Study on the Mechanism of SST Variations in the Indian Ocean Dipole Regions

By using a new heat budget equation that is closely related to the sea surface temperature (SST) and a dataset from an ocean general circulation model (MOM2) with 10-a integration (1987-1996), the relative importance of various processes determining SST variations in two regions of the Indian Ocean is compared. These regions are defined by the Indian Ocean Dipole Index and will be referred to hereafter as the eastern (0°-10°S, 90°-110°E) and western regions (10°S-10°N, 50°-70°E), respectively. It is shown that in each region there is a falling of SST in boreal summer and a rising in most months of other seasons, but the phases are quite different. In the eastern region, maximum cooling rate occurs in July,whereas in the western region it occurs in June with much larger magnitude. Maximum heating rate occurs in November in the eastern region, but in March in the western one. The western region exhibits another peak of increasing rate of SST in October, indicating a typical half-year period. Net surface heat flux and entrainment show roughly the same phases as the time-varying term, but the former has much larger contribution in most of a year, whereas the latter is important in the boreal summer. Horizontal advection, however, shows completely different seasonal variations as compared with any other terms in the heat budget equation. In the eastern region, it has a maximum in June/November and a minimum in March/September, manifesting a half-year period; in the western region, it reaches the maximum in August and the minimum in November. Further investigation of the horizontal advection indicates that the zonal advection has almost the opposite sign to the meridional advection. In the eastern region, the zonal advection is negative with a peak in August, whereas the meridional one is positive with two peaks in June and October. In the western region, the zonal advection is negative from March to November with two peaks in June and November, whereas the meridional one is positive with one peak in July.Different phases can be clearly seen between the two regions for each component of the horizontal advection. A detailed analysis of the data of 1994, a year identified when the Indian Ocean dipole event happened, indicates that the horizontal advection plays a dominant role in the remarkable cooling of the eastern region, in which zonal and meridional advections have the same sign of anomaly. However, in the western region in 1994 no any specialty was shown as compared with other years, for the SST anomaly is not positive in large part of this region. All these imply that the eastern and western regions may be related in a quite complex way and have many differences in dynamics. Further study is needed.

Winter heat budget in the Huanghai Sea and the effect from Huanghai Warm Current (Yellow Sea Warm Current)

Four sources of surface heat flux （SHF） and the satellite remote sensing sea surface temperature （SST） data are combined to investigate the heat budget closure of the Huanghai Sea （HS） in winter.It is found that heat loss occurs all over the HS during winter and the area averaged heat content change decreases with a rate of-106 W/m 2.Comparing with the area averaged SHF of-150 W/m 2 from the four SHF data sets,it can be concluded that the SHF plays a dominant role in the HS heat budget during winter.In contrast,the heat advection transported by the Huanghai Warm Current （Yellow Sea Warm Current,HWC） accounted for up to 29% of the HS heat content change.Close correlation,especially in February,between the storm events and the SST increase demonstrates that the HWC behaves strongly as a wind-driven compensation current.

On the heat budget and water mass exchange in the Andaman Sea

The characteristics of the T/S structures,water mass exchange and deep circulation in the Andaman Sea are investigated based on the simulation from a high-resolution general circulation model(MITgcm).The results show that,below 1000 m,the water mass is saltier,warmer and more homogeneous in the Andaman Sea than that in the Bay of Bengal,attributing to the strong vertical mixing at the depth of^1800 m.The water mass exchange between the Andaman Sea and the Bay of Bengal goes through three major channels,which manifests itself as follows:the northern channel(Preparis Channel)is the main passage of water mass transport from the Bay of Bengal to the Andaman Sea,whereas the Middle Channel(the south of Andaman Islands and the north of Nicobar Islands)has an opposite transport;the southern channel(Great Channel)features with a four-layer water exchange which results in the least net transport among the three channels;all the transports through the three channels have an intra-annual variation with a period of half a year.At 1000-m depth,the entire Andaman Sea is occupied by a cyclonic circulation in January and July while by an anticyclonic one in April and October.The semiannual cycle found in both the deep circulation and water mass exchange is likely associated with the downwelling eastward-propagating Kelvin waves induced by the semiannual westerly component in the equatorial Indian Ocean during intermonsoon seasons.

Estimation of the surface heat budget over the South China Sea

In situ data are employed to evaluate five gridded surface heat flux datasets over the South China Sea. The surface heat budgets for these gridded datasets are computed. The authors find that the gridded datasets tend to underestimate both the solar radiation and sensible heat flux in general, while the latent heat fluxes are close to the observations, except for that of NOC unadjusted version 2 （NOC2）, which overestimates both the latent and sensible heat flux. The underestimation of solar radiation also indicates that the gridded datasets might underestimate the surface heat budget. The net surface heat flux of the five gridded datasets is always positive. However, the net surface heat flux of COADS, NOC1, NOC2, and OAFlux, in the range 48-56 W m-2, is around twofold more than that of NOC1 a （22 W m-2）. The budget for NOC2 is smaller than that of NOC1 and OAFlux, by approximately 49 W m-2, because of the large release of latent heat flux. Based on the comparison, the authors believe that the net surface heat flux over the South China Sea should be higher than 56 W m-2, which is significantly larger （around 10%-20%） than previous estimations.

Effects of monsoon onset vortex on heat budget in the mixed layer of the Bay of Bengal

We investigated the effects of monsoon onset vortex(MOV)on the mixed layer heat budget in the Bay of Bengal(BOB)in spring 2003 using the reanalysis datasets.The results suggest that the solar radiation flux penetrating the mixed layer and the existence of barrier layer are both able to modulate the effects of MOV on the evolution of sea surface temperature(SST)in the BOB.Prior to the formation of BOB MOV,the local SST raised quickly due to mass of solar radiation reaching the sea surface under the clear-sky condition.Meanwhile,since the mixed layer was shallow before the onset of the Asian summer monsoon(ASM),some solar radiation flux could penetrate to directly heat the deeper water,which partly offset the warming effect of shortwave radiation.On the other hand,the in-situ SST started to cool due to the upwelling of cold water when the MOV generated over the BOB,along with the rapidly increased surface wind speed and its resultant deeper mixed layer.As the MOV developed and moved northward,the SST tended to decrease remarkably because of the strong upward surface latent heat flux over the BOB ascribed to the wind-evaporation mechanism.However,the MOV-related precipitation brought more fresh water into the upper ocean to produce a thicker barrier layer,whose thermal barrier effect damped the cooling effect of entrainment upwelling on the decrease tendency of the BOB SST.In other words,the thermal barrier effect could slow down the decreasing trend of the BOB SST even after the onset of ASM,which facilitated the further enhancement of the MOV.

Heat Budget of the South-Central Equatorial Pacific in CMIP3 Models

ABSTRACT Using data from 17 coupled models and nine sets of corresponding Atmospheric Model Intercomparison Project （AMIP） results, we investigated annual and seasonal variation biases in the upper 50 m of the south-central equatorial Pacific, with a focus on the double-ITCZ bias, and examined the causes for the amplitude biases by using heat budget analysis. The results showed that, in the research region, most of the models simulate SSTs that are higher than or similar to observed. The simulated seasonal phase is close to that observed, but the amplitudes of more than half of the model results are larger than or equal to observations. Heat budget analysis demonstrated that strong shortwave radiation in individual atmospheric models is the main factor that leads to high SST values and that weak southward cold advection is an important mechanism for maintaining a high SST. For seasonal circulation, large surface shortwave radiation amplitudes cause large SST amplitudes.

Evaluation of the surface heat budget over the tropical Indian Ocean in two versions of FGOALS

Changes of the net ocean surface heat flux（Q_（net）） into the tropical Indian Ocean（TIO） may be an indicator of the climate changes in the Asia and Indian–Pacific Ocean regions with the steadily warming trend in the TIO since the 1950 s. Using two observational ocean surface flux products,this letter evaluates the historical simulations of Q_（net） over the TIO during 1984–2005 in two versions of FGOALS, from CMIP5. The results show that both models present a basin-wide underestimation of net surface heat flux, possibly resulting from the positive latent heat flux biases extending over almost the entire TIO basin. Both models share an Indian Ocean dipole-like bias in the net surface heat flux, consistent with precipitation, SST, and subsurface ocean temperature biases, which can be traced to errors in the South Asian summer monsoon. Area-averaged annual time series analyses of the surface heat budget imply that the FGOALS-s2 bias lies more in radiative imbalance, illustrating the need to improve cloud simulation; while the FGOALS-g2 bias presents ocean surface turbulence flux as the key process, requiring improvement in the simulation of oceanic processes. Neither FGOALS-g2 nor FGOALS-s2 can capture the decreasing tendency of Q_（net） well. All observed and simulated datasets imply surface latent heat flux as the primary contributing component, indicating the simulation biases of models may derive mainly from the biases in simulating latent heat flux. A small latent heat flux increase in models can be considered to be slowed by relaxed wind, increased stability, and surface relative humidity.

SEASONAL HEAT BUDGET IN THE TROPICAL WESTERN PACIFIC OCEAN IN A GLOBAL GCM I. GENERAL DESCRIPTION*

This paper describes the large scale aspects of the seasonal surface heat budget and discusses its main forcing mechanisms in the tropical Western Pacific Ocean. The high - resolution general circulation model (Semtner & Chervin, 1992) used in this study reproduced well the observed upper-layer thermal structure and circulation. It is shown that at least on the average of the study region (20 °N -20°N, west boundary-160 °E) the semiannual variation is a dominant signal for all heat budget components and is presumably due to the sun's passing across the equator twice a year; but that the components have substantial differences in amplitude. The local Ekman divergence in the region does not change significantly through the year. As a result, the change in surface heat content is roughly half due to ocean ?atmosphere heat exchange and half due to heat advection by remotely forced verti-cal motion. Horizontal currents do not play a significant role directly by advection, because the wat-er which enters the region is not very much different in temperature from the water which leaves it.

Analysis of Heat Budget during the Intensification of Atlantic Tropical Cyclone

Based on air-sea observations and reanalysis data,the numerical simulation and diagnostic analysis of typical Atlantic TC cases during 2010-2015 were carried out,and the influence of thermodynamic factors in air-sea exchange and atmospheric environment field on TC intensity was quantitatively calculated.TC was considered as a cylinder with a minimum pressure as the center and a radius of 300 km extending from sea level to 100 hPa,and the input and output of heat at each boundary of TC were quantitatively calculated.In order to understand the heat contribution of Atlantic TC during its development,the heat input at each boundary of 18 Atlantic TC cases was analyzed to study the main heat sources promoting TC strengthening.The results show that the heat directly from the atmosphere was the main source of heat during TC development.Due to the errors in the selection and calculation of data,one of Atlantic TC cases was selected for simulation verification at last,and the simulation results reveal that the simulated TC was in good agreement with the actual observed TC.

Surface Heat Budget and Solar Radiation Allocation at a Melt Pond During Summer in the Central Arctic Ocean

The heat budget of a melt pond surface and the solar radiation allocation at the melt pond are studied using the 2010 Chinese National Arctic Research Expedition data collected in the central Arctic. Temperature at a melt pond surface is proportional to the air temperature above it. However, the linear relationship between the two varies, depending on whether the air temperature is higher or lower than 0℃. The melt pond surface temperature is strongly influenced by the air temperature when the latter is lower than 0℃. Both net longwave radiation and turbulent heat flux can cause energy loss in a melt pond, but the loss by the latter is larger than that by the former. The turbulent heat flux is more than twice the net longwave radiation when the air temperature is lower than 0℃. More than 50% of the radiation energy entering the pond surface is absorbed by pond water. Very thin ice sheet on the pond surface(black ice) appears when the air temperature is lower than 0℃; on the other hand, only a small percentage(5.5%) of net longwave in the solar radiation is absorbed by such a thin ice sheet.

Study of the Oceanic Heat Budget Components over the Arabian Sea during the Formation and Evolution of Super Cyclone, Gonu

Oceans play a vital role in the global climate system. They absorb the incoming solar energy and redistribute the energy through horizontal and vertical transports. In this context it is important to investigate the variation of heat budget components during the formation of a low-pressure system. In 2007, the monsoon onset was on 28th May. A well-marked low-pressure area was formed in the eastern Arabian Sea after the onset and it further developed into a cyclone. We have analysed the heat budget components during different stages of the cyclone. The data used for the computation of heat budget components is Objectively Analyzed air-sea flux data obtained from WHOI (Woods Hole Oceanographic Institution) project. Its horizontal resolution is 1° × 1°. Over the low-pressure area, the latent heat flux was 180 Wm﹣2. It increased to a maximum value of 210 Wm﹣2 on 1st June 2007, on which the system was intensified into a cyclone (Gonu) with latent heat flux values ranging from 200 to 250 Wm﹣2. It sharply decreased after the passage of cyclone. The high value of latent heat flux is attributed to the latent heat release due to the cyclone by the formation of clouds. Long wave radiation flux is decreased sharply from 100 Wm﹣2 to 30 Wm﹣2 when the low-pressure system intensified into a cyclone. The decrease in long wave radiation flux is due to the presence of clouds. Net heat flux also decreases sharply to ﹣200 Wm﹣2 on 1st June 2007. After the passage, the flux value increased to normal value (150 Wm﹣2) within one day. A sharp increase in the sensible heat flux value (20 Wm﹣2) is observed on 1st June 2007 and it decreased thereafter. Short wave radiation flux decreased from 300 Wm﹣2 to 90 Wm﹣2 during the intensification on 1st June 2007. Over this region, short wave radiation flux sharply increased to higher value soon after the passage of the cyclone.

SEASONAL HEAT BUDGET IN THE TROPICAL WESTERN PACIFIC OCEAN IN A GLOBAL GCM Ⅱ. IN FIVE SUBREGIONS

The general features of the seasonal suuface heat budget in the tropical western Pacific Ocean,20°S-20°N, western boundary-160°E, were documented by Qu (1995) using a high-resolution generalcirculation model (GCM, Semtner & Chervin,1992) ard existing observations.Close inspection of thesmaller areas, with the whole region further partitioned into six parts, showed different mechanisms balancethe seasonal surface heat budget in different parts of the region The results of study on five subregionsare detailed in this article. In the equatorial (3°S - 3°N) aed North Equatorial Countercurrent(3°N-9°N) region, the surface the flux the does not change significantly throughout the year, so the surface heat content is determined largely by vertical motion near the equator and roughly helf due to horizontal and halfdue to vertical circulation in the region of the North Equatorial Countercurrent(NECC). In the othersubregions (9°N-20°N, 20°S -11°S aed 11°S -3°S ), however, in addition to ocean

Borehole Heat Budget Calculator: A New Tool for the Quick Exploitation of High-Resolution Temperature Profiles by Hydrogeologists

Distributed temperature sensing is known to provide sharp signals which are very efficient for mapping hydraulically active fractures in wellbores. High-resolution temperature sensing has specifically demonstrated its capacity to characterize very low flows in wellbores. But as sharp as they can be, temperature profiles are often difficult to decipher. The aim of the present work is to provide and to test the “Borehole Heat Budget Calculator” (BHB Calculator), which is implemented as a fast and easy to use tool for the quantitative analysis of depth-temperature profiles. The Calculator is suitable for most pumping and draining configurations, as the heat budget is generalized for modelling multidirectional flow systems within the same wellbore. The formatted worksheet allows the quick exploitation of temperature logs, and is applicable for the characterization of distributed fractures in long screened wellbores. Objectives of the heat modelling are to enhance the readability of complex depth-temperature data, as well as to quantify distribution of inflow intensities and temperatures with depth. The use of heat budget helps to clearly visualize how heat conduction and heat advection contributions are distributed along wellbores profiles. Calculations of inflow temperatures and their evolution through pumping duration is a prerequisite to infer about the nature of aquifer properties (i.e. conduits, distributed or discrete fractures, porous media), as well as to give insight information about the mapping of effective flow paths draining the aquifer. The efficiency and limitations of the BHB Calculator are being tested through high-resolution temperature logging, along with complementary flowmetering and televiewing logging in fractured aquifers located in the St-Lawrence Lowlands, Quebec, Canada.

Heat and Moisture Budgets during the Period of HUBEX/GAME in the Summer of 1998

By using the high-resolution GAME reanalysis data, the heat and moisture budgets during the period of HUBEX/GAME in the summer of 1998 are calculated for exploring the thermodynamic features of Meiyu over the Changjiang-Huaihe (CH) valley. During the CH Meiyu period, an intensive vertically-integrated heat source and moisture sink are predominant over the heavy rainfall area of the CH valley, accompanied by strong upward motion at 500 hPa. The heat and moisture budgets show that the main diabatic heating component is condensation latent heat released by rainfall. As residual terms, the evaporation and sensible heating are relatively small. Based on the vertical distribution of the heat source and moisture sink, the nature of the rainfall is mixed, in which the convective rainfall is dominant with a considerable percentage of continuous stratiform rainfall. There are similar time evolutions of the main physical parameters (〈Q 1〉, 〈Q 2〉, and vertical motion ω at 500 hPa). The time variations of 〈Q 1〉 and 〈Q 2〉 are in phase with those of −ω 500, and have their main peaks within the CH Meiyu period. This shows the influence of the heat source on the dynamic structure of the atmosphere. The wavelet analyses of those time series display similar multiple timescale characteristics. During the CH Meiyu period, both the synoptic scale(∼6 days) and mesoscale (∼2 days and ∼12 hours) increase obviously and cause heavy rainfall as well as the appearances of the maxima of the main physical parameters. Among them, the mesoscale systems are the main factors.

Estimation of ground heat flux and its impact on the surface energy budget for a semi-arid grassland

Three approaches, i.e., the harmonic analysis （HA） technique, the thermal diffusion equation and correction （TDEC） method, and the calorimetric method used to estimate ground heat flux, are evaluated by using observations from the Semi-Arid Climate and Environment Observatory of Lanzhou University （SACOL） in July, 2008. The calorimetric method, which involves soil heat flux measurement with an HFP01SC self-calibrating heat flux plate buried at a depth of 5 cm and heat storage in the soil between the plate and the surface, is here called the ITHP approach. The results show good linear relationships between the soil heat fluxes measured with the HFP01SC heat flux plate and those calculated with the HA technique and the TDEC method, respectively, at a depth of 5 cm. The soil heat fluxes calculated with the latter two methods well follow the phase measured with the HFP01SC heat flux plate. The magnitudes of the soil heat flux calculated with the HA technique and the TDEC method are close to each other, and they are about 2 percent and 6 percent larger than the measured soil heat flux, respectively, which mainly occur during the nighttime. Moreover, the ground heat fluxes calculated with the TDEC method and the HA technique are highly correlated with each other （R2= 0.97）, and their difference is only about 1 percent. The TDEC-calculated ground heat flux also has a good linear relationship with the ITttP-calculated ground heat flux （R2 = 0.99）, but their difference is larger （about 9 percent）. Furthermore, compared to the HFP01SC direct measurements at a depth of 5 cm, the ground heat flux calculated with the HA technique, the TDEC method, and the ITHP approach can improve the surface energy budget closure by about 6 percent, 7 percent, and 6 percent at SACOL site, respectively. Therefore, the contribution of ground heat flux to the surface energy budget is very important for the semi-arid grassland over the Loess Plateau in China. Using turbulent heat fluxes with common corrections, soil heat storage between the surface and the heat flux plate can improve the surface energy budget closure by about 6 to 7 percent, resulting in a closure of 82 to 83 percent at the SACOL site.

高温不稳定多年冻土区保温护道路基热状况监测分析

基于高温不稳定多年冻土区保温护道路段地温监测数据,分析了天然场地及左右路肩下地温、年平均地层温度、热收支及多年冻土上限变化等,探讨了气候变暖及阴阳坡效应下路基不同位置不同深度热状态变化特性及其与天然场地的差异。结果表明:左右路肩阴阳坡效应显著,左路肩下多年冻土最大融化深度为右路肩的2倍,最大融化深度降低速率为右路肩的5倍,且左路肩下多年冻土上限下降速率为右路肩的1.5倍;右路肩处在阴坡且保温护道可能对其多年冻土维持稳定起到了一定积极作用,抬升了其人为冻土上限并减缓了上限下降速率。不同位置年平均地层温度均呈上升趋势,且增长速率随深度逐渐降低,然而左路肩的路基与天然场地交界面附近温度增长速率大于2.5 m深度处,表明此特殊位置土层在多因素作用下可能受到更强的热扰动影响。一般情况下,冻土吸热放热量均随深度降低逐渐减少,但多年冻土上限处在0℃等温线的特殊位置,可能出现吸热量突然增大的现象;多年冻土上限处由于深度较深,热收支增长速率已不受阴阳坡效应影响,该断面左路肩多年冻土上限处年平均热收支为右路肩的2.92倍,但其热收支增长速率几乎相等。

青藏高原东南缘攀西一次突发性山地暴雨成因分析

利用地面气象站、LMF1.0三维雷电监测系统、CMPAS多源融合降水、FY-4A卫星云顶亮温等综合观测数据和ERA5再分析资料,对2023年8月20—21日发生在青藏高原东南缘攀西地区的一次突发性山地暴雨的动热力及水汽特征进行诊断分析。结果表明:(1)本次暴雨过程发生在弱天气尺度背景下,500 hPa和700 hPa切变线是主要影响系统,为中尺度对流系统(MCS)发生提供了有利的动力条件,且MCS后向发展较为明显;(2)在中低层高能高湿和强对流不稳定层结条件下,持续的辐合上升运动有利于对流性强降水的发展和维持,局地经向环流的上升支加剧了大暴雨区水汽凝结潜热释放,致使极端短时强降水出现;(3)青藏高原东南缘大地形对云贵高原偏东、偏南气流的阻挡作用造成中低层水汽大量堆积,边界层水汽强辐合,以及中高层较强的垂直水汽通量对局地持续性强降水的发生和维持起到非常关键的作用,强降水区大部分水汽输送集中在边界层至低层,并以云贵高原偏东转偏南路径为主,水汽净收支的演变对降水发展具有一定的指示作用。

2020—2022年与2010—2012年两个“二次变冷”La Nina事件的特征与机制对比

厄尔尼诺-南方涛动(EI Nino-Southern Oscillation, ENSO)是由热带太平洋海-气相互作用产生的显著年际变率,其负位相的拉尼娜(La Nina)事件对中国极端天气有巨大影响。本文利用海洋、大气观测、再分析资料集,对比研究了2010—2012年和2020—2022年两个“二次变冷”La Nina事件演变过程中各阶段的物理过程和机制。结果表明,2010—2012年La Nina事件第一个峰值强于2020—2022年La Nina事件,但第二个峰值较后者弱,且其海表温度异常(Sea surface temperature anomaly, SSTA)偏西,该SSTA的强度和位置特征可从次表层海温异常得到进一步验证。另外,赤道太平洋的东风异常也在2010年夏秋季明显比2020年偏强、偏西;而偏东且增强的东风异常使2020—2022年La Nina事件的第二个冬季峰值强于2010—2012事件。通过海洋混合层热收支诊断分析,纬向平流反馈(海表面热通量异常)是引起La Nina事件发展(衰减)的主要因素。在发展阶段,东风异常引起的纬向海流异常将冷水向西输运,成为赤道中-东太平洋冷SSTA发展的主导因子,垂直方向温跃层反馈过程的贡献也不可忽略。本研究以近十年来的两个“二次变冷”La Nina事件为例进行定性和定量的对比分析,明晰了二者生命演变史过程中的物理机制,为探究La Nina事件生消机理和ENSO不对称性在全球变暖下的可能变化提供了一定的参考。